Merge branch 'nd/commit-util-to-slab'
authorJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:35 +0000 (13:22 -0700)
committerJunio C Hamano <gitster@pobox.com>
Mon, 25 Jun 2018 20:22:35 +0000 (13:22 -0700)
The in-core "commit" object had an all-purpose "void *util" field,
which was tricky to use especially in library-ish part of the
code. All of the existing uses of the field has been migrated to a
more dedicated "commit-slab" mechanism and the field is eliminated.

* nd/commit-util-to-slab:
commit.h: delete 'util' field in struct commit
merge: use commit-slab in merge remote desc instead of commit->util
log: use commit-slab in prepare_bases() instead of commit->util
show-branch: note about its object flags usage
show-branch: use commit-slab for commit-name instead of commit->util
name-rev: use commit-slab for rev-name instead of commit->util
bisect.c: use commit-slab for commit weight instead of commit->util
revision.c: use commit-slab for show_source
sequencer.c: use commit-slab to associate todo items to commits
sequencer.c: use commit-slab to mark seen commits
shallow.c: use commit-slab for commit depth instead of commit->util
describe: use commit-slab for commit names instead of commit->util
blame: use commit-slab for blame suspects instead of commit->util
commit-slab: support shared commit-slab
commit-slab.h: code split

14 files changed:
1  2 
blame.c
builtin/blame.c
builtin/describe.c
builtin/fast-export.c
builtin/log.c
builtin/merge.c
commit.c
commit.h
log-tree.c
merge-recursive.c
object.h
revision.c
sequencer.c
shallow.c
diff --combined blame.c
index 14d0e0b5751c2abaad16dac81a71436ca29ddde4,18e8bd996a4612ce01a0c18e743078af6bbc0dc4..ba1b33c7f4e92c432d4cbdcb43b8d061e436f027
+++ b/blame.c
@@@ -6,6 -6,24 +6,24 @@@
  #include "diffcore.h"
  #include "tag.h"
  #include "blame.h"
+ #include "commit-slab.h"
+ define_commit_slab(blame_suspects, struct blame_origin *);
+ static struct blame_suspects blame_suspects;
+ struct blame_origin *get_blame_suspects(struct commit *commit)
+ {
+       struct blame_origin **result;
+       result = blame_suspects_peek(&blame_suspects, commit);
+       return result ? *result : NULL;
+ }
+ static void set_blame_suspects(struct commit *commit, struct blame_origin *origin)
+ {
+       *blame_suspects_at(&blame_suspects, commit) = origin;
+ }
  
  void blame_origin_decref(struct blame_origin *o)
  {
                        blame_origin_decref(o->previous);
                free(o->file.ptr);
                /* Should be present exactly once in commit chain */
-               for (p = o->commit->util; p; l = p, p = p->next) {
+               for (p = get_blame_suspects(o->commit); p; l = p, p = p->next) {
                        if (p == o) {
                                if (l)
                                        l->next = p->next;
                                else
-                                       o->commit->util = p->next;
+                                       set_blame_suspects(o->commit, p->next);
                                free(o);
                                return;
                        }
@@@ -41,8 -59,8 +59,8 @@@ static struct blame_origin *make_origin
        FLEX_ALLOC_STR(o, path, path);
        o->commit = commit;
        o->refcnt = 1;
-       o->next = commit->util;
-       commit->util = o;
+       o->next = get_blame_suspects(commit);
+       set_blame_suspects(commit, o);
        return o;
  }
  
@@@ -54,13 -72,13 +72,13 @@@ static struct blame_origin *get_origin(
  {
        struct blame_origin *o, *l;
  
-       for (o = commit->util, l = NULL; o; l = o, o = o->next) {
+       for (o = get_blame_suspects(commit), l = NULL; o; l = o, o = o->next) {
                if (!strcmp(o->path, path)) {
                        /* bump to front */
                        if (l) {
                                l->next = o->next;
-                               o->next = commit->util;
-                               commit->util = o;
+                               o->next = get_blame_suspects(commit);
+                               set_blame_suspects(commit, o);
                        }
                        return blame_origin_incref(o);
                }
@@@ -81,7 -99,7 +99,7 @@@ static void verify_working_tree_path(st
                unsigned mode;
  
                if (!get_tree_entry(commit_oid, path, &blob_oid, &mode) &&
 -                  oid_object_info(&blob_oid, NULL) == OBJ_BLOB)
 +                  oid_object_info(the_repository, &blob_oid, NULL) == OBJ_BLOB)
                        return;
        }
  
@@@ -478,7 -496,7 +496,7 @@@ static void queue_blames(struct blame_s
                porigin->suspects = blame_merge(porigin->suspects, sorted);
        else {
                struct blame_origin *o;
-               for (o = porigin->commit->util; o; o = o->next) {
+               for (o = get_blame_suspects(porigin->commit); o; o = o->next) {
                        if (o->suspects) {
                                porigin->suspects = sorted;
                                return;
@@@ -504,7 -522,7 +522,7 @@@ static int fill_blob_sha1_and_mode(stru
                return 0;
        if (get_tree_entry(&origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode))
                goto error_out;
 -      if (oid_object_info(&origin->blob_oid, NULL) != OBJ_BLOB)
 +      if (oid_object_info(the_repository, &origin->blob_oid, NULL) != OBJ_BLOB)
                goto error_out;
        return 0;
   error_out:
@@@ -525,7 -543,7 +543,7 @@@ static struct blame_origin *find_origin
        const char *paths[2];
  
        /* First check any existing origins */
-       for (porigin = parent->util; porigin; porigin = porigin->next)
+       for (porigin = get_blame_suspects(parent); porigin; porigin = porigin->next)
                if (!strcmp(porigin->path, origin->path)) {
                        /*
                         * The same path between origin and its parent
        diff_setup_done(&diff_opts);
  
        if (is_null_oid(&origin->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &origin->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(origin->commit),
                              "", &diff_opts);
        diffcore_std(&diff_opts);
  
@@@ -620,10 -638,10 +638,10 @@@ static struct blame_origin *find_rename
        diff_setup_done(&diff_opts);
  
        if (is_null_oid(&origin->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &origin->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(origin->commit),
                              "", &diff_opts);
        diffcore_std(&diff_opts);
  
@@@ -1255,10 -1273,10 +1273,10 @@@ static void find_copy_in_parent(struct 
                diff_opts.flags.find_copies_harder = 1;
  
        if (is_null_oid(&target->commit->object.oid))
 -              do_diff_cache(&parent->tree->object.oid, &diff_opts);
 +              do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
        else
 -              diff_tree_oid(&parent->tree->object.oid,
 -                            &target->commit->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
 +                            get_commit_tree_oid(target->commit),
                              "", &diff_opts);
  
        if (!diff_opts.flags.find_copies_harder)
@@@ -1550,7 -1568,7 +1568,7 @@@ void assign_blame(struct blame_scoreboa
  
        while (commit) {
                struct blame_entry *ent;
-               struct blame_origin *suspect = commit->util;
+               struct blame_origin *suspect = get_blame_suspects(commit);
  
                /* find one suspect to break down */
                while (suspect && !suspect->suspects)
@@@ -1752,6 -1770,8 +1770,8 @@@ void setup_scoreboard(struct blame_scor
        struct commit *final_commit = NULL;
        enum object_type type;
  
+       init_blame_suspects(&blame_suspects);
        if (sb->reverse && sb->contents_from)
                die(_("--contents and --reverse do not blend well."));
  
                        l->item = c;
                        if (add_decoration(&sb->revs->children,
                                           &c->parents->item->object, l))
 -                              die("BUG: not unique item in first-parent chain");
 +                              BUG("not unique item in first-parent chain");
                        c = c->parents->item;
                }
  
        }
  
        if (is_null_oid(&sb->final->object.oid)) {
-               o = sb->final->util;
+               o = get_blame_suspects(sb->final);
                sb->final_buf = xmemdupz(o->file.ptr, o->file.size);
                sb->final_buf_size = o->file.size;
        }
diff --combined builtin/blame.c
index 3295718841aab1051ee8bdde0b1fc0aa26ae5f00,969572810d54b22118dcd2becf4fba9381d7c2e2..5a0388aaef580e8d3592e1b5b767618fe638ca0b
@@@ -7,7 -7,6 +7,7 @@@
  
  #include "cache.h"
  #include "config.h"
 +#include "color.h"
  #include "builtin.h"
  #include "commit.h"
  #include "diff.h"
@@@ -24,7 -23,6 +24,7 @@@
  #include "dir.h"
  #include "progress.h"
  #include "blame.h"
 +#include "string-list.h"
  
  static char blame_usage[] = N_("git blame [<options>] [<rev-opts>] [<rev>] [--] <file>");
  
@@@ -48,8 -46,6 +48,8 @@@ static int xdl_opts
  static int abbrev = -1;
  static int no_whole_file_rename;
  static int show_progress;
 +static char repeated_meta_color[COLOR_MAXLEN];
 +static int coloring_mode;
  
  static struct date_mode blame_date_mode = { DATE_ISO8601 };
  static size_t blame_date_width;
@@@ -320,12 -316,10 +320,12 @@@ static const char *format_time(timestam
  #define OUTPUT_PORCELAIN      010
  #define OUTPUT_SHOW_NAME      020
  #define OUTPUT_SHOW_NUMBER    040
 -#define OUTPUT_SHOW_SCORE      0100
 -#define OUTPUT_NO_AUTHOR       0200
 +#define OUTPUT_SHOW_SCORE     0100
 +#define OUTPUT_NO_AUTHOR      0200
  #define OUTPUT_SHOW_EMAIL     0400
 -#define OUTPUT_LINE_PORCELAIN 01000
 +#define OUTPUT_LINE_PORCELAIN 01000
 +#define OUTPUT_COLOR_LINE     02000
 +#define OUTPUT_SHOW_AGE_WITH_COLOR    04000
  
  static void emit_porcelain_details(struct blame_origin *suspect, int repeat)
  {
@@@ -373,64 -367,6 +373,64 @@@ static void emit_porcelain(struct blame
                putchar('\n');
  }
  
 +static struct color_field {
 +      timestamp_t hop;
 +      char col[COLOR_MAXLEN];
 +} *colorfield;
 +static int colorfield_nr, colorfield_alloc;
 +
 +static void parse_color_fields(const char *s)
 +{
 +      struct string_list l = STRING_LIST_INIT_DUP;
 +      struct string_list_item *item;
 +      enum { EXPECT_DATE, EXPECT_COLOR } next = EXPECT_COLOR;
 +
 +      colorfield_nr = 0;
 +
 +      /* Ideally this would be stripped and split at the same time? */
 +      string_list_split(&l, s, ',', -1);
 +      ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
 +
 +      for_each_string_list_item(item, &l) {
 +              switch (next) {
 +              case EXPECT_DATE:
 +                      colorfield[colorfield_nr].hop = approxidate(item->string);
 +                      next = EXPECT_COLOR;
 +                      colorfield_nr++;
 +                      ALLOC_GROW(colorfield, colorfield_nr + 1, colorfield_alloc);
 +                      break;
 +              case EXPECT_COLOR:
 +                      if (color_parse(item->string, colorfield[colorfield_nr].col))
 +                              die(_("expecting a color: %s"), item->string);
 +                      next = EXPECT_DATE;
 +                      break;
 +              }
 +      }
 +
 +      if (next == EXPECT_COLOR)
 +              die (_("must end with a color"));
 +
 +      colorfield[colorfield_nr].hop = TIME_MAX;
 +      string_list_clear(&l, 0);
 +}
 +
 +static void setup_default_color_by_age(void)
 +{
 +      parse_color_fields("blue,12 month ago,white,1 month ago,red");
 +}
 +
 +static void determine_line_heat(struct blame_entry *ent, const char **dest_color)
 +{
 +      int i = 0;
 +      struct commit_info ci;
 +      get_commit_info(ent->suspect->commit, &ci, 1);
 +
 +      while (i < colorfield_nr && ci.author_time > colorfield[i].hop)
 +              i++;
 +
 +      *dest_color = colorfield[i].col;
 +}
 +
  static void emit_other(struct blame_scoreboard *sb, struct blame_entry *ent, int opt)
  {
        int cnt;
        struct commit_info ci;
        char hex[GIT_MAX_HEXSZ + 1];
        int show_raw_time = !!(opt & OUTPUT_RAW_TIMESTAMP);
 +      const char *default_color = NULL, *color = NULL, *reset = NULL;
  
        get_commit_info(suspect->commit, &ci, 1);
        oid_to_hex_r(hex, &suspect->commit->object.oid);
  
        cp = blame_nth_line(sb, ent->lno);
 +
 +      if (opt & OUTPUT_SHOW_AGE_WITH_COLOR) {
 +              determine_line_heat(ent, &default_color);
 +              color = default_color;
 +              reset = GIT_COLOR_RESET;
 +      }
 +
        for (cnt = 0; cnt < ent->num_lines; cnt++) {
                char ch;
                int length = (opt & OUTPUT_LONG_OBJECT_NAME) ? GIT_SHA1_HEXSZ : abbrev;
  
 +              if (opt & OUTPUT_COLOR_LINE) {
 +                      if (cnt > 0) {
 +                              color = repeated_meta_color;
 +                              reset = GIT_COLOR_RESET;
 +                      } else  {
 +                              color = default_color ? default_color : NULL;
 +                              reset = default_color ? GIT_COLOR_RESET : NULL;
 +                      }
 +              }
 +              if (color)
 +                      fputs(color, stdout);
 +
                if (suspect->commit->object.flags & UNINTERESTING) {
                        if (blank_boundary)
                                memset(hex, ' ', length);
                        printf(" %*d) ",
                               max_digits, ent->lno + 1 + cnt);
                }
 +              if (reset)
 +                      fputs(reset, stdout);
                do {
                        ch = *cp++;
                        putchar(ch);
@@@ -543,7 -457,7 +543,7 @@@ static void output(struct blame_scorebo
                        struct commit *commit = ent->suspect->commit;
                        if (commit->object.flags & MORE_THAN_ONE_PATH)
                                continue;
-                       for (suspect = commit->util; suspect; suspect = suspect->next) {
+                       for (suspect = get_blame_suspects(commit); suspect; suspect = suspect->next) {
                                if (suspect->guilty && count++) {
                                        commit->object.flags |= MORE_THAN_ONE_PATH;
                                        break;
@@@ -693,30 -607,6 +693,30 @@@ static int git_blame_config(const char 
                parse_date_format(value, &blame_date_mode);
                return 0;
        }
 +      if (!strcmp(var, "color.blame.repeatedlines")) {
 +              if (color_parse_mem(value, strlen(value), repeated_meta_color))
 +                      warning(_("invalid color '%s' in color.blame.repeatedLines"),
 +                              value);
 +              return 0;
 +      }
 +      if (!strcmp(var, "color.blame.highlightrecent")) {
 +              parse_color_fields(value);
 +              return 0;
 +      }
 +
 +      if (!strcmp(var, "blame.coloring")) {
 +              if (!strcmp(value, "repeatedLines")) {
 +                      coloring_mode |= OUTPUT_COLOR_LINE;
 +              } else if (!strcmp(value, "highlightRecent")) {
 +                      coloring_mode |= OUTPUT_SHOW_AGE_WITH_COLOR;
 +              } else if (!strcmp(value, "none")) {
 +                      coloring_mode &= ~(OUTPUT_COLOR_LINE |
 +                                          OUTPUT_SHOW_AGE_WITH_COLOR);
 +              } else {
 +                      warning(_("invalid value for blame.coloring"));
 +                      return 0;
 +              }
 +      }
  
        if (git_diff_heuristic_config(var, value, cb) < 0)
                return -1;
@@@ -765,7 -655,7 +765,7 @@@ static int is_a_rev(const char *name
  
        if (get_oid(name, &oid))
                return 0;
 -      return OBJ_NONE < oid_object_info(&oid, NULL);
 +      return OBJ_NONE < oid_object_info(the_repository, &oid, NULL);
  }
  
  int cmd_blame(int argc, const char **argv, const char *prefix)
                OPT_BIT('s', NULL, &output_option, N_("Suppress author name and timestamp (Default: off)"), OUTPUT_NO_AUTHOR),
                OPT_BIT('e', "show-email", &output_option, N_("Show author email instead of name (Default: off)"), OUTPUT_SHOW_EMAIL),
                OPT_BIT('w', NULL, &xdl_opts, N_("Ignore whitespace differences"), XDF_IGNORE_WHITESPACE),
 +              OPT_BIT(0, "color-lines", &output_option, N_("color redundant metadata from previous line differently"), OUTPUT_COLOR_LINE),
 +              OPT_BIT(0, "color-by-age", &output_option, N_("color lines by age"), OUTPUT_SHOW_AGE_WITH_COLOR),
  
                /*
                 * The following two options are parsed by parse_revision_opt()
        unsigned int range_i;
        long anchor;
  
 +      setup_default_color_by_age();
        git_config(git_blame_config, &output_option);
        init_revisions(&revs, NULL);
        revs.date_mode = blame_date_mode;
@@@ -1062,17 -949,8 +1062,17 @@@ parse_done
  
        blame_coalesce(&sb);
  
 -      if (!(output_option & OUTPUT_PORCELAIN))
 +      if (!(output_option & (OUTPUT_COLOR_LINE | OUTPUT_SHOW_AGE_WITH_COLOR)))
 +              output_option |= coloring_mode;
 +
 +      if (!(output_option & OUTPUT_PORCELAIN)) {
                find_alignment(&sb, &output_option);
 +              if (!*repeated_meta_color &&
 +                  (output_option & OUTPUT_COLOR_LINE))
 +                      strcpy(repeated_meta_color, GIT_COLOR_CYAN);
 +      }
 +      if (output_option & OUTPUT_ANNOTATE_COMPAT)
 +              output_option &= ~(OUTPUT_COLOR_LINE | OUTPUT_SHOW_AGE_WITH_COLOR);
  
        output(&sb, output_option);
        free((void *)sb.final_buf);
diff --combined builtin/describe.c
index cf1ae77d7c705cdfb34bdb5403bad8db4148eccf,1b6ca425537870bf874a0cd8e910df5c592afa62..bec2513b66cea8e5b3c7bae5de2c2e0bd31aecc9
  #include "run-command.h"
  #include "revision.h"
  #include "list-objects.h"
+ #include "commit-slab.h"
  
  #define MAX_TAGS      (FLAG_BITS - 1)
  
+ define_commit_slab(commit_names, struct commit_name *);
  static const char * const describe_usage[] = {
        N_("git describe [<options>] [<commit-ish>...]"),
        N_("git describe [<options>] --dirty"),
@@@ -37,6 -40,7 +40,7 @@@ static struct string_list patterns = ST
  static struct string_list exclude_patterns = STRING_LIST_INIT_NODUP;
  static int always;
  static const char *suffix, *dirty, *broken;
+ static struct commit_names commit_names;
  
  /* diff-index command arguments to check if working tree is dirty. */
  static const char *diff_index_args[] = {
@@@ -321,11 -325,14 +325,14 @@@ static void describe_commit(struct obje
        if (!have_util) {
                struct hashmap_iter iter;
                struct commit *c;
-               struct commit_name *n = hashmap_iter_first(&names, &iter);
+               struct commit_name *n;
+               init_commit_names(&commit_names);
+               n = hashmap_iter_first(&names, &iter);
                for (; n; n = hashmap_iter_next(&iter)) {
                        c = lookup_commit_reference_gently(&n->peeled, 1);
                        if (c)
-                               c->util = n;
+                               *commit_names_at(&commit_names, c) = n;
                }
                have_util = 1;
        }
        while (list) {
                struct commit *c = pop_commit(&list);
                struct commit_list *parents = c->parents;
+               struct commit_name **slot;
                seen_commits++;
-               n = c->util;
+               slot = commit_names_peek(&commit_names, c);
+               n = slot ? *slot : NULL;
                if (n) {
                        if (!tags && !all && n->prio < 2) {
                                unannotated_cnt++;
@@@ -502,7 -512,7 +512,7 @@@ static void describe(const char *arg, i
  
        if (cmit)
                describe_commit(&oid, &sb);
 -      else if (oid_object_info(&oid, NULL) == OBJ_BLOB)
 +      else if (oid_object_info(the_repository, &oid, NULL) == OBJ_BLOB)
                describe_blob(oid, &sb);
        else
                die(_("%s is neither a commit nor blob"), arg);
@@@ -612,7 -622,7 +622,7 @@@ int cmd_describe(int argc, const char *
                                suffix = broken;
                        }
                } else if (dirty) {
 -                      static struct lock_file index_lock;
 +                      struct lock_file index_lock = LOCK_INIT;
                        struct rev_info revs;
                        struct argv_array args = ARGV_ARRAY_INIT;
                        int fd, result;
diff --combined builtin/fast-export.c
index 6c9768742fd4faecb3719e9c87997df3d490502a,5aaf5c8e59cf19dab157d655d680e09ea92d6d43..73d12c1020c4c13ff00210ad4eafc028bd33b322
@@@ -7,7 -7,6 +7,7 @@@
  #include "cache.h"
  #include "config.h"
  #include "refs.h"
 +#include "refspec.h"
  #include "commit.h"
  #include "object.h"
  #include "tag.h"
@@@ -22,6 -21,7 +22,7 @@@
  #include "quote.h"
  #include "remote.h"
  #include "blob.h"
+ #include "commit-slab.h"
  
  static const char *fast_export_usage[] = {
        N_("git fast-export [rev-list-opts]"),
@@@ -36,8 -36,10 +37,9 @@@ static int use_done_feature
  static int no_data;
  static int full_tree;
  static struct string_list extra_refs = STRING_LIST_INIT_NODUP;
 -static struct refspec *refspecs;
 -static int refspecs_nr;
 +static struct refspec refspecs = REFSPEC_INIT_FETCH;
  static int anonymize;
+ static struct revision_sources revision_sources;
  
  static int parse_opt_signed_tag_mode(const struct option *opt,
                                     const char *arg, int unset)
@@@ -156,14 -158,15 +158,14 @@@ static void anonymize_path(struct strbu
        }
  }
  
 -/* Since intptr_t is C99, we do not use it here */
 -static inline uint32_t *mark_to_ptr(uint32_t mark)
 +static inline void *mark_to_ptr(uint32_t mark)
  {
 -      return ((uint32_t *)NULL) + mark;
 +      return (void *)(uintptr_t)mark;
  }
  
  static inline uint32_t ptr_to_mark(void * mark)
  {
 -      return (uint32_t *)mark - (uint32_t *)NULL;
 +      return (uint32_t)(uintptr_t)mark;
  }
  
  static inline void mark_object(struct object *object, uint32_t mark)
@@@ -516,7 -519,7 +518,7 @@@ static void anonymize_ident_line(const 
        /* skip "committer", "author", "tagger", etc */
        end_of_header = strchr(*beg, ' ');
        if (!end_of_header)
 -              die("BUG: malformed line fed to anonymize_ident_line: %.*s",
 +              BUG("malformed line fed to anonymize_ident_line: %.*s",
                    (int)(*end - *beg), *beg);
        end_of_header++;
        strbuf_add(out, *beg, end_of_header - *beg);
@@@ -577,11 -580,11 +579,11 @@@ static void handle_commit(struct commi
            get_object_mark(&commit->parents->item->object) != 0 &&
            !full_tree) {
                parse_commit_or_die(commit->parents->item);
 -              diff_tree_oid(&commit->parents->item->tree->object.oid,
 -                            &commit->tree->object.oid, "", &rev->diffopt);
 +              diff_tree_oid(get_commit_tree_oid(commit->parents->item),
 +                            get_commit_tree_oid(commit), "", &rev->diffopt);
        }
        else
 -              diff_root_tree_oid(&commit->tree->object.oid,
 +              diff_root_tree_oid(get_commit_tree_oid(commit),
                                   "", &rev->diffopt);
  
        /* Export the referenced blobs, and remember the marks. */
                if (!S_ISGITLINK(diff_queued_diff.queue[i]->two->mode))
                        export_blob(&diff_queued_diff.queue[i]->two->oid);
  
-       refname = commit->util;
+       refname = *revision_sources_at(&revision_sources, commit);
        if (anonymize) {
                refname = anonymize_refname(refname);
                anonymize_ident_line(&committer, &committer_end);
@@@ -828,9 -831,9 +830,9 @@@ static void get_tags_and_duplicates(str
                if (dwim_ref(e->name, strlen(e->name), &oid, &full_name) != 1)
                        continue;
  
 -              if (refspecs) {
 +              if (refspecs.nr) {
                        char *private;
 -                      private = apply_refspecs(refspecs, refspecs_nr, full_name);
 +                      private = apply_refspecs(&refspecs, full_name);
                        if (private) {
                                free(full_name);
                                full_name = private;
                 * This ref will not be updated through a commit, lets make
                 * sure it gets properly updated eventually.
                 */
-               if (commit->util || commit->object.flags & SHOWN)
+               if (*revision_sources_at(&revision_sources, commit) ||
+                   commit->object.flags & SHOWN)
                        string_list_append(&extra_refs, full_name)->util = commit;
-               if (!commit->util)
-                       commit->util = full_name;
+               if (!*revision_sources_at(&revision_sources, commit))
+                       *revision_sources_at(&revision_sources, commit) = full_name;
        }
  }
  
@@@ -949,7 -953,7 +952,7 @@@ static void import_marks(char *input_fi
                if (last_idnum < mark)
                        last_idnum = mark;
  
 -              type = oid_object_info(&oid, NULL);
 +              type = oid_object_info(the_repository, &oid, NULL);
                if (type < 0)
                        die("object not found: %s", oid_to_hex(&oid));
  
  static void handle_deletes(void)
  {
        int i;
 -      for (i = 0; i < refspecs_nr; i++) {
 -              struct refspec *refspec = &refspecs[i];
 +      for (i = 0; i < refspecs.nr; i++) {
 +              struct refspec_item *refspec = &refspecs.items[i];
                if (*refspec->src)
                        continue;
  
@@@ -1028,8 -1032,9 +1031,9 @@@ int cmd_fast_export(int argc, const cha
        git_config(git_default_config, NULL);
  
        init_revisions(&revs, prefix);
+       init_revision_sources(&revision_sources);
        revs.topo_order = 1;
-       revs.show_source = 1;
+       revs.sources = &revision_sources;
        revs.rewrite_parents = 1;
        argc = parse_options(argc, argv, prefix, options, fast_export_usage,
                        PARSE_OPT_KEEP_ARGV0 | PARSE_OPT_KEEP_UNKNOWN);
                usage_with_options (fast_export_usage, options);
  
        if (refspecs_list.nr) {
 -              const char **refspecs_str;
                int i;
  
