t5702: use test_commit_bulk
[gitweb.git] / diff.c
diff --git a/diff.c b/diff.c
index 8d387280a4a63171361ae4f3c1294c7e5997d35e..1ee04e321b1b5cc4e3f6bde37f49b7d3c0694aa6 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -25,6 +25,7 @@
 #include "packfile.h"
 #include "parse-options.h"
 #include "help.h"
+#include "fetch-object.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
@@ -174,6 +175,10 @@ static int parse_submodule_params(struct diff_options *options, const char *valu
                options->submodule_format = DIFF_SUBMODULE_SHORT;
        else if (!strcmp(value, "diff"))
                options->submodule_format = DIFF_SUBMODULE_INLINE_DIFF;
+       /*
+        * Please update $__git_diff_submodule_formats in
+        * git-completion.bash when you add new formats.
+        */
        else
                return -1;
        return 0;
@@ -200,6 +205,10 @@ long parse_algorithm_value(const char *value)
                return XDF_PATIENCE_DIFF;
        else if (!strcasecmp(value, "histogram"))
                return XDF_HISTOGRAM_DIFF;
+       /*
+        * Please update $__git_diff_algorithms in git-completion.bash
+        * when you add new algorithms.
+        */
        return -1;
 }
 
@@ -300,7 +309,9 @@ static unsigned parse_color_moved_ws(const char *arg)
                strbuf_addstr(&sb, i->string);
                strbuf_trim(&sb);
 
-               if (!strcmp(sb.buf, "ignore-space-change"))
+               if (!strcmp(sb.buf, "no"))
+                       ret = 0;
+               else if (!strcmp(sb.buf, "ignore-space-change"))
                        ret |= XDF_IGNORE_WHITESPACE_CHANGE;
                else if (!strcmp(sb.buf, "ignore-space-at-eol"))
                        ret |= XDF_IGNORE_WHITESPACE_AT_EOL;
@@ -318,7 +329,7 @@ static unsigned parse_color_moved_ws(const char *arg)
 
        if ((ret & COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) &&
            (ret & XDF_WHITESPACE_FLAGS)) {
-               error(_("color-moved-ws: allow-indentation-change cannot be combined with other white space modes"));
+               error(_("color-moved-ws: allow-indentation-change cannot be combined with other whitespace modes"));
                ret |= COLOR_MOVED_WS_ERROR;
        }
 
@@ -489,7 +500,7 @@ static const char *external_diff(void)
 
        if (done_preparing)
                return external_diff_cmd;
-       external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
+       external_diff_cmd = xstrdup_or_null(getenv("GIT_EXTERNAL_DIFF"));
        if (!external_diff_cmd)
                external_diff_cmd = external_diff_cmd_cfg;
        done_preparing = 1;
@@ -750,6 +761,8 @@ struct emitted_diff_symbol {
        const char *line;
        int len;
        int flags;
+       int indent_off;   /* Offset to first non-whitespace character */
+       int indent_width; /* The visual width of the indentation */
        enum diff_symbol s;
 };
 #define EMITTED_DIFF_SYMBOL_INIT {NULL}
@@ -780,44 +793,85 @@ struct moved_entry {
        struct moved_entry *next_line;
 };
 
-/**
- * The struct ws_delta holds white space differences between moved lines, i.e.
- * between '+' and '-' lines that have been detected to be a move.
- * The string contains the difference in leading white spaces, before the
- * rest of the line is compared using the white space config for move
- * coloring. The current_longer indicates if the first string in the
- * comparision is longer than the second.
- */
-struct ws_delta {
-       char *string;
-       unsigned int current_longer : 1;
-};
-#define WS_DELTA_INIT { NULL, 0 }
-
 struct moved_block {
        struct moved_entry *match;
-       struct ws_delta wsd;
+       int wsd; /* The whitespace delta of this block */
 };
 
 static void moved_block_clear(struct moved_block *b)
 {
-       FREE_AND_NULL(b->wsd.string);
-       b->match = NULL;
+       memset(b, 0, sizeof(*b));
 }
 
