contrib: add credential helper for OS X Keychain
[gitweb.git] / merge-recursive.c
index db9ba19ddf94fec3a5cfff450b35f5bb7b46c35e..cc664c39b66b0bb499dec13a22880a6096423fa6 100644 (file)
@@ -66,10 +66,12 @@ static int sha_eq(const unsigned char *a, const unsigned char *b)
 enum rename_type {
        RENAME_NORMAL = 0,
        RENAME_DELETE,
-       RENAME_ONE_FILE_TO_TWO
+       RENAME_ONE_FILE_TO_ONE,
+       RENAME_ONE_FILE_TO_TWO,
+       RENAME_TWO_FILES_TO_ONE
 };
 
-struct rename_df_conflict_info {
+struct rename_conflict_info {
        enum rename_type rename_type;
        struct diff_filepair *pair1;
        struct diff_filepair *pair2;
@@ -77,6 +79,8 @@ struct rename_df_conflict_info {
        const char *branch2;
        struct stage_data *dst_entry1;
        struct stage_data *dst_entry2;
+       struct diff_filespec ren1_other;
+       struct diff_filespec ren2_other;
 };
 
 /*
@@ -88,34 +92,54 @@ struct stage_data {
                unsigned mode;
                unsigned char sha[20];
        } stages[4];
-       struct rename_df_conflict_info *rename_df_conflict_info;
+       struct rename_conflict_info *rename_conflict_info;
        unsigned processed:1;
 };
 
-static inline void setup_rename_df_conflict_info(enum rename_type rename_type,
-                                                struct diff_filepair *pair1,
-                                                struct diff_filepair *pair2,
-                                                const char *branch1,
-                                                const char *branch2,
-                                                struct stage_data *dst_entry1,
-                                                struct stage_data *dst_entry2)
+static inline void setup_rename_conflict_info(enum rename_type rename_type,
+                                             struct diff_filepair *pair1,
+                                             struct diff_filepair *pair2,
+                                             const char *branch1,
+                                             const char *branch2,
+                                             struct stage_data *dst_entry1,
+                                             struct stage_data *dst_entry2,
+                                             struct merge_options *o,
+                                             struct stage_data *src_entry1,
+                                             struct stage_data *src_entry2)
 {
-       struct rename_df_conflict_info *ci = xcalloc(1, sizeof(struct rename_df_conflict_info));
+       struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
        ci->rename_type = rename_type;
        ci->pair1 = pair1;
        ci->branch1 = branch1;
        ci->branch2 = branch2;
 
        ci->dst_entry1 = dst_entry1;
-       dst_entry1->rename_df_conflict_info = ci;
+       dst_entry1->rename_conflict_info = ci;
        dst_entry1->processed = 0;
 
        assert(!pair2 == !dst_entry2);
        if (dst_entry2) {
                ci->dst_entry2 = dst_entry2;
                ci->pair2 = pair2;
-               dst_entry2->rename_df_conflict_info = ci;
-               dst_entry2->processed = 0;
+               dst_entry2->rename_conflict_info = ci;
+       }
+
+       if (rename_type == RENAME_TWO_FILES_TO_ONE) {
+               /*
+                * For each rename, there could have been
+                * modifications on the side of history where that
+                * file was not renamed.
+                */
+               int ostage1 = o->branch1 == branch1 ? 3 : 2;
+               int ostage2 = ostage1 ^ 1;
+
+               ci->ren1_other.path = pair1->one->path;
+               hashcpy(ci->ren1_other.sha1, src_entry1->stages[ostage1].sha);
+               ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
+
+               ci->ren2_other.path = pair2->one->path;
+               hashcpy(ci->ren2_other.sha1, src_entry2->stages[ostage2].sha);
+               ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
        }
 }
 
@@ -230,7 +254,7 @@ struct tree *write_tree_from_memory(struct merge_options *o)
                for (i = 0; i < active_nr; i++) {
                        struct cache_entry *ce = active_cache[i];
                        if (ce_stage(ce))
-                               fprintf(stderr, "BUG: %d %.*s", ce_stage(ce),
+                               fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
                                        (int)ce_namelen(ce), ce->name);
                }
                die("Bug in merge-recursive.c");
@@ -333,44 +357,90 @@ static struct string_list *get_unmerged(void)
        return unmerged;
 }
 
-static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
-                                                     struct string_list *entries)
+static int string_list_df_name_compare(const void *a, const void *b)
 {
-       /* If there are D/F conflicts, and the paths currently exist
-        * in the working copy as a file, we want to remove them to
-        * make room for the corresponding directory.  Such paths will
-        * later be processed in process_df_entry() at the end.  If
-        * the corresponding directory ends up being removed by the
-        * merge, then the file will be reinstated at that time;
-        * otherwise, if the file is not supposed to be removed by the
-        * merge, the contents of the file will be placed in another
-        * unique filename.
+       const struct string_list_item *one = a;
+       const struct string_list_item *two = b;
+       int onelen = strlen(one->string);
+       int twolen = strlen(two->string);
+       /*
+        * Here we only care that entries for D/F conflicts are
+        * adjacent, in particular with the file of the D/F conflict
+        * appearing before files below the corresponding directory.
+        * The order of the rest of the list is irrelevant for us.
         *
-        * NOTE: This function relies on the fact that entries for a
-        * D/F conflict will appear adjacent in the index, with the
-        * entries for the file appearing before entries for paths
-        * below the corresponding directory.
+        * To achieve this, we sort with df_name_compare and provide
+        * the mode S_IFDIR so that D/F conflicts will sort correctly.
+        * We use the mode S_IFDIR for everything else for simplicity,
+        * since in other cases any changes in their order due to
+        * sorting cause no problems for us.
+        */
+       int cmp = df_name_compare(one->string, onelen, S_IFDIR,
+                                 two->string, twolen, S_IFDIR);
+       /*
+        * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
+        * that 'foo' comes before 'foo/bar'.
         */
+       if (cmp)
+               return cmp;
+       return onelen - twolen;
+}
+
+static void record_df_conflict_files(struct merge_options *o,
+                                    struct string_list *entries)
+{
+       /* If there is a D/F conflict and the file for such a conflict
+        * currently exist in the working tree, we want to allow it to be
+        * removed to make room for the corresponding directory if needed.
+        * The files underneath the directories of such D/F conflicts will
+        * be processed before the corresponding file involved in the D/F
+        * conflict.  If the D/F directory ends up being removed by the
+        * merge, then we won't have to touch the D/F file.  If the D/F
+        * directory needs to be written to the working copy, then the D/F
+        * file will simply be removed (in make_room_for_path()) to make
+        * room for the necessary paths.  Note that if both the directory
+        * and the file need to be present, then the D/F file will be
+        * reinstated with a new unique name at the time it is processed.
+        */
+       struct string_list df_sorted_entries;
        const char *last_file = NULL;
        int last_len = 0;
        int i;
 