 -              ALLOC_ARRAY(refspecs_str, refspecs_list.nr);
                for (i = 0; i < refspecs_list.nr; i++)
 -                      refspecs_str[i] = refspecs_list.items[i].string;
 -
 -              refspecs_nr = refspecs_list.nr;
 -              refspecs = parse_fetch_refspec(refspecs_nr, refspecs_str);
 +                      refspec_append(&refspecs, refspecs_list.items[i].string);
  
                string_list_clear(&refspecs_list, 1);
 -              free(refspecs_str);
        }
  
        if (use_done_feature)
        if (use_done_feature)
                printf("done\n");
  
 -      free_refspec(refspecs_nr, refspecs);
 +      refspec_clear(&refspecs);
  
        return 0;
  }
diff --combined builtin/log.c
index 4686f68594829a85e9d73bcf0b6298c1e61b6852,967fbc5caaecd3a2271bd566e2dc145a74119185..0583f7f383a481f353909dc5b406b38745549c63
@@@ -28,6 -28,7 +28,7 @@@
  #include "mailmap.h"
  #include "gpg-interface.h"
  #include "progress.h"
+ #include "commit-slab.h"
  
  #define MAIL_DEFAULT_WRAP 72
  
@@@ -148,6 -149,7 +149,7 @@@ static void cmd_log_init_finish(int arg
        static struct string_list decorate_refs_include = STRING_LIST_INIT_NODUP;
        struct decoration_filter decoration_filter = {&decorate_refs_include,
                                                      &decorate_refs_exclude};
+       static struct revision_sources revision_sources;
  
        const struct option builtin_log_options[] = {
                OPT__QUIET(&quiet, N_("suppress diff output")),
            rev->diffopt.filter || rev->diffopt.flags.follow_renames)
                rev->always_show_header = 0;
  
-       if (source)
-               rev->show_source = 1;
+       if (source) {
+               init_revision_sources(&revision_sources);
+               rev->sources = &revision_sources;
+       }
  
        if (mailmap) {
                rev->mailmap = xcalloc(1, sizeof(struct string_list));
@@@ -1019,7 -1023,7 +1023,7 @@@ static void make_cover_letter(struct re
            open_next_file(NULL, rev->numbered_files ? NULL : "cover-letter", rev, quiet))
                return;
  
 -      log_write_email_headers(rev, head, &pp.after_subject, &need_8bit_cte);
 +      log_write_email_headers(rev, head, &pp.after_subject, &need_8bit_cte, 0);
  
        for (i = 0; !need_8bit_cte && i < nr; i++) {
                const char *buf = get_commit_buffer(list[i], NULL);
  
        diff_setup_done(&opts);
  
 -      diff_tree_oid(&origin->tree->object.oid,
 -                    &head->tree->object.oid,
 +      diff_tree_oid(get_commit_tree_oid(origin),
 +                    get_commit_tree_oid(head),
                      "", &opts);
        diffcore_std(&opts);
        diff_flush(&opts);
@@@ -1337,6 -1341,8 +1341,8 @@@ static struct commit *get_base_commit(c
        return base;
  }
  
+ define_commit_slab(commit_base, int);
  static void prepare_bases(struct base_tree_info *bases,
                          struct commit *base,
                          struct commit **list,
        struct commit *commit;
        struct rev_info revs;
        struct diff_options diffopt;
+       struct commit_base commit_base;
        int i;
  
        if (!base)
                return;
  
+       init_commit_base(&commit_base);
        diff_setup(&diffopt);
        diffopt.flags.recursive = 1;
        diff_setup_done(&diffopt);
        for (i = 0; i < total; i++) {
                list[i]->object.flags &= ~UNINTERESTING;
                add_pending_object(&revs, &list[i]->object, "rev_list");
-               list[i]->util = (void *)1;
+               *commit_base_at(&commit_base, list[i]) = 1;
        }
        base->object.flags |= UNINTERESTING;
        add_pending_object(&revs, &base->object, "base");
        while ((commit = get_revision(&revs)) != NULL) {
                struct object_id oid;
                struct object_id *patch_id;
-               if (commit->util)
+               if (*commit_base_at(&commit_base, commit))
                        continue;
                if (commit_patch_id(commit, &diffopt, &oid, 0))
                        die(_("cannot get patch id"));
                oidcpy(patch_id, &oid);
                bases->nr_patch_id++;
        }
+       clear_commit_base(&commit_base);
  }
  
  static void print_bases(struct base_tree_info *bases, FILE *file)
@@@ -1474,9 -1483,9 +1483,9 @@@ int cmd_format_patch(int argc, const ch
                         N_("output all-zero hash in From header")),
                OPT_BOOL(0, "ignore-if-in-upstream", &ignore_if_in_upstream,
                         N_("don't include a patch matching a commit upstream")),
 -              { OPTION_SET_INT, 'p', "no-stat", &use_patch_format, NULL,
 -                N_("show patch format instead of default (patch + stat)"),
 -                PARSE_OPT_NONEG | PARSE_OPT_NOARG, NULL, 1},
 +              OPT_SET_INT_F('p', "no-stat", &use_patch_format,
 +                            N_("show patch format instead of default (patch + stat)"),
 +                            1, PARSE_OPT_NONEG),
                OPT_GROUP(N_("Messaging")),
                { OPTION_CALLBACK, 0, "add-header", NULL, N_("header"),
                            N_("add email header"), 0, header_callback },
diff --combined builtin/merge.c
index b00d6f4821e7dc4067997bf515702edcfa413501,fc55bc264bb9cdc58352cf607330761f041aa674..fb4faca2507fdf00a1bbd48817e2ff0bc9957fc3
@@@ -14,7 -14,6 +14,7 @@@
  #include "run-command.h"
  #include "diff.h"
  #include "refs.h"
 +#include "refspec.h"
  #include "commit.h"
  #include "diffcore.h"
  #include "revision.h"
@@@ -35,7 -34,6 +35,7 @@@
  #include "string-list.h"
  #include "packfile.h"
  #include "tag.h"
 +#include "alias.h"
  
  #define DEFAULT_TWOHEAD (1<<0)
  #define DEFAULT_OCTOPUS (1<<1)
@@@ -215,9 -213,9 +215,9 @@@ static struct option builtin_merge_opti
        OPT_BOOL('e', "edit", &option_edit,
                N_("edit message before committing")),
        OPT_SET_INT(0, "ff", &fast_forward, N_("allow fast-forward (default)"), FF_ALLOW),
 -      { OPTION_SET_INT, 0, "ff-only", &fast_forward, NULL,
 -              N_("abort if fast-forward is not possible"),
 -              PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, FF_ONLY },
 +      OPT_SET_INT_F(0, "ff-only", &fast_forward,
 +                    N_("abort if fast-forward is not possible"),
 +                    FF_ONLY, PARSE_OPT_NONEG),
        OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
        OPT_BOOL(0, "verify-signatures", &verify_signatures,
                N_("verify that the named commit has a valid GPG signature")),
@@@ -282,7 -280,7 +282,7 @@@ out
        return rc;
  }
  
 -static void read_empty(unsigned const char *sha1, int verbose)
 +static void read_empty(const struct object_id *oid, int verbose)
  {
        int i = 0;
        const char *args[7];
                args[i++] = "-v";
        args[i++] = "-m";
        args[i++] = "-u";
 -      args[i++] = EMPTY_TREE_SHA1_HEX;
 -      args[i++] = sha1_to_hex(sha1);
 +      args[i++] = empty_tree_oid_hex();
 +      args[i++] = oid_to_hex(oid);
        args[i] = NULL;
  
        if (run_command_v_opt(args, RUN_GIT_CMD))
                die(_("read-tree failed"));
  }
  
 -static void reset_hard(unsigned const char *sha1, int verbose)
 +static void reset_hard(const struct object_id *oid, int verbose)
  {
        int i = 0;
        const char *args[6];
                args[i++] = "-v";
        args[i++] = "--reset";
        args[i++] = "-u";
 -      args[i++] = sha1_to_hex(sha1);
 +      args[i++] = oid_to_hex(oid);
        args[i] = NULL;
  
        if (run_command_v_opt(args, RUN_GIT_CMD))
@@@ -326,7 -324,7 +326,7 @@@ static void restore_state(const struct 
        if (is_null_oid(stash))
                return;
  
 -      reset_hard(head->hash, 1);
 +      reset_hard(head, 1);
  
        args[2] = oid_to_hex(stash);
  
@@@ -445,6 -443,7 +445,7 @@@ static void merge_name(const char *remo
        struct object_id branch_head;
        struct strbuf buf = STRBUF_INIT;
        struct strbuf bname = STRBUF_INIT;
+       struct merge_remote_desc *desc;
        const char *ptr;
        char *found_ref;
        int len, early;
                strbuf_release(&truname);
        }
  
-       if (remote_head->util) {
-               struct merge_remote_desc *desc;
-               desc = merge_remote_util(remote_head);
-               if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
-                       strbuf_addf(msg, "%s\t\t%s '%s'\n",
-                                   oid_to_hex(&desc->obj->oid),
-                                   type_name(desc->obj->type),
-                                   remote);
-                       goto cleanup;
-               }
+       desc = merge_remote_util(remote_head);
+       if (desc && desc->obj && desc->obj->type == OBJ_TAG) {
+               strbuf_addf(msg, "%s\t\t%s '%s'\n",
+                           oid_to_hex(&desc->obj->oid),
+                           type_name(desc->obj->type),
+                           remote);
+               goto cleanup;
        }
  
        strbuf_addf(msg, "%s\t\tcommit '%s'\n",
@@@ -649,7 -645,7 +647,7 @@@ static int try_merge_strategy(const cha
                              struct commit_list *remoteheads,
                              struct commit *head)
  {
 -      static struct lock_file lock;
 +      struct lock_file lock = LOCK_INIT;
        const char *head_arg = "HEAD";
  
        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
@@@ -807,7 -803,7 +805,7 @@@ static int merge_trivial(struct commit 
  {
        struct object_id result_tree, result_commit;
        struct commit_list *parents, **pptr = &parents;
 -      static struct lock_file lock;
 +      struct lock_file lock = LOCK_INIT;
  
        hold_locked_index(&lock, LOCK_DIE_ON_ERROR);
        refresh_cache(REFRESH_QUIET);
@@@ -934,8 -930,11 +932,11 @@@ static void write_merge_heads(struct co
        for (j = remoteheads; j; j = j->next) {
                struct object_id *oid;
                struct commit *c = j->item;
-               if (c->util && merge_remote_util(c)->obj) {
-                       oid = &merge_remote_util(c)->obj->oid;
+               struct merge_remote_desc *desc;
+               desc = merge_remote_util(c);
+               if (desc && desc->obj) {
+                       oid = &desc->obj->oid;
                } else {
                        oid = &c->object.oid;
                }
@@@ -1299,7 -1298,7 +1300,7 @@@ int cmd_merge(int argc, const char **ar
                if (remoteheads->next)
                        die(_("Can merge only exactly one commit into empty head"));
                remote_head_oid = &remoteheads->item->object.oid;
 -              read_empty(remote_head_oid->hash, 0);
 +              read_empty(remote_head_oid, 0);
                update_ref("initial pull", "HEAD", remote_head_oid, NULL, 0,
                           UPDATE_REFS_DIE_ON_ERR);
                goto done;
diff --combined commit.c
index 0030e79940ff8564b5c8c5ebab462eb1bd745174,e63a8dfeaa5e04ab621522c4ca7031bd769fa247..2d4431a21fd16f55d873b6fe2ba1126722d3c4bf
+++ b/commit.c
@@@ -13,7 -13,6 +13,7 @@@
  #include "prio-queue.h"
  #include "sha1-lookup.h"
  #include "wt-status.h"
 +#include "advice.h"
  
  static struct commit_extra_header *read_commit_extra_header_lines(const char *buf, size_t len, const char **);
  
@@@ -178,15 -177,6 +178,15 @@@ static int read_graft_file(const char *
        struct strbuf buf = STRBUF_INIT;
        if (!fp)
                return -1;
 +      if (advice_graft_file_deprecated)
 +              advise(_("Support for <GIT_DIR>/info/grafts is deprecated\n"
 +                       "and will be removed in a future Git version.\n"
 +                       "\n"
 +                       "Please use \"git replace --convert-graft-file\"\n"
 +                       "to convert the grafts into replace refs.\n"
 +                       "\n"
 +                       "Turn this message off by running\n"
 +                       "\"git config advice.graftFileDeprecated false\""));
        while (!strbuf_getwholeline(&buf, fp, '\n')) {
                /* The format is just "Commit Parent1 Parent2 ...\n" */
                struct commit_graft *graft = read_graft_line(&buf);
@@@ -207,9 -197,6 +207,9 @@@ static void prepare_commit_graft(void
  
        if (commit_graft_prepared)
                return;
 +      if (!startup_info->have_repository)
 +              return;
 +
        graft_file = get_graft_file();
        read_graft_file(graft_file);
        /* make sure shallows are read */
@@@ -309,22 -296,6 +309,22 @@@ void free_commit_buffer(struct commit *
        }
  }
  
 +struct tree *get_commit_tree(const struct commit *commit)
 +{
 +      if (commit->maybe_tree || !commit->object.parsed)
 +              return commit->maybe_tree;
 +
 +      if (commit->graph_pos == COMMIT_NOT_FROM_GRAPH)
 +              BUG("commit has NULL tree, but was not loaded from commit-graph");
 +
 +      return get_commit_tree_in_graph(commit);
 +}
 +
 +struct object_id *get_commit_tree_oid(const struct commit *commit)
 +{
 +      return &get_commit_tree(commit)->object.oid;
 +}
 +
  const void *detach_commit_buffer(struct commit *commit, unsigned long *sizep)
  {
        struct commit_buffer *v = buffer_slab_peek(&buffer_slab, commit);
@@@ -361,10 -332,10 +361,10 @@@ int parse_commit_buffer(struct commit *
        if (tail <= bufptr + tree_entry_len + 1 || memcmp(bufptr, "tree ", 5) ||
                        bufptr[tree_entry_len] != '\n')
                return error("bogus commit object %s", oid_to_hex(&item->object.oid));
 -      if (get_sha1_hex(bufptr + 5, parent.hash) < 0)
 +      if (get_oid_hex(bufptr + 5, &parent) < 0)
                return error("bad tree pointer in commit %s",
                             oid_to_hex(&item->object.oid));
 -      item->tree = lookup_tree(&parent);
 +      item->maybe_tree = lookup_tree(&parent);
        bufptr += tree_entry_len + 1; /* "tree " + "hex sha1" + "\n" */
        pptr = &item->parents;
  
                struct commit *new_parent;
  
                if (tail <= bufptr + parent_entry_len + 1 ||
 -                  get_sha1_hex(bufptr + 7, parent.hash) ||
 +                  get_oid_hex(bufptr + 7, &parent) ||
                    bufptr[parent_entry_len] != '\n')
                        return error("bad parents in commit %s", oid_to_hex(&item->object.oid));
                bufptr += parent_entry_len + 1;
@@@ -1320,19 -1291,17 +1320,19 @@@ struct commit_extra_header *read_commit
        return extra;
  }
  
 -void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
 +int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data)
  {
        struct commit_extra_header *extra, *to_free;
 +      int res = 0;
  
        to_free = read_commit_extra_headers(commit, NULL);
 -      for (extra = to_free; extra; extra = extra->next) {
 +      for (extra = to_free; !res && extra; extra = extra->next) {
                if (strcmp(extra->key, "mergetag"))
                        continue; /* not a merge tag */
 -              fn(commit, extra, data);
 +              res = fn(commit, extra, data);
        }
        free_commit_extra_headers(to_free);
 +      return res;
  }
  
  static inline int standard_header_field(const char *field, size_t len)
        return result;
  }
  
+ define_commit_slab(merge_desc_slab, struct merge_remote_desc *);
+ static struct merge_desc_slab merge_desc_slab = COMMIT_SLAB_INIT(1, merge_desc_slab);
+ struct merge_remote_desc *merge_remote_util(struct commit *commit)
+ {
+       return *merge_desc_slab_at(&merge_desc_slab, commit);
+ }
  void set_merge_remote_desc(struct commit *commit,
                           const char *name, struct object *obj)
  {
        struct merge_remote_desc *desc;
        FLEX_ALLOC_STR(desc, name, name);
        desc->obj = obj;
-       commit->util = desc;
+       *merge_desc_slab_at(&merge_desc_slab, commit) = desc;
  }
  
  struct commit *get_merge_parent(const char *name)
                return NULL;
        obj = parse_object(&oid);
        commit = (struct commit *)peel_to_type(name, 0, obj, OBJ_COMMIT);
-       if (commit && !commit->util)
+       if (commit && !merge_remote_util(commit))
                set_merge_remote_desc(commit, name, obj);
        return commit;
  }
diff --combined commit.h
index c3af512f8b1b90b3963d0921f7ec0d0a43a2fcbe,4432458367f16ca23336737ee4d4e111aca85f06..e48f05dffcac2fc780386626701cdc64bd795076
+++ b/commit.h
@@@ -16,20 -16,18 +16,24 @@@ struct commit_list 
        struct commit_list *next;
  };
  
+ /*
+  * The size of this struct matters in full repo walk operations like
+  * 'git clone' or 'git gc'. Consider using commit-slab to attach data
+  * to a commit instead of adding new fields here.
+  */
  struct commit {
        struct object object;
-       void *util;
 -      unsigned int index;
        timestamp_t date;
        struct commit_list *parents;
 -      struct tree *tree;
 +
 +      /*
 +       * If the commit is loaded from the commit-graph file, then this
 +       * member may be NULL. Only access it through get_commit_tree()
 +       * or get_commit_tree_oid().
 +       */
 +      struct tree *maybe_tree;
        uint32_t graph_pos;
 +      unsigned int index;
  };
  
  extern int save_commit_buffer;
@@@ -108,9 -106,6 +112,9 @@@ void unuse_commit_buffer(const struct c
   */
  void free_commit_buffer(struct commit *);
  
 +struct tree *get_commit_tree(const struct commit *);
 +struct object_id *get_commit_tree_oid(const struct commit *);
 +
  /*
   * Disassociate any cached object buffer from the commit, but do not free it.
   * The buffer (or NULL, if none) is returned.
@@@ -303,16 -298,16 +307,16 @@@ extern const char *find_commit_header(c
  /* Find the end of the log message, the right place for a new trailer. */
  extern int ignore_non_trailer(const char *buf, size_t len);
  
 -typedef void (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
 +typedef int (*each_mergetag_fn)(struct commit *commit, struct commit_extra_header *extra,
                                 void *cb_data);
  
 -extern void for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
 +extern int for_each_mergetag(each_mergetag_fn fn, struct commit *commit, void *data);
  
  struct merge_remote_desc {
        struct object *obj; /* the named object, could be a tag */
        char name[FLEX_ARRAY];
  };
- #define merge_remote_util(commit) ((struct merge_remote_desc *)((commit)->util))
+ extern struct merge_remote_desc *merge_remote_util(struct commit *);
  extern void set_merge_remote_desc(struct commit *commit,
                                  const char *name, struct object *obj);
  
diff --combined log-tree.c
index 4aef85331e0b696d0373cf1bdb0743a7e6b58c36,0b41ee32350ab1dd406ecdb19a4e4882d79682b9..0b97de5e879a9d90d8d62412d1743a37b7915fd3
@@@ -295,8 -295,12 +295,12 @@@ void show_decorations(struct rev_info *
  {
        struct strbuf sb = STRBUF_INIT;
  
-       if (opt->show_source && commit->util)
-               fprintf(opt->diffopt.file, "\t%s", (char *) commit->util);
+       if (opt->sources) {
+               char **slot = revision_sources_peek(opt->sources, commit);
+               if (slot && *slot)
+                       fprintf(opt->diffopt.file, "\t%s", *slot);
+       }
        if (!opt->show_decorations)
                return;
        format_decorations(&sb, commit, opt->diffopt.use_color);
@@@ -362,8 -366,7 +366,8 @@@ void fmt_output_email_subject(struct st
  
  void log_write_email_headers(struct rev_info *opt, struct commit *commit,
                             const char **extra_headers_p,
 -                           int *need_8bit_cte_p)
 +                           int *need_8bit_cte_p,
 +                           int maybe_multipart)
  {
        const char *extra_headers = opt->extra_headers;
        const char *name = oid_to_hex(opt->zero_commit ?
                               opt->ref_message_ids->items[i].string);
                graph_show_oneline(opt->graph);
        }
 -      if (opt->mime_boundary) {
 -              static char subject_buffer[1024];
 -              static char buffer[1024];
 +      if (opt->mime_boundary && maybe_multipart) {
 +              static struct strbuf subject_buffer = STRBUF_INIT;
 +              static struct strbuf buffer = STRBUF_INIT;
                struct strbuf filename =  STRBUF_INIT;
                *need_8bit_cte_p = -1; /* NEVER */
 -              snprintf(subject_buffer, sizeof(subject_buffer) - 1,
 +
 +              strbuf_reset(&subject_buffer);
 +              strbuf_reset(&buffer);
 +
 +              strbuf_addf(&subject_buffer,
                         "%s"
                         "MIME-Version: 1.0\n"
                         "Content-Type: multipart/mixed;"
                         extra_headers ? extra_headers : "",
                         mime_boundary_leader, opt->mime_boundary,
                         mime_boundary_leader, opt->mime_boundary);
 -              extra_headers = subject_buffer;
 +              extra_headers = subject_buffer.buf;
  
                if (opt->numbered_files)
                        strbuf_addf(&filename, "%d", opt->nr);
                else
                        fmt_output_commit(&filename, commit, opt);
 -              snprintf(buffer, sizeof(buffer) - 1,
 +              strbuf_addf(&buffer,
                         "\n--%s%s\n"
                         "Content-Type: text/x-patch;"
                         " name=\"%s\"\n"
                         filename.buf,
                         opt->no_inline ? "attachment" : "inline",
                         filename.buf);
 -              opt->diffopt.stat_sep = buffer;
 +              opt->diffopt.stat_sep = buffer.buf;
                strbuf_release(&filename);
        }
        *extra_headers_p = extra_headers;
@@@ -493,9 -492,9 +497,9 @@@ static int is_common_merge(const struc
                && !commit->parents->next->next);
  }
  
 -static void show_one_mergetag(struct commit *commit,
 -                            struct commit_extra_header *extra,
 -                            void *data)
 +static int show_one_mergetag(struct commit *commit,
 +                           struct commit_extra_header *extra,
 +                           void *data)
  {
        struct rev_info *opt = (struct rev_info *)data;
        struct object_id oid;
        hash_object_file(extra->value, extra->len, type_name(OBJ_TAG), &oid);
        tag = lookup_tag(&oid);
        if (!tag)
 -              return; /* error message already given */
 +              return -1; /* error message already given */
  
        strbuf_init(&verify_message, 256);
        if (parse_tag_buffer(tag, extra->value, extra->len))
  
        show_sig_lines(opt, status, verify_message.buf);
        strbuf_release(&verify_message);
 +      return 0;
  }
  
 -static void show_mergetag(struct rev_info *opt, struct commit *commit)
 +static int show_mergetag(struct rev_info *opt, struct commit *commit)
  {
 -      for_each_mergetag(show_one_mergetag, commit, opt);
 +      return for_each_mergetag(show_one_mergetag, commit, opt);
  }
  
  void show_log(struct rev_info *opt)
  
        if (cmit_fmt_is_mail(opt->commit_format)) {
                log_write_email_headers(opt, commit, &extra_headers,
 -                                      &ctx.need_8bit_cte);
 +                                      &ctx.need_8bit_cte, 1);
                ctx.rev = opt;
                ctx.print_email_subject = 1;
        } else if (opt->commit_format != CMIT_FMT_USERFORMAT) {
@@@ -812,7 -810,7 +816,7 @@@ static int log_tree_diff(struct rev_inf
                return 0;
  
        parse_commit_or_die(commit);
 -      oid = &commit->tree->object.oid;
 +      oid = get_commit_tree_oid(commit);
  
        /* Root commit? */
        parents = get_saved_parents(opt, commit);
                         * we merged _in_.
                         */
                        parse_commit_or_die(parents->item);
 -                      diff_tree_oid(&parents->item->tree->object.oid,
 +                      diff_tree_oid(get_commit_tree_oid(parents->item),
                                      oid, "", &opt->diffopt);
                        log_tree_diff_flush(opt);
                        return !opt->loginfo;
                struct commit *parent = parents->item;
  
                parse_commit_or_die(parent);
 -              diff_tree_oid(&parent->tree->object.oid,
 +              diff_tree_oid(get_commit_tree_oid(parent),
                              oid, "", &opt->diffopt);
                log_tree_diff_flush(opt);
  
diff --combined merge-recursive.c
index f110e1c5ecbd6254b25785ecb49f29cb7bb75ed2,5537f01f8edcb0e8df27c58a7a2cc65041c7ef15..404f050cafe919023ec86d14230a0f6455714538
@@@ -23,7 -23,6 +23,7 @@@
  #include "merge-recursive.h"
  #include "dir.h"
  #include "submodule.h"
 +#include "revision.h"
  
  struct path_hashmap_entry {
        struct hashmap_entry e;
@@@ -50,67 -49,6 +50,67 @@@ static unsigned int path_hash(const cha
        return ignore_case ? strihash(path) : strhash(path);
  }
  