-static int compute_ws_delta(const struct emitted_diff_symbol *a,
-                            const struct emitted_diff_symbol *b,
-                            struct ws_delta *out)
+#define INDENT_BLANKLINE INT_MIN
+
+static void fill_es_indent_data(struct emitted_diff_symbol *es)
 {
-       const struct emitted_diff_symbol *longer =  a->len > b->len ? a : b;
-       const struct emitted_diff_symbol *shorter = a->len > b->len ? b : a;
-       int d = longer->len - shorter->len;
+       unsigned int off = 0, i;
+       int width = 0, tab_width = es->flags & WS_TAB_WIDTH_MASK;
+       const char *s = es->line;
+       const int len = es->len;
+
+       /* skip any \v \f \r at start of indentation */
+       while (s[off] == '\f' || s[off] == '\v' ||
+              (s[off] == '\r' && off < len - 1))
+               off++;
+
+       /* calculate the visual width of indentation */
+       while(1) {
+               if (s[off] == ' ') {
+                       width++;
+                       off++;
+               } else if (s[off] == '\t') {
+                       width += tab_width - (width % tab_width);
+                       while (s[++off] == '\t')
+                               width += tab_width;
+               } else {
+                       break;
+               }
+       }
+
+       /* check if this line is blank */
+       for (i = off; i < len; i++)
+               if (!isspace(s[i]))
+                   break;
 
-       if (strncmp(longer->line + d, shorter->line, shorter->len))
+       if (i == len) {
+               es->indent_width = INDENT_BLANKLINE;
+               es->indent_off = len;
+       } else {
+               es->indent_off = off;
+               es->indent_width = width;
+       }
+}
+
+static int compute_ws_delta(const struct emitted_diff_symbol *a,
+                           const struct emitted_diff_symbol *b,
+                           int *out)
+{
+       int a_len = a->len,
+           b_len = b->len,
+           a_off = a->indent_off,
+           a_width = a->indent_width,
+           b_off = b->indent_off,
+           b_width = b->indent_width;
+       int delta;
+
+       if (a_width == INDENT_BLANKLINE && b_width == INDENT_BLANKLINE) {
+               *out = INDENT_BLANKLINE;
+               return 1;
+       }
+
+       if (a->s == DIFF_SYMBOL_PLUS)
+               delta = a_width - b_width;
+       else
+               delta = b_width - a_width;
+
+       if (a_len - a_off != b_len - b_off ||
+           memcmp(a->line + a_off, b->line + b_off, a_len - a_off))
                return 0;
 
-       out->string = xmemdupz(longer->line, d);
-       out->current_longer = (a == longer);
+       *out = delta;
 
        return 1;
 }
@@ -829,51 +883,53 @@ static int cmp_in_block_with_wsd(const struct diff_options *o,
                                 int n)
 {
        struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
-       int al = cur->es->len, cl = l->len;
+       int al = cur->es->len, bl = match->es->len, cl = l->len;
        const char *a = cur->es->line,
                   *b = match->es->line,
                   *c = l->line;
-
-       int wslen;
+       int a_off = cur->es->indent_off,
+           a_width = cur->es->indent_width,
+           c_off = l->indent_off,
+           c_width = l->indent_width;
+       int delta;
 
        /*
-        * We need to check if 'cur' is equal to 'match'.
-        * As those are from the same (+/-) side, we do not need to adjust for
-        * indent changes. However these were found using fuzzy matching
-        * so we do have to check if they are equal.
+        * We need to check if 'cur' is equal to 'match'.  As those
+        * are from the same (+/-) side, we do not need to adjust for
+        * indent changes. However these were found using fuzzy
+        * matching so we do have to check if they are equal. Here we
+        * just check the lengths. We delay calling memcmp() to check
+        * the contents until later as if the length comparison for a
+        * and c fails we can avoid the call all together.
         */
-       if (strcmp(a, b))
+       if (al != bl)
                return 1;
 
-       if (!pmb->wsd.string)
-               /*
-                * The white space delta is not active? This can happen
-                * when we exit early in this function.
-                */
-               return 1;
+       /* If 'l' and 'cur' are both blank then they match. */
+       if (a_width == INDENT_BLANKLINE && c_width == INDENT_BLANKLINE)
+               return 0;
 