+       /*
+        * If we're merging merge-bases, we don't want to bother with
+        * any working directory changes.
+        */
+       if (o->call_depth)
+               return;
+
+       /* Ensure D/F conflicts are adjacent in the entries list. */
+       memset(&df_sorted_entries, 0, sizeof(struct string_list));
        for (i = 0; i < entries->nr; i++) {
-               const char *path = entries->items[i].string;
+               struct string_list_item *next = &entries->items[i];
+               string_list_append(&df_sorted_entries, next->string)->util =
+                                  next->util;
+       }
+       qsort(df_sorted_entries.items, entries->nr, sizeof(*entries->items),
+             string_list_df_name_compare);
+
+       string_list_clear(&o->df_conflict_file_set, 1);
+       for (i = 0; i < df_sorted_entries.nr; i++) {
+               const char *path = df_sorted_entries.items[i].string;
                int len = strlen(path);
-               struct stage_data *e = entries->items[i].util;
+               struct stage_data *e = df_sorted_entries.items[i].util;
 
                /*
                 * Check if last_file & path correspond to a D/F conflict;
                 * i.e. whether path is last_file+'/'+<something>.
-                * If so, remove last_file to make room for path and friends.
+                * If so, record that it's okay to remove last_file to make
+                * room for path and friends if needed.
                 */
                if (last_file &&
                    len > last_len &&
                    memcmp(path, last_file, last_len) == 0 &&
                    path[last_len] == '/') {
-                       output(o, 3, "Removing %s to make room for subdirectory; may re-add later.", last_file);
-                       unlink(last_file);
+                       string_list_insert(&o->df_conflict_file_set, last_file);
                }
 
                /*
@@ -386,6 +456,7 @@ static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
                        last_file = NULL;
                }
        }
+       string_list_clear(&df_sorted_entries, 0);
 }
 
 struct rename {
@@ -461,10 +532,21 @@ static struct string_list *get_renames(struct merge_options *o,
        return renames;
 }
 
-static int update_stages_options(const char *path, struct diff_filespec *o,
-                        struct diff_filespec *a, struct diff_filespec *b,
-                        int clear, int options)
+static int update_stages(const char *path, const struct diff_filespec *o,
+                        const struct diff_filespec *a,
+                        const struct diff_filespec *b)
 {
+
+       /*
+        * NOTE: It is usually a bad idea to call update_stages on a path
+        * before calling update_file on that same path, since it can
+        * sometimes lead to spurious "refusing to lose untracked file..."
+        * messages from update_file (via make_room_for path via
+        * would_lose_untracked).  Instead, reverse the order of the calls
+        * (executing update_file first and then update_stages).
+        */
+       int clear = 1;
+       int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
        if (clear)
                if (remove_file_from_cache(path))
                        return -1;
@@ -480,23 +562,11 @@ static int update_stages_options(const char *path, struct diff_filespec *o,
        return 0;
 }
 
-static int update_stages(const char *path, struct diff_filespec *o,
-                        struct diff_filespec *a, struct diff_filespec *b,
-                        int clear)
+static void update_entry(struct stage_data *entry,
+                        struct diff_filespec *o,
+                        struct diff_filespec *a,
+                        struct diff_filespec *b)
 {
-       int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
-       return update_stages_options(path, o, a, b, clear, options);
-}
-
-static int update_stages_and_entry(const char *path,
-                                  struct stage_data *entry,
-                                  struct diff_filespec *o,
-                                  struct diff_filespec *a,
-                                  struct diff_filespec *b,
-                                  int clear)
-{
-       int options;
-
        entry->processed = 0;
        entry->stages[1].mode = o->mode;
        entry->stages[2].mode = a->mode;
@@ -504,8 +574,6 @@ static int update_stages_and_entry(const char *path,
        hashcpy(entry->stages[1].sha, o->sha1);
        hashcpy(entry->stages[2].sha, a->sha1);
        hashcpy(entry->stages[3].sha, b->sha1);
-       options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
-       return update_stages_options(path, o, a, b, clear, options);
 }
 
 static int remove_file(struct merge_options *o, int clean,
@@ -563,7 +631,31 @@ static void flush_buffer(int fd, const char *buf, unsigned long size)
        }
 }
 
-static int would_lose_untracked(const char *path)
+static int dir_in_way(const char *path, int check_working_copy)
+{
+       int pos, pathlen = strlen(path);
+       char *dirpath = xmalloc(pathlen + 2);
+       struct stat st;
+
+       strcpy(dirpath, path);
+       dirpath[pathlen] = '/';
+       dirpath[pathlen+1] = '\0';
+
+       pos = cache_name_pos(dirpath, pathlen+1);
+
+       if (pos < 0)
+               pos = -1 - pos;
+       if (pos < active_nr &&
+           !strncmp(dirpath, active_cache[pos]->name, pathlen+1)) {
+               free(dirpath);
+               return 1;
+       }
+
+       free(dirpath);
+       return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
+}
+
+static int was_tracked(const char *path)
 {
        int pos = cache_name_pos(path, strlen(path));
 
@@ -580,18 +672,42 @@ static int would_lose_untracked(const char *path)
                switch (ce_stage(active_cache[pos])) {
                case 0:
                case 2:
-                       return 0;
+                       return 1;
                }
                pos++;
        }
-       return file_exists(path);
+       return 0;
 }
 
-static int make_room_for_path(const char *path)
+static int would_lose_untracked(const char *path)
 {
-       int status;
+       return !was_tracked(path) && file_exists(path);
+}
+
+static int make_room_for_path(struct merge_options *o, const char *path)
+{
+       int status, i;
        const char *msg = "failed to create path '%s'%s";
 
+       /* Unlink any D/F conflict files that are in the way */
+       for (i = 0; i < o->df_conflict_file_set.nr; i++) {
+               const char *df_path = o->df_conflict_file_set.items[i].string;
+               size_t pathlen = strlen(path);
+               size_t df_pathlen = strlen(df_path);
+               if (df_pathlen < pathlen &&
+                   path[df_pathlen] == '/' &&
+                   strncmp(path, df_path, df_pathlen) == 0) {
+                       output(o, 3,
+                              "Removing %s to make room for subdirectory\n",
+                              df_path);
+                       unlink(df_path);
+                       unsorted_string_list_delete_item(&o->df_conflict_file_set,
+                                                        i, 0);
+                       break;
+               }
+       }
+
+       /* Make sure leading directories are created */
        status = safe_create_leading_directories_const(path);
        if (status) {
                if (status == -3) {
@@ -659,7 +775,7 @@ static void update_file_flags(struct merge_options *o,
                        }
                }
 