 +static struct dir_rename_entry *dir_rename_find_entry(struct hashmap *hashmap,
 +                                                    char *dir)
 +{
 +      struct dir_rename_entry key;
 +
 +      if (dir == NULL)
 +              return NULL;
 +      hashmap_entry_init(&key, strhash(dir));
 +      key.dir = dir;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int dir_rename_cmp(const void *unused_cmp_data,
 +                        const void *entry,
 +                        const void *entry_or_key,
 +                        const void *unused_keydata)
 +{
 +      const struct dir_rename_entry *e1 = entry;
 +      const struct dir_rename_entry *e2 = entry_or_key;
 +
 +      return strcmp(e1->dir, e2->dir);
 +}
 +
 +static void dir_rename_init(struct hashmap *map)
 +{
 +      hashmap_init(map, dir_rename_cmp, NULL, 0);
 +}
 +
 +static void dir_rename_entry_init(struct dir_rename_entry *entry,
 +                                char *directory)
 +{
 +      hashmap_entry_init(entry, strhash(directory));
 +      entry->dir = directory;
 +      entry->non_unique_new_dir = 0;
 +      strbuf_init(&entry->new_dir, 0);
 +      string_list_init(&entry->possible_new_dirs, 0);
 +}
 +
 +static struct collision_entry *collision_find_entry(struct hashmap *hashmap,
 +                                                  char *target_file)
 +{
 +      struct collision_entry key;
 +
 +      hashmap_entry_init(&key, strhash(target_file));
 +      key.target_file = target_file;
 +      return hashmap_get(hashmap, &key, NULL);
 +}
 +
 +static int collision_cmp(void *unused_cmp_data,
 +                       const struct collision_entry *e1,
 +                       const struct collision_entry *e2,
 +                       const void *unused_keydata)
 +{
 +      return strcmp(e1->target_file, e2->target_file);
 +}
 +
 +static void collision_init(struct hashmap *map)
 +{
 +      hashmap_init(map, (hashmap_cmp_fn) collision_cmp, NULL, 0);
 +}
 +
  static void flush_output(struct merge_options *o)
  {
        if (o->buffer_output < 2 && o->obuf.len) {
@@@ -163,7 -101,7 +163,7 @@@ static struct commit *make_virtual_comm
        struct commit *commit = alloc_commit_node();
  
        set_merge_remote_desc(commit, comment, (struct object *)commit);
 -      commit->tree = tree;
 +      commit->maybe_tree = tree;
        commit->object.parsed = 1;
        return commit;
  }
@@@ -181,7 -119,6 +181,7 @@@ static int oid_eq(const struct object_i
  
  enum rename_type {
        RENAME_NORMAL = 0,
 +      RENAME_DIR,
        RENAME_DELETE,
        RENAME_ONE_FILE_TO_ONE,
        RENAME_ONE_FILE_TO_TWO,
@@@ -286,10 -223,12 +286,12 @@@ static void output(struct merge_option
  
  static void output_commit_title(struct merge_options *o, struct commit *commit)
  {
+       struct merge_remote_desc *desc;
        strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
-       if (commit->util)
-               strbuf_addf(&o->obuf, "virtual %s\n",
-                       merge_remote_util(commit)->name);
+       desc = merge_remote_util(commit);
+       if (desc)
+               strbuf_addf(&o->obuf, "virtual %s\n", desc->name);
        else {
                strbuf_add_unique_abbrev(&o->obuf, &commit->object.oid,
                                         DEFAULT_ABBREV);
@@@ -317,7 -256,7 +319,7 @@@ static int add_cacheinfo(struct merge_o
  
        ce = make_cache_entry(mode, oid ? oid->hash : null_sha1, path, stage, 0);
        if (!ce)
 -              return err(o, _("addinfo_cache failed for path '%s'"), path);
 +              return err(o, _("add_cacheinfo failed for path '%s'; merge aborting."), path);
  
        ret = add_cache_entry(ce, options);
        if (refresh) {
  
                nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
                if (!nce)
 -                      return err(o, _("addinfo_cache failed for path '%s'"), path);
 +                      return err(o, _("add_cacheinfo failed to refresh for path '%s'; merge aborting."), path);
                if (nce != ce)
                        ret = add_cache_entry(nce, options);
        }
@@@ -338,54 -277,36 +340,54 @@@ static void init_tree_desc_from_tree(st
        init_tree_desc(desc, tree->buffer, tree->size);
  }
  
 -static int git_merge_trees(int index_only,
 -                         struct tree *common,
 -                         struct tree *head,
 -                         struct tree *merge)
 +static int unpack_trees_start(struct merge_options *o,
 +                            struct tree *common,
 +                            struct tree *head,
 +                            struct tree *merge)
  {
        int rc;
        struct tree_desc t[3];
 -      struct unpack_trees_options opts;
 +      struct index_state tmp_index = { NULL };
  
 -      memset(&opts, 0, sizeof(opts));
 -      if (index_only)
 -              opts.index_only = 1;
 +      memset(&o->unpack_opts, 0, sizeof(o->unpack_opts));
 +      if (o->call_depth)
 +              o->unpack_opts.index_only = 1;
        else
 -              opts.update = 1;
 -      opts.merge = 1;
 -      opts.head_idx = 2;
 -      opts.fn = threeway_merge;
 -      opts.src_index = &the_index;
 -      opts.dst_index = &the_index;
 -      setup_unpack_trees_porcelain(&opts, "merge");
 +              o->unpack_opts.update = 1;
 +      o->unpack_opts.merge = 1;
 +      o->unpack_opts.head_idx = 2;
 +      o->unpack_opts.fn = threeway_merge;
 +      o->unpack_opts.src_index = &the_index;
 +      o->unpack_opts.dst_index = &tmp_index;
 +      o->unpack_opts.aggressive = !merge_detect_rename(o);
 +      setup_unpack_trees_porcelain(&o->unpack_opts, "merge");
  
        init_tree_desc_from_tree(t+0, common);
        init_tree_desc_from_tree(t+1, head);
        init_tree_desc_from_tree(t+2, merge);
  
 -      rc = unpack_trees(3, t, &opts);
 +      rc = unpack_trees(3, t, &o->unpack_opts);
        cache_tree_free(&active_cache_tree);
 +
 +      /*
 +       * Update the_index to match the new results, AFTER saving a copy
 +       * in o->orig_index.  Update src_index to point to the saved copy.
 +       * (verify_uptodate() checks src_index, and the original index is
 +       * the one that had the necessary modification timestamps.)
 +       */
 +      o->orig_index = the_index;
 +      the_index = tmp_index;
 +      o->unpack_opts.src_index = &o->orig_index;
 +
        return rc;
  }
  
 +static void unpack_trees_finish(struct merge_options *o)
 +{
 +      discard_index(&o->orig_index);
 +      clear_unpack_trees_porcelain(&o->unpack_opts);
 +}
 +
  struct tree *write_tree_from_memory(struct merge_options *o)
  {
        struct tree *result = NULL;
                                fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
                                        (int)ce_namelen(ce), ce->name);
                }
 -              die("BUG: unmerged index entries in merge-recursive.c");
 +              BUG("unmerged index entries in merge-recursive.c");
        }
  
        if (!active_cache_tree)
@@@ -441,21 -362,6 +443,21 @@@ static void get_files_dirs(struct merge
        read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o);
  }
  
 +static int get_tree_entry_if_blob(const struct object_id *tree,
 +                                const char *path,
 +                                struct object_id *hashy,
 +                                unsigned int *mode_o)
 +{
 +      int ret;
 +
 +      ret = get_tree_entry(tree, path, hashy, mode_o);
 +      if (S_ISDIR(*mode_o)) {
 +              oidcpy(hashy, &null_oid);
 +              *mode_o = 0;
 +      }
 +      return ret;
 +}
 +
  /*
   * Returns an index_entry instance which doesn't have to correspond to
   * a real cache entry in Git's index.
@@@ -466,12 -372,12 +468,12 @@@ static struct stage_data *insert_stage_
  {
        struct string_list_item *item;
        struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 -      get_tree_entry(&o->object.oid, path,
 -                      &e->stages[1].oid, &e->stages[1].mode);
 -      get_tree_entry(&a->object.oid, path,
 -                      &e->stages[2].oid, &e->stages[2].mode);
 -      get_tree_entry(&b->object.oid, path,
 -                      &e->stages[3].oid, &e->stages[3].mode);
 +      get_tree_entry_if_blob(&o->object.oid, path,
 +                             &e->stages[1].oid, &e->stages[1].mode);
 +      get_tree_entry_if_blob(&a->object.oid, path,
 +                             &e->stages[2].oid, &e->stages[2].mode);
 +      get_tree_entry_if_blob(&b->object.oid, path,
 +                             &e->stages[3].oid, &e->stages[3].mode);
        item = string_list_insert(entries, path);
        item->util = e;
        return e;
@@@ -630,10 -536,78 +632,10 @@@ struct rename 
         */
        struct stage_data *src_entry;
        struct stage_data *dst_entry;
 +      unsigned add_turned_into_rename:1;
        unsigned processed:1;
  };
  
 -/*
 - * Get information of all renames which occurred between 'o_tree' and
 - * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 - * 'b_tree') to be able to associate the correct cache entries with
 - * the rename information. 'tree' is always equal to either a_tree or b_tree.
 - */
 -static struct string_list *get_renames(struct merge_options *o,
 -                                     struct tree *tree,
 -                                     struct tree *o_tree,
 -                                     struct tree *a_tree,
 -                                     struct tree *b_tree,
 -                                     struct string_list *entries)
 -{
 -      int i;
 -      struct string_list *renames;
 -      struct diff_options opts;
 -
 -      renames = xcalloc(1, sizeof(struct string_list));
 -      if (!o->detect_rename)
 -              return renames;
 -
 -      diff_setup(&opts);
 -      opts.flags.recursive = 1;
 -      opts.flags.rename_empty = 0;
 -      opts.detect_rename = DIFF_DETECT_RENAME;
 -      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 -                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 -                          1000;
 -      opts.rename_score = o->rename_score;
 -      opts.show_rename_progress = o->show_rename_progress;
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_setup_done(&opts);
 -      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 -      diffcore_std(&opts);
 -      if (opts.needed_rename_limit > o->needed_rename_limit)
 -              o->needed_rename_limit = opts.needed_rename_limit;
 -      for (i = 0; i < diff_queued_diff.nr; ++i) {
 -              struct string_list_item *item;
 -              struct rename *re;
 -              struct diff_filepair *pair = diff_queued_diff.queue[i];
 -              if (pair->status != 'R') {
 -                      diff_free_filepair(pair);
 -                      continue;
 -              }
 -              re = xmalloc(sizeof(*re));
 -              re->processed = 0;
 -              re->pair = pair;
 -              item = string_list_lookup(entries, re->pair->one->path);
 -              if (!item)
 -                      re->src_entry = insert_stage_data(re->pair->one->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->src_entry = item->util;
 -
 -              item = string_list_lookup(entries, re->pair->two->path);
 -              if (!item)
 -                      re->dst_entry = insert_stage_data(re->pair->two->path,
 -                                      o_tree, a_tree, b_tree, entries);
 -              else
 -                      re->dst_entry = item->util;
 -              item = string_list_insert(renames, pair->one->path);
 -              item->util = re;
 -      }
 -      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 -      diff_queued_diff.nr = 0;
 -      diff_flush(&opts);
 -      return renames;
 -}
 -
  static int update_stages(struct merge_options *opt, const char *path,
                         const struct diff_filespec *o,
                         const struct diff_filespec *a,
        return 0;
  }
  
 +static int update_stages_for_stage_data(struct merge_options *opt,
 +                                      const char *path,
 +                                      const struct stage_data *stage_data)
 +{
 +      struct diff_filespec o, a, b;
 +
 +      o.mode = stage_data->stages[1].mode;
 +      oidcpy(&o.oid, &stage_data->stages[1].oid);
 +
 +      a.mode = stage_data->stages[2].mode;
 +      oidcpy(&a.oid, &stage_data->stages[2].oid);
 +
 +      b.mode = stage_data->stages[3].mode;
 +      oidcpy(&b.oid, &stage_data->stages[3].oid);
 +
 +      return update_stages(opt, path,
 +                           is_null_oid(&o.oid) ? NULL : &o,
 +                           is_null_oid(&a.oid) ? NULL : &a,
 +                           is_null_oid(&b.oid) ? NULL : &b);
 +}
 +
  static void update_entry(struct stage_data *entry,
                         struct diff_filespec *o,
                         struct diff_filespec *a,
@@@ -787,92 -740,31 +789,92 @@@ static int dir_in_way(const char *path
                !(empty_ok && is_empty_dir(path));
  }
  
 -static int was_tracked(const char *path)
 +/*
 + * Returns whether path was tracked in the index before the merge started,
 + * and its oid and mode match the specified values
 + */
 +static int was_tracked_and_matches(struct merge_options *o, const char *path,
 +                                 const struct object_id *oid, unsigned mode)
  {
 -      int pos = cache_name_pos(path, strlen(path));
 +      int pos = index_name_pos(&o->orig_index, path, strlen(path));
 +      struct cache_entry *ce;
 +
 +      if (0 > pos)
 +              /* we were not tracking this path before the merge */
 +              return 0;
 +
 +      /* See if the file we were tracking before matches */
 +      ce = o->orig_index.cache[pos];
 +      return (oid_eq(&ce->oid, oid) && ce->ce_mode == mode);
 +}
 +
 +/*
 + * Returns whether path was tracked in the index before the merge started
 + */
 +static int was_tracked(struct merge_options *o, const char *path)
 +{
 +      int pos = index_name_pos(&o->orig_index, path, strlen(path));
  
        if (0 <= pos)
 -              /* we have been tracking this path */
 +              /* we were tracking this path before the merge */
                return 1;
  
 -      /*
 -       * Look for an unmerged entry for the path,
 -       * specifically stage #2, which would indicate
 -       * that "our" side before the merge started
 -       * had the path tracked (and resulted in a conflict).
 -       */
 -      for (pos = -1 - pos;
 -           pos < active_nr && !strcmp(path, active_cache[pos]->name);
 -           pos++)
 -              if (ce_stage(active_cache[pos]) == 2)
 -                      return 1;
        return 0;
  }
  
  static int would_lose_untracked(const char *path)
  {
 -      return !was_tracked(path) && file_exists(path);
 +      /*
 +       * This may look like it can be simplified to:
 +       *   return !was_tracked(o, path) && file_exists(path)
 +       * but it can't.  This function needs to know whether path was in
 +       * the working tree due to EITHER having been tracked in the index
 +       * before the merge OR having been put into the working copy and
 +       * index by unpack_trees().  Due to that either-or requirement, we
 +       * check the current index instead of the original one.
 +       *
 +       * Note that we do not need to worry about merge-recursive itself
 +       * updating the index after unpack_trees() and before calling this
 +       * function, because we strictly require all code paths in
 +       * merge-recursive to update the working tree first and the index
 +       * second.  Doing otherwise would break
 +       * update_file()/would_lose_untracked(); see every comment in this
 +       * file which mentions "update_stages".
 +       */
 +      int pos = cache_name_pos(path, strlen(path));
 +
 +      if (pos < 0)
 +              pos = -1 - pos;
 +      while (pos < active_nr &&
 +             !strcmp(path, active_cache[pos]->name)) {
 +              /*
 +               * If stage #0, it is definitely tracked.
 +               * If it has stage #2 then it was tracked
 +               * before this merge started.  All other
 +               * cases the path was not tracked.
 +               */
 +              switch (ce_stage(active_cache[pos])) {
 +              case 0:
 +              case 2:
 +                      return 0;
 +              }
 +              pos++;
 +      }
 +      return file_exists(path);
 +}
 +
 +static int was_dirty(struct merge_options *o, const char *path)
 +{
 +      struct cache_entry *ce;
 +      int dirty = 1;
 +
 +      if (o->call_depth || !was_tracked(o, path))
 +              return !dirty;
 +
 +      ce = index_file_exists(o->unpack_opts.src_index,
 +                             path, strlen(path), ignore_case);
 +      dirty = verify_uptodate(ce, &o->unpack_opts) != 0;
 +      return dirty;
  }
  
  static int make_room_for_path(struct merge_options *o, const char *path)
@@@ -1003,9 -895,7 +1005,9 @@@ static int update_file_flags(struct mer
        }
   update_index:
        if (!ret && update_cache)
 -              add_cacheinfo(o, mode, oid, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 +              if (add_cacheinfo(o, mode, oid, path, 0, update_wd,
 +                                ADD_CACHE_OK_TO_ADD))
 +                      return -1;
        return ret;
  }
  
@@@ -1089,193 -979,13 +1091,193 @@@ static int merge_3way(struct merge_opti
        return merge_status;
  }
  
 +static int find_first_merges(struct object_array *result, const char *path,
 +              struct commit *a, struct commit *b)
 +{
 +      int i, j;
 +      struct object_array merges = OBJECT_ARRAY_INIT;
 +      struct commit *commit;
 +      int contains_another;
 +
 +      char merged_revision[42];
 +      const char *rev_args[] = { "rev-list", "--merges", "--ancestry-path",
 +                                 "--all", merged_revision, NULL };
 +      struct rev_info revs;
 +      struct setup_revision_opt rev_opts;
 +
 +      memset(result, 0, sizeof(struct object_array));
 +      memset(&rev_opts, 0, sizeof(rev_opts));
 +
 +      /* get all revisions that merge commit a */
 +      xsnprintf(merged_revision, sizeof(merged_revision), "^%s",
 +                      oid_to_hex(&a->object.oid));
 +      init_revisions(&revs, NULL);
 +      rev_opts.submodule = path;
 +      /* FIXME: can't handle linked worktrees in submodules yet */
 +      revs.single_worktree = path != NULL;
 +      setup_revisions(ARRAY_SIZE(rev_args)-1, rev_args, &revs, &rev_opts);
 +
 +      /* save all revisions from the above list that contain b */
 +      if (prepare_revision_walk(&revs))
 +              die("revision walk setup failed");
 +      while ((commit = get_revision(&revs)) != NULL) {
 +              struct object *o = &(commit->object);
 +              if (in_merge_bases(b, commit))
 +                      add_object_array(o, NULL, &merges);
 +      }
 +      reset_revision_walk();
 +
 +      /* Now we've got all merges that contain a and b. Prune all
 +       * merges that contain another found merge and save them in
 +       * result.
 +       */
 +      for (i = 0; i < merges.nr; i++) {
 +              struct commit *m1 = (struct commit *) merges.objects[i].item;
 +
 +              contains_another = 0;
 +              for (j = 0; j < merges.nr; j++) {
 +                      struct commit *m2 = (struct commit *) merges.objects[j].item;
 +                      if (i != j && in_merge_bases(m2, m1)) {
 +                              contains_another = 1;
 +                              break;
 +                      }
 +              }
 +
 +              if (!contains_another)
 +                      add_object_array(merges.objects[i].item, NULL, result);
 +      }
 +
 +      object_array_clear(&merges);
 +      return result->nr;
 +}
 +
 +static void print_commit(struct commit *commit)
 +{
 +      struct strbuf sb = STRBUF_INIT;
 +      struct pretty_print_context ctx = {0};
 +      ctx.date_mode.type = DATE_NORMAL;
 +      format_commit_message(commit, " %h: %m %s", &sb, &ctx);
 +      fprintf(stderr, "%s\n", sb.buf);
 +      strbuf_release(&sb);
 +}
 +
 +static int merge_submodule(struct merge_options *o,
 +                         struct object_id *result, const char *path,
 +                         const struct object_id *base, const struct object_id *a,
 +                         const struct object_id *b)
 +{
 +      struct commit *commit_base, *commit_a, *commit_b;
 +      int parent_count;
 +      struct object_array merges;
 +
 +      int i;
 +      int search = !o->call_depth;
 +
 +      /* store a in result in case we fail */
 +      oidcpy(result, a);
 +
 +      /* we can not handle deletion conflicts */
 +      if (is_null_oid(base))
 +              return 0;
 +      if (is_null_oid(a))
 +              return 0;
 +      if (is_null_oid(b))
 +              return 0;
 +
 +      if (add_submodule_odb(path)) {
 +              output(o, 1, _("Failed to merge submodule %s (not checked out)"), path);
 +              return 0;
 +      }
 +
 +      if (!(commit_base = lookup_commit_reference(base)) ||
 +          !(commit_a = lookup_commit_reference(a)) ||
 +          !(commit_b = lookup_commit_reference(b))) {
 +              output(o, 1, _("Failed to merge submodule %s (commits not present)"), path);
 +              return 0;
 +      }
 +
 +      /* check whether both changes are forward */
 +      if (!in_merge_bases(commit_base, commit_a) ||
 +          !in_merge_bases(commit_base, commit_b)) {
 +              output(o, 1, _("Failed to merge submodule %s (commits don't follow merge-base)"), path);
 +              return 0;
 +      }
 +
 +      /* Case #1: a is contained in b or vice versa */
 +      if (in_merge_bases(commit_a, commit_b)) {
 +              oidcpy(result, b);
 +              if (show(o, 3)) {
 +                      output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
 +                      output_commit_title(o, commit_b);
 +              } else if (show(o, 2))
 +                      output(o, 2, _("Fast-forwarding submodule %s"), path);
 +              else
 +                      ; /* no output */
 +
 +              return 1;
 +      }
 +      if (in_merge_bases(commit_b, commit_a)) {
 +              oidcpy(result, a);
 +              if (show(o, 3)) {
 +                      output(o, 3, _("Fast-forwarding submodule %s to the following commit:"), path);
 +                      output_commit_title(o, commit_a);
 +              } else if (show(o, 2))
 +                      output(o, 2, _("Fast-forwarding submodule %s"), path);
 +              else
 +                      ; /* no output */
 +
 +              return 1;
 +      }
 +
 +      /*
 +       * Case #2: There are one or more merges that contain a and b in
 +       * the submodule. If there is only one, then present it as a
 +       * suggestion to the user, but leave it marked unmerged so the
 +       * user needs to confirm the resolution.
 +       */
 +
 +      /* Skip the search if makes no sense to the calling context.  */
 +      if (!search)
 +              return 0;
 +
 +      /* find commit which merges them */
 +      parent_count = find_first_merges(&merges, path, commit_a, commit_b);
 +      switch (parent_count) {
 +      case 0:
 +              output(o, 1, _("Failed to merge submodule %s (merge following commits not found)"), path);
 +              break;
 +
 +      case 1:
 +              output(o, 1, _("Failed to merge submodule %s (not fast-forward)"), path);
 +              output(o, 2, _("Found a possible merge resolution for the submodule:\n"));
 +              print_commit((struct commit *) merges.objects[0].item);
 +              output(o, 2, _(
 +                      "If this is correct simply add it to the index "
 +                      "for example\n"
 +                      "by using:\n\n"
 +                      "  git update-index --cacheinfo 160000 %s \"%s\"\n\n"
 +                      "which will accept this suggestion.\n"),
 +                      oid_to_hex(&merges.objects[0].item->oid), path);
 +              break;
 +
 +      default:
 +              output(o, 1, _("Failed to merge submodule %s (multiple merges found)"), path);
 +              for (i = 0; i < merges.nr; i++)
 +                      print_commit((struct commit *) merges.objects[i].item);
 +      }
 +
 +      object_array_clear(&merges);
 +      return 0;
 +}
 +
  static int merge_file_1(struct merge_options *o,
 -                                         const struct diff_filespec *one,
 -                                         const struct diff_filespec *a,
 -                                         const struct diff_filespec *b,
 -                                         const char *branch1,
 -                                         const char *branch2,
 -                                         struct merge_file_info *result)
 +                      const struct diff_filespec *one,
 +                      const struct diff_filespec *a,
 +                      const struct diff_filespec *b,
 +                      const char *filename,
 +                      const char *branch1,
 +                      const char *branch2,
 +                      struct merge_file_info *result)
  {
        result->merge = 0;
        result->clean = 1;
                                return ret;
                        result->clean = (merge_status == 0);
                } else if (S_ISGITLINK(a->mode)) {
 -                      result->clean = merge_submodule(&result->oid,
 +                      result->clean = merge_submodule(o, &result->oid,
                                                       one->path,
                                                       &one->oid,
                                                       &a->oid,
 -                                                     &b->oid,
 -                                                     !o->call_depth);
 +                                                     &b->oid);
                } else if (S_ISLNK(a->mode)) {
                        switch (o->recursive_variant) {
                        case MERGE_RECURSIVE_NORMAL:
                                break;
                        }
                } else
 -                      die("BUG: unsupported object type in the tree");
 +                      BUG("unsupported object type in the tree");
        }
  
 +      if (result->merge)
 +              output(o, 2, _("Auto-merging %s"), filename);
 +
        return 0;
  }
  
  static int merge_file_special_markers(struct merge_options *o,
 -                         const struct diff_filespec *one,
 -                         const struct diff_filespec *a,
 -                         const struct diff_filespec *b,
 -                         const char *branch1,
 -                         const char *filename1,
 -                         const char *branch2,
 -                         const char *filename2,
 -                         struct merge_file_info *mfi)
 +                                    const struct diff_filespec *one,
 +                                    const struct diff_filespec *a,
 +                                    const struct diff_filespec *b,
 +                                    const char *target_filename,
 +                                    const char *branch1,
 +                                    const char *filename1,
 +                                    const char *branch2,
 +                                    const char *filename2,
 +                                    struct merge_file_info *mfi)
  {
        char *side1 = NULL;
        char *side2 = NULL;
        if (filename2)
                side2 = xstrfmt("%s:%s", branch2, filename2);
  
 -      ret = merge_file_1(o, one, a, b,
 +      ret = merge_file_1(o, one, a, b, target_filename,
                           side1 ? side1 : branch1,
                           side2 ? side2 : branch2, mfi);
 +
        free(side1);
        free(side2);
        return ret;
  }
  
  static int merge_file_one(struct merge_options *o,
 -                                       const char *path,
 -                                       const struct object_id *o_oid, int o_mode,
 -                                       const struct object_id *a_oid, int a_mode,
 -                                       const struct object_id *b_oid, int b_mode,
 -                                       const char *branch1,
 -                                       const char *branch2,
 -                                       struct merge_file_info *mfi)
 +                        const char *path,
 +                        const struct object_id *o_oid, int o_mode,
 +                        const struct object_id *a_oid, int a_mode,
 +                        const struct object_id *b_oid, int b_mode,
 +                        const char *branch1,
 +                        const char *branch2,
 +                        struct merge_file_info *mfi)
  {
        struct diff_filespec one, a, b;
  
        a.mode = a_mode;
        oidcpy(&b.oid, b_oid);
        b.mode = b_mode;
 -      return merge_file_1(o, &one, &a, &b, branch1, branch2, mfi);
 +      return merge_file_1(o, &one, &a, &b, path, branch1, branch2, mfi);
 +}
 +
 +static int conflict_rename_dir(struct merge_options *o,
 +                             struct diff_filepair *pair,
 +                             const char *rename_branch,
 +                             const char *other_branch)
 +{
 +      const struct diff_filespec *dest = pair->two;
 +
 +      if (!o->call_depth && would_lose_untracked(dest->path)) {
 +              char *alt_path = unique_path(o, dest->path, rename_branch);
 +
 +              output(o, 1, _("Error: Refusing to lose untracked file at %s; "
 +                             "writing to %s instead."),
 +                     dest->path, alt_path);
 +              /*
 +               * Write the file in worktree at alt_path, but not in the
 +               * index.  Instead, write to dest->path for the index but
 +               * only at the higher appropriate stage.
 +               */
 +              if (update_file(o, 0, &dest->oid, dest->mode, alt_path))
 +                      return -1;
 +              free(alt_path);
 +              return update_stages(o, dest->path, NULL,
 +                                   rename_branch == o->branch1 ? dest : NULL,
 +                                   rename_branch == o->branch1 ? NULL : dest);
 +      }
 +
 +      /* Update dest->path both in index and in worktree */
 +      if (update_file(o, 1, &dest->oid, dest->mode, dest->path))
 +              return -1;
 +      return 0;
  }
  
  static int handle_change_delete(struct merge_options *o,
        const char *update_path = path;
        int ret = 0;
  
 -      if (dir_in_way(path, !o->call_depth, 0)) {
 +      if (dir_in_way(path, !o->call_depth, 0) ||
 +          (!o->call_depth && would_lose_untracked(path))) {
                update_path = alt_path = unique_path(o, path, change_branch);
        }
  