        /*
-        * The indent changes of the block are known and stored in
-        * pmb->wsd; however we need to check if the indent changes of the
-        * current line are still the same as before.
-        *
-        * To do so we need to compare 'l' to 'cur', adjusting the
-        * one of them for the white spaces, depending which was longer.
+        * The indent changes of the block are known and stored in pmb->wsd;
+        * however we need to check if the indent changes of the current line
+        * match those of the current block and that the text of 'l' and 'cur'
+        * after the indentation match.
         */
+       if (cur->es->s == DIFF_SYMBOL_PLUS)
+               delta = a_width - c_width;
+       else
+               delta = c_width - a_width;
 
-       wslen = strlen(pmb->wsd.string);
-       if (pmb->wsd.current_longer) {
-               c += wslen;
-               cl -= wslen;
-       } else {
-               a += wslen;
-               al -= wslen;
-       }
-
-       if (al != cl || memcmp(a, c, al))
-               return 1;
+       /*
+        * If the previous lines of this block were all blank then set its
+        * whitespace delta.
+        */
+       if (pmb->wsd == INDENT_BLANKLINE)
+               pmb->wsd = delta;
 
-       return 0;
+       return !(delta == pmb->wsd && al - a_off == cl - c_off &&
+                !memcmp(a, b, al) && !
+                memcmp(a + a_off, c + c_off, al - a_off));
 }
 
 static int moved_entry_cmp(const void *hashmap_cmp_fn_data,
@@ -939,6 +995,9 @@ static void add_lines_to_move_detection(struct diff_options *o,
                        continue;
                }
 
+               if (o->color_moved_ws_handling &
+                   COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
+                       fill_es_indent_data(&o->emitted_symbols->buf[n]);
                key = prepare_entry(o, n);
                if (prev_line && prev_line->es->s == o->emitted_symbols->buf[n].s)
                        prev_line->next_line = key;
@@ -1017,8 +1076,7 @@ static int shrink_potential_moved_blocks(struct moved_block *pmb,
 
                if (lp < pmb_nr && rp > -1 && lp < rp) {
                        pmb[lp] = pmb[rp];
-                       pmb[rp].match = NULL;
-                       pmb[rp].wsd.string = NULL;
+                       memset(&pmb[rp], 0, sizeof(pmb[rp]));
                        rp--;
                        lp++;
                }
@@ -1038,14 +1096,17 @@ static int shrink_potential_moved_blocks(struct moved_block *pmb,
  * The last block consists of the (n - block_length)'th line up to but not
  * including the nth line.
  *
+ * Returns 0 if the last block is empty or is unset by this function, non zero
+ * otherwise.
+ *
  * NEEDSWORK: This uses the same heuristic as blame_entry_score() in blame.c.
  * Think of a way to unify them.
  */
-static void adjust_last_block(struct diff_options *o, int n, int block_length)
+static int adjust_last_block(struct diff_options *o, int n, int block_length)
 {
        int i, alnum_count = 0;
        if (o->color_moved == COLOR_MOVED_PLAIN)
-               return;
+               return block_length;
        for (i = 1; i < block_length + 1; i++) {
                const char *c = o->emitted_symbols->buf[n - i].line;
                for (; *c; c++) {
@@ -1053,11 +1114,12 @@ static void adjust_last_block(struct diff_options *o, int n, int block_length)
                                continue;
                        alnum_count++;
                        if (alnum_count >= COLOR_MOVED_MIN_ALNUM_COUNT)
-                               return;
+                               return 1;
                }
        }
        for (i = 1; i < block_length + 1; i++)
                o->emitted_symbols->buf[n - i].flags &= ~DIFF_SYMBOL_MOVED_LINE;
+       return 0;
 }
 