-               if (make_room_for_path(path) < 0) {
+               if (make_room_for_path(o, path) < 0) {
                        update_wd = 0;
                        free(buf);
                        goto update_index;
@@ -712,9 +828,9 @@ struct merge_file_info {
 
 static int merge_3way(struct merge_options *o,
                      mmbuffer_t *result_buf,
-                     struct diff_filespec *one,
-                     struct diff_filespec *a,
-                     struct diff_filespec *b,
+                     const struct diff_filespec *one,
+                     const struct diff_filespec *a,
+                     const struct diff_filespec *b,
                      const char *branch1,
                      const char *branch2)
 {
@@ -771,12 +887,12 @@ static int merge_3way(struct merge_options *o,
        return merge_status;
 }
 
-static struct merge_file_info merge_file(struct merge_options *o,
-                                        struct diff_filespec *one,
-                                        struct diff_filespec *a,
-                                        struct diff_filespec *b,
-                                        const char *branch1,
-                                        const char *branch2)
+static struct merge_file_info 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;
        result.merge = 0;
@@ -830,8 +946,10 @@ static struct merge_file_info merge_file(struct merge_options *o,
                        free(result_buf.ptr);
                        result.clean = (merge_status == 0);
                } else if (S_ISGITLINK(a->mode)) {
-                       result.clean = merge_submodule(result.sha, one->path, one->sha1,
-                                                      a->sha1, b->sha1);
+                       result.clean = merge_submodule(result.sha,
+                                                      one->path, one->sha1,
+                                                      a->sha1, b->sha1,
+                                                      !o->call_depth);
                } else if (S_ISLNK(a->mode)) {
                        hashcpy(result.sha, a->sha1);
 
@@ -845,94 +963,303 @@ static struct merge_file_info merge_file(struct merge_options *o,
        return result;
 }
 
+static struct merge_file_info
+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)
+{
+       char *side1 = NULL;
+       char *side2 = NULL;
+       struct merge_file_info mfi;
+
+       if (filename1) {
+               side1 = xmalloc(strlen(branch1) + strlen(filename1) + 2);
+               sprintf(side1, "%s:%s", branch1, filename1);
+       }
+       if (filename2) {
+               side2 = xmalloc(strlen(branch2) + strlen(filename2) + 2);
+               sprintf(side2, "%s:%s", branch2, filename2);
+       }
+
+       mfi = merge_file_1(o, one, a, b,
+                          side1 ? side1 : branch1, side2 ? side2 : branch2);
+       free(side1);
+       free(side2);
+       return mfi;
+}
+
+static struct merge_file_info merge_file(struct merge_options *o,
+                                        const char *path,
+                                        const unsigned char *o_sha, int o_mode,
+                                        const unsigned char *a_sha, int a_mode,
+                                        const unsigned char *b_sha, int b_mode,
+                                        const char *branch1,
+                                        const char *branch2)
+{
+       struct diff_filespec one, a, b;
+
+       one.path = a.path = b.path = (char *)path;
+       hashcpy(one.sha1, o_sha);
+       one.mode = o_mode;
+       hashcpy(a.sha1, a_sha);
+       a.mode = a_mode;
+       hashcpy(b.sha1, b_sha);
+       b.mode = b_mode;
+       return merge_file_1(o, &one, &a, &b, branch1, branch2);
+}
+
+static void handle_change_delete(struct merge_options *o,
+                                const char *path,
+                                const unsigned char *o_sha, int o_mode,
+                                const unsigned char *a_sha, int a_mode,
+                                const unsigned char *b_sha, int b_mode,
+                                const char *change, const char *change_past)
+{
+       char *renamed = NULL;
+       if (dir_in_way(path, !o->call_depth)) {
+               renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
+       }
+
+       if (o->call_depth) {
+               /*
+                * We cannot arbitrarily accept either a_sha or b_sha as
+                * correct; since there is no true "middle point" between
+                * them, simply reuse the base version for virtual merge base.
+                */
+               remove_file_from_cache(path);
+               update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
+       } else if (!a_sha) {
+               output(o, 1, "CONFLICT (%s/delete): %s deleted in %s "
+                      "and %s in %s. Version %s of %s left in tree%s%s.",
+                      change, path, o->branch1,
+                      change_past, o->branch2, o->branch2, path,
+                      NULL == renamed ? "" : " at ",
+                      NULL == renamed ? "" : renamed);
+               update_file(o, 0, b_sha, b_mode, renamed ? renamed : path);
+       } else {
+               output(o, 1, "CONFLICT (%s/delete): %s deleted in %s "
+                      "and %s in %s. Version %s of %s left in tree%s%s.",
+                      change, path, o->branch2,
+                      change_past, o->branch1, o->branch1, path,
+                      NULL == renamed ? "" : " at ",
+                      NULL == renamed ? "" : renamed);
+               if (renamed)
+                       update_file(o, 0, a_sha, a_mode, renamed);
+               /*
+                * No need to call update_file() on path when !renamed, since
+                * that would needlessly touch path.  We could call
+                * update_file_flags() with update_cache=0 and update_wd=0,
+                * but that's a no-op.
+                */
+       }
+       free(renamed);
+}
+
 static void conflict_rename_delete(struct merge_options *o,
                                   struct diff_filepair *pair,
                                   const char *rename_branch,
                                   const char *other_branch)
 {
-       char *dest_name = pair->two->path;
-       int df_conflict = 0;
-       struct stat st;
+       const struct diff_filespec *orig = pair->one;
+       const struct diff_filespec *dest = pair->two;
+       const unsigned char *a_sha = NULL;
+       const unsigned char *b_sha = NULL;
+       int a_mode = 0;
+       int b_mode = 0;
+
+       if (rename_branch == o->branch1) {
+               a_sha = dest->sha1;
+               a_mode = dest->mode;
+       } else {
+               b_sha = dest->sha1;
+               b_mode = dest->mode;
+       }
 
-       output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
-              "and deleted in %s",
-              pair->one->path, pair->two->path, rename_branch,
-              other_branch);
-       if (!o->call_depth)
-               update_stages(dest_name, NULL,
-                             rename_branch == o->branch1 ? pair->two : NULL,
-                             rename_branch == o->branch1 ? NULL : pair->two,
-                             1);
-       if (lstat(dest_name, &st) == 0 && S_ISDIR(st.st_mode)) {
-               dest_name = unique_path(o, dest_name, rename_branch);
-               df_conflict = 1;
+       handle_change_delete(o,
+                            o->call_depth ? orig->path : dest->path,
+                            orig->sha1, orig->mode,
+                            a_sha, a_mode,
+                            b_sha, b_mode,
+                            "rename", "renamed");
+
+       if (o->call_depth) {
+               remove_file_from_cache(dest->path);
+       } else {
+               update_stages(dest->path, NULL,
+                             rename_branch == o->branch1 ? dest : NULL,
+                             rename_branch == o->branch1 ? NULL : dest);
        }
-       update_file(o, 0, pair->two->sha1, pair->two->mode, dest_name);
-       if (df_conflict)
-               free(dest_name);
+
 }
 