@@@ -1571,34 -1244,17 +1573,34 @@@ static int handle_file(struct merge_opt
  
        add = filespec_from_entry(&other, dst_entry, stage ^ 1);
        if (add) {
 +              int ren_src_was_dirty = was_dirty(o, rename->path);
                char *add_name = unique_path(o, rename->path, other_branch);
                if (update_file(o, 0, &add->oid, add->mode, add_name))
                        return -1;
  
 -              remove_file(o, 0, rename->path, 0);
 +              if (ren_src_was_dirty) {
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             rename->path);
 +              }
 +              /*
 +               * Because the double negatives somehow keep confusing me...
 +               *    1) update_wd iff !ren_src_was_dirty.
 +               *    2) no_wd iff !update_wd
 +               *    3) so, no_wd == !!ren_src_was_dirty == ren_src_was_dirty
 +               */
 +              remove_file(o, 0, rename->path, ren_src_was_dirty);
                dst_name = unique_path(o, rename->path, cur_branch);
        } else {
                if (dir_in_way(rename->path, !o->call_depth, 0)) {
                        dst_name = unique_path(o, rename->path, cur_branch);
                        output(o, 1, _("%s is a directory in %s adding as %s instead"),
                               rename->path, other_branch, dst_name);
 +              } else if (!o->call_depth &&
 +                         would_lose_untracked(rename->path)) {
 +                      dst_name = unique_path(o, rename->path, cur_branch);
 +                      output(o, 1, _("Refusing to lose untracked file at %s; "
 +                                     "adding as %s instead"),
 +                             rename->path, dst_name);
                }
        }
        if ((ret = update_file(o, 0, &rename->oid, rename->mode, dst_name)))
@@@ -1685,8 -1341,6 +1687,8 @@@ static int conflict_rename_rename_2to1(
        struct diff_filespec *c1 = ci->pair1->two;
        struct diff_filespec *c2 = ci->pair2->two;
        char *path = c1->path; /* == c2->path */
 +      char *path_side_1_desc;
 +      char *path_side_2_desc;
        struct merge_file_info mfi_c1;
        struct merge_file_info mfi_c2;
        int ret;
        remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
        remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
  
 +      path_side_1_desc = xstrfmt("%s (was %s)", path, a->path);
 +      path_side_2_desc = xstrfmt("%s (was %s)", path, b->path);
        if (merge_file_special_markers(o, a, c1, &ci->ren1_other,
 +                                     path_side_1_desc,
                                       o->branch1, c1->path,
                                       o->branch2, ci->ren1_other.path, &mfi_c1) ||
            merge_file_special_markers(o, b, &ci->ren2_other, c2,
 +                                     path_side_2_desc,
                                       o->branch1, ci->ren2_other.path,
                                       o->branch2, c2->path, &mfi_c2))
                return -1;
 +      free(path_side_1_desc);
 +      free(path_side_2_desc);
  
        if (o->call_depth) {
                /*
                char *new_path2 = unique_path(o, path, ci->branch2);
                output(o, 1, _("Renaming %s to %s and %s to %s instead"),
                       a->path, new_path1, b->path, new_path2);
 -              remove_file(o, 0, path, 0);
 +              if (was_dirty(o, path))
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             path);
 +              else if (would_lose_untracked(path))
 +                      /*
 +                       * Only way we get here is if both renames were from
 +                       * a directory rename AND user had an untracked file
 +                       * at the location where both files end up after the
 +                       * two directory renames.  See testcase 10d of t6043.
 +                       */
 +                      output(o, 1, _("Refusing to lose untracked file at "
 +                                     "%s, even though it's in the way."),
 +                             path);
 +              else
 +                      remove_file(o, 0, path, 0);
                ret = update_file(o, 0, &mfi_c1.oid, mfi_c1.mode, new_path1);
                if (!ret)
                        ret = update_file(o, 0, &mfi_c2.oid, mfi_c2.mode,
                                          new_path2);
 +              /*
 +               * unpack_trees() actually populates the index for us for
 +               * "normal" rename/rename(2to1) situtations so that the
 +               * correct entries are at the higher stages, which would
 +               * make the call below to update_stages_for_stage_data
 +               * unnecessary.  However, if either of the renames came
 +               * from a directory rename, then unpack_trees() will not
 +               * have gotten the right data loaded into the index, so we
 +               * need to do so now.  (While it'd be tempting to move this
 +               * call to update_stages_for_stage_data() to
 +               * apply_directory_rename_modifications(), that would break
 +               * our intermediate calls to would_lose_untracked() since
 +               * those rely on the current in-memory index.  See also the
 +               * big "NOTE" in update_stages()).
 +               */
 +              if (update_stages_for_stage_data(o, path, ci->dst_entry1))
 +                      ret = -1;
 +
                free(new_path2);
                free(new_path1);
        }
        return ret;
  }
  
 -static int process_renames(struct merge_options *o,
 -                         struct string_list *a_renames,
 -                         struct string_list *b_renames)
 +/*
 + * Get the diff_filepairs changed between o_tree and tree.
 + */
 +static struct diff_queue_struct *get_diffpairs(struct merge_options *o,
 +                                             struct tree *o_tree,
 +                                             struct tree *tree)
  {
 -      int clean_merge = 1, i, j;
 -      struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 -      struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
 -      const struct rename *sre;
 +      struct diff_queue_struct *ret;
 +      struct diff_options opts;
  
 -      for (i = 0; i < a_renames->nr; i++) {
 -              sre = a_renames->items[i].util;
 -              string_list_insert(&a_by_dst, sre->pair->two->path)->util
 -                      = (void *)sre;
 -      }
 -      for (i = 0; i < b_renames->nr; i++) {
 -              sre = b_renames->items[i].util;
 -              string_list_insert(&b_by_dst, sre->pair->two->path)->util
 -                      = (void *)sre;
 -      }
 +      diff_setup(&opts);
 +      opts.flags.recursive = 1;
 +      opts.flags.rename_empty = 0;
 +      opts.detect_rename = merge_detect_rename(o);
 +      /*
 +       * We do not have logic to handle the detection of copies.  In
 +       * fact, it may not even make sense to add such logic: would we
 +       * really want a change to a base file to be propagated through
 +       * multiple other files by a merge?
 +       */
 +      if (opts.detect_rename > DIFF_DETECT_RENAME)
 +              opts.detect_rename = DIFF_DETECT_RENAME;
 +      opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 +                          o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 +                          1000;
 +      opts.rename_score = o->rename_score;
 +      opts.show_rename_progress = o->show_rename_progress;
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_setup_done(&opts);
 +      diff_tree_oid(&o_tree->object.oid, &tree->object.oid, "", &opts);
 +      diffcore_std(&opts);
 +      if (opts.needed_rename_limit > o->needed_rename_limit)
 +              o->needed_rename_limit = opts.needed_rename_limit;
 +
 +      ret = xmalloc(sizeof(*ret));
 +      *ret = diff_queued_diff;
 +
 +      opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 +      diff_queued_diff.nr = 0;
 +      diff_queued_diff.queue = NULL;
 +      diff_flush(&opts);
 +      return ret;
 +}
 +
 +static int tree_has_path(struct tree *tree, const char *path)
 +{
 +      struct object_id hashy;
 +      unsigned int mode_o;
 +
 +      return !get_tree_entry(&tree->object.oid, path,
 +                             &hashy, &mode_o);
 +}
 +
 +/*
 + * Return a new string that replaces the beginning portion (which matches
 + * entry->dir), with entry->new_dir.  In perl-speak:
 + *   new_path_name = (old_path =~ s/entry->dir/entry->new_dir/);
 + * NOTE:
 + *   Caller must ensure that old_path starts with entry->dir + '/'.
 + */
 +static char *apply_dir_rename(struct dir_rename_entry *entry,
 +                            const char *old_path)
 +{
 +      struct strbuf new_path = STRBUF_INIT;
 +      int oldlen, newlen;
 +
 +      if (entry->non_unique_new_dir)
 +              return NULL;
 +
 +      oldlen = strlen(entry->dir);
 +      newlen = entry->new_dir.len + (strlen(old_path) - oldlen) + 1;
 +      strbuf_grow(&new_path, newlen);
 +      strbuf_addbuf(&new_path, &entry->new_dir);
 +      strbuf_addstr(&new_path, &old_path[oldlen]);
 +
 +      return strbuf_detach(&new_path, NULL);
 +}
 +
 +static void get_renamed_dir_portion(const char *old_path, const char *new_path,
 +                                  char **old_dir, char **new_dir)
 +{
 +      char *end_of_old, *end_of_new;
 +      int old_len, new_len;
 +
 +      *old_dir = NULL;
 +      *new_dir = NULL;
 +
 +      /*
 +       * For
 +       *    "a/b/c/d/e/foo.c" -> "a/b/some/thing/else/e/foo.c"
 +       * the "e/foo.c" part is the same, we just want to know that
 +       *    "a/b/c/d" was renamed to "a/b/some/thing/else"
 +       * so, for this example, this function returns "a/b/c/d" in
 +       * *old_dir and "a/b/some/thing/else" in *new_dir.
 +       *
 +       * Also, if the basename of the file changed, we don't care.  We
 +       * want to know which portion of the directory, if any, changed.
 +       */
 +      end_of_old = strrchr(old_path, '/');
 +      end_of_new = strrchr(new_path, '/');
 +
 +      if (end_of_old == NULL || end_of_new == NULL)
 +              return;
 +      while (*--end_of_new == *--end_of_old &&
 +             end_of_old != old_path &&
 +             end_of_new != new_path)
 +              ; /* Do nothing; all in the while loop */
 +      /*
 +       * We've found the first non-matching character in the directory
 +       * paths.  That means the current directory we were comparing
 +       * represents the rename.  Move end_of_old and end_of_new back
 +       * to the full directory name.
 +       */
 +      if (*end_of_old == '/')
 +              end_of_old++;
 +      if (*end_of_old != '/')
 +              end_of_new++;
 +      end_of_old = strchr(end_of_old, '/');
 +      end_of_new = strchr(end_of_new, '/');
 +
 +      /*
 +       * It may have been the case that old_path and new_path were the same
 +       * directory all along.  Don't claim a rename if they're the same.
 +       */
 +      old_len = end_of_old - old_path;
 +      new_len = end_of_new - new_path;
 +
 +      if (old_len != new_len || strncmp(old_path, new_path, old_len)) {
 +              *old_dir = xstrndup(old_path, old_len);
 +              *new_dir = xstrndup(new_path, new_len);
 +      }
 +}
 +
 +static void remove_hashmap_entries(struct hashmap *dir_renames,
 +                                 struct string_list *items_to_remove)
 +{
 +      int i;
 +      struct dir_rename_entry *entry;
 +
 +      for (i = 0; i < items_to_remove->nr; i++) {
 +              entry = items_to_remove->items[i].util;
 +              hashmap_remove(dir_renames, entry, NULL);
 +      }
 +      string_list_clear(items_to_remove, 0);
 +}
 +
 +/*
 + * See if there is a directory rename for path, and if there are any file
 + * level conflicts for the renamed location.  If there is a rename and
 + * there are no conflicts, return the new name.  Otherwise, return NULL.
 + */
 +static char *handle_path_level_conflicts(struct merge_options *o,
 +                                       const char *path,
 +                                       struct dir_rename_entry *entry,
 +                                       struct hashmap *collisions,
 +                                       struct tree *tree)
 +{
 +      char *new_path = NULL;
 +      struct collision_entry *collision_ent;
 +      int clean = 1;
 +      struct strbuf collision_paths = STRBUF_INIT;
 +
 +      /*
 +       * entry has the mapping of old directory name to new directory name
 +       * that we want to apply to path.
 +       */
 +      new_path = apply_dir_rename(entry, path);
 +
 +      if (!new_path) {
 +              /* This should only happen when entry->non_unique_new_dir set */
 +              if (!entry->non_unique_new_dir)
 +                      BUG("entry->non_unqiue_dir not set and !new_path");
 +              output(o, 1, _("CONFLICT (directory rename split): "
 +                             "Unclear where to place %s because directory "
 +                             "%s was renamed to multiple other directories, "
 +                             "with no destination getting a majority of the "
 +                             "files."),
 +                     path, entry->dir);
 +              clean = 0;
 +              return NULL;
 +      }
 +
 +      /*
 +       * The caller needs to have ensured that it has pre-populated
 +       * collisions with all paths that map to new_path.  Do a quick check
 +       * to ensure that's the case.
 +       */
 +      collision_ent = collision_find_entry(collisions, new_path);
 +      if (collision_ent == NULL)
 +              BUG("collision_ent is NULL");
 +
 +      /*
 +       * Check for one-sided add/add/.../add conflicts, i.e.
 +       * where implicit renames from the other side doing
 +       * directory rename(s) can affect this side of history
 +       * to put multiple paths into the same location.  Warn
 +       * and bail on directory renames for such paths.
 +       */
 +      if (collision_ent->reported_already) {
 +              clean = 0;
 +      } else if (tree_has_path(tree, new_path)) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Existing "
 +                             "file/dir at %s in the way of implicit "
 +                             "directory rename(s) putting the following "
 +                             "path(s) there: %s."),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      } else if (collision_ent->source_files.nr > 1) {
 +              collision_ent->reported_already = 1;
 +              strbuf_add_separated_string_list(&collision_paths, ", ",
 +                                               &collision_ent->source_files);
 +              output(o, 1, _("CONFLICT (implicit dir rename): Cannot map "
 +                             "more than one path to %s; implicit directory "
 +                             "renames tried to put these paths there: %s"),
 +                     new_path, collision_paths.buf);
 +              clean = 0;
 +      }
 +
 +      /* Free memory we no longer need */
 +      strbuf_release(&collision_paths);
 +      if (!clean && new_path) {
 +              free(new_path);
 +              return NULL;
 +      }
 +
 +      return new_path;
 +}
 +
 +/*
 + * There are a couple things we want to do at the directory level:
 + *   1. Check for both sides renaming to the same thing, in order to avoid
 + *      implicit renaming of files that should be left in place.  (See
 + *      testcase 6b in t6043 for details.)
 + *   2. Prune directory renames if there are still files left in the
 + *      the original directory.  These represent a partial directory rename,
 + *      i.e. a rename where only some of the files within the directory
 + *      were renamed elsewhere.  (Technically, this could be done earlier
 + *      in get_directory_renames(), except that would prevent us from
 + *      doing the previous check and thus failing testcase 6b.)
 + *   3. Check for rename/rename(1to2) conflicts (at the directory level).
 + *      In the future, we could potentially record this info as well and
 + *      omit reporting rename/rename(1to2) conflicts for each path within
 + *      the affected directories, thus cleaning up the merge output.
 + *   NOTE: We do NOT check for rename/rename(2to1) conflicts at the
 + *         directory level, because merging directories is fine.  If it
 + *         causes conflicts for files within those merged directories, then
 + *         that should be detected at the individual path level.
 + */
 +static void handle_directory_level_conflicts(struct merge_options *o,
 +                                           struct hashmap *dir_re_head,
 +                                           struct tree *head,
 +                                           struct hashmap *dir_re_merge,
 +                                           struct tree *merge)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *head_ent;
 +      struct dir_rename_entry *merge_ent;
 +
 +      struct string_list remove_from_head = STRING_LIST_INIT_NODUP;
 +      struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
 +
 +      hashmap_iter_init(dir_re_head, &iter);
 +      while ((head_ent = hashmap_iter_next(&iter))) {
 +              merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
 +              if (merge_ent &&
 +                  !head_ent->non_unique_new_dir &&
 +                  !merge_ent->non_unique_new_dir &&
 +                  !strbuf_cmp(&head_ent->new_dir, &merge_ent->new_dir)) {
 +                      /* 1. Renamed identically; remove it from both sides */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              } else if (tree_has_path(head, head_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +
 +      hashmap_iter_init(dir_re_merge, &iter);
 +      while ((merge_ent = hashmap_iter_next(&iter))) {
 +              head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
 +              if (tree_has_path(merge, merge_ent->dir)) {
 +                      /* 2. This wasn't a directory rename after all */
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +              } else if (head_ent &&
 +                         !head_ent->non_unique_new_dir &&
 +                         !merge_ent->non_unique_new_dir) {
 +                      /* 3. rename/rename(1to2) */
 +                      /*
 +                       * We can assume it's not rename/rename(1to1) because
 +                       * that was case (1), already checked above.  So we
 +                       * know that head_ent->new_dir and merge_ent->new_dir
 +                       * are different strings.
 +                       */
 +                      output(o, 1, _("CONFLICT (rename/rename): "
 +                                     "Rename directory %s->%s in %s. "
 +                                     "Rename directory %s->%s in %s"),
 +                             head_ent->dir, head_ent->new_dir.buf, o->branch1,
 +                             head_ent->dir, merge_ent->new_dir.buf, o->branch2);
 +                      string_list_append(&remove_from_head,
 +                                         head_ent->dir)->util = head_ent;
 +                      strbuf_release(&head_ent->new_dir);
 +                      string_list_append(&remove_from_merge,
 +                                         merge_ent->dir)->util = merge_ent;
 +                      strbuf_release(&merge_ent->new_dir);
 +              }
 +      }
 +
 +      remove_hashmap_entries(dir_re_head, &remove_from_head);
 +      remove_hashmap_entries(dir_re_merge, &remove_from_merge);
 +}
 +
 +static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs,
 +                                           struct tree *tree)
 +{
 +      struct hashmap *dir_renames;
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *entry;
 +      int i;
 +
 +      /*
 +       * Typically, we think of a directory rename as all files from a
 +       * certain directory being moved to a target directory.  However,
 +       * what if someone first moved two files from the original
 +       * directory in one commit, and then renamed the directory
 +       * somewhere else in a later commit?  At merge time, we just know
 +       * that files from the original directory went to two different
 +       * places, and that the bulk of them ended up in the same place.
 +       * We want each directory rename to represent where the bulk of the
 +       * files from that directory end up; this function exists to find
 +       * where the bulk of the files went.
 +       *
 +       * The first loop below simply iterates through the list of file
 +       * renames, finding out how often each directory rename pair
 +       * possibility occurs.
 +       */
 +      dir_renames = xmalloc(sizeof(*dir_renames));
 +      dir_rename_init(dir_renames);
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              int *count;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *old_dir, *new_dir;
 +
 +              /* File not part of directory rename if it wasn't renamed */
 +              if (pair->status != 'R')
 +                      continue;
 +
 +              get_renamed_dir_portion(pair->one->path, pair->two->path,
 +                                      &old_dir,        &new_dir);
 +              if (!old_dir)
 +                      /* Directory didn't change at all; ignore this one. */
 +                      continue;
 +
 +              entry = dir_rename_find_entry(dir_renames, old_dir);
 +              if (!entry) {
 +                      entry = xmalloc(sizeof(*entry));
 +                      dir_rename_entry_init(entry, old_dir);
 +                      hashmap_put(dir_renames, entry);
 +              } else {
 +                      free(old_dir);
 +              }
 +              item = string_list_lookup(&entry->possible_new_dirs, new_dir);
 +              if (!item) {
 +                      item = string_list_insert(&entry->possible_new_dirs,
 +                                                new_dir);
 +                      item->util = xcalloc(1, sizeof(int));
 +              } else {
 +                      free(new_dir);
 +              }
 +              count = item->util;
 +              *count += 1;
 +      }
 +
 +      /*
 +       * For each directory with files moved out of it, we find out which
 +       * target directory received the most files so we can declare it to
 +       * be the "winning" target location for the directory rename.  This
 +       * winner gets recorded in new_dir.  If there is no winner
 +       * (multiple target directories received the same number of files),
 +       * we set non_unique_new_dir.  Once we've determined the winner (or
 +       * that there is no winner), we no longer need possible_new_dirs.
 +       */
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((entry = hashmap_iter_next(&iter))) {
 +              int max = 0;
 +              int bad_max = 0;
 +              char *best = NULL;
 +
 +              for (i = 0; i < entry->possible_new_dirs.nr; i++) {
 +                      int *count = entry->possible_new_dirs.items[i].util;
 +
 +                      if (*count == max)
 +                              bad_max = max;
 +                      else if (*count > max) {
 +                              max = *count;
 +                              best = entry->possible_new_dirs.items[i].string;
 +                      }
 +              }
 +              if (bad_max == max)
 +                      entry->non_unique_new_dir = 1;
 +              else {
 +                      assert(entry->new_dir.len == 0);
 +                      strbuf_addstr(&entry->new_dir, best);
 +              }
 +              /*
 +               * The relevant directory sub-portion of the original full
 +               * filepaths were xstrndup'ed before inserting into
 +               * possible_new_dirs, and instead of manually iterating the
 +               * list and free'ing each, just lie and tell
 +               * possible_new_dirs that it did the strdup'ing so that it
 +               * will free them for us.
 +               */
 +              entry->possible_new_dirs.strdup_strings = 1;
 +              string_list_clear(&entry->possible_new_dirs, 1);
 +      }
 +
 +      return dir_renames;
 +}
 +
 +static struct dir_rename_entry *check_dir_renamed(const char *path,
 +                                                struct hashmap *dir_renames)
 +{
 +      char *temp = xstrdup(path);
 +      char *end;
 +      struct dir_rename_entry *entry = NULL;;
 +
 +      while ((end = strrchr(temp, '/'))) {
 +              *end = '\0';
 +              entry = dir_rename_find_entry(dir_renames, temp);
 +              if (entry)
 +                      break;
 +      }
 +      free(temp);
 +      return entry;
 +}
 +
 +static void compute_collisions(struct hashmap *collisions,
 +                             struct hashmap *dir_renames,
 +                             struct diff_queue_struct *pairs)
 +{
 +      int i;
 +
 +      /*
 +       * Multiple files can be mapped to the same path due to directory
 +       * renames done by the other side of history.  Since that other
 +       * side of history could have merged multiple directories into one,
 +       * if our side of history added the same file basename to each of
 +       * those directories, then all N of them would get implicitly
 +       * renamed by the directory rename detection into the same path,
 +       * and we'd get an add/add/.../add conflict, and all those adds
 +       * from *this* side of history.  This is not representable in the
 +       * index, and users aren't going to easily be able to make sense of
 +       * it.  So we need to provide a good warning about what's
 +       * happening, and fall back to no-directory-rename detection
 +       * behavior for those paths.
 +       *
 +       * See testcases 9e and all of section 5 from t6043 for examples.
 +       */
 +      collision_init(collisions);
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct dir_rename_entry *dir_rename_ent;
 +              struct collision_entry *collision_ent;
 +              char *new_path;
 +              struct diff_filepair *pair = pairs->queue[i];
 +
 +              if (pair->status != 'A' && pair->status != 'R')
 +                      continue;
 +              dir_rename_ent = check_dir_renamed(pair->two->path,
 +                                                 dir_renames);
 +              if (!dir_rename_ent)
 +                      continue;
 +
 +              new_path = apply_dir_rename(dir_rename_ent, pair->two->path);
 +              if (!new_path)
 +                      /*
 +                       * dir_rename_ent->non_unique_new_path is true, which
 +                       * means there is no directory rename for us to use,
 +                       * which means it won't cause us any additional
 +                       * collisions.
 +                       */
 +                      continue;
 +              collision_ent = collision_find_entry(collisions, new_path);
 +              if (!collision_ent) {
 +                      collision_ent = xcalloc(1,
 +                                              sizeof(struct collision_entry));
 +                      hashmap_entry_init(collision_ent, strhash(new_path));
 +                      hashmap_put(collisions, collision_ent);
 +                      collision_ent->target_file = new_path;
 +              } else {
 +                      free(new_path);
 +              }
 +              string_list_insert(&collision_ent->source_files,
 +                                 pair->two->path);
 +      }
 +}
 +
 +static char *check_for_directory_rename(struct merge_options *o,
 +                                      const char *path,
 +                                      struct tree *tree,
 +                                      struct hashmap *dir_renames,
 +                                      struct hashmap *dir_rename_exclusions,
 +                                      struct hashmap *collisions,
 +                                      int *clean_merge)
 +{
 +      char *new_path = NULL;
 +      struct dir_rename_entry *entry = check_dir_renamed(path, dir_renames);
 +      struct dir_rename_entry *oentry = NULL;
 +
 +      if (!entry)
 +              return new_path;
 +
 +      /*
 +       * This next part is a little weird.  We do not want to do an
 +       * implicit rename into a directory we renamed on our side, because
 +       * that will result in a spurious rename/rename(1to2) conflict.  An
 +       * example:
 +       *   Base commit: dumbdir/afile, otherdir/bfile
 +       *   Side 1:      smrtdir/afile, otherdir/bfile
 +       *   Side 2:      dumbdir/afile, dumbdir/bfile
 +       * Here, while working on Side 1, we could notice that otherdir was
 +       * renamed/merged to dumbdir, and change the diff_filepair for
 +       * otherdir/bfile into a rename into dumbdir/bfile.  However, Side
 +       * 2 will notice the rename from dumbdir to smrtdir, and do the
 +       * transitive rename to move it from dumbdir/bfile to
 +       * smrtdir/bfile.  That gives us bfile in dumbdir vs being in
 +       * smrtdir, a rename/rename(1to2) conflict.  We really just want
 +       * the file to end up in smrtdir.  And the way to achieve that is
 +       * to not let Side1 do the rename to dumbdir, since we know that is
 +       * the source of one of our directory renames.
 +       *
 +       * That's why oentry and dir_rename_exclusions is here.
 +       *
 +       * As it turns out, this also prevents N-way transient rename
 +       * confusion; See testcases 9c and 9d of t6043.
 +       */
 +      oentry = dir_rename_find_entry(dir_rename_exclusions, entry->new_dir.buf);
 +      if (oentry) {
 +              output(o, 1, _("WARNING: Avoiding applying %s -> %s rename "
 +                             "to %s, because %s itself was renamed."),
 +                     entry->dir, entry->new_dir.buf, path, entry->new_dir.buf);
 +      } else {
 +              new_path = handle_path_level_conflicts(o, path, entry,
 +                                                     collisions, tree);
 +              *clean_merge &= (new_path != NULL);
 +      }
 +
 +      return new_path;
 +}
 +
 +static void apply_directory_rename_modifications(struct merge_options *o,
 +                                               struct diff_filepair *pair,
 +                                               char *new_path,
 +                                               struct rename *re,
 +                                               struct tree *tree,
 +                                               struct tree *o_tree,
 +                                               struct tree *a_tree,
 +                                               struct tree *b_tree,
 +                                               struct string_list *entries,
 +                                               int *clean)
 +{
 +      struct string_list_item *item;
 +      int stage = (tree == a_tree ? 2 : 3);
 +      int update_wd;
 +
 +      /*
 +       * In all cases where we can do directory rename detection,
 +       * unpack_trees() will have read pair->two->path into the
 +       * index and the working copy.  We need to remove it so that
 +       * we can instead place it at new_path.  It is guaranteed to
 +       * not be untracked (unpack_trees() would have errored out
 +       * saying the file would have been overwritten), but it might
 +       * be dirty, though.
 +       */
 +      update_wd = !was_dirty(o, pair->two->path);
 +      if (!update_wd)
 +              output(o, 1, _("Refusing to lose dirty file at %s"),
 +                     pair->two->path);
 +      remove_file(o, 1, pair->two->path, !update_wd);
 +
 +      /* Find or create a new re->dst_entry */
 +      item = string_list_lookup(entries, new_path);
 +      if (item) {
 +              /*
 +               * Since we're renaming on this side of history, and it's
 +               * due to a directory rename on the other side of history
 +               * (which we only allow when the directory in question no
 +               * longer exists on the other side of history), the
 +               * original entry for re->dst_entry is no longer
 +               * necessary...
 +               */
 +              re->dst_entry->processed = 1;
 +
 +              /*
 +               * ...because we'll be using this new one.
 +               */
 +              re->dst_entry = item->util;
 +      } else {
 +              /*
 +               * re->dst_entry is for the before-dir-rename path, and we
 +               * need it to hold information for the after-dir-rename
 +               * path.  Before creating a new entry, we need to mark the
 +               * old one as unnecessary (...unless it is shared by
 +               * src_entry, i.e. this didn't use to be a rename, in which
 +               * case we can just allow the normal processing to happen
 +               * for it).
 +               */
 +              if (pair->status == 'R')
 +                      re->dst_entry->processed = 1;
 +
 +              re->dst_entry = insert_stage_data(new_path,
 +                                                o_tree, a_tree, b_tree,
 +                                                entries);
 +              item = string_list_insert(entries, new_path);
 +              item->util = re->dst_entry;
 +      }
 +
 +      /*
 +       * Update the stage_data with the information about the path we are
 +       * moving into place.  That slot will be empty and available for us
 +       * to write to because of the collision checks in
 +       * handle_path_level_conflicts().  In other words,
 +       * re->dst_entry->stages[stage].oid will be the null_oid, so it's
 +       * open for us to write to.
 +       *
 +       * It may be tempting to actually update the index at this point as
 +       * well, using update_stages_for_stage_data(), but as per the big
 +       * "NOTE" in update_stages(), doing so will modify the current
 +       * in-memory index which will break calls to would_lose_untracked()
 +       * that we need to make.  Instead, we need to just make sure that
 +       * the various conflict_rename_*() functions update the index
 +       * explicitly rather than relying on unpack_trees() to have done it.
 +       */
 +      get_tree_entry(&tree->object.oid,
 +                     pair->two->path,
 +                     &re->dst_entry->stages[stage].oid,
 +                     &re->dst_entry->stages[stage].mode);
 +
 +      /* Update pair status */
 +      if (pair->status == 'A') {
 +              /*
 +               * Recording rename information for this add makes it look
 +               * like a rename/delete conflict.  Make sure we can
 +               * correctly handle this as an add that was moved to a new
 +               * directory instead of reporting a rename/delete conflict.
 +               */
 +              re->add_turned_into_rename = 1;
 +      }
 +      /*
 +       * We don't actually look at pair->status again, but it seems
 +       * pedagogically correct to adjust it.
 +       */
 +      pair->status = 'R';
 +
 +      /*
 +       * Finally, record the new location.
 +       */
 +      pair->two->path = new_path;
 +}
 +
 +/*
 + * Get information of all renames which occurred in 'pairs', making use of
 + * any implicit directory renames inferred from the other side of history.
 + * We need the three trees in the merge ('o_tree', 'a_tree' and 'b_tree')
 + * to be able to associate the correct cache entries with the rename
 + * information; tree is always equal to either a_tree or b_tree.
 + */
 +static struct string_list *get_renames(struct merge_options *o,
 +                                     struct diff_queue_struct *pairs,
 +                                     struct hashmap *dir_renames,
 +                                     struct hashmap *dir_rename_exclusions,
 +                                     struct tree *tree,
 +                                     struct tree *o_tree,
 +                                     struct tree *a_tree,
 +                                     struct tree *b_tree,
 +                                     struct string_list *entries,
 +                                     int *clean_merge)
 +{
 +      int i;
 +      struct hashmap collisions;
 +      struct hashmap_iter iter;
 +      struct collision_entry *e;
 +      struct string_list *renames;
 +
 +      compute_collisions(&collisions, dir_renames, pairs);
 +      renames = xcalloc(1, sizeof(struct string_list));
 +
 +      for (i = 0; i < pairs->nr; ++i) {
 +              struct string_list_item *item;
 +              struct rename *re;
 +              struct diff_filepair *pair = pairs->queue[i];
 +              char *new_path; /* non-NULL only with directory renames */
 +
 +              if (pair->status != 'A' && pair->status != 'R') {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +              new_path = check_for_directory_rename(o, pair->two->path, tree,
 +                                                    dir_renames,
 +                                                    dir_rename_exclusions,
 +                                                    &collisions,
 +                                                    clean_merge);
 +              if (pair->status != 'R' && !new_path) {
 +                      diff_free_filepair(pair);
 +                      continue;
 +              }
 +
 +              re = xmalloc(sizeof(*re));
 +              re->processed = 0;
 +              re->add_turned_into_rename = 0;
 +              re->pair = pair;
 +              item = string_list_lookup(entries, re->pair->one->path);
 +              if (!item)
 +                      re->src_entry = insert_stage_data(re->pair->one->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->src_entry = item->util;
 +
 +              item = string_list_lookup(entries, re->pair->two->path);
 +              if (!item)
 +                      re->dst_entry = insert_stage_data(re->pair->two->path,
 +                                      o_tree, a_tree, b_tree, entries);
 +              else
 +                      re->dst_entry = item->util;
 +              item = string_list_insert(renames, pair->one->path);
 +              item->util = re;
 +              if (new_path)
 +                      apply_directory_rename_modifications(o, pair, new_path,
 +                                                           re, tree, o_tree,
 +                                                           a_tree, b_tree,
 +                                                           entries,
 +                                                           clean_merge);
 +      }
 +
 +      hashmap_iter_init(&collisions, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->target_file);
 +              string_list_clear(&e->source_files, 0);
 +      }
 +      hashmap_free(&collisions, 1);
 +      return renames;
 +}
 +
 +static int process_renames(struct merge_options *o,
 +                         struct string_list *a_renames,
 +                         struct string_list *b_renames)
 +{
 +      int clean_merge = 1, i, j;
 +      struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 +      struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
 +      const struct rename *sre;
 +
 +      for (i = 0; i < a_renames->nr; i++) {
 +              sre = a_renames->items[i].util;
 +              string_list_insert(&a_by_dst, sre->pair->two->path)->util
 +                      = (void *)sre;
 +      }
 +      for (i = 0; i < b_renames->nr; i++) {
 +              sre = b_renames->items[i].util;
 +              string_list_insert(&b_by_dst, sre->pair->two->path)->util
 +                      = (void *)sre;
 +      }
  