 /* Find blocks of moved code, delegate actual coloring decision to helper */
@@ -1067,7 +1129,7 @@ static void mark_color_as_moved(struct diff_options *o,
 {
        struct moved_block *pmb = NULL; /* potentially moved blocks */
        int pmb_nr = 0, pmb_alloc = 0;
-       int n, flipped_block = 1, block_length = 0;
+       int n, flipped_block = 0, block_length = 0;
 
 
        for (n = 0; n < o->emitted_symbols->nr; n++) {
@@ -1075,6 +1137,7 @@ static void mark_color_as_moved(struct diff_options *o,
                struct moved_entry *key;
                struct moved_entry *match = NULL;
                struct emitted_diff_symbol *l = &o->emitted_symbols->buf[n];
+               enum diff_symbol last_symbol = 0;
 
                switch (l->s) {
                case DIFF_SYMBOL_PLUS:
@@ -1090,7 +1153,7 @@ static void mark_color_as_moved(struct diff_options *o,
                        free(key);
                        break;
                default:
-                       flipped_block = 1;
+                       flipped_block = 0;
                }
 
                if (!match) {
@@ -1101,13 +1164,16 @@ static void mark_color_as_moved(struct diff_options *o,
                                moved_block_clear(&pmb[i]);
                        pmb_nr = 0;
                        block_length = 0;
+                       flipped_block = 0;
+                       last_symbol = l->s;
                        continue;
                }
 
-               l->flags |= DIFF_SYMBOL_MOVED_LINE;
-
-               if (o->color_moved == COLOR_MOVED_PLAIN)
+               if (o->color_moved == COLOR_MOVED_PLAIN) {
+                       last_symbol = l->s;
+                       l->flags |= DIFF_SYMBOL_MOVED_LINE;
                        continue;
+               }
 
                if (o->color_moved_ws_handling &
                    COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE)
@@ -1130,21 +1196,27 @@ static void mark_color_as_moved(struct diff_options *o,
                                                             &pmb[pmb_nr].wsd))
                                                pmb[pmb_nr++].match = match;
                                } else {
-                                       pmb[pmb_nr].wsd.string = NULL;
+                                       pmb[pmb_nr].wsd = 0;
                                        pmb[pmb_nr++].match = match;
                                }
                        }
 
-                       flipped_block = (flipped_block + 1) % 2;
+                       if (adjust_last_block(o, n, block_length) &&
+                           pmb_nr && last_symbol != l->s)
+                               flipped_block = (flipped_block + 1) % 2;
+                       else
+                               flipped_block = 0;
 
-                       adjust_last_block(o, n, block_length);
                        block_length = 0;
                }
 
-               block_length++;
-
-               if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
-                       l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
+               if (pmb_nr) {
+                       block_length++;
+                       l->flags |= DIFF_SYMBOL_MOVED_LINE;
+                       if (flipped_block && o->color_moved != COLOR_MOVED_BLOCKS)
+                               l->flags |= DIFF_SYMBOL_MOVED_LINE_ALT;
+               }
+               last_symbol = l->s;
        }
        adjust_last_block(o, n, block_length);
 
@@ -1488,7 +1560,7 @@ static void emit_diff_symbol_from_struct(struct diff_options *o,
 static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
                             const char *line, int len, unsigned flags)
 {
-       struct emitted_diff_symbol e = {line, len, flags, s};
+       struct emitted_diff_symbol e = {line, len, flags, 0, 0, s};
 
        if (o->emitted_symbols)
                append_emitted_diff_symbol(o, &e);
@@ -1546,8 +1618,7 @@ static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line
        return ws_blank_line(line, len, ecbdata->ws_rule);
 }
 
-static void emit_add_line(const char *reset,
-                         struct emit_callback *ecbdata,
+static void emit_add_line(struct emit_callback *ecbdata,
                          const char *line, int len)
 {
        unsigned flags = WSEH_NEW | ecbdata->ws_rule;
@@ -1557,16 +1628,14 @@ static void emit_add_line(const char *reset,
        emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_PLUS, line, len, flags);
 }
 
-static void emit_del_line(const char *reset,
-                         struct emit_callback *ecbdata,
+static void emit_del_line(struct emit_callback *ecbdata,
                          const char *line, int len)
 {
        unsigned flags = WSEH_OLD | ecbdata->ws_rule;
        emit_diff_symbol(ecbdata->opt, DIFF_SYMBOL_MINUS, line, len, flags);
 }
 