-static void conflict_rename_rename_1to2(struct merge_options *o,
-                                       struct diff_filepair *pair1,
-                                       const char *branch1,
-                                       struct diff_filepair *pair2,
-                                       const char *branch2)
+static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
+                                                struct stage_data *entry,
+                                                int stage)
 {
-       /* One file was renamed in both branches, but to different names. */
-       char *del[2];
-       int delp = 0;
-       const char *ren1_dst = pair1->two->path;
-       const char *ren2_dst = pair2->two->path;
-       const char *dst_name1 = ren1_dst;
-       const char *dst_name2 = ren2_dst;
-       struct stat st;
-       if (lstat(ren1_dst, &st) == 0 && S_ISDIR(st.st_mode)) {
-               dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
-               output(o, 1, "%s is a directory in %s adding as %s instead",
-                      ren1_dst, branch2, dst_name1);
+       unsigned char *sha = entry->stages[stage].sha;
+       unsigned mode = entry->stages[stage].mode;
+       if (mode == 0 || is_null_sha1(sha))
+               return NULL;
+       hashcpy(target->sha1, sha);
+       target->mode = mode;
+       return target;
+}
+
+static void handle_file(struct merge_options *o,
+                       struct diff_filespec *rename,
+                       int stage,
+                       struct rename_conflict_info *ci)
+{
+       char *dst_name = rename->path;
+       struct stage_data *dst_entry;
+       const char *cur_branch, *other_branch;
+       struct diff_filespec other;
+       struct diff_filespec *add;
+
+       if (stage == 2) {
+               dst_entry = ci->dst_entry1;
+               cur_branch = ci->branch1;
+               other_branch = ci->branch2;
+       } else {
+               dst_entry = ci->dst_entry2;
+               cur_branch = ci->branch2;
+               other_branch = ci->branch1;
        }
-       if (lstat(ren2_dst, &st) == 0 && S_ISDIR(st.st_mode)) {
-               dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
-               output(o, 1, "%s is a directory in %s adding as %s instead",
-                      ren2_dst, branch1, dst_name2);
+
+       add = filespec_from_entry(&other, dst_entry, stage ^ 1);
+       if (add) {
+               char *add_name = unique_path(o, rename->path, other_branch);
+               update_file(o, 0, add->sha1, add->mode, add_name);
+
+               remove_file(o, 0, rename->path, 0);
+               dst_name = unique_path(o, rename->path, cur_branch);
+       } else {
+               if (dir_in_way(rename->path, !o->call_depth)) {
+                       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);
+               }
        }
+       update_file(o, 0, rename->sha1, rename->mode, dst_name);
+       if (stage == 2)
+               update_stages(rename->path, NULL, rename, add);
+       else
+               update_stages(rename->path, NULL, add, rename);
+
+       if (dst_name != rename->path)
+               free(dst_name);
+}
+
+static void conflict_rename_rename_1to2(struct merge_options *o,
+                                       struct rename_conflict_info *ci)
+{
+       /* One file was renamed in both branches, but to different names. */
+       struct diff_filespec *one = ci->pair1->one;
+       struct diff_filespec *a = ci->pair1->two;
+       struct diff_filespec *b = ci->pair2->two;
+
+       output(o, 1, "CONFLICT (rename/rename): "
+              "Rename \"%s\"->\"%s\" in branch \"%s\" "
+              "rename \"%s\"->\"%s\" in \"%s\"%s",
+              one->path, a->path, ci->branch1,
+              one->path, b->path, ci->branch2,
+              o->call_depth ? " (left unresolved)" : "");
        if (o->call_depth) {
-               remove_file_from_cache(dst_name1);
-               remove_file_from_cache(dst_name2);
+               struct merge_file_info mfi;
+               struct diff_filespec other;
+               struct diff_filespec *add;
+               mfi = merge_file(o, one->path,
+                                one->sha1, one->mode,
+                                a->sha1, a->mode,
+                                b->sha1, b->mode,
+                                ci->branch1, ci->branch2);
                /*
-                * Uncomment to leave the conflicting names in the resulting tree
-                *
-                * update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
-                * update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
+                * FIXME: For rename/add-source conflicts (if we could detect
+                * such), this is wrong.  We should instead find a unique
+                * pathname and then either rename the add-source file to that
+                * unique path, or use that unique path instead of src here.
                 */
-       } else {
-               update_stages(ren1_dst, NULL, pair1->two, NULL, 1);
-               update_stages(ren2_dst, NULL, NULL, pair2->two, 1);
+               update_file(o, 0, mfi.sha, mfi.mode, one->path);
 
-               update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
-               update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
+               /*
+                * Above, we put the merged content at the merge-base's
+                * path.  Now we usually need to delete both a->path and
+                * b->path.  However, the rename on each side of the merge
+                * could also be involved in a rename/add conflict.  In
+                * such cases, we should keep the added file around,
+                * resolving the conflict at that path in its favor.
+                */
+               add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
+               if (add)
+                       update_file(o, 0, add->sha1, add->mode, a->path);
+               else
+                       remove_file_from_cache(a->path);
+               add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
+               if (add)
+                       update_file(o, 0, add->sha1, add->mode, b->path);
+               else
+                       remove_file_from_cache(b->path);
+       } else {
+               handle_file(o, a, 2, ci);
+               handle_file(o, b, 3, ci);
        }
-       while (delp--)
-               free(del[delp]);
 }
 
 static void conflict_rename_rename_2to1(struct merge_options *o,
-                                       struct rename *ren1,
-                                       const char *branch1,
-                                       struct rename *ren2,
-                                       const char *branch2)
+                                       struct rename_conflict_info *ci)
 {
-       /* Two files were renamed to the same thing. */
-       char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
-       char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
-       output(o, 1, "Renaming %s to %s and %s to %s instead",
-              ren1->pair->one->path, new_path1,
-              ren2->pair->one->path, new_path2);
-       remove_file(o, 0, ren1->pair->two->path, 0);
-       update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
-       update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
-       free(new_path2);
-       free(new_path1);
+       /* Two files, a & b, were renamed to the same thing, c. */
+       struct diff_filespec *a = ci->pair1->one;
+       struct diff_filespec *b = ci->pair2->one;
+       struct diff_filespec *c1 = ci->pair1->two;
+       struct diff_filespec *c2 = ci->pair2->two;
+       char *path = c1->path; /* == c2->path */
+       struct merge_file_info mfi_c1;
+       struct merge_file_info mfi_c2;
+
+       output(o, 1, "CONFLICT (rename/rename): "
+              "Rename %s->%s in %s. "
+              "Rename %s->%s in %s",
+              a->path, c1->path, ci->branch1,
+              b->path, c2->path, ci->branch2);
+
+       remove_file(o, 1, a->path, would_lose_untracked(a->path));
+       remove_file(o, 1, b->path, would_lose_untracked(b->path));
+
+       mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
+                                           o->branch1, c1->path,
+                                           o->branch2, ci->ren1_other.path);
+       mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
+                                           o->branch1, ci->ren2_other.path,
+                                           o->branch2, c2->path);
+
+       if (o->call_depth) {
+               /*
+                * If mfi_c1.clean && mfi_c2.clean, then it might make
+                * sense to do a two-way merge of those results.  But, I
+                * think in all cases, it makes sense to have the virtual
+                * merge base just undo the renames; they can be detected
+                * again later for the non-recursive merge.
+                */
+               remove_file(o, 0, path, 0);
+               update_file(o, 0, mfi_c1.sha, mfi_c1.mode, a->path);
+               update_file(o, 0, mfi_c2.sha, mfi_c2.mode, b->path);
+       } else {
+               char *new_path1 = unique_path(o, path, ci->branch1);
+               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);
+               update_file(o, 0, mfi_c1.sha, mfi_c1.mode, new_path1);
+               update_file(o, 0, mfi_c2.sha, mfi_c2.mode, new_path2);
+               free(new_path2);
+               free(new_path1);
+       }
 }
 