        for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
                struct string_list *renames1, *renames2Dst;
                        const char *ren2_dst = ren2->pair->two->path;
                        enum rename_type rename_type;
                        if (strcmp(ren1_src, ren2_src) != 0)
 -                              die("BUG: ren1_src != ren2_src");
 +                              BUG("ren1_src != ren2_src");
                        ren2->dst_entry->processed = 1;
                        ren2->processed = 1;
                        if (strcmp(ren1_dst, ren2_dst) != 0) {
                        ren2 = lookup->util;
                        ren2_dst = ren2->pair->two->path;
                        if (strcmp(ren1_dst, ren2_dst) != 0)
 -                              die("BUG: ren1_dst != ren2_dst");
 +                              BUG("ren1_dst != ren2_dst");
  
                        clean_merge = 0;
                        ren2->processed = 1;
                         * add-source case).
                         */
                        remove_file(o, 1, ren1_src,
 -                                  renamed_stage == 2 || !was_tracked(ren1_src));
 +                                  renamed_stage == 2 || !was_tracked(o, ren1_src));
  
                        oidcpy(&src_other.oid,
                               &ren1->src_entry->stages[other_stage].oid);
                        dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
                        try_merge = 0;
  
 -                      if (oid_eq(&src_other.oid, &null_oid)) {
 +                      if (oid_eq(&src_other.oid, &null_oid) &&
 +                          ren1->add_turned_into_rename) {
 +                              setup_rename_conflict_info(RENAME_DIR,
 +                                                         ren1->pair,
 +                                                         NULL,
 +                                                         branch1,
 +                                                         branch2,
 +                                                         ren1->dst_entry,
 +                                                         NULL,
 +                                                         o,
 +                                                         NULL,
 +                                                         NULL);
 +                      } else if (oid_eq(&src_other.oid, &null_oid)) {
                                setup_rename_conflict_info(RENAME_DELETE,
                                                           ren1->pair,
                                                           NULL,
@@@ -2799,105 -1647,6 +2801,105 @@@ cleanup_and_return
        return clean_merge;
  }
  
 +struct rename_info {
 +      struct string_list *head_renames;
 +      struct string_list *merge_renames;
 +};
 +
 +static void initial_cleanup_rename(struct diff_queue_struct *pairs,
 +                                 struct hashmap *dir_renames)
 +{
 +      struct hashmap_iter iter;
 +      struct dir_rename_entry *e;
 +
 +      hashmap_iter_init(dir_renames, &iter);
 +      while ((e = hashmap_iter_next(&iter))) {
 +              free(e->dir);
 +              strbuf_release(&e->new_dir);
 +              /* possible_new_dirs already cleared in get_directory_renames */
 +      }
 +      hashmap_free(dir_renames, 1);
 +      free(dir_renames);
 +
 +      free(pairs->queue);
 +      free(pairs);
 +}
 +
 +static int handle_renames(struct merge_options *o,
 +                        struct tree *common,
 +                        struct tree *head,
 +                        struct tree *merge,
 +                        struct string_list *entries,
 +                        struct rename_info *ri)
 +{
 +      struct diff_queue_struct *head_pairs, *merge_pairs;
 +      struct hashmap *dir_re_head, *dir_re_merge;
 +      int clean = 1;
 +
 +      ri->head_renames = NULL;
 +      ri->merge_renames = NULL;
 +
 +      if (!merge_detect_rename(o))
 +              return 1;
 +
 +      head_pairs = get_diffpairs(o, common, head);
 +      merge_pairs = get_diffpairs(o, common, merge);
 +
 +      dir_re_head = get_directory_renames(head_pairs, head);
 +      dir_re_merge = get_directory_renames(merge_pairs, merge);
 +
 +      handle_directory_level_conflicts(o,
 +                                       dir_re_head, head,
 +                                       dir_re_merge, merge);
 +
 +      ri->head_renames  = get_renames(o, head_pairs,
 +                                      dir_re_merge, dir_re_head, head,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      ri->merge_renames = get_renames(o, merge_pairs,
 +                                      dir_re_head, dir_re_merge, merge,
 +                                      common, head, merge, entries,
 +                                      &clean);
 +      if (clean < 0)
 +              goto cleanup;
 +      clean &= process_renames(o, ri->head_renames, ri->merge_renames);
 +
 +cleanup:
 +      /*
 +       * Some cleanup is deferred until cleanup_renames() because the
 +       * data structures are still needed and referenced in
 +       * process_entry().  But there are a few things we can free now.
 +       */
 +      initial_cleanup_rename(head_pairs, dir_re_head);
 +      initial_cleanup_rename(merge_pairs, dir_re_merge);
 +
 +      return clean;
 +}
 +
 +static void final_cleanup_rename(struct string_list *rename)
 +{
 +      const struct rename *re;
 +      int i;
 +
 +      if (rename == NULL)
 +              return;
 +
 +      for (i = 0; i < rename->nr; i++) {
 +              re = rename->items[i].util;
 +              diff_free_filepair(re->pair);
 +      }
 +      string_list_clear(rename, 1);
 +      free(rename);
 +}
 +
 +static void final_cleanup_renames(struct rename_info *re_info)
 +{
 +      final_cleanup_rename(re_info->head_renames);
 +      final_cleanup_rename(re_info->merge_renames);
 +}
 +
  static struct object_id *stage_oid(const struct object_id *oid, unsigned mode)
  {
        return (is_null_oid(oid) || mode == 0) ? NULL: (struct object_id *)oid;
@@@ -2988,7 -1737,6 +2990,7 @@@ static int handle_modify_delete(struct 
  
  static int merge_content(struct merge_options *o,
                         const char *path,
 +                       int is_dirty,
                         struct object_id *o_oid, int o_mode,
                         struct object_id *a_oid, int a_mode,
                         struct object_id *b_oid, int b_mode,
                               S_ISGITLINK(pair1->two->mode)))
                        df_conflict_remains = 1;
        }
 -      if (merge_file_special_markers(o, &one, &a, &b,
 +      if (merge_file_special_markers(o, &one, &a, &b, path,
                                       o->branch1, path1,
                                       o->branch2, path2, &mfi))
                return -1;
  
 -      if (mfi.clean && !df_conflict_remains &&
 -          oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
 -              int path_renamed_outside_HEAD;
 +      /*
 +       * We can skip updating the working tree file iff:
 +       *   a) The merge is clean
 +       *   b) The merge matches what was in HEAD (content, mode, pathname)
 +       *   c) The target path is usable (i.e. not involved in D/F conflict)
 +       */
 +      if (mfi.clean &&
 +          was_tracked_and_matches(o, path, &mfi.oid, mfi.mode) &&
 +          !df_conflict_remains) {
                output(o, 3, _("Skipped %s (merged same as existing)"), path);
 -              /*
 -               * The content merge resulted in the same file contents we
 -               * already had.  We can return early if those file contents
 -               * are recorded at the correct path (which may not be true
 -               * if the merge involves a rename).
 -               */
 -              path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
 -              if (!path_renamed_outside_HEAD) {
 -                      add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 -                                    0, (!o->call_depth), 0);
 -                      return mfi.clean;
 -              }
 -      } else
 -              output(o, 2, _("Auto-merging %s"), path);
 +              if (add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 +                                0, (!o->call_depth && !is_dirty), 0))
 +                      return -1;
 +              return mfi.clean;
 +      }
  
        if (!mfi.clean) {
                if (S_ISGITLINK(mfi.mode))
                                return -1;
        }
  
 -      if (df_conflict_remains) {
 +      if (df_conflict_remains || is_dirty) {
                char *new_path;
                if (o->call_depth) {
                        remove_file_from_cache(path);
                                if (update_stages(o, path, &one, &a, &b))
                                        return -1;
                        } else {
 -                              int file_from_stage2 = was_tracked(path);
 +                              int file_from_stage2 = was_tracked(o, path);
                                struct diff_filespec merged;
                                oidcpy(&merged.oid, &mfi.oid);
                                merged.mode = mfi.mode;
  
                }
                new_path = unique_path(o, path, rename_conflict_info->branch1);
 +              if (is_dirty) {
 +                      output(o, 1, _("Refusing to lose dirty file at %s"),
 +                             path);
 +              }
                output(o, 1, _("Adding as %s instead"), new_path);
                if (update_file(o, 0, &mfi.oid, mfi.mode, new_path)) {
                        free(new_path);
                mfi.clean = 0;
        } else if (update_file(o, mfi.clean, &mfi.oid, mfi.mode, path))
                return -1;
 -      return mfi.clean;
 +      return !is_dirty && mfi.clean;
 +}
 +
 +static int conflict_rename_normal(struct merge_options *o,
 +                                const char *path,
 +                                struct object_id *o_oid, unsigned int o_mode,
 +                                struct object_id *a_oid, unsigned int a_mode,
 +                                struct object_id *b_oid, unsigned int b_mode,
 +                                struct rename_conflict_info *ci)
 +{
 +      /* Merge the content and write it out */
 +      return merge_content(o, path, was_dirty(o, path),
 +                           o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 +                           ci);
  }
  
  /* Per entry merge function */
@@@ -3130,20 -1864,9 +3132,20 @@@ static int process_entry(struct merge_o
                switch (conflict_info->rename_type) {
                case RENAME_NORMAL:
                case RENAME_ONE_FILE_TO_ONE:
 -                      clean_merge = merge_content(o, path,
 -                                                  o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
 -                                                  conflict_info);
 +                      clean_merge = conflict_rename_normal(o,
 +                                                           path,
 +                                                           o_oid, o_mode,
 +                                                           a_oid, a_mode,
 +                                                           b_oid, b_mode,
 +                                                           conflict_info);
 +                      break;
 +              case RENAME_DIR:
 +                      clean_merge = 1;
 +                      if (conflict_rename_dir(o,
 +                                              conflict_info->pair1,
 +                                              conflict_info->branch1,
 +                                              conflict_info->branch2))
 +                              clean_merge = -1;
                        break;
                case RENAME_DELETE:
                        clean_merge = 0;
        } else if (a_oid && b_oid) {
                /* Case C: Added in both (check for same permissions) and */
                /* case D: Modified in both, but differently. */
 -              clean_merge = merge_content(o, path,
 +              int is_dirty = 0; /* unpack_trees would have bailed if dirty */
 +              clean_merge = merge_content(o, path, is_dirty,
                                            o_oid, o_mode, a_oid, a_mode, b_oid, b_mode,
                                            NULL);
        } else if (!o_oid && !a_oid && !b_oid) {
                 */
                remove_file(o, 1, path, !a_mode);
        } else
 -              die("BUG: fatal merge failure, shouldn't happen.");
 +              BUG("fatal merge failure, shouldn't happen.");
  
        return clean_merge;
  }
@@@ -3273,20 -1995,18 +3275,20 @@@ int merge_trees(struct merge_options *o
                return 1;
        }
  
 -      code = git_merge_trees(o->call_depth, common, head, merge);
 +      code = unpack_trees_start(o, common, head, merge);
  
        if (code != 0) {
                if (show(o, 4) || o->call_depth)
                        err(o, _("merging of trees %s and %s failed"),
                            oid_to_hex(&head->object.oid),
                            oid_to_hex(&merge->object.oid));
 +              unpack_trees_finish(o);
                return -1;
        }
  
        if (unmerged_cache()) {
 -              struct string_list *entries, *re_head, *re_merge;
 +              struct string_list *entries;
 +              struct rename_info re_info;
                int i;
                /*
                 * Only need the hashmap while processing entries, so
                get_files_dirs(o, merge);
  
                entries = get_unmerged();
 -              re_head  = get_renames(o, head, common, head, merge, entries);
 -              re_merge = get_renames(o, merge, common, head, merge, entries);
 -              clean = process_renames(o, re_head, re_merge);
 +              clean = handle_renames(o, common, head, merge, entries,
 +                                     &re_info);
                record_df_conflict_files(o, entries);
                if (clean < 0)
                        goto cleanup;
                for (i = 0; i < entries->nr; i++) {
                        struct stage_data *e = entries->items[i].util;
                        if (!e->processed)
 -                              die("BUG: unprocessed path??? %s",
 +                              BUG("unprocessed path??? %s",
                                    entries->items[i].string);
                }
  
  cleanup:
 -              string_list_clear(re_merge, 0);
 -              string_list_clear(re_head, 0);
 +              final_cleanup_renames(&re_info);
 +
                string_list_clear(entries, 1);
 +              free(entries);
  
                hashmap_free(&o->current_file_dir_set, 1);
  
 -              free(re_merge);
 -              free(re_head);
 -              free(entries);
 -
 -              if (clean < 0)
 +              if (clean < 0) {
 +                      unpack_trees_finish(o);
                        return clean;
 +              }
        }
        else
                clean = 1;
  
 +      unpack_trees_finish(o);
 +
        if (o->call_depth && !(*result = write_tree_from_memory(o)))
                return -1;
  
@@@ -3436,8 -2156,7 +3438,8 @@@ int merge_recursive(struct merge_option
                read_cache();
  
        o->ancestor = "merged common ancestors";
 -      clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
 +      clean = merge_trees(o, get_commit_tree(h1), get_commit_tree(h2),
 +                          get_commit_tree(merged_common_ancestors),
                            &mrtree);
        if (clean < 0) {
                flush_output(o);
@@@ -3515,18 -2234,9 +3517,18 @@@ int merge_recursive_generic(struct merg
  
  static void merge_recursive_config(struct merge_options *o)
  {
 +      char *value = NULL;
        git_config_get_int("merge.verbosity", &o->verbosity);
        git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
        git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
 +      if (!git_config_get_string("diff.renames", &value)) {
 +              o->diff_detect_rename = git_config_rename("diff.renames", value);
 +              free(value);
 +      }
 +      if (!git_config_get_string("merge.renames", &value)) {
 +              o->merge_detect_rename = git_config_rename("merge.renames", value);
 +              free(value);
 +      }
        git_config(git_xmerge_config, NULL);
  }
  
@@@ -3539,8 -2249,7 +3541,8 @@@ void init_merge_options(struct merge_op
        o->diff_rename_limit = -1;
        o->merge_rename_limit = -1;
        o->renormalize = 0;
 -      o->detect_rename = 1;
 +      o->diff_detect_rename = -1;
 +      o->merge_detect_rename = -1;
        merge_recursive_config(o);
        merge_verbosity = getenv("GIT_MERGE_VERBOSITY");
        if (merge_verbosity)
@@@ -3591,16 -2300,16 +3593,16 @@@ int parse_merge_opt(struct merge_option
        else if (!strcmp(s, "no-renormalize"))
                o->renormalize = 0;
        else if (!strcmp(s, "no-renames"))
 -              o->detect_rename = 0;
 +              o->merge_detect_rename = 0;
        else if (!strcmp(s, "find-renames")) {
 -              o->detect_rename = 1;
 +              o->merge_detect_rename = 1;
                o->rename_score = 0;
        }
        else if (skip_prefix(s, "find-renames=", &arg) ||
                 skip_prefix(s, "rename-threshold=", &arg)) {
                if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
                        return -1;
 -              o->detect_rename = 1;
 +              o->merge_detect_rename = 1;
        }
        else
                return -1;
diff --combined object.h
index 5c13955000cdaec252f29a3b93599560c35deb8a,caf36529f3698036504ee789a62a7cf5496e4eba..acc560b24e4ba57d820b61896ba07d4d3f640f33
+++ b/object.h
@@@ -25,6 -25,7 +25,6 @@@ struct object_array 
  
  #define OBJECT_ARRAY_INIT { 0, 0, NULL }
  
 -#define TYPE_BITS   3
  /*
   * object flag allocation:
   * revision.h:               0---------10                                26
@@@ -42,6 -43,7 +42,7 @@@
   * builtin/index-pack.c:                                     2021
   * builtin/pack-objects.c:                                   20
   * builtin/reflog.c:                   10--12
+  * builtin/show-branch.c:    0-------------------------------------------26
   * builtin/unpack-objects.c:                                 2021
   */
  #define FLAG_BITS  27
diff --combined revision.c
index 40fd91ff2b16bffc725f8602f45117279e27ba19,be8fe7d67b1ee417c310943ea04d88efa3072470..0afae4744a12b9b1bfd484c12440db82e19c8c9f
@@@ -29,6 -29,8 +29,8 @@@ volatile show_early_output_fn_t show_ea
  static const char *term_bad;
  static const char *term_good;
  
+ implement_shared_commit_slab(revision_sources, char *);
  void show_object_with_name(FILE *out, struct object *obj, const char *name)
  {
        const char *p;
@@@ -52,9 -54,12 +54,9 @@@ static void mark_tree_contents_unintere
  {
        struct tree_desc desc;
        struct name_entry entry;
 -      struct object *obj = &tree->object;
  
 -      if (!has_object_file(&obj->oid))
 +      if (parse_tree_gently(tree, 1) < 0)
                return;
 -      if (parse_tree(tree) < 0)
 -              die("bad tree %s", oid_to_hex(&obj->oid));
  
        init_tree_desc(&desc, tree->buffer, tree->size);
        while (tree_entry(&desc, &entry)) {
@@@ -92,63 -97,50 +94,63 @@@ void mark_tree_uninteresting(struct tre
        mark_tree_contents_uninteresting(tree);
  }
  
 -void mark_parents_uninteresting(struct commit *commit)
 +struct commit_stack {
 +      struct commit **items;
 +      size_t nr, alloc;
 +};
 +#define COMMIT_STACK_INIT { NULL, 0, 0 }
 +
 +static void commit_stack_push(struct commit_stack *stack, struct commit *commit)
  {
 -      struct commit_list *parents = NULL, *l;
 +      ALLOC_GROW(stack->items, stack->nr + 1, stack->alloc);
 +      stack->items[stack->nr++] = commit;
 +}
  
 -      for (l = commit->parents; l; l = l->next)
 -              commit_list_insert(l->item, &parents);
 +static struct commit *commit_stack_pop(struct commit_stack *stack)
 +{
 +      return stack->nr ? stack->items[--stack->nr] : NULL;
 +}
  
 -      while (parents) {
 -              struct commit *commit = pop_commit(&parents);
 +static void commit_stack_clear(struct commit_stack *stack)
 +{
 +      FREE_AND_NULL(stack->items);
 +      stack->nr = stack->alloc = 0;
 +}
  
 -              while (commit) {
 -                      /*
 -                       * A missing commit is ok iff its parent is marked
 -                       * uninteresting.
 -                       *
 -                       * We just mark such a thing parsed, so that when
 -                       * it is popped next time around, we won't be trying
 -                       * to parse it and get an error.
 -                       */
 -                      if (!commit->object.parsed &&
 -                          !has_object_file(&commit->object.oid))
 -                              commit->object.parsed = 1;
 +static void mark_one_parent_uninteresting(struct commit *commit,
 +                                        struct commit_stack *pending)
 +{
 +      struct commit_list *l;
  
 -                      if (commit->object.flags & UNINTERESTING)
 -                              break;
 +      if (commit->object.flags & UNINTERESTING)
 +              return;
 +      commit->object.flags |= UNINTERESTING;
 +
 +      /*
 +       * Normally we haven't parsed the parent
 +       * yet, so we won't have a parent of a parent
 +       * here. However, it may turn out that we've
 +       * reached this commit some other way (where it
 +       * wasn't uninteresting), in which case we need
 +       * to mark its parents recursively too..
 +       */
 +      for (l = commit->parents; l; l = l->next)
 +              commit_stack_push(pending, l->item);
 +}
  
 -                      commit->object.flags |= UNINTERESTING;
 +void mark_parents_uninteresting(struct commit *commit)
 +{
 +      struct commit_stack pending = COMMIT_STACK_INIT;
 +      struct commit_list *l;
  