-static void emit_context_line(const char *reset,
-                             struct emit_callback *ecbdata,
+static void emit_context_line(struct emit_callback *ecbdata,
                              const char *line, int len)
 {
        unsigned flags = WSEH_CONTEXT | ecbdata->ws_rule;
@@ -1675,7 +1744,6 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
                               int prefix, const char *data, int size)
 {
        const char *endp = NULL;
-       const char *reset = diff_get_color(ecb->color_diff, DIFF_RESET);
 
        while (0 < size) {
                int len;
@@ -1684,10 +1752,10 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
                len = endp ? (endp - data + 1) : size;
                if (prefix != '+') {
                        ecb->lno_in_preimage++;
-                       emit_del_line(reset, ecb, data, len);
+                       emit_del_line(ecb, data, len);
                } else {
                        ecb->lno_in_postimage++;
-                       emit_add_line(reset, ecb, data, len);
+                       emit_add_line(ecb, data, len);
                }
                size -= len;
                data += len;
@@ -2224,7 +2292,7 @@ const char *diff_line_prefix(struct diff_options *opt)
        return msgbuf->buf;
 }
 
-static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
+static unsigned long sane_truncate_line(char *line, unsigned long len)
 {
        const char *cp;
        unsigned long allot;
@@ -2258,7 +2326,6 @@ static void find_lno(const char *line, struct emit_callback *ecbdata)
 static void fn_out_consume(void *priv, char *line, unsigned long len)
 {
        struct emit_callback *ecbdata = priv;
-       const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
        struct diff_options *o = ecbdata->opt;
 
        o->found_changes = 1;
@@ -2289,7 +2356,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        if (line[0] == '@') {
                if (ecbdata->diff_words)
                        diff_words_flush(ecbdata);
-               len = sane_truncate_line(ecbdata, line, len);
+               len = sane_truncate_line(line, len);
                find_lno(line, ecbdata);
                emit_hunk_header(ecbdata, line, len);
                return;
@@ -2325,16 +2392,16 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        switch (line[0]) {
        case '+':
                ecbdata->lno_in_postimage++;
-               emit_add_line(reset, ecbdata, line + 1, len - 1);
+               emit_add_line(ecbdata, line + 1, len - 1);
                break;
        case '-':
                ecbdata->lno_in_preimage++;
-               emit_del_line(reset, ecbdata, line + 1, len - 1);
+               emit_del_line(ecbdata, line + 1, len - 1);
                break;
        case ' ':
                ecbdata->lno_in_postimage++;
                ecbdata->lno_in_preimage++;
-               emit_context_line(reset, ecbdata, line + 1, len - 1);
+               emit_context_line(ecbdata, line + 1, len - 1);
                break;
        default:
                /* incomplete line at the end */
@@ -3477,7 +3544,7 @@ static void builtin_diff(const char *name_a,
                o->found_changes = 1;
        } else {
                /* Crazy xdl interfaces.. */
-               const char *diffopts = getenv("GIT_DIFF_OPTS");
+               const char *diffopts;
                const char *v;
                xpparam_t xpp;
                xdemitconf_t xecfg;
@@ -3520,12 +3587,15 @@ static void builtin_diff(const char *name_a,
                        xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
                if (pe)
                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
+
+               diffopts = getenv("GIT_DIFF_OPTS");
                if (!diffopts)
                        ;
                else if (skip_prefix(diffopts, "--unified=", &v))
                        xecfg.ctxlen = strtoul(v, NULL, 10);
                else if (skip_prefix(diffopts, "-u", &v))
                        xecfg.ctxlen = strtoul(v, NULL, 10);
+
                if (o->word_diff)
                        init_diff_words_data(&ecbdata, o, one, two);
                if (xdi_diff_outf(&mf1, &mf2, NULL, fn_out_consume,
@@ -4113,7 +4183,6 @@ static void run_external_diff(const char *pgm,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
                              const char *xfrm_msg,
-                             int complete_rewrite,
                              struct diff_options *o)
 {
        struct argv_array argv = ARGV_ARRAY_INIT;
@@ -4271,8 +4340,7 @@ static void run_diff_cmd(const char *pgm,
        }
 
        if (pgm) {
-               run_external_diff(pgm, name, other, one, two, xfrm_msg,
-                                 complete_rewrite, o);
+               run_external_diff(pgm, name, other, one, two, xfrm_msg, o);
                return;
        }
        if (one && two)
@@ -4573,50 +4641,6 @@ void diff_setup_done(struct diff_options *options)
        FREE_AND_NULL(options->parseopts);
 }
 