 static int process_renames(struct merge_options *o,
@@ -947,12 +1274,12 @@ static int process_renames(struct merge_options *o,
        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
-                       = sre->dst_entry;
+                       = (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
-                       = sre->dst_entry;
+                       = (void *)sre;
        }
 
        for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
@@ -960,6 +1287,7 @@ static int process_renames(struct merge_options *o,
                struct rename *ren1 = NULL, *ren2 = NULL;
                const char *branch1, *branch2;
                const char *ren1_src, *ren1_dst;
+               struct string_list_item *lookup;
 
                if (i >= a_renames->nr) {
                        ren2 = b_renames->items[j++].util;
@@ -991,44 +1319,82 @@ static int process_renames(struct merge_options *o,
                        ren1 = tmp;
                }
 
-               ren1->dst_entry->processed = 1;
-               ren1->src_entry->processed = 1;
-
                if (ren1->processed)
                        continue;
                ren1->processed = 1;
+               ren1->dst_entry->processed = 1;
+               /* BUG: We should only mark src_entry as processed if we
+                * are not dealing with a rename + add-source case.
+                */
+               ren1->src_entry->processed = 1;
 
                ren1_src = ren1->pair->one->path;
                ren1_dst = ren1->pair->two->path;
 
                if (ren2) {
+                       /* One file renamed on both sides */
                        const char *ren2_src = ren2->pair->one->path;
                        const char *ren2_dst = ren2->pair->two->path;
-                       /* Renamed in 1 and renamed in 2 */
+                       enum rename_type rename_type;
                        if (strcmp(ren1_src, ren2_src) != 0)
-                               die("ren1.src != ren2.src");
+                               die("ren1_src != ren2_src");
                        ren2->dst_entry->processed = 1;
                        ren2->processed = 1;
                        if (strcmp(ren1_dst, ren2_dst) != 0) {
-                               setup_rename_df_conflict_info(RENAME_ONE_FILE_TO_TWO,
-                                                             ren1->pair,
-                                                             ren2->pair,
-                                                             branch1,
-                                                             branch2,
-                                                             ren1->dst_entry,
-                                                             ren2->dst_entry);
+                               rename_type = RENAME_ONE_FILE_TO_TWO;
+                               clean_merge = 0;
                        } else {
+                               rename_type = RENAME_ONE_FILE_TO_ONE;
+                               /* BUG: We should only remove ren1_src in
+                                * the base stage (think of rename +
+                                * add-source cases).
+                                */
                                remove_file(o, 1, ren1_src, 1);
-                               update_stages_and_entry(ren1_dst,
-                                                       ren1->dst_entry,
-                                                       ren1->pair->one,
-                                                       ren1->pair->two,
-                                                       ren2->pair->two,
-                                                       1 /* clear */);
+                               update_entry(ren1->dst_entry,
+                                            ren1->pair->one,
+                                            ren1->pair->two,
+                                            ren2->pair->two);
                        }
+                       setup_rename_conflict_info(rename_type,
+                                                  ren1->pair,
+                                                  ren2->pair,
+                                                  branch1,
+                                                  branch2,
+                                                  ren1->dst_entry,
+                                                  ren2->dst_entry,
+                                                  o,
+                                                  NULL,
+                                                  NULL);
+               } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
+                       /* Two different files renamed to the same thing */
+                       char *ren2_dst;
+                       ren2 = lookup->util;
+                       ren2_dst = ren2->pair->two->path;
+                       if (strcmp(ren1_dst, ren2_dst) != 0)
+                               die("ren1_dst != ren2_dst");
+
+                       clean_merge = 0;
+                       ren2->processed = 1;
+                       /*
+                        * BUG: We should only mark src_entry as processed
+                        * if we are not dealing with a rename + add-source
+                        * case.
+                        */
+                       ren2->src_entry->processed = 1;
+
+                       setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
+                                                  ren1->pair,
+                                                  ren2->pair,
+                                                  branch1,
+                                                  branch2,
+                                                  ren1->dst_entry,
+                                                  ren2->dst_entry,
+                                                  o,
+                                                  ren1->src_entry,
+                                                  ren2->src_entry);
+
                } else {
                        /* Renamed in 1, maybe changed in 2 */
-                       struct string_list_item *item;
                        /* we only use sha1 and mode of these */
                        struct diff_filespec src_other, dst_other;
                        int try_merge;
@@ -1042,7 +1408,12 @@ static int process_renames(struct merge_options *o,
                        int renamed_stage = a_renames == renames1 ? 2 : 3;
                        int other_stage =   a_renames == renames1 ? 3 : 2;
 
-                       remove_file(o, 1, ren1_src, o->call_depth || renamed_stage == 2);
+                       /* BUG: We should only remove ren1_src in the base
+                        * stage and in other_stage (think of rename +
+                        * add-source case).
+                        */
+                       remove_file(o, 1, ren1_src,
+                                   renamed_stage == 2 || !was_tracked(ren1_src));
 
                        hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
                        src_other.mode = ren1->src_entry->stages[other_stage].mode;
@@ -1051,27 +1422,33 @@ static int process_renames(struct merge_options *o,
                        try_merge = 0;
 