 -                      /*
 -                       * Normally we haven't parsed the parent
 -                       * yet, so we won't have a parent of a parent
 -                       * here. However, it may turn out that we've
 -                       * reached this commit some other way (where it
 -                       * wasn't uninteresting), in which case we need
 -                       * to mark its parents recursively too..
 -                       */
 -                      if (!commit->parents)
 -                              break;
 +      for (l = commit->parents; l; l = l->next)
 +              mark_one_parent_uninteresting(l->item, &pending);
  
 -                      for (l = commit->parents->next; l; l = l->next)
 -                              commit_list_insert(l->item, &parents);
 -                      commit = commit->parents->item;
 -              }
 -      }
 +      while (pending.nr > 0)
 +              mark_one_parent_uninteresting(commit_stack_pop(&pending),
 +                                            &pending);
 +
 +      commit_stack_clear(&pending);
  }
  
  static void add_pending_object_with_path(struct rev_info *revs,
@@@ -265,14 -257,19 +267,19 @@@ static struct commit *handle_commit(str
         */
        if (object->type == OBJ_COMMIT) {
                struct commit *commit = (struct commit *)object;
                if (parse_commit(commit) < 0)
                        die("unable to parse commit %s", name);
                if (flags & UNINTERESTING) {
                        mark_parents_uninteresting(commit);
                        revs->limited = 1;
                }
-               if (revs->show_source && !commit->util)
-                       commit->util = xstrdup(name);
+               if (revs->sources) {
+                       char **slot = revision_sources_at(revs->sources, commit);
+                       if (!*slot)
+                               *slot = xstrdup(name);
+               }
                return commit;
        }
  
@@@ -451,8 -448,8 +458,8 @@@ static void file_change(struct diff_opt
  static int rev_compare_tree(struct rev_info *revs,
                            struct commit *parent, struct commit *commit)
  {
 -      struct tree *t1 = parent->tree;
 -      struct tree *t2 = commit->tree;
 +      struct tree *t1 = get_commit_tree(parent);
 +      struct tree *t2 = get_commit_tree(commit);
  
        if (!t1)
                return REV_TREE_NEW;
  static int rev_same_tree_as_empty(struct rev_info *revs, struct commit *commit)
  {
        int retval;
 -      struct tree *t1 = commit->tree;
 +      struct tree *t1 = get_commit_tree(commit);
  
        if (!t1)
                return 0;
@@@ -626,7 -623,7 +633,7 @@@ static void try_to_simplify_commit(stru
        if (!revs->prune)
                return;
  
 -      if (!commit->tree)
 +      if (!get_commit_tree(commit))
                return;
  
        if (!commit->parents) {
@@@ -824,8 -821,12 +831,12 @@@ static int add_parents_to_list(struct r
                        }
                        return -1;
                }
-               if (revs->show_source && !p->util)
-                       p->util = commit->util;
+               if (revs->sources) {
+                       char **slot = revision_sources_at(revs->sources, p);
+                       if (!*slot)
+                               *slot = *revision_sources_at(revs->sources, commit);
+               }
                p->object.flags |= left_flag;
                if (!(p->object.flags & SEEN)) {
                        p->object.flags |= SEEN;
@@@ -1762,7 -1763,6 +1773,7 @@@ static int handle_revision_opt(struct r
        const char *arg = argv[0];
        const char *optarg;
        int argcount;
 +      const unsigned hexsz = the_hash_algo->hexsz;
  
        /* pseudo revision arguments */
        if (!strcmp(arg, "--all") || !strcmp(arg, "--branches") ||
                revs->abbrev = strtoul(optarg, NULL, 10);
                if (revs->abbrev < MINIMUM_ABBREV)
                        revs->abbrev = MINIMUM_ABBREV;
 -              else if (revs->abbrev > 40)
 -                      revs->abbrev = 40;
 +              else if (revs->abbrev > hexsz)
 +                      revs->abbrev = hexsz;
        } else if (!strcmp(arg, "--abbrev-commit")) {
                revs->abbrev_commit = 1;
                revs->abbrev_commit_given = 1;
                revs->ignore_missing = 1;
        } else if (!strcmp(arg, "--exclude-promisor-objects")) {
                if (fetch_if_missing)
 -                      die("BUG: exclude_promisor_objects can only be used when fetch_if_missing is 0");
 +                      BUG("exclude_promisor_objects can only be used when fetch_if_missing is 0");
                revs->exclude_promisor_objects = 1;
        } else {
                int opts = diff_opt_parse(&revs->diffopt, argv, argc, revs->prefix);
@@@ -2185,7 -2185,7 +2196,7 @@@ static int handle_revision_pseudo_opt(c
                 * supported right now, so stick to single worktree.
                 */
                if (!revs->single_worktree)
 -                      die("BUG: --single-worktree cannot be used together with submodule");
 +                      BUG("--single-worktree cannot be used together with submodule");
                refs = get_submodule_ref_store(submodule);
        } else
                refs = get_main_ref_store(the_repository);
@@@ -3098,7 -3098,7 +3109,7 @@@ enum commit_action get_commit_action(st
  {
        if (commit->object.flags & SHOWN)
                return commit_ignore;
 -      if (revs->unpacked && has_sha1_pack(commit->object.oid.hash))
 +      if (revs->unpacked && has_object_pack(&commit->object.oid))
                return commit_ignore;
        if (commit->object.flags & UNINTERESTING)
                return commit_ignore;
diff --combined sequencer.c
index 4034c0461b5022dad01b25d824cdc4f47ee09d13,3b6d56d0856aa591ffdd703bb4d5e6f0bb6443fe..ee1f7b2df74572b1bff71436fa7961f47ac25378
  #include "hashmap.h"
  #include "notes-utils.h"
  #include "sigchain.h"
 +#include "unpack-trees.h"
 +#include "worktree.h"
 +#include "oidmap.h"
 +#include "oidset.h"
+ #include "commit-slab.h"
 +#include "alias.h"
  
  #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
  
@@@ -79,6 -75,13 +80,6 @@@ static GIT_PATH_FUNC(rebase_path_messag
   * previous commit and from the first squash/fixup commit are written
   * to it. The commit message for each subsequent squash/fixup commit
   * is appended to the file as it is processed.
 - *
 - * The first line of the file is of the form
 - *     # This is a combination of $count commits.
 - * where $count is the number of commits whose messages have been
 - * written to the file so far (including the initial "pick" commit).
 - * Each time that a commit message is processed, this line is read and
 - * updated. It is deleted just before the combined commit is made.
   */
  static GIT_PATH_FUNC(rebase_path_squash_msg, "rebase-merge/message-squash")
  /*
   * commit without opening the editor.)
   */
  static GIT_PATH_FUNC(rebase_path_fixup_msg, "rebase-merge/message-fixup")
 +/*
 + * This file contains the list fixup/squash commands that have been
 + * accumulated into message-fixup or message-squash so far.
 + */
 +static GIT_PATH_FUNC(rebase_path_current_fixups, "rebase-merge/current-fixups")
  /*
   * A script to set the GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
   * GIT_AUTHOR_DATE that will be used for the commit that is currently
@@@ -123,19 -121,6 +124,19 @@@ static GIT_PATH_FUNC(rebase_path_stoppe
  static GIT_PATH_FUNC(rebase_path_rewritten_list, "rebase-merge/rewritten-list")
  static GIT_PATH_FUNC(rebase_path_rewritten_pending,
        "rebase-merge/rewritten-pending")
 +
 +/*
 + * The path of the file containig the OID of the "squash onto" commit, i.e.
 + * the dummy commit used for `reset [new root]`.
 + */
 +static GIT_PATH_FUNC(rebase_path_squash_onto, "rebase-merge/squash-onto")
 +
 +/*
 + * The path of the file listing refs that need to be deleted after the rebase
 + * finishes. This is used by the `label` command to record the need for cleanup.
 + */
 +static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
 +
  /*
   * The following files are written by git-rebase just after parsing the
   * command-line (and are only consumed, not modified, by the sequencer).
@@@ -261,35 -246,18 +262,35 @@@ static const char *gpg_sign_opt_quoted(
  
  int sequencer_remove_state(struct replay_opts *opts)
  {
 -      struct strbuf dir = STRBUF_INIT;
 +      struct strbuf buf = STRBUF_INIT;
        int i;
  
 +      if (is_rebase_i(opts) &&
 +          strbuf_read_file(&buf, rebase_path_refs_to_delete(), 0) > 0) {
 +              char *p = buf.buf;
 +              while (*p) {
 +                      char *eol = strchr(p, '\n');
 +                      if (eol)
 +                              *eol = '\0';
 +                      if (delete_ref("(rebase -i) cleanup", p, NULL, 0) < 0)
 +                              warning(_("could not delete '%s'"), p);
 +                      if (!eol)
 +                              break;
 +                      p = eol + 1;
 +              }
 +      }
 +
        free(opts->gpg_sign);
        free(opts->strategy);
        for (i = 0; i < opts->xopts_nr; i++)
                free(opts->xopts[i]);
        free(opts->xopts);
 +      strbuf_release(&opts->current_fixups);
  
 -      strbuf_addstr(&dir, get_dir(opts));
 -      remove_dir_recursively(&dir, 0);
 -      strbuf_release(&dir);
 +      strbuf_reset(&buf);
 +      strbuf_addstr(&buf, get_dir(opts));
 +      remove_dir_recursively(&buf, 0);
 +      strbuf_release(&buf);
  
        return 0;
  }
@@@ -379,14 -347,12 +380,14 @@@ static int write_message(const void *bu
        if (msg_fd < 0)
                return error_errno(_("could not lock '%s'"), filename);
        if (write_in_full(msg_fd, buf, len) < 0) {
 +              error_errno(_("could not write to '%s'"), filename);
                rollback_lock_file(&msg_file);
 -              return error_errno(_("could not write to '%s'"), filename);
 +              return -1;
        }
        if (append_eol && write(msg_fd, "\n", 1) < 0) {
 +              error_errno(_("could not write eol to '%s'"), filename);
                rollback_lock_file(&msg_file);
 -              return error_errno(_("could not write eol to '%s'"), filename);
 +              return -1;
        }
        if (commit_lock_file(&msg_file) < 0)
                return error(_("failed to finalize '%s'"), filename);
@@@ -476,8 -442,7 +477,8 @@@ static int fast_forward_to(const struc
        transaction = ref_transaction_begin(&err);
        if (!transaction ||
            ref_transaction_update(transaction, "HEAD",
 -                                 to, unborn ? &null_oid : from,
 +                                 to, unborn && !is_rebase_i(opts) ?
 +                                 &null_oid : from,
                                   0, sb.buf, &err) ||
            ref_transaction_commit(transaction, &err)) {
                ref_transaction_free(transaction);
@@@ -536,8 -501,8 +537,8 @@@ static int do_recursive_merge(struct co
        o.show_rename_progress = 1;
  
        head_tree = parse_tree_indirect(head);
 -      next_tree = next ? next->tree : empty_tree();
 -      base_tree = base ? base->tree : empty_tree();
 +      next_tree = next ? get_commit_tree(next) : empty_tree();
 +      base_tree = base ? get_commit_tree(base) : empty_tree();
  
        for (xopt = opts->xopts; xopt != opts->xopts + opts->xopts_nr; xopt++)
                parse_merge_opt(&o, *xopt);
        return !clean;
  }
  
 +static struct object_id *get_cache_tree_oid(void)
 +{
 +      if (!active_cache_tree)
 +              active_cache_tree = cache_tree();
 +
 +      if (!cache_tree_fully_valid(active_cache_tree))
 +              if (cache_tree_update(&the_index, 0)) {
 +                      error(_("unable to update cache tree"));
 +                      return NULL;
 +              }
 +
 +      return &active_cache_tree->oid;
 +}
 +
  static int is_index_unchanged(void)
  {
 -      struct object_id head_oid;
 +      struct object_id head_oid, *cache_tree_oid;
        struct commit *head_commit;
  
        if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
        if (parse_commit(head_commit))
                return -1;
  
 -      if (!active_cache_tree)
 -              active_cache_tree = cache_tree();
 -
 -      if (!cache_tree_fully_valid(active_cache_tree))
 -              if (cache_tree_update(&the_index, 0))
 -                      return error(_("unable to update cache tree"));
 +      if (!(cache_tree_oid = get_cache_tree_oid()))
 +              return -1;
  
 -      return !oidcmp(&active_cache_tree->oid,
 -                     &head_commit->tree->object.oid);
 +      return !oidcmp(cache_tree_oid, get_commit_tree_oid(head_commit));
  }
  
  static int write_author_script(const char *message)
@@@ -699,52 -655,6 +700,52 @@@ static char *get_author(const char *mes
        return NULL;
  }
  
 +/* Read author-script and return an ident line (author <email> timestamp) */
 +static const char *read_author_ident(struct strbuf *buf)
 +{
 +      const char *keys[] = {
 +              "GIT_AUTHOR_NAME=", "GIT_AUTHOR_EMAIL=", "GIT_AUTHOR_DATE="
 +      };
 +      char *in, *out, *eol;
 +      int i = 0, len;
 +
 +      if (strbuf_read_file(buf, rebase_path_author_script(), 256) <= 0)
 +              return NULL;
 +
 +      /* dequote values and construct ident line in-place */
 +      for (in = out = buf->buf; i < 3 && in - buf->buf < buf->len; i++) {
 +              if (!skip_prefix(in, keys[i], (const char **)&in)) {
 +                      warning("could not parse '%s' (looking for '%s'",
 +                              rebase_path_author_script(), keys[i]);
 +                      return NULL;
 +              }
 +
 +              eol = strchrnul(in, '\n');
 +              *eol = '\0';
 +              sq_dequote(in);
 +              len = strlen(in);
 +
 +              if (i > 0) /* separate values by spaces */
 +                      *(out++) = ' ';
 +              if (i == 1) /* email needs to be surrounded by <...> */
 +                      *(out++) = '<';
 +              memmove(out, in, len);
 +              out += len;
 +              if (i == 1) /* email needs to be surrounded by <...> */
 +                      *(out++) = '>';
 +              in = eol + 1;
 +      }
 +
 +      if (i < 3) {
 +              warning("could not parse '%s' (looking for '%s')",
 +                      rebase_path_author_script(), keys[i]);
 +              return NULL;
 +      }
 +
 +      buf->len = out - buf->buf;
 +      return buf->buf;
 +}
 +
  static const char staged_changes_advice[] =
  N_("you have staged changes in your working tree\n"
  "If these changes are meant to be squashed into the previous commit, run:\n"
  #define AMEND_MSG   (1<<2)
  #define CLEANUP_MSG (1<<3)
  #define VERIFY_MSG  (1<<4)
 +#define CREATE_ROOT_COMMIT (1<<5)
  
  /*
   * If we are cherry-pick, and if the merge did not result in
@@@ -784,40 -693,6 +785,40 @@@ static int run_git_commit(const char *d
        struct child_process cmd = CHILD_PROCESS_INIT;
        const char *value;
  
 +      if ((flags & CREATE_ROOT_COMMIT) && !(flags & AMEND_MSG)) {
 +              struct strbuf msg = STRBUF_INIT, script = STRBUF_INIT;
 +              const char *author = is_rebase_i(opts) ?
 +                      read_author_ident(&script) : NULL;
 +              struct object_id root_commit, *cache_tree_oid;
 +              int res = 0;
 +
 +              if (!defmsg)
 +                      BUG("root commit without message");
 +
 +              if (!(cache_tree_oid = get_cache_tree_oid()))
 +                      res = -1;
 +
 +              if (!res)
 +                      res = strbuf_read_file(&msg, defmsg, 0);
 +
 +              if (res <= 0)
 +                      res = error_errno(_("could not read '%s'"), defmsg);
 +              else
 +                      res = commit_tree(msg.buf, msg.len, cache_tree_oid,
 +                                        NULL, &root_commit, author,
 +                                        opts->gpg_sign);
 +
 +              strbuf_release(&msg);
 +              strbuf_release(&script);
 +              if (!res) {
 +                      update_ref(NULL, "CHERRY_PICK_HEAD", &root_commit, NULL,
 +                                 REF_NO_DEREF, UPDATE_REFS_MSG_ON_ERR);
 +                      res = update_ref(NULL, "HEAD", &root_commit, NULL, 0,
 +                                       UPDATE_REFS_MSG_ON_ERR);
 +              }
 +              return res < 0 ? error(_("writing root commit")) : 0;
 +      }
 +
        cmd.git_cmd = 1;
  
        if (is_rebase_i(opts)) {
                argv_array_pushf(&cmd.args, "-S%s", opts->gpg_sign);
        if (defmsg)
                argv_array_pushl(&cmd.args, "-F", defmsg, NULL);
 +      else if (!(flags & EDIT_MSG))
 +              argv_array_pushl(&cmd.args, "-C", "HEAD", NULL);
        if ((flags & CLEANUP_MSG))
                argv_array_push(&cmd.args, "--cleanup=strip");
        if ((flags & EDIT_MSG))
@@@ -1247,8 -1120,8 +1248,8 @@@ static int try_to_commit(struct strbuf 
        }
  
        if (!(flags & ALLOW_EMPTY) && !oidcmp(current_head ?
 -                                            &current_head->tree->object.oid :
 -                                            &empty_tree_oid, &tree)) {
 +                                            get_commit_tree_oid(current_head) :
 +                                            the_hash_algo->empty_tree, &tree)) {
                res = 1; /* run 'git commit' to display error message */
                goto out;
        }
@@@ -1308,8 -1181,7 +1309,8 @@@ static int do_commit(const char *msg_fi
  {
        int res = 1;
  
 -      if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG)) {
 +      if (!(flags & EDIT_MSG) && !(flags & VERIFY_MSG) &&
 +          !(flags & CREATE_ROOT_COMMIT)) {
                struct object_id oid;
                struct strbuf sb = STRBUF_INIT;
  
@@@ -1348,12 -1220,12 +1349,12 @@@ static int is_original_commit_empty(str
                if (parse_commit(parent))
                        return error(_("could not parse parent commit %s"),
                                oid_to_hex(&parent->object.oid));
 -              ptree_oid = &parent->tree->object.oid;
 +              ptree_oid = get_commit_tree_oid(parent);
        } else {
                ptree_oid = the_hash_algo->empty_tree; /* commit is root */
        }
  
 -      return !oidcmp(ptree_oid, &commit->tree->object.oid);
 +      return !oidcmp(ptree_oid, get_commit_tree_oid(commit));
  }
  
  /*
@@@ -1409,9 -1281,6 +1410,9 @@@ enum todo_command 
        TODO_SQUASH,
        /* commands that do something else than handling a single commit */
        TODO_EXEC,
 +      TODO_LABEL,
 +      TODO_RESET,
 +      TODO_MERGE,
        /* commands that do nothing but are counted for reporting progress */
        TODO_NOOP,
        TODO_DROP,
@@@ -1430,9 -1299,6 +1431,9 @@@ static struct 
        { 'f', "fixup" },
        { 's', "squash" },
        { 'x', "exec" },
 +      { 'l', "label" },
 +      { 't', "reset" },
 +      { 'm', "merge" },
        { 0,   "noop" },
        { 'd', "drop" },
        { 0,   NULL }
@@@ -1462,43 -1328,38 +1463,43 @@@ static int is_fixup(enum todo_command c
        return command == TODO_FIXUP || command == TODO_SQUASH;
  }
  
 +/* Does this command create a (non-merge) commit? */
 +static int is_pick_or_similar(enum todo_command command)
 +{
 +      switch (command) {
 +      case TODO_PICK:
 +      case TODO_REVERT:
 +      case TODO_EDIT:
 +      case TODO_REWORD:
 +      case TODO_FIXUP:
 +      case TODO_SQUASH:
 +              return 1;
 +      default:
 +              return 0;
 +      }
 +}
 +
  static int update_squash_messages(enum todo_command command,
                struct commit *commit, struct replay_opts *opts)
  {
        struct strbuf buf = STRBUF_INIT;
 -      int count, res;
 +      int res;
        const char *message, *body;
  
 -      if (file_exists(rebase_path_squash_msg())) {
 +      if (opts->current_fixup_count > 0) {
                struct strbuf header = STRBUF_INIT;
 -              char *eol, *p;
 +              char *eol;
  
 -              if (strbuf_read_file(&buf, rebase_path_squash_msg(), 2048) <= 0)
 +              if (strbuf_read_file(&buf, rebase_path_squash_msg(), 9) <= 0)
                        return error(_("could not read '%s'"),
                                rebase_path_squash_msg());
  
 -              p = buf.buf + 1;
 -              eol = strchrnul(buf.buf, '\n');
 -              if (buf.buf[0] != comment_line_char ||
 -                  (p += strcspn(p, "0123456789\n")) == eol)
 -                      return error(_("unexpected 1st line of squash message:"
 -                                     "\n\n\t%.*s"),
 -                                   (int)(eol - buf.buf), buf.buf);
 -              count = strtol(p, NULL, 10);
 -
 -              if (count < 1)
 -                      return error(_("invalid 1st line of squash message:\n"
 -                                     "\n\t%.*s"),
 -                                   (int)(eol - buf.buf), buf.buf);
 +              eol = buf.buf[0] != comment_line_char ?
 +                      buf.buf : strchrnul(buf.buf, '\n');
  
                strbuf_addf(&header, "%c ", comment_line_char);
 -              strbuf_addf(&header,
 -                          _("This is a combination of %d commits."), ++count);
 +              strbuf_addf(&header, _("This is a combination of %d commits."),
 +                          opts->current_fixup_count + 2);
                strbuf_splice(&buf, 0, eol - buf.buf, header.buf, header.len);
                strbuf_release(&header);
        } else {
                                     rebase_path_fixup_msg());
                }
  
 -              count = 2;
                strbuf_addf(&buf, "%c ", comment_line_char);
 -              strbuf_addf(&buf, _("This is a combination of %d commits."),
 -                          count);
 +              strbuf_addf(&buf, _("This is a combination of %d commits."), 2);
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addstr(&buf, _("This is the 1st commit message:"));
                strbuf_addstr(&buf, "\n\n");
        if (command == TODO_SQUASH) {
                unlink(rebase_path_fixup_msg());
                strbuf_addf(&buf, "\n%c ", comment_line_char);
 -              strbuf_addf(&buf, _("This is the commit message #%d:"), count);
 +              strbuf_addf(&buf, _("This is the commit message #%d:"),
 +                          ++opts->current_fixup_count);
                strbuf_addstr(&buf, "\n\n");
                strbuf_addstr(&buf, body);
        } else if (command == TODO_FIXUP) {
                strbuf_addf(&buf, "\n%c ", comment_line_char);
                strbuf_addf(&buf, _("The commit message #%d will be skipped:"),
 -                          count);
 +                          ++opts->current_fixup_count);
                strbuf_addstr(&buf, "\n\n");
                strbuf_add_commented_lines(&buf, body, strlen(body));
        } else
  
        res = write_message(buf.buf, buf.len, rebase_path_squash_msg(), 0);
        strbuf_release(&buf);
 +
 +      if (!res) {
 +              strbuf_addf(&opts->current_fixups, "%s%s %s",
 +                          opts->current_fixups.len ? "\n" : "",
 +                          command_to_string(command),
 +                          oid_to_hex(&commit->object.oid));
 +              res = write_message(opts->current_fixups.buf,
 +                                  opts->current_fixups.len,
 +                                  rebase_path_current_fixups(), 0);
 +      }
 +
        return res;
  }
  
@@@ -1631,16 -1482,9 +1632,16 @@@ static int do_pick_commit(enum todo_com
                        return error(_("your index file is unmerged."));
        } else {
                unborn = get_oid("HEAD", &head);
 -              if (unborn)
 +              /* Do we want to generate a root commit? */
 +              if (is_pick_or_similar(command) && opts->have_squash_onto &&
 +                  !oidcmp(&head, &opts->squash_onto)) {
 +                      if (is_fixup(command))
 +                              return error(_("cannot fixup root commit"));
 +                      flags |= CREATE_ROOT_COMMIT;
 +                      unborn = 1;
 +              } else if (unborn)
                        oidcpy(&head, the_hash_algo->empty_tree);
 -              if (index_differs_from(unborn ? EMPTY_TREE_SHA1_HEX : "HEAD",
 +              if (index_differs_from(unborn ? empty_tree_oid_hex() : "HEAD",
                                       NULL, 0))
                        return error_dirty_index(opts);
        }
@@@ -1835,9 -1679,6 +1836,9 @@@ fast_forward_edit
        if (!res && final_fixup) {
                unlink(rebase_path_fixup_msg());
                unlink(rebase_path_squash_msg());
 +              unlink(rebase_path_current_fixups());
 +              strbuf_reset(&opts->current_fixups);
 +              opts->current_fixup_count = 0;
        }
  
  leave:
@@@ -1885,14 -1726,9 +1886,14 @@@ static int read_and_refresh_cache(struc
        return 0;
  }
  
 +enum todo_item_flags {
 +      TODO_EDIT_MERGE_MSG = 1
 +};
 +
  struct todo_item {
        enum todo_command command;
        struct commit *commit;
 +      unsigned int flags;
        const char *arg;
        int arg_len;
        size_t offset_in_buf;
@@@ -1927,8 -1763,6 +1928,8 @@@ static int parse_insn_line(struct todo_
        char *end_of_object_name;
        int i, saved, status, padding;
  
 +      item->flags = 0;
 +
        /* left-trim */
        bol += strspn(bol, " \t");
  
                return error(_("missing arguments for %s"),
                             command_to_string(item->command));
  
 -      if (item->command == TODO_EXEC) {
 +      if (item->command == TODO_EXEC || item->command == TODO_LABEL ||
 +          item->command == TODO_RESET) {
                item->commit = NULL;
                item->arg = bol;
                item->arg_len = (int)(eol - bol);
                return 0;
        }
  
 +      if (item->command == TODO_MERGE) {
 +              if (skip_prefix(bol, "-C", &bol))
 +                      bol += strspn(bol, " \t");
 +              else if (skip_prefix(bol, "-c", &bol)) {
 +                      bol += strspn(bol, " \t");
 +                      item->flags |= TODO_EDIT_MERGE_MSG;
 +              } else {
 +                      item->flags |= TODO_EDIT_MERGE_MSG;
 +                      item->commit = NULL;
 +                      item->arg = bol;
 +                      item->arg_len = (int)(eol - bol);
 +                      return 0;
 +              }
 +      }
 +
        end_of_object_name = (char *) bol + strcspn(bol, " \t\n");
        saved = *end_of_object_name;
        *end_of_object_name = '\0';
@@@ -2054,23 -1872,6 +2055,23 @@@ static int count_commands(struct todo_l
        return count;
  }
  