-static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
-{
-       char c, *eq;
-       int len;
-
-       if (*arg != '-')
-               return 0;
-       c = *++arg;
-       if (!c)
-               return 0;
-       if (c == arg_short) {
-               c = *++arg;
-               if (!c)
-                       return 1;
-               if (val && isdigit(c)) {
-                       char *end;
-                       int n = strtoul(arg, &end, 10);
-                       if (*end)
-                               return 0;
-                       *val = n;
-                       return 1;
-               }
-               return 0;
-       }
-       if (c != '-')
-               return 0;
-       arg++;
-       eq = strchrnul(arg, '=');
-       len = eq - arg;
-       if (!len || strncmp(arg, arg_long, len))
-               return 0;
-       if (*eq) {
-               int n;
-               char *end;
-               if (!isdigit(*++eq))
-                       return 0;
-               n = strtoul(eq, &end, 10);
-               if (*end)
-                       return 0;
-               *val = n;
-       }
-       return 1;
-}
-
 int parse_long_opt(const char *opt, const char **argv,
                   const char **optarg)
 {
@@ -4736,6 +4760,12 @@ static unsigned filter_bit_tst(char status, const struct diff_options *opt)
        return opt->filter & filter_bit[(int) status];
 }
 
+unsigned diff_filter_bit(char status)
+{
+       prepare_filter_bits();
+       return filter_bit[(int) status];
+}
+
 static int diff_opt_diff_filter(const struct option *option,
                                const char *optarg, int unset)
 {
@@ -4885,6 +4915,45 @@ static int diff_opt_char(const struct option *opt,
        return 0;
 }
 
+static int diff_opt_color_moved(const struct option *opt,
+                               const char *arg, int unset)
+{
+       struct diff_options *options = opt->value;
+
+       if (unset) {
+               options->color_moved = COLOR_MOVED_NO;
+       } else if (!arg) {
+               if (diff_color_moved_default)
+                       options->color_moved = diff_color_moved_default;
+               if (options->color_moved == COLOR_MOVED_NO)
+                       options->color_moved = COLOR_MOVED_DEFAULT;
+       } else {
+               int cm = parse_color_moved(arg);
+               if (cm < 0)
+                       return error(_("bad --color-moved argument: %s"), arg);
+               options->color_moved = cm;
+       }
+       return 0;
+}
+
+static int diff_opt_color_moved_ws(const struct option *opt,
+                                  const char *arg, int unset)
+{
+       struct diff_options *options = opt->value;
+       unsigned cm;
+
+       if (unset) {
+               options->color_moved_ws_handling = 0;
+               return 0;
+       }
+
+       cm = parse_color_moved_ws(arg);
+       if (cm & COLOR_MOVED_WS_ERROR)
+               return error(_("invalid mode '%s' in --color-moved-ws"), arg);
+       options->color_moved_ws_handling = cm;
+       return 0;
+}
+
 static int diff_opt_color_words(const struct option *opt,
                                const char *arg, int unset)
 {
@@ -5010,6 +5079,30 @@ static int diff_opt_ignore_submodules(const struct option *opt,
        return 0;
 }
 