                        if (sha_eq(src_other.sha1, null_sha1)) {
-                               if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
-                                       ren1->dst_entry->processed = 0;
-                                       setup_rename_df_conflict_info(RENAME_DELETE,
-                                                                     ren1->pair,
-                                                                     NULL,
-                                                                     branch1,
-                                                                     branch2,
-                                                                     ren1->dst_entry,
-                                                                     NULL);
-                               } else {
-                                       clean_merge = 0;
-                                       conflict_rename_delete(o, ren1->pair, branch1, branch2);
-                               }
+                               setup_rename_conflict_info(RENAME_DELETE,
+                                                          ren1->pair,
+                                                          NULL,
+                                                          branch1,
+                                                          branch2,
+                                                          ren1->dst_entry,
+                                                          NULL,
+                                                          o,
+                                                          NULL,
+                                                          NULL);
                        } else if ((dst_other.mode == ren1->pair->two->mode) &&
                                   sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
-                               /* Added file on the other side
-                                  identical to the file being
-                                  renamed: clean merge */
-                               update_file(o, 1, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
+                               /*
+                                * Added file on the other side identical to
+                                * the file being renamed: clean merge.
+                                * Also, there is no need to overwrite the
+                                * file already in the working copy, so call
+                                * update_file_flags() instead of
+                                * update_file().
+                                */
+                               update_file_flags(o,
+                                                 ren1->pair->two->sha1,
+                                                 ren1->pair->two->mode,
+                                                 ren1_dst,
+                                                 1, /* update_cache */
+                                                 0  /* update_wd    */);
                        } else if (!sha_eq(dst_other.sha1, null_sha1)) {
-                               const char *new_path;
                                clean_merge = 0;
                                try_merge = 1;
                                output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
@@ -1080,40 +1457,19 @@ static int process_renames(struct merge_options *o,
                                       ren1_dst, branch2);
                                if (o->call_depth) {
                                        struct merge_file_info mfi;
-                                       struct diff_filespec one, a, b;
-
-                                       one.path = a.path = b.path =
-                                               (char *)ren1_dst;
-                                       hashcpy(one.sha1, null_sha1);
-                                       one.mode = 0;
-                                       hashcpy(a.sha1, ren1->pair->two->sha1);
-                                       a.mode = ren1->pair->two->mode;
-                                       hashcpy(b.sha1, dst_other.sha1);
-                                       b.mode = dst_other.mode;
-                                       mfi = merge_file(o, &one, &a, &b,
-                                                        branch1,
-                                                        branch2);
+                                       mfi = merge_file(o, ren1_dst, null_sha1, 0,
+                                                        ren1->pair->two->sha1, ren1->pair->two->mode,
+                                                        dst_other.sha1, dst_other.mode,
+                                                        branch1, branch2);
                                        output(o, 1, "Adding merged %s", ren1_dst);
-                                       update_file(o, 0,
-                                                   mfi.sha,
-                                                   mfi.mode,
-                                                   ren1_dst);
+                                       update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
                                        try_merge = 0;
                                } else {
-                                       new_path = unique_path(o, ren1_dst, branch2);
+                                       char *new_path = unique_path(o, ren1_dst, branch2);
                                        output(o, 1, "Adding as %s instead", new_path);
                                        update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
+                                       free(new_path);
                                }
-                       } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
-                               ren2 = item->util;
-                               clean_merge = 0;
-                               ren2->processed = 1;
-                               output(o, 1, "CONFLICT (rename/rename): "
-                                      "Rename %s->%s in %s. "
-                                      "Rename %s->%s in %s",
-                                      ren1_src, ren1_dst, branch1,
-                                      ren2->pair->one->path, ren2->pair->two->path, branch2);
-                               conflict_rename_rename_2to1(o, ren1, branch1, ren2, branch2);
                        } else
                                try_merge = 1;
 
@@ -1129,16 +1485,17 @@ static int process_renames(struct merge_options *o,
                                        b = ren1->pair->two;
                                        a = &src_other;
                                }
-                               update_stages_and_entry(ren1_dst, ren1->dst_entry, one, a, b, 1);
-                               if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
-                                       setup_rename_df_conflict_info(RENAME_NORMAL,
-                                                                     ren1->pair,
-                                                                     NULL,
-                                                                     branch1,
-                                                                     NULL,
-                                                                     ren1->dst_entry,
-                                                                     NULL);
-                               }
+                               update_entry(ren1->dst_entry, one, a, b);
+                               setup_rename_conflict_info(RENAME_NORMAL,
+                                                          ren1->pair,
+                                                          NULL,
+                                                          branch1,
+                                                          NULL,
+                                                          ren1->dst_entry,
+                                                          NULL,
+                                                          o,
+                                                          NULL,
+                                                          NULL);
                        }
                }
        }
@@ -1200,29 +1557,18 @@ static int blob_unchanged(const unsigned char *o_sha,
        return ret;
 }
 
-static void handle_delete_modify(struct merge_options *o,
+static void handle_modify_delete(struct merge_options *o,
                                 const char *path,
-                                const char *new_path,
+                                unsigned char *o_sha, int o_mode,
                                 unsigned char *a_sha, int a_mode,
                                 unsigned char *b_sha, int b_mode)
 {
-       if (!a_sha) {
-               output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
-                      "and modified in %s. Version %s of %s left in tree%s%s.",
-                      path, o->branch1,
-                      o->branch2, o->branch2, path,
-                      path == new_path ? "" : " at ",
-                      path == new_path ? "" : new_path);
-               update_file(o, 0, b_sha, b_mode, new_path);
-       } else {
-               output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
-                      "and modified in %s. Version %s of %s left in tree%s%s.",
-                      path, o->branch2,
-                      o->branch1, o->branch1, path,
-                      path == new_path ? "" : " at ",
-                      path == new_path ? "" : new_path);
-               update_file(o, 0, a_sha, a_mode, new_path);
-       }
+       handle_change_delete(o,
+                            path,
+                            o_sha, o_mode,
+                            a_sha, a_mode,
+                            b_sha, b_mode,
+                            "modify", "modified");
 }
 
 static int merge_content(struct merge_options *o,
@@ -1230,12 +1576,12 @@ static int merge_content(struct merge_options *o,
                         unsigned char *o_sha, int o_mode,
                         unsigned char *a_sha, int a_mode,
                         unsigned char *b_sha, int b_mode,
-                        const char *df_rename_conflict_branch)
+                        struct rename_conflict_info *rename_conflict_info)
 {
        const char *reason = "content";
+       const char *path1 = NULL, *path2 = NULL;
        struct merge_file_info mfi;
        struct diff_filespec one, a, b;
-       struct stat st;
        unsigned df_conflict_remains = 0;
 
        if (!o_sha) {
@@ -1250,16 +1596,43 @@ static int merge_content(struct merge_options *o,
        hashcpy(b.sha1, b_sha);
        b.mode = b_mode;
 