 +static int get_item_line_offset(struct todo_list *todo_list, int index)
 +{
 +      return index < todo_list->nr ?
 +              todo_list->items[index].offset_in_buf : todo_list->buf.len;
 +}
 +
 +static const char *get_item_line(struct todo_list *todo_list, int index)
 +{
 +      return todo_list->buf.buf + get_item_line_offset(todo_list, index);
 +}
 +
 +static int get_item_line_length(struct todo_list *todo_list, int index)
 +{
 +      return get_item_line_offset(todo_list, index + 1)
 +              -  get_item_line_offset(todo_list, index);
 +}
 +
  static ssize_t strbuf_read_file_or_whine(struct strbuf *sb, const char *path)
  {
        int fd;
@@@ -2254,22 -2055,6 +2255,22 @@@ static int read_populate_opts(struct re
                read_strategy_opts(opts, &buf);
                strbuf_release(&buf);
  
 +              if (read_oneliner(&opts->current_fixups,
 +                                rebase_path_current_fixups(), 1)) {
 +                      const char *p = opts->current_fixups.buf;
 +                      opts->current_fixup_count = 1;
 +                      while ((p = strchr(p, '\n'))) {
 +                              opts->current_fixup_count++;
 +                              p++;
 +                      }
 +              }
 +
 +              if (read_oneliner(&buf, rebase_path_squash_onto(), 0)) {
 +                      if (get_oid_hex(buf.buf, &opts->squash_onto) < 0)
 +                              return error(_("unusable squash-onto"));
 +                      opts->have_squash_onto = 1;
 +              }
 +
                return 0;
        }
  
@@@ -2343,9 -2128,9 +2344,9 @@@ static int save_head(const char *head
        written = write_in_full(fd, buf.buf, buf.len);
        strbuf_release(&buf);
        if (written < 0) {
 +              error_errno(_("could not write to '%s'"), git_path_head_file());
                rollback_lock_file(&head_lock);
 -              return error_errno(_("could not write to '%s'"),
 -                                 git_path_head_file());
 +              return -1;
        }
        if (commit_lock_file(&head_lock) < 0)
                return error(_("failed to finalize '%s'"), git_path_head_file());
@@@ -2466,27 -2251,29 +2467,27 @@@ static int save_todo(struct todo_list *
        fd = hold_lock_file_for_update(&todo_lock, todo_path, 0);
        if (fd < 0)
                return error_errno(_("could not lock '%s'"), todo_path);
 -      offset = next < todo_list->nr ?
 -              todo_list->items[next].offset_in_buf : todo_list->buf.len;
 +      offset = get_item_line_offset(todo_list, next);
        if (write_in_full(fd, todo_list->buf.buf + offset,
                        todo_list->buf.len - offset) < 0)
                return error_errno(_("could not write to '%s'"), todo_path);
        if (commit_lock_file(&todo_lock) < 0)
                return error(_("failed to finalize '%s'"), todo_path);
  
 -      if (is_rebase_i(opts)) {
 -              const char *done_path = rebase_path_done();
 -              int fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
 -              int prev_offset = !next ? 0 :
 -                      todo_list->items[next - 1].offset_in_buf;
 +      if (is_rebase_i(opts) && next > 0) {
 +              const char *done = rebase_path_done();
 +              int fd = open(done, O_CREAT | O_WRONLY | O_APPEND, 0666);
 +              int ret = 0;
  
 -              if (fd >= 0 && offset > prev_offset &&
 -                  write_in_full(fd, todo_list->buf.buf + prev_offset,
 -                                offset - prev_offset) < 0) {
 -                      close(fd);
 -                      return error_errno(_("could not write to '%s'"),
 -                                         done_path);
 -              }
 -              if (fd >= 0)
 -                      close(fd);
 +              if (fd < 0)
 +                      return 0;
 +              if (write_in_full(fd, get_item_line(todo_list, next - 1),
 +                                get_item_line_length(todo_list, next - 1))
 +                  < 0)
 +                      ret = error_errno(_("could not write to '%s'"), done);
 +              if (close(fd) < 0)
 +                      ret = error_errno(_("failed to finalize '%s'"), done);
 +              return ret;
        }
        return 0;
  }
@@@ -2614,9 -2401,10 +2615,9 @@@ static int error_with_patch(struct comm
  static int error_failed_squash(struct commit *commit,
        struct replay_opts *opts, int subject_len, const char *subject)
  {
 -      if (rename(rebase_path_squash_msg(), rebase_path_message()))
 -              return error(_("could not rename '%s' to '%s'"),
 +      if (copy_file(rebase_path_message(), rebase_path_squash_msg(), 0666))
 +              return error(_("could not copy '%s' to '%s'"),
                        rebase_path_squash_msg(), rebase_path_message());
 -      unlink(rebase_path_fixup_msg());
        unlink(git_path_merge_msg());
        if (copy_file(git_path_merge_msg(), rebase_path_message(), 0666))
                return error(_("could not copy '%s' to '%s'"),
@@@ -2669,377 -2457,6 +2670,377 @@@ static int do_exec(const char *command_
        return status;
  }
  
 +static int safe_append(const char *filename, const char *fmt, ...)
 +{
 +      va_list ap;
 +      struct lock_file lock = LOCK_INIT;
 +      int fd = hold_lock_file_for_update(&lock, filename,
 +                                         LOCK_REPORT_ON_ERROR);
 +      struct strbuf buf = STRBUF_INIT;
 +
 +      if (fd < 0)
 +              return -1;
 +
 +      if (strbuf_read_file(&buf, filename, 0) < 0 && errno != ENOENT) {
 +              error_errno(_("could not read '%s'"), filename);
 +              rollback_lock_file(&lock);
 +              return -1;
 +      }
 +      strbuf_complete(&buf, '\n');
 +      va_start(ap, fmt);
 +      strbuf_vaddf(&buf, fmt, ap);
 +      va_end(ap);
 +
 +      if (write_in_full(fd, buf.buf, buf.len) < 0) {
 +              error_errno(_("could not write to '%s'"), filename);
 +              strbuf_release(&buf);
 +              rollback_lock_file(&lock);
 +              return -1;
 +      }
 +      if (commit_lock_file(&lock) < 0) {
 +              strbuf_release(&buf);
 +              rollback_lock_file(&lock);
 +              return error(_("failed to finalize '%s'"), filename);
 +      }
 +
 +      strbuf_release(&buf);
 +      return 0;
 +}
 +
 +static int do_label(const char *name, int len)
 +{
 +      struct ref_store *refs = get_main_ref_store(the_repository);
 +      struct ref_transaction *transaction;
 +      struct strbuf ref_name = STRBUF_INIT, err = STRBUF_INIT;
 +      struct strbuf msg = STRBUF_INIT;
 +      int ret = 0;
 +      struct object_id head_oid;
 +
 +      if (len == 1 && *name == '#')
 +              return error("Illegal label name: '%.*s'", len, name);
 +
 +      strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
 +      strbuf_addf(&msg, "rebase -i (label) '%.*s'", len, name);
 +
 +      transaction = ref_store_transaction_begin(refs, &err);
 +      if (!transaction) {
 +              error("%s", err.buf);
 +              ret = -1;
 +      } else if (get_oid("HEAD", &head_oid)) {
 +              error(_("could not read HEAD"));
 +              ret = -1;
 +      } else if (ref_transaction_update(transaction, ref_name.buf, &head_oid,
 +                                        NULL, 0, msg.buf, &err) < 0 ||
 +                 ref_transaction_commit(transaction, &err)) {
 +              error("%s", err.buf);
 +              ret = -1;
 +      }
 +      ref_transaction_free(transaction);
 +      strbuf_release(&err);
 +      strbuf_release(&msg);
 +
 +      if (!ret)
 +              ret = safe_append(rebase_path_refs_to_delete(),
 +                                "%s\n", ref_name.buf);
 +      strbuf_release(&ref_name);
 +
 +      return ret;
 +}
 +
 +static const char *reflog_message(struct replay_opts *opts,
 +      const char *sub_action, const char *fmt, ...);
 +
 +static int do_reset(const char *name, int len, struct replay_opts *opts)
 +{
 +      struct strbuf ref_name = STRBUF_INIT;
 +      struct object_id oid;
 +      struct lock_file lock = LOCK_INIT;
 +      struct tree_desc desc;
 +      struct tree *tree;
 +      struct unpack_trees_options unpack_tree_opts;
 +      int ret = 0, i;
 +
 +      if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0)
 +              return -1;
 +
 +      if (len == 10 && !strncmp("[new root]", name, len)) {
 +              if (!opts->have_squash_onto) {
 +                      const char *hex;
 +                      if (commit_tree("", 0, the_hash_algo->empty_tree,
 +                                      NULL, &opts->squash_onto,
 +                                      NULL, NULL))
 +                              return error(_("writing fake root commit"));
 +                      opts->have_squash_onto = 1;
 +                      hex = oid_to_hex(&opts->squash_onto);
 +                      if (write_message(hex, strlen(hex),
 +                                        rebase_path_squash_onto(), 0))
 +                              return error(_("writing squash-onto"));
 +              }
 +              oidcpy(&oid, &opts->squash_onto);
 +      } else {
 +              /* Determine the length of the label */
 +              for (i = 0; i < len; i++)
 +                      if (isspace(name[i]))
 +                              len = i;
 +
 +              strbuf_addf(&ref_name, "refs/rewritten/%.*s", len, name);
 +              if (get_oid(ref_name.buf, &oid) &&
 +                  get_oid(ref_name.buf + strlen("refs/rewritten/"), &oid)) {
 +                      error(_("could not read '%s'"), ref_name.buf);
 +                      rollback_lock_file(&lock);
 +                      strbuf_release(&ref_name);
 +                      return -1;
 +              }
 +      }
 +
 +      memset(&unpack_tree_opts, 0, sizeof(unpack_tree_opts));
 +      setup_unpack_trees_porcelain(&unpack_tree_opts, "reset");
 +      unpack_tree_opts.head_idx = 1;
 +      unpack_tree_opts.src_index = &the_index;
 +      unpack_tree_opts.dst_index = &the_index;
 +      unpack_tree_opts.fn = oneway_merge;
 +      unpack_tree_opts.merge = 1;
 +      unpack_tree_opts.update = 1;
 +
 +      if (read_cache_unmerged()) {
 +              rollback_lock_file(&lock);
 +              strbuf_release(&ref_name);
 +              return error_resolve_conflict(_(action_name(opts)));
 +      }
 +
 +      if (!fill_tree_descriptor(&desc, &oid)) {
 +              error(_("failed to find tree of %s"), oid_to_hex(&oid));
 +              rollback_lock_file(&lock);
 +              free((void *)desc.buffer);
 +              strbuf_release(&ref_name);
 +              return -1;
 +      }
 +
 +      if (unpack_trees(1, &desc, &unpack_tree_opts)) {
 +              rollback_lock_file(&lock);
 +              free((void *)desc.buffer);
 +              strbuf_release(&ref_name);
 +              return -1;
 +      }
 +
 +      tree = parse_tree_indirect(&oid);
 +      prime_cache_tree(&the_index, tree);
 +
 +      if (write_locked_index(&the_index, &lock, COMMIT_LOCK) < 0)
 +              ret = error(_("could not write index"));
 +      free((void *)desc.buffer);
 +
 +      if (!ret)
 +              ret = update_ref(reflog_message(opts, "reset", "'%.*s'",
 +                                              len, name), "HEAD", &oid,
 +                               NULL, 0, UPDATE_REFS_MSG_ON_ERR);
 +
 +      strbuf_release(&ref_name);
 +      return ret;
 +}
 +
 +static int do_merge(struct commit *commit, const char *arg, int arg_len,
 +                  int flags, struct replay_opts *opts)
 +{
 +      int run_commit_flags = (flags & TODO_EDIT_MERGE_MSG) ?
 +              EDIT_MSG | VERIFY_MSG : 0;
 +      struct strbuf ref_name = STRBUF_INIT;
 +      struct commit *head_commit, *merge_commit, *i;
 +      struct commit_list *bases, *j, *reversed = NULL;
 +      struct merge_options o;
 +      int merge_arg_len, oneline_offset, can_fast_forward, ret;
 +      static struct lock_file lock;
 +      const char *p;
 +
 +      if (hold_locked_index(&lock, LOCK_REPORT_ON_ERROR) < 0) {
 +              ret = -1;
 +              goto leave_merge;
 +      }
 +
 +      head_commit = lookup_commit_reference_by_name("HEAD");
 +      if (!head_commit) {
 +              ret = error(_("cannot merge without a current revision"));
 +              goto leave_merge;
 +      }
 +
 +      oneline_offset = arg_len;
 +      merge_arg_len = strcspn(arg, " \t\n");
 +      p = arg + merge_arg_len;
 +      p += strspn(p, " \t\n");
 +      if (*p == '#' && (!p[1] || isspace(p[1]))) {
 +              p += 1 + strspn(p + 1, " \t\n");
 +              oneline_offset = p - arg;
 +      } else if (p - arg < arg_len)
 +              BUG("octopus merges are not supported yet: '%s'", p);
 +
 +      strbuf_addf(&ref_name, "refs/rewritten/%.*s", merge_arg_len, arg);
 +      merge_commit = lookup_commit_reference_by_name(ref_name.buf);
 +      if (!merge_commit) {
 +              /* fall back to non-rewritten ref or commit */
 +              strbuf_splice(&ref_name, 0, strlen("refs/rewritten/"), "", 0);
 +              merge_commit = lookup_commit_reference_by_name(ref_name.buf);
 +      }
 +
 +      if (!merge_commit) {
 +              ret = error(_("could not resolve '%s'"), ref_name.buf);
 +              goto leave_merge;
 +      }
 +
 +      if (opts->have_squash_onto &&
 +          !oidcmp(&head_commit->object.oid, &opts->squash_onto)) {
 +              /*
 +               * When the user tells us to "merge" something into a
 +               * "[new root]", let's simply fast-forward to the merge head.
 +               */
 +              rollback_lock_file(&lock);
 +              ret = fast_forward_to(&merge_commit->object.oid,
 +                                     &head_commit->object.oid, 0, opts);
 +              goto leave_merge;
 +      }
 +
 +      if (commit) {
 +              const char *message = get_commit_buffer(commit, NULL);
 +              const char *body;
 +              int len;
 +
 +              if (!message) {
 +                      ret = error(_("could not get commit message of '%s'"),
 +                                  oid_to_hex(&commit->object.oid));
 +                      goto leave_merge;
 +              }
 +              write_author_script(message);
 +              find_commit_subject(message, &body);
 +              len = strlen(body);
 +              ret = write_message(body, len, git_path_merge_msg(), 0);
 +              unuse_commit_buffer(commit, message);
 +              if (ret) {
 +                      error_errno(_("could not write '%s'"),
 +                                  git_path_merge_msg());
 +                      goto leave_merge;
 +              }
 +      } else {
 +              struct strbuf buf = STRBUF_INIT;
 +              int len;
 +
 +              strbuf_addf(&buf, "author %s", git_author_info(0));
 +              write_author_script(buf.buf);
 +              strbuf_reset(&buf);
 +
 +              if (oneline_offset < arg_len) {
 +                      p = arg + oneline_offset;
 +                      len = arg_len - oneline_offset;
 +              } else {
 +                      strbuf_addf(&buf, "Merge branch '%.*s'",
 +                                  merge_arg_len, arg);
 +                      p = buf.buf;
 +                      len = buf.len;
 +              }
 +
 +              ret = write_message(p, len, git_path_merge_msg(), 0);
 +              strbuf_release(&buf);
 +              if (ret) {
 +                      error_errno(_("could not write '%s'"),
 +                                  git_path_merge_msg());
 +                      goto leave_merge;
 +              }
 +      }
 +
 +      /*
 +       * If HEAD is not identical to the first parent of the original merge
 +       * commit, we cannot fast-forward.
 +       */
 +      can_fast_forward = opts->allow_ff && commit && commit->parents &&
 +              !oidcmp(&commit->parents->item->object.oid,
 +                      &head_commit->object.oid);
 +
 +      /*
 +       * If the merge head is different from the original one, we cannot
 +       * fast-forward.
 +       */
 +      if (can_fast_forward) {
 +              struct commit_list *second_parent = commit->parents->next;
 +
 +              if (second_parent && !second_parent->next &&
 +                  oidcmp(&merge_commit->object.oid,
 +                         &second_parent->item->object.oid))
 +                      can_fast_forward = 0;
 +      }
 +
 +      if (can_fast_forward && commit->parents->next &&
 +          !commit->parents->next->next &&
 +          !oidcmp(&commit->parents->next->item->object.oid,
 +                  &merge_commit->object.oid)) {
 +              rollback_lock_file(&lock);
 +              ret = fast_forward_to(&commit->object.oid,
 +                                    &head_commit->object.oid, 0, opts);
 +              goto leave_merge;
 +      }
 +
 +      write_message(oid_to_hex(&merge_commit->object.oid), GIT_SHA1_HEXSZ,
 +                    git_path_merge_head(), 0);
 +      write_message("no-ff", 5, git_path_merge_mode(), 0);
 +
 +      bases = get_merge_bases(head_commit, merge_commit);
 +      if (bases && !oidcmp(&merge_commit->object.oid,
 +                           &bases->item->object.oid)) {
 +              ret = 0;
 +              /* skip merging an ancestor of HEAD */
 +              goto leave_merge;
 +      }
 +
 +      for (j = bases; j; j = j->next)
 +              commit_list_insert(j->item, &reversed);
 +      free_commit_list(bases);
 +
 +      read_cache();
 +      init_merge_options(&o);
 +      o.branch1 = "HEAD";
 +      o.branch2 = ref_name.buf;
 +      o.buffer_output = 2;
 +
 +      ret = merge_recursive(&o, head_commit, merge_commit, reversed, &i);
 +      if (ret <= 0)
 +              fputs(o.obuf.buf, stdout);
 +      strbuf_release(&o.obuf);
 +      if (ret < 0) {
 +              error(_("could not even attempt to merge '%.*s'"),
 +                    merge_arg_len, arg);
 +              goto leave_merge;
 +      }
 +      /*
 +       * The return value of merge_recursive() is 1 on clean, and 0 on
 +       * unclean merge.
 +       *
 +       * Let's reverse that, so that do_merge() returns 0 upon success and
 +       * 1 upon failed merge (keeping the return value -1 for the cases where
 +       * we will want to reschedule the `merge` command).
 +       */
 +      ret = !ret;
 +
 +      if (active_cache_changed &&
 +          write_locked_index(&the_index, &lock, COMMIT_LOCK)) {
 +              ret = error(_("merge: Unable to write new index file"));
 +              goto leave_merge;
 +      }
 +
 +      rollback_lock_file(&lock);
 +      if (ret)
 +              rerere(opts->allow_rerere_auto);
 +      else
 +              /*
 +               * In case of problems, we now want to return a positive
 +               * value (a negative one would indicate that the `merge`
 +               * command needs to be rescheduled).
 +               */
 +              ret = !!run_git_commit(git_path_merge_msg(), opts,
 +                                   run_commit_flags);
 +
 +leave_merge:
 +      strbuf_release(&ref_name);
 +      rollback_lock_file(&lock);
 +      return ret;
 +}
 +
  static int is_final_fixup(struct todo_list *todo_list)
  {
        int i = todo_list->current;
@@@ -3130,20 -2547,9 +3131,20 @@@ static const char *reflog_message(struc
        return buf.buf;
  }
  
 +static const char rescheduled_advice[] =
 +N_("Could not execute the todo command\n"
 +"\n"
 +"    %.*s"
 +"\n"
 +"It has been rescheduled; To edit the command before continuing, please\n"
 +"edit the todo list first:\n"
 +"\n"
 +"    git rebase --edit-todo\n"
 +"    git rebase --continue\n");
 +
  static int pick_commits(struct todo_list *todo_list, struct replay_opts *opts)
  {
 -      int res = 0;
 +      int res = 0, reschedule = 0;
  
        setenv(GIT_REFLOG_ACTION, action_name(opts), 0);
        if (opts->allow_ff)
                                        opts, is_final_fixup(todo_list));
                        if (is_rebase_i(opts) && res < 0) {
                                /* Reschedule */
 +                              advise(_(rescheduled_advice),
 +                                     get_item_line_length(todo_list,
 +                                                          todo_list->current),
 +                                     get_item_line(todo_list,
 +                                                   todo_list->current));
                                todo_list->current--;
                                if (save_todo(todo_list, opts))
                                        return -1;
                                        intend_to_amend();
                                return error_failed_squash(item->commit, opts,
                                        item->arg_len, item->arg);
 -                      } else if (res && is_rebase_i(opts))
 +                      } else if (res && is_rebase_i(opts) && item->commit)
                                return res | error_with_patch(item->commit,
                                        item->arg, item->arg_len, opts, res,
                                        item->command == TODO_REWORD);
                                /* `current` will be incremented below */
                                todo_list->current = -1;
                        }
 +              } else if (item->command == TODO_LABEL) {
 +                      if ((res = do_label(item->arg, item->arg_len)))
 +                              reschedule = 1;
 +              } else if (item->command == TODO_RESET) {
 +                      if ((res = do_reset(item->arg, item->arg_len, opts)))
 +                              reschedule = 1;
 +              } else if (item->command == TODO_MERGE) {
 +                      if ((res = do_merge(item->commit,
 +                                          item->arg, item->arg_len,
 +                                          item->flags, opts)) < 0)
 +                              reschedule = 1;
 +                      else if (item->commit)
 +                              record_in_rewritten(&item->commit->object.oid,
 +                                                  peek_command(todo_list, 1));
 +                      if (res > 0)
 +                              /* failed with merge conflicts */
 +                              return error_with_patch(item->commit,
 +                                                      item->arg,
 +                                                      item->arg_len, opts,
 +                                                      res, 0);
                } else if (!is_noop(item->command))
                        return error(_("unknown command %d"), item->command);
  
 +              if (reschedule) {
 +                      advise(_(rescheduled_advice),
 +                             get_item_line_length(todo_list,
 +                                                  todo_list->current),
 +                             get_item_line(todo_list, todo_list->current));
 +                      todo_list->current--;
 +                      if (save_todo(todo_list, opts))
 +                              return -1;
 +                      if (item->commit)
 +                              return error_with_patch(item->commit,
 +                                                      item->arg,
 +                                                      item->arg_len, opts,
 +                                                      res, 0);
 +              }
 +
                todo_list->current++;
                if (res)
                        return res;
@@@ -3404,16 -2770,19 +3405,16 @@@ static int continue_single_pick(void
        return run_command_v_opt(argv, RUN_GIT_CMD);
  }
  
 -static int commit_staged_changes(struct replay_opts *opts)
 +static int commit_staged_changes(struct replay_opts *opts,
 +                               struct todo_list *todo_list)
  {
        unsigned int flags = ALLOW_EMPTY | EDIT_MSG;
 +      unsigned int final_fixup = 0, is_clean;
  
        if (has_unstaged_changes(1))
                return error(_("cannot rebase: You have unstaged changes."));
 -      if (!has_uncommitted_changes(0)) {
 -              const char *cherry_pick_head = git_path_cherry_pick_head();
  
 -              if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
 -                      return error(_("could not remove CHERRY_PICK_HEAD"));
 -              return 0;
 -      }
 +      is_clean = !has_uncommitted_changes(0);
  
        if (file_exists(rebase_path_amend())) {
                struct strbuf rev = STRBUF_INIT;
                if (get_oid_hex(rev.buf, &to_amend))
                        return error(_("invalid contents: '%s'"),
                                rebase_path_amend());
 -              if (oidcmp(&head, &to_amend))
 +              if (!is_clean && oidcmp(&head, &to_amend))
                        return error(_("\nYou have uncommitted changes in your "
                                       "working tree. Please, commit them\n"
                                       "first and then run 'git rebase "
                                       "--continue' again."));
 +              /*
 +               * When skipping a failed fixup/squash, we need to edit the
 +               * commit message, the current fixup list and count, and if it
 +               * was the last fixup/squash in the chain, we need to clean up
 +               * the commit message and if there was a squash, let the user
 +               * edit it.
 +               */
 +              if (is_clean && !oidcmp(&head, &to_amend) &&
 +                  opts->current_fixup_count > 0 &&
 +                  file_exists(rebase_path_stopped_sha())) {
 +                      const char *p = opts->current_fixups.buf;
 +                      int len = opts->current_fixups.len;
 +
 +                      opts->current_fixup_count--;
 +                      if (!len)
 +                              BUG("Incorrect current_fixups:\n%s", p);
 +                      while (len && p[len - 1] != '\n')
 +                              len--;
 +                      strbuf_setlen(&opts->current_fixups, len);
 +                      if (write_message(p, len, rebase_path_current_fixups(),
 +                                        0) < 0)
 +                              return error(_("could not write file: '%s'"),
 +                                           rebase_path_current_fixups());
 +
 +                      /*
 +                       * If a fixup/squash in a fixup/squash chain failed, the
 +                       * commit message is already correct, no need to commit
 +                       * it again.
 +                       *
 +                       * Only if it is the final command in the fixup/squash
 +                       * chain, and only if the chain is longer than a single
 +                       * fixup/squash command (which was just skipped), do we
 +                       * actually need to re-commit with a cleaned up commit
 +                       * message.
 +                       */
 +                      if (opts->current_fixup_count > 0 &&
 +                          !is_fixup(peek_command(todo_list, 0))) {
 +                              final_fixup = 1;
 +                              /*
 +                               * If there was not a single "squash" in the
 +                               * chain, we only need to clean up the commit
 +                               * message, no need to bother the user with
 +                               * opening the commit message in the editor.
 +                               */
 +                              if (!starts_with(p, "squash ") &&
 +                                  !strstr(p, "\nsquash "))
 +                                      flags = (flags & ~EDIT_MSG) | CLEANUP_MSG;
 +                      } else if (is_fixup(peek_command(todo_list, 0))) {
 +                              /*
 +                               * We need to update the squash message to skip
 +                               * the latest commit message.
 +                               */
 +                              struct commit *commit;
 +                              const char *path = rebase_path_squash_msg();
 +
 +                              if (parse_head(&commit) ||
 +                                  !(p = get_commit_buffer(commit, NULL)) ||
 +                                  write_message(p, strlen(p), path, 0)) {
 +                                      unuse_commit_buffer(commit, p);
 +                                      return error(_("could not write file: "
 +                                                     "'%s'"), path);
 +                              }
 +                              unuse_commit_buffer(commit, p);
 +                      }
 +              }
  
                strbuf_release(&rev);
                flags |= AMEND_MSG;
        }
  
 -      if (run_git_commit(rebase_path_message(), opts, flags))
 +      if (is_clean) {
 +              const char *cherry_pick_head = git_path_cherry_pick_head();
 +
 +              if (file_exists(cherry_pick_head) && unlink(cherry_pick_head))
 +                      return error(_("could not remove CHERRY_PICK_HEAD"));
 +              if (!final_fixup)
 +                      return 0;
 +      }
 +
 +      if (run_git_commit(final_fixup ? NULL : rebase_path_message(),
 +                         opts, flags))
                return error(_("could not commit staged changes."));
        unlink(rebase_path_amend());
 +      if (final_fixup) {
 +              unlink(rebase_path_fixup_msg());
 +              unlink(rebase_path_squash_msg());
 +      }
 +      if (opts->current_fixup_count > 0) {
 +              /*
 +               * Whether final fixup or not, we just cleaned up the commit
 +               * message...
 +               */
 +              unlink(rebase_path_current_fixups());
 +              strbuf_reset(&opts->current_fixups);
 +              opts->current_fixup_count = 0;
 +      }
        return 0;
  }
  
@@@ -3538,16 -2819,14 +3539,16 @@@ int sequencer_continue(struct replay_op
        if (read_and_refresh_cache(opts))
                return -1;
  
 +      if (read_populate_opts(opts))
 +              return -1;
        if (is_rebase_i(opts)) {
 -              if (commit_staged_changes(opts))
 +              if ((res = read_populate_todo(&todo_list, opts)))
 +                      goto release_todo_list;
 +              if (commit_staged_changes(opts, &todo_list))
                        return -1;
        } else if (!file_exists(get_todo_path(opts)))
                return continue_single_pick();
 -      if (read_populate_opts(opts))
 -              return -1;
 -      if ((res = read_populate_todo(&todo_list, opts)))
 +      else if ((res = read_populate_todo(&todo_list, opts)))
                goto release_todo_list;
  
        if (!is_rebase_i(opts)) {
@@@ -3606,8 -2885,7 +3607,8 @@@ int sequencer_pick_revisions(struct rep
  
                if (!get_oid(name, &oid)) {
                        if (!lookup_commit_reference_gently(&oid, 1)) {
 -                              enum object_type type = oid_object_info(&oid,
 +                              enum object_type type = oid_object_info(the_repository,
 +                                                                      &oid,
                                                                        NULL);
                                return error(_("%s: can't cherry-pick a %s"),
                                        name, type_name(type));
@@@ -3718,348 -2996,6 +3719,348 @@@ void append_signoff(struct strbuf *msgb
        strbuf_release(&sob);
  }
  
 +struct labels_entry {
 +      struct hashmap_entry entry;
 +      char label[FLEX_ARRAY];
 +};
 +
 +static int labels_cmp(const void *fndata, const struct labels_entry *a,
 +                    const struct labels_entry *b, const void *key)
 +{
 +      return key ? strcmp(a->label, key) : strcmp(a->label, b->label);
 +}
 +
 +struct string_entry {
 +      struct oidmap_entry entry;
 +      char string[FLEX_ARRAY];
 +};
 +
 +struct label_state {
 +      struct oidmap commit2label;
 +      struct hashmap labels;
 +      struct strbuf buf;
 +};
 +
 +static const char *label_oid(struct object_id *oid, const char *label,
 +                           struct label_state *state)
 +{
 +      struct labels_entry *labels_entry;
 +      struct string_entry *string_entry;
 +      struct object_id dummy;
 +      size_t len;
 +      int i;
 +
 +      string_entry = oidmap_get(&state->commit2label, oid);
 +      if (string_entry)
 +              return string_entry->string;
 +
 +      /*
 +       * For "uninteresting" commits, i.e. commits that are not to be
 +       * rebased, and which can therefore not be labeled, we use a unique
 +       * abbreviation of the commit name. This is slightly more complicated
 +       * than calling find_unique_abbrev() because we also need to make
 +       * sure that the abbreviation does not conflict with any other
 +       * label.
 +       *
 +       * We disallow "interesting" commits to be labeled by a string that
 +       * is a valid full-length hash, to ensure that we always can find an
 +       * abbreviation for any uninteresting commit's names that does not
 +       * clash with any other label.
 +       */
 +      if (!label) {
 +              char *p;
 +
 +              strbuf_reset(&state->buf);
 +              strbuf_grow(&state->buf, GIT_SHA1_HEXSZ);
 +              label = p = state->buf.buf;
 +
 +              find_unique_abbrev_r(p, oid, default_abbrev);
 +
 +              /*
 +               * We may need to extend the abbreviated hash so that there is
 +               * no conflicting label.
 +               */
 +              if (hashmap_get_from_hash(&state->labels, strihash(p), p)) {
 +                      size_t i = strlen(p) + 1;
 +
 +                      oid_to_hex_r(p, oid);
 +                      for (; i < GIT_SHA1_HEXSZ; i++) {
 +                              char save = p[i];
 +                              p[i] = '\0';
 +                              if (!hashmap_get_from_hash(&state->labels,
 +                                                         strihash(p), p))
 +                                      break;
 +                              p[i] = save;
 +                      }
 +              }
 +      } else if (((len = strlen(label)) == the_hash_algo->hexsz &&
 +                  !get_oid_hex(label, &dummy)) ||
 +                 (len == 1 && *label == '#') ||
 +                 hashmap_get_from_hash(&state->labels,
 +                                       strihash(label), label)) {
 +              /*
 +               * If the label already exists, or if the label is a valid full
 +               * OID, or the label is a '#' (which we use as a separator
 +               * between merge heads and oneline), we append a dash and a
 +               * number to make it unique.
 +               */
 +              struct strbuf *buf = &state->buf;
 +
 +              strbuf_reset(buf);
 +              strbuf_add(buf, label, len);
 +
 +              for (i = 2; ; i++) {
 +                      strbuf_setlen(buf, len);
 +                      strbuf_addf(buf, "-%d", i);
 +                      if (!hashmap_get_from_hash(&state->labels,
 +                                                 strihash(buf->buf),
 +                                                 buf->buf))
 +                              break;
 +              }
 +
 +              label = buf->buf;
 +      }
 +
 +      FLEX_ALLOC_STR(labels_entry, label, label);
 +      hashmap_entry_init(labels_entry, strihash(label));
 +      hashmap_add(&state->labels, labels_entry);
 +
 +      FLEX_ALLOC_STR(string_entry, string, label);
 +      oidcpy(&string_entry->entry.oid, oid);
 +      oidmap_put(&state->commit2label, string_entry);
 +
 +      return string_entry->string;
 +}
 +
 +static int make_script_with_merges(struct pretty_print_context *pp,
 +                                 struct rev_info *revs, FILE *out,
 +                                 unsigned flags)
 +{
 +      int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
 +      int rebase_cousins = flags & TODO_LIST_REBASE_COUSINS;
 +      struct strbuf buf = STRBUF_INIT, oneline = STRBUF_INIT;
 +      struct strbuf label = STRBUF_INIT;
 +      struct commit_list *commits = NULL, **tail = &commits, *iter;
 +      struct commit_list *tips = NULL, **tips_tail = &tips;
 +      struct commit *commit;
 +      struct oidmap commit2todo = OIDMAP_INIT;
 +      struct string_entry *entry;
 +      struct oidset interesting = OIDSET_INIT, child_seen = OIDSET_INIT,
 +              shown = OIDSET_INIT;
 +      struct label_state state = { OIDMAP_INIT, { NULL }, STRBUF_INIT };
 +
 +      int abbr = flags & TODO_LIST_ABBREVIATE_CMDS;
 +      const char *cmd_pick = abbr ? "p" : "pick",
 +              *cmd_label = abbr ? "l" : "label",
 +              *cmd_reset = abbr ? "t" : "reset",
 +              *cmd_merge = abbr ? "m" : "merge";
 +
 +      oidmap_init(&commit2todo, 0);
 +      oidmap_init(&state.commit2label, 0);
 +      hashmap_init(&state.labels, (hashmap_cmp_fn) labels_cmp, NULL, 0);
 +      strbuf_init(&state.buf, 32);
 +
 +      if (revs->cmdline.nr && (revs->cmdline.rev[0].flags & BOTTOM)) {
 +              struct object_id *oid = &revs->cmdline.rev[0].item->oid;
 +              FLEX_ALLOC_STR(entry, string, "onto");
 +              oidcpy(&entry->entry.oid, oid);
 +              oidmap_put(&state.commit2label, entry);
 +      }
 +
 +      /*
 +       * First phase:
 +       * - get onelines for all commits
 +       * - gather all branch tips (i.e. 2nd or later parents of merges)
 +       * - label all branch tips
 +       */
 +      while ((commit = get_revision(revs))) {
 +              struct commit_list *to_merge;
 +              int is_octopus;
 +              const char *p1, *p2;
 +              struct object_id *oid;
 +              int is_empty;
 +
 +              tail = &commit_list_insert(commit, tail)->next;
 +              oidset_insert(&interesting, &commit->object.oid);
 +
 +              is_empty = is_original_commit_empty(commit);
 +              if (!is_empty && (commit->object.flags & PATCHSAME))
 +                      continue;
 +
 +              strbuf_reset(&oneline);
 +              pretty_print_commit(pp, commit, &oneline);
 +
 +              to_merge = commit->parents ? commit->parents->next : NULL;
 +              if (!to_merge) {
 +                      /* non-merge commit: easy case */
 +                      strbuf_reset(&buf);
 +                      if (!keep_empty && is_empty)
 +                              strbuf_addf(&buf, "%c ", comment_line_char);
 +                      strbuf_addf(&buf, "%s %s %s", cmd_pick,
 +                                  oid_to_hex(&commit->object.oid),
 +                                  oneline.buf);
 +
 +                      FLEX_ALLOC_STR(entry, string, buf.buf);
 +                      oidcpy(&entry->entry.oid, &commit->object.oid);
 +                      oidmap_put(&commit2todo, entry);
 +
 +                      continue;
 +              }
 +
 +              is_octopus = to_merge && to_merge->next;
 +
 +              if (is_octopus)
 +                      BUG("Octopus merges not yet supported");
 +
 +              /* Create a label */
 +              strbuf_reset(&label);
 +              if (skip_prefix(oneline.buf, "Merge ", &p1) &&
 +                  (p1 = strchr(p1, '\'')) &&
 +                  (p2 = strchr(++p1, '\'')))
 +                      strbuf_add(&label, p1, p2 - p1);
 +              else if (skip_prefix(oneline.buf, "Merge pull request ",
 +                                   &p1) &&
 +                       (p1 = strstr(p1, " from ")))
 +                      strbuf_addstr(&label, p1 + strlen(" from "));
 +              else
 +                      strbuf_addbuf(&label, &oneline);
 +
 +              for (p1 = label.buf; *p1; p1++)
 +                      if (isspace(*p1))
 +                              *(char *)p1 = '-';
 +
 +              strbuf_reset(&buf);
 +              strbuf_addf(&buf, "%s -C %s",
 +                          cmd_merge, oid_to_hex(&commit->object.oid));
 +
 +              /* label the tip of merged branch */
 +              oid = &to_merge->item->object.oid;
 +              strbuf_addch(&buf, ' ');
 +
 +              if (!oidset_contains(&interesting, oid))
 +                      strbuf_addstr(&buf, label_oid(oid, NULL, &state));
 +              else {
 +                      tips_tail = &commit_list_insert(to_merge->item,
 +                                                      tips_tail)->next;
 +
 +                      strbuf_addstr(&buf, label_oid(oid, label.buf, &state));
 +              }
 +              strbuf_addf(&buf, " # %s", oneline.buf);
 +
 +              FLEX_ALLOC_STR(entry, string, buf.buf);
 +              oidcpy(&entry->entry.oid, &commit->object.oid);
 +              oidmap_put(&commit2todo, entry);
 +      }
 +
 +      /*
 +       * Second phase:
 +       * - label branch points
 +       * - add HEAD to the branch tips
 +       */
 +      for (iter = commits; iter; iter = iter->next) {
 +              struct commit_list *parent = iter->item->parents;
 +              for (; parent; parent = parent->next) {
 +                      struct object_id *oid = &parent->item->object.oid;
 +                      if (!oidset_contains(&interesting, oid))
 +                              continue;
 +                      if (!oidset_contains(&child_seen, oid))
 +                              oidset_insert(&child_seen, oid);
 +                      else
 +                              label_oid(oid, "branch-point", &state);
 +              }
 +
 +              /* Add HEAD as implict "tip of branch" */
 +              if (!iter->next)
 +                      tips_tail = &commit_list_insert(iter->item,
 +                                                      tips_tail)->next;
 +      }
 +
 +      /*
 +       * Third phase: output the todo list. This is a bit tricky, as we
 +       * want to avoid jumping back and forth between revisions. To
 +       * accomplish that goal, we walk backwards from the branch tips,
 +       * gathering commits not yet shown, reversing the list on the fly,
 +       * then outputting that list (labeling revisions as needed).
 +       */
 +      fprintf(out, "%s onto\n", cmd_label);
 +      for (iter = tips; iter; iter = iter->next) {
 +              struct commit_list *list = NULL, *iter2;
 +
 +              commit = iter->item;
 +              if (oidset_contains(&shown, &commit->object.oid))
 +                      continue;
 +              entry = oidmap_get(&state.commit2label, &commit->object.oid);
 +
 +              if (entry)
 +                      fprintf(out, "\n# Branch %s\n", entry->string);
 +              else
 +                      fprintf(out, "\n");
 +
 +              while (oidset_contains(&interesting, &commit->object.oid) &&
 +                     !oidset_contains(&shown, &commit->object.oid)) {
 +                      commit_list_insert(commit, &list);
 +                      if (!commit->parents) {
 +                              commit = NULL;
 +                              break;
 +                      }
 +                      commit = commit->parents->item;
 +              }
 +
 +              if (!commit)
 +                      fprintf(out, "%s %s\n", cmd_reset,
 +                              rebase_cousins ? "onto" : "[new root]");
 +              else {
 +                      const char *to = NULL;
 +
 +                      entry = oidmap_get(&state.commit2label,
 +                                         &commit->object.oid);
 +                      if (entry)
 +                              to = entry->string;
 +                      else if (!rebase_cousins)
 +                              to = label_oid(&commit->object.oid, NULL,
 +                                             &state);
 +
 +                      if (!to || !strcmp(to, "onto"))
 +                              fprintf(out, "%s onto\n", cmd_reset);
 +                      else {
 +                              strbuf_reset(&oneline);
 +                              pretty_print_commit(pp, commit, &oneline);
 +                              fprintf(out, "%s %s # %s\n",
 +                                      cmd_reset, to, oneline.buf);
 +                      }
 +              }
 +
 +              for (iter2 = list; iter2; iter2 = iter2->next) {
 +                      struct object_id *oid = &iter2->item->object.oid;
 +                      entry = oidmap_get(&commit2todo, oid);
 +                      /* only show if not already upstream */
 +                      if (entry)
 +                              fprintf(out, "%s\n", entry->string);
 +                      entry = oidmap_get(&state.commit2label, oid);
 +                      if (entry)
 +                              fprintf(out, "%s %s\n",
 +                                      cmd_label, entry->string);
 +                      oidset_insert(&shown, oid);
 +              }
 +
 +              free_commit_list(list);
 +      }
 +
 +      free_commit_list(commits);
 +      free_commit_list(tips);
 +
 +      strbuf_release(&label);
 +      strbuf_release(&oneline);
 +      strbuf_release(&buf);
 +
 +      oidmap_free(&commit2todo, 1);
 +      oidmap_free(&state.commit2label, 1);
 +      hashmap_free(&state.labels, 1);
 +      strbuf_release(&state.buf);
 +
 +      return 0;
 +}
 +
  int sequencer_make_script(FILE *out, int argc, const char **argv,
                          unsigned flags)
  {
        struct commit *commit;
        int keep_empty = flags & TODO_LIST_KEEP_EMPTY;
        const char *insn = flags & TODO_LIST_ABBREVIATE_CMDS ? "p" : "pick";
 +      int rebase_merges = flags & TODO_LIST_REBASE_MERGES;
  
        init_revisions(&revs, NULL);
        revs.verbose_header = 1;
 -      revs.max_parents = 1;
 +      if (!rebase_merges)
 +              revs.max_parents = 1;
        revs.cherry_mark = 1;
        revs.limited = 1;
        revs.reverse = 1;
        if (prepare_revision_walk(&revs) < 0)
                return error(_("make_script: error preparing revisions"));
  
 +      if (rebase_merges)
 +              return make_script_with_merges(&pp, &revs, out, flags);
 +
        while ((commit = get_revision(&revs))) {
                int is_empty  = is_original_commit_empty(commit);
  
@@@ -4196,16 -3127,8 +4197,16 @@@ int transform_todos(unsigned flags
                                          short_commit_name(item->commit) :
                                          oid_to_hex(&item->commit->object.oid);
  
 +                      if (item->command == TODO_MERGE) {
 +                              if (item->flags & TODO_EDIT_MERGE_MSG)
 +                                      strbuf_addstr(&buf, " -c");
 +                              else
 +                                      strbuf_addstr(&buf, " -C");
 +                      }
 +
                        strbuf_addf(&buf, " %s", oid);
                }
 +
                /* add all the rest */
                if (!item->arg_len)
                        strbuf_addch(&buf, '\n');
@@@ -4238,6 -3161,7 +4239,7 @@@ static enum check_level get_missing_com
        return CHECK_IGNORE;
  }
  
+ define_commit_slab(commit_seen, unsigned char);
  /*
   * Check if the user dropped some commits by mistake
   * Behaviour determined by rebase.missingCommitsCheck.
@@@ -4251,6 -3175,9 +4253,9 @@@ int check_todo_list(void
        struct todo_list todo_list = TODO_LIST_INIT;
        struct strbuf missing = STRBUF_INIT;
        int advise_to_edit_todo = 0, res = 0, i;
+       struct commit_seen commit_seen;
+       init_commit_seen(&commit_seen);
  
        strbuf_addstr(&todo_file, rebase_path_todo());
        if (strbuf_read_file_or_whine(&todo_list.buf, todo_file.buf) < 0) {
        for (i = 0; i < todo_list.nr; i++) {
                struct commit *commit = todo_list.items[i].commit;
                if (commit)
-                       commit->util = (void *)1;
+                       *commit_seen_at(&commit_seen, commit) = 1;
        }
  
        todo_list_release(&todo_list);
        for (i = todo_list.nr - 1; i >= 0; i--) {
                struct todo_item *item = todo_list.items + i;
                struct commit *commit = item->commit;
-               if (commit && !commit->util) {
+               if (commit && !*commit_seen_at(&commit_seen, commit)) {
                        strbuf_addf(&missing, " - %s %.*s\n",
                                    short_commit_name(commit),
                                    item->arg_len, item->arg);
-                       commit->util = (void *)1;
+                       *commit_seen_at(&commit_seen, commit) = 1;
                }
        }
  
                "The possible behaviours are: ignore, warn, error.\n\n"));
  
  leave_check:
+       clear_commit_seen(&commit_seen);
        strbuf_release(&todo_file);
        todo_list_release(&todo_list);
  
@@@ -4385,7 -3313,8 +4391,7 @@@ int skip_unnecessary_picks(void
                oid = &item->commit->object.oid;
        }
        if (i > 0) {
 -              int offset = i < todo_list.nr ?
 -                      todo_list.items[i].offset_in_buf : todo_list.buf.len;
 +              int offset = get_item_line_offset(&todo_list, i);
                const char *done_path = rebase_path_done();
  
                fd = open(done_path, O_CREAT | O_WRONLY | O_APPEND, 0666);
@@@ -4433,6 -3362,8 +4439,8 @@@ static int subject2item_cmp(const void 
        return key ? strcmp(a->subject, key) : strcmp(a->subject, b->subject);
  }
  
+ define_commit_slab(commit_todo_item, struct todo_item *);
  /*
   * Rearrange the todo list that has both "pick commit-id msg" and "pick
   * commit-id fixup!/squash! msg" in it so that the latter is put immediately
@@@ -4449,6 -3380,7 +4457,7 @@@ int rearrange_squash(void
        struct hashmap subject2item;
        int res = 0, rearranged = 0, *next, *tail, i;
        char **subjects;
+       struct commit_todo_item commit_todo;
  
        if (strbuf_read_file_or_whine(&todo_list.buf, todo_file) < 0)
                return -1;
                return -1;
        }
  
+       init_commit_todo_item(&commit_todo);
        /*
         * The hashmap maps onelines to the respective todo list index.
         *
                struct subject2item_entry *entry;
  
                next[i] = tail[i] = -1;
 -              if (item->command >= TODO_EXEC) {
 +              if (!item->commit || item->command == TODO_DROP) {
                        subjects[i] = NULL;
                        continue;
                }
  
                if (is_fixup(item->command)) {
                        todo_list_release(&todo_list);
+                       clear_commit_todo_item(&commit_todo);
                        return error(_("the script was already rearranged."));
                }
  
-               item->commit->util = item;
+               *commit_todo_item_at(&commit_todo, item->commit) = item;
  
                parse_commit(item->commit);
                commit_buffer = get_commit_buffer(item->commit, NULL);
                        else if (!strchr(p, ' ') &&
                                 (commit2 =
                                  lookup_commit_reference_by_name(p)) &&
-                                commit2->util)
+                                *commit_todo_item_at(&commit_todo, commit2))
                                /* found by commit name */
-                               i2 = (struct todo_item *)commit2->util
+                               i2 = *commit_todo_item_at(&commit_todo, commit2)
                                        - todo_list.items;
                        else {
                                /* copy can be a prefix of the commit subject */
                                continue;
  
                        while (cur >= 0) {
 -                              int offset = todo_list.items[cur].offset_in_buf;
 -                              int end_offset = cur + 1 < todo_list.nr ?
 -                                      todo_list.items[cur + 1].offset_in_buf :
 -                                      todo_list.buf.len;
 -                              char *bol = todo_list.buf.buf + offset;
 -                              char *eol = todo_list.buf.buf + end_offset;
 +                              const char *bol =
 +                                      get_item_line(&todo_list, cur);
 +                              const char *eol =
 +                                      get_item_line(&todo_list, cur + 1);
  
                                /* replace 'pick', by 'fixup' or 'squash' */
                                command = todo_list.items[cur].command;
        hashmap_free(&subject2item, 1);
        todo_list_release(&todo_list);
  
+       clear_commit_todo_item(&commit_todo);
        return res;
  }
diff --combined shallow.c
index 9ff83cabcd3be2614f7ed770884ac237294b05e4,030104978170305ed06c8bba68620b0ee004cb02..2abebeb8c857067315cf79b96dbba6b26a69a076
+++ b/shallow.c
@@@ -12,6 -12,7 +12,7 @@@
  #include "commit-slab.h"
  #include "revision.h"
  #include "list-objects.h"
+ #include "commit-slab.h"
  
  static int is_shallow = -1;
  static struct stat_validity shallow_stat;
@@@ -20,7 -21,7 +21,7 @@@ static char *alternate_shallow_file
  void set_alternate_shallow_file(const char *path, int override)
  {
        if (is_shallow != -1)
 -              die("BUG: is_repository_shallow must not be called before set_alternate_shallow_file");
 +              BUG("is_repository_shallow must not be called before set_alternate_shallow_file");
        if (alternate_shallow_file && !override)
                return;
        free(alternate_shallow_file);
@@@ -74,6 -75,11 +75,11 @@@ int is_repository_shallow(void
        return is_shallow;
  }
  
+ /*
+  * TODO: use "int" elemtype instead of "int *" when/if commit-slab
+  * supports a "valid" flag.
+  */
+ define_commit_slab(commit_depth, int *);
  struct commit_list *get_shallow_commits(struct object_array *heads, int depth,
                int shallow_flag, int not_shallow_flag)
  {
        struct object_array stack = OBJECT_ARRAY_INIT;
        struct commit *commit = NULL;
        struct commit_graft *graft;
+       struct commit_depth depths;
  
+       init_commit_depth(&depths);
        while (commit || i < heads->nr || stack.nr) {
                struct commit_list *p;
                if (!commit) {
                        if (i < heads->nr) {
+                               int **depth_slot;
                                commit = (struct commit *)
                                        deref_tag(heads->objects[i++].item, NULL, 0);
                                if (!commit || commit->object.type != OBJ_COMMIT) {
                                        commit = NULL;
                                        continue;
                                }
-                               if (!commit->util)
-                                       commit->util = xmalloc(sizeof(int));
-                               *(int *)commit->util = 0;
+                               depth_slot = commit_depth_at(&depths, commit);
+                               if (!*depth_slot)
+                                       *depth_slot = xmalloc(sizeof(int));
+                               **depth_slot = 0;
                                cur_depth = 0;
                        } else {
                                commit = (struct commit *)
                                        object_array_pop(&stack);
-                               cur_depth = *(int *)commit->util;
+                               cur_depth = **commit_depth_at(&depths, commit);
                        }
                }
                parse_commit_or_die(commit);
                }
                commit->object.flags |= not_shallow_flag;
                for (p = commit->parents, commit = NULL; p; p = p->next) {
-                       if (!p->item->util) {
-                               int *pointer = xmalloc(sizeof(int));
-                               p->item->util = pointer;
-                               *pointer =  cur_depth;
+                       int **depth_slot = commit_depth_at(&depths, p->item);
+                       if (!*depth_slot) {
+                               *depth_slot = xmalloc(sizeof(int));
+                               **depth_slot = cur_depth;
                        } else {
-                               int *pointer = p->item->util;
-                               if (cur_depth >= *pointer)
+                               if (cur_depth >= **depth_slot)
                                        continue;
-                               *pointer = cur_depth;
+                               **depth_slot = cur_depth;
                        }
                        if (p->next)
                                add_object_array(&p->item->object,
                                                NULL, &stack);
                        else {
                                commit = p->item;
-                               cur_depth = *(int *)commit->util;
+                               cur_depth = **commit_depth_at(&depths, commit);
                        }
                }
        }
+       for (i = 0; i < depths.slab_count; i++) {
+               int j;
+               for (j = 0; j < depths.slab_size; j++)
+                       free(depths.slab[i][j]);
+       }
+       clear_commit_depth(&depths);
  
        return result;
  }
@@@ -218,7 -234,7 +234,7 @@@ struct commit_list *get_shallow_commits
  static void check_shallow_file_for_update(void)
  {
        if (is_shallow == -1)
 -              die("BUG: shallow must be initialized by now");
 +              BUG("shallow must be initialized by now");
  
        if (!stat_validity_check(&shallow_stat, git_path_shallow()))
                die("shallow file has changed since we read it");
@@@ -353,7 -369,7 +369,7 @@@ void advertise_shallow_grafts(int fd
   */
  void prune_shallow(int show_only)
  {
 -      static struct lock_file shallow_lock;
 +      struct lock_file shallow_lock = LOCK_INIT;
        struct strbuf sb = STRBUF_INIT;
        int fd;
  
@@@ -446,7 -462,7 +462,7 @@@ static uint32_t *paint_alloc(struct pai
        void *p;
        if (!info->pool_count || size > info->end - info->free) {
                if (size > POOL_SIZE)
 -                      die("BUG: pool size too small for %d in paint_alloc()",
 +                      BUG("pool size too small for %d in paint_alloc()",
                            size);
                info->pool_count++;
                REALLOC_ARRAY(info->pools, info->pool_count);