-       mfi = merge_file(o, &one, &a, &b, o->branch1, o->branch2);
-       if (df_rename_conflict_branch &&
-           lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
-               df_conflict_remains = 1;
+       if (rename_conflict_info) {
+               struct diff_filepair *pair1 = rename_conflict_info->pair1;
+
+               path1 = (o->branch1 == rename_conflict_info->branch1) ?
+                       pair1->two->path : pair1->one->path;
+               /* If rename_conflict_info->pair2 != NULL, we are in
+                * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
+                * normal rename.
+                */
+               path2 = (rename_conflict_info->pair2 ||
+                        o->branch2 == rename_conflict_info->branch1) ?
+                       pair1->two->path : pair1->one->path;
+
+               if (dir_in_way(path, !o->call_depth))
+                       df_conflict_remains = 1;
        }
+       mfi = merge_file_special_markers(o, &one, &a, &b,
+                                        o->branch1, path1,
+                                        o->branch2, path2);
 
        if (mfi.clean && !df_conflict_remains &&
-           sha_eq(mfi.sha, a_sha) && mfi.mode == a.mode)
+           sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
+               int path_renamed_outside_HEAD;
                output(o, 3, "Skipped %s (merged same as existing)", path);
-       else
+               /*
+                * 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(mfi.mode, mfi.sha, path,
+                                     0, (!o->call_depth), 0);
+                       return mfi.clean;
+               }
+       } else
                output(o, 2, "Auto-merging %s", path);
 
        if (!mfi.clean) {
@@ -1267,16 +1640,34 @@ static int merge_content(struct merge_options *o,
                        reason = "submodule";
                output(o, 1, "CONFLICT (%s): Merge conflict in %s",
                                reason, path);
+               if (rename_conflict_info && !df_conflict_remains)
+                       update_stages(path, &one, &a, &b);
        }
 
        if (df_conflict_remains) {
-               const char *new_path;
-               update_file_flags(o, mfi.sha, mfi.mode, path,
-                                 o->call_depth || mfi.clean, 0);
-               new_path = unique_path(o, path, df_rename_conflict_branch);
-               mfi.clean = 0;
+               char *new_path;
+               if (o->call_depth) {
+                       remove_file_from_cache(path);
+               } else {
+                       if (!mfi.clean)
+                               update_stages(path, &one, &a, &b);
+                       else {
+                               int file_from_stage2 = was_tracked(path);
+                               struct diff_filespec merged;
+                               hashcpy(merged.sha1, mfi.sha);
+                               merged.mode = mfi.mode;
+
+                               update_stages(path, NULL,
+                                             file_from_stage2 ? &merged : NULL,
+                                             file_from_stage2 ? NULL : &merged);
+                       }
+
+               }
+               new_path = unique_path(o, path, rename_conflict_info->branch1);
                output(o, 1, "Adding as %s instead", new_path);
-               update_file_flags(o, mfi.sha, mfi.mode, new_path, 0, 1);
+               update_file(o, 0, mfi.sha, mfi.mode, new_path);
+               free(new_path);
+               mfi.clean = 0;
        } else {
                update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
        }
@@ -1301,104 +1692,15 @@ static int process_entry(struct merge_options *o,
        unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
        unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
 
-       if (entry->rename_df_conflict_info)
-               return 1; /* Such cases are handled elsewhere. */
-
-       entry->processed = 1;
-       if (o_sha && (!a_sha || !b_sha)) {
-               /* Case A: Deleted in one */
-               if ((!a_sha && !b_sha) ||
-                   (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
-                   (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
-                       /* Deleted in both or deleted in one and
-                        * unchanged in the other */
-                       if (a_sha)
-                               output(o, 2, "Removing %s", path);
-                       /* do not touch working file if it did not exist */
-                       remove_file(o, 1, path, !a_sha);
-               } else if (string_list_has_string(&o->current_directory_set,
-                                                 path)) {
-                       entry->processed = 0;
-                       return 1; /* Assume clean until processed */
-               } else {
-                       /* Deleted in one and changed in the other */
-                       clean_merge = 0;
-                       handle_delete_modify(o, path, path,
-                                            a_sha, a_mode, b_sha, b_mode);
-               }
-
-       } else if ((!o_sha && a_sha && !b_sha) ||
-                  (!o_sha && !a_sha && b_sha)) {
-               /* Case B: Added in one. */
-               unsigned mode;
-               const unsigned char *sha;
-
-               if (a_sha) {
-                       mode = a_mode;
-                       sha = a_sha;
-               } else {
-                       mode = b_mode;
-                       sha = b_sha;
-               }
-               if (string_list_has_string(&o->current_directory_set, path)) {
-                       /* Handle D->F conflicts after all subfiles */
-                       entry->processed = 0;
-                       return 1; /* Assume clean until processed */
-               } else {
-                       output(o, 2, "Adding %s", path);
-                       update_file(o, 1, sha, mode, path);
-               }
-       } else if (a_sha && b_sha) {
-               /* Case C: Added in both (check for same permissions) and */
-               /* case D: Modified in both, but differently. */
-               clean_merge = merge_content(o, path,
-                                           o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
-                                           NULL);
-       } else if (!o_sha && !a_sha && !b_sha) {
-               /*
-                * this entry was deleted altogether. a_mode == 0 means
-                * we had that path and want to actively remove it.
-                */
-               remove_file(o, 1, path, !a_mode);
-       } else
-               die("Fatal merge failure, shouldn't happen.");
-
-       return clean_merge;
-}
-
-/*
- * Per entry merge function for D/F (and/or rename) conflicts.  In the
- * cases we can cleanly resolve D/F conflicts, process_entry() can
- * clean out all the files below the directory for us.  All D/F
- * conflict cases must be handled here at the end to make sure any
- * directories that can be cleaned out, are.
- *
- * Some rename conflicts may also be handled here that don't necessarily
- * involve D/F conflicts, since the code to handle them is generic enough
- * to handle those rename conflicts with or without D/F conflicts also
- * being involved.
- */
-static int process_df_entry(struct merge_options *o,
-                           const char *path, struct stage_data *entry)
-{
-       int clean_merge = 1;
-       unsigned o_mode = entry->stages[1].mode;
-       unsigned a_mode = entry->stages[2].mode;
-       unsigned b_mode = entry->stages[3].mode;
-       unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
-       unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
-       unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
-       struct stat st;
-
        entry->processed = 1;
-       if (entry->rename_df_conflict_info) {
-               struct rename_df_conflict_info *conflict_info = entry->rename_df_conflict_info;
-               char *src;
+       if (entry->rename_conflict_info) {
+               struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
                switch (conflict_info->rename_type) {
                case RENAME_NORMAL:
+               case RENAME_ONE_FILE_TO_ONE:
                        clean_merge = merge_content(o, path,
                                                    o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
-                                                   conflict_info->branch1);
+                                                   conflict_info);
                        break;
                case RENAME_DELETE:
                        clean_merge = 0;
@@ -1407,39 +1709,39 @@ static int process_df_entry(struct merge_options *o,
                                               conflict_info->branch2);
                        break;
                case RENAME_ONE_FILE_TO_TWO:
-                       src = conflict_info->pair1->one->path;
                        clean_merge = 0;
-                       output(o, 1, "CONFLICT (rename/rename): "
-                              "Rename \"%s\"->\"%s\" in branch \"%s\" "
-                              "rename \"%s\"->\"%s\" in \"%s\"%s",
-                              src, conflict_info->pair1->two->path, conflict_info->branch1,
-                              src, conflict_info->pair2->two->path, conflict_info->branch2,
-                              o->call_depth ? " (left unresolved)" : "");
-                       if (o->call_depth) {
-                               remove_file_from_cache(src);
-                               update_file(o, 0, conflict_info->pair1->one->sha1,
-                                           conflict_info->pair1->one->mode, src);
-                       }
-                       conflict_rename_rename_1to2(o, conflict_info->pair1,
-                                                   conflict_info->branch1,
-                                                   conflict_info->pair2,
-                                                   conflict_info->branch2);
-                       conflict_info->dst_entry2->processed = 1;
+                       conflict_rename_rename_1to2(o, conflict_info);
+                       break;
+               case RENAME_TWO_FILES_TO_ONE:
+                       clean_merge = 0;
+                       conflict_rename_rename_2to1(o, conflict_info);
                        break;
                default:
                        entry->processed = 0;
                        break;
                }
        } else if (o_sha && (!a_sha || !b_sha)) {
-               /* Modify/delete; deleted side may have put a directory in the way */
-               const char *new_path = path;
-               if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode))
-                       new_path = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
-               clean_merge = 0;
-               handle_delete_modify(o, path, new_path,
-                                    a_sha, a_mode, b_sha, b_mode);
-       } else if (!o_sha && !!a_sha != !!b_sha) {
-               /* directory -> (directory, file) */
+               /* Case A: Deleted in one */
+               if ((!a_sha && !b_sha) ||
+                   (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
+                   (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
+                       /* Deleted in both or deleted in one and
+                        * unchanged in the other */
+                       if (a_sha)
+                               output(o, 2, "Removing %s", path);
+                       /* do not touch working file if it did not exist */
+                       remove_file(o, 1, path, !a_sha);
+               } else {
+                       /* Modify/delete; deleted side may have put a directory in the way */
+                       clean_merge = 0;
+                       handle_modify_delete(o, path, o_sha, o_mode,
+                                            a_sha, a_mode, b_sha, b_mode);
+               }
+       } else if ((!o_sha && a_sha && !b_sha) ||
+                  (!o_sha && !a_sha && b_sha)) {
+               /* Case B: Added in one. */
+               /* [nothing|directory] -> ([nothing|directory], file) */
+
                const char *add_branch;
                const char *other_branch;
                unsigned mode;
@@ -1459,21 +1761,37 @@ static int process_df_entry(struct merge_options *o,
                        sha = b_sha;
                        conf = "directory/file";
                }
-               if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
-                       const char *new_path = unique_path(o, path, add_branch);
+               if (dir_in_way(path, !o->call_depth)) {
+                       char *new_path = unique_path(o, path, add_branch);
                        clean_merge = 0;
                        output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
                               "Adding %s as %s",
                               conf, path, other_branch, path, new_path);
+                       if (o->call_depth)
+                               remove_file_from_cache(path);
                        update_file(o, 0, sha, mode, new_path);
+                       if (o->call_depth)
+                               remove_file_from_cache(path);
+                       free(new_path);
                } else {
                        output(o, 2, "Adding %s", path);
-                       update_file(o, 1, sha, mode, path);
+                       /* do not overwrite file if already present */
+                       update_file_flags(o, sha, mode, path, 1, !a_sha);
                }
-       } else {
-               entry->processed = 0;
-               return 1; /* not handled; assume clean until processed */
-       }
+       } else if (a_sha && b_sha) {
+               /* Case C: Added in both (check for same permissions) and */
+               /* case D: Modified in both, but differently. */
+               clean_merge = merge_content(o, path,
+                                           o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
+                                           NULL);
+       } else if (!o_sha && !a_sha && !b_sha) {
+               /*
+                * this entry was deleted altogether. a_mode == 0 means
+                * we had that path and want to actively remove it.
+                */
+               remove_file(o, 1, path, !a_mode);
+       } else
+               die("Fatal merge failure, shouldn't happen.");
 
        return clean_merge;
 }
@@ -1517,24 +1835,17 @@ int merge_trees(struct merge_options *o,
                get_files_dirs(o, merge);
 
                entries = get_unmerged();
-               make_room_for_directories_of_df_conflicts(o, entries);
+               record_df_conflict_files(o, entries);
                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);
-               for (i = 0; i < entries->nr; i++) {
+               for (i = entries->nr-1; 0 <= i; i--) {
                        const char *path = entries->items[i].string;
                        struct stage_data *e = entries->items[i].util;
                        if (!e->processed
                                && !process_entry(o, path, e))
                                clean = 0;
                }
-               for (i = 0; i < entries->nr; i++) {
-                       const char *path = entries->items[i].string;
-                       struct stage_data *e = entries->items[i].util;
-                       if (!e->processed
-                               && !process_df_entry(o, path, e))
-                               clean = 0;
-               }
                for (i = 0; i < entries->nr; i++) {
                        struct stage_data *e = entries->items[i].util;
                        if (!e->processed)
@@ -1601,12 +1912,10 @@ int merge_recursive(struct merge_options *o,
 
        merged_common_ancestors = pop_commit(&ca);
        if (merged_common_ancestors == NULL) {
-               /* if there is no common ancestor, make an empty tree */
-               struct tree *tree = xcalloc(1, sizeof(struct tree));
+               /* if there is no common ancestor, use an empty tree */
+               struct tree *tree;
 
-               tree->object.parsed = 1;
-               tree->object.type = OBJ_TREE;
-               pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
+               tree = lookup_tree((const unsigned char *)EMPTY_TREE_SHA1_BIN);
                merged_common_ancestors = make_virtual_commit(tree, "ancestor");
        }
 
@@ -1743,6 +2052,8 @@ void init_merge_options(struct merge_options *o)
        o->current_file_set.strdup_strings = 1;
        memset(&o->current_directory_set, 0, sizeof(struct string_list));
        o->current_directory_set.strdup_strings = 1;
+       memset(&o->df_conflict_file_set, 0, sizeof(struct string_list));
+       o->df_conflict_file_set.strdup_strings = 1;
 }
 
 int parse_merge_opt(struct merge_options *o, const char *s)
@@ -1759,6 +2070,8 @@ int parse_merge_opt(struct merge_options *o, const char *s)
                o->subtree_shift = s + strlen("subtree=");
        else if (!strcmp(s, "patience"))
                o->xdl_opts |= XDF_PATIENCE_DIFF;
+       else if (!strcmp(s, "histogram"))
+               o->xdl_opts |= XDF_HISTOGRAM_DIFF;
        else if (!strcmp(s, "ignore-space-change"))
                o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
        else if (!strcmp(s, "ignore-all-space"))