+static int diff_opt_line_prefix(const struct option *opt,
+                               const char *optarg, int unset)
+{
+       struct diff_options *options = opt->value;
+
+       BUG_ON_OPT_NEG(unset);
+       options->line_prefix = optarg;
+       options->line_prefix_length = strlen(options->line_prefix);
+       graph_setup_line_prefix(options);
+       return 0;
+}
+
+static int diff_opt_no_prefix(const struct option *opt,
+                             const char *optarg, int unset)
+{
+       struct diff_options *options = opt->value;
+
+       BUG_ON_OPT_NEG(unset);
+       BUG_ON_OPT_ARG(optarg);
+       options->a_prefix = "";
+       options->b_prefix = "";
+       return 0;
+}
+
 static enum parse_opt_result diff_opt_output(struct parse_opt_ctx_t *ctx,
                                             const struct option *opt,
                                             const char *arg, int unset)
@@ -5118,9 +5211,11 @@ static int diff_opt_unified(const struct option *opt,
 
        BUG_ON_OPT_NEG(unset);
 
-       options->context = strtol(arg, &s, 10);
-       if (*s)
-               return error(_("%s expects a numerical value"), "--unified");
+       if (arg) {
+               options->context = strtol(arg, &s, 10);
+               if (*s)
+                       return error(_("%s expects a numerical value"), "--unified");
+       }
        enable_patch_output(&options->output_format);
 
        return 0;
@@ -5179,7 +5274,7 @@ static void prep_parse_options(struct diff_options *options)
                          DIFF_FORMAT_PATCH, DIFF_FORMAT_NO_OUTPUT),
                OPT_CALLBACK_F('U', "unified", options, N_("<n>"),
                               N_("generate diffs with <n> lines context"),
-                              PARSE_OPT_NONEG, diff_opt_unified),
+                              PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_unified),
                OPT_BOOL('W', "function-context", &options->flags.funccontext,
                         N_("generate diffs with <n> lines context")),
                OPT_BIT_F(0, "raw", &options->output_format,
@@ -5255,6 +5350,21 @@ static void prep_parse_options(struct diff_options *options)
                            N_("do not munge pathnames and use NULs as output field terminators in --raw or --numstat"),
                            0),
                OPT__ABBREV(&options->abbrev),
+               OPT_STRING_F(0, "src-prefix", &options->a_prefix, N_("<prefix>"),
+                            N_("show the given source prefix instead of \"a/\""),
+                            PARSE_OPT_NONEG),
+               OPT_STRING_F(0, "dst-prefix", &options->b_prefix, N_("<prefix>"),
+                            N_("show the given destination prefix instead of \"b/\""),
+                            PARSE_OPT_NONEG),
+               OPT_CALLBACK_F(0, "line-prefix", options, N_("<prefix>"),
+                              N_("prepend an additional prefix to every line of output"),
+                              PARSE_OPT_NONEG, diff_opt_line_prefix),
+               OPT_CALLBACK_F(0, "no-prefix", options, NULL,
+                              N_("do not show any source or destination prefix"),
+                              PARSE_OPT_NONEG | PARSE_OPT_NOARG, diff_opt_no_prefix),
+               OPT_INTEGER_F(0, "inter-hunk-context", &options->interhunkcontext,
+                             N_("show context between diff hunks up to the specified number of lines"),
+                             PARSE_OPT_NONEG),
                OPT_CALLBACK_F(0, "output-indicator-new",
                               &options->output_indicators[OUTPUT_INDICATOR_NEW],
                               N_("<char>"),
@@ -5344,8 +5454,14 @@ static void prep_parse_options(struct diff_options *options)
                OPT_CALLBACK_F(0, "color-words", options, N_("<regex>"),
                               N_("equivalent to --word-diff=color --word-diff-regex=<regex>"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG, diff_opt_color_words),
-
-               OPT_GROUP(N_("Diff other options")),
+               OPT_CALLBACK_F(0, "color-moved", options, N_("<mode>"),
+                              N_("moved lines of code are colored differently"),
+                              PARSE_OPT_OPTARG, diff_opt_color_moved),
+               OPT_CALLBACK_F(0, "color-moved-ws", options, N_("<mode>"),
+                              N_("how white spaces are ignored in --color-moved"),
+                              0, diff_opt_color_moved_ws),
+
+               OPT_GROUP(N_("Other diff options")),
                OPT_CALLBACK_F(0, "relative", options, N_("<prefix>"),
                               N_("when run from subdir, exclude changes outside and show relative paths"),
                               PARSE_OPT_NONEG | PARSE_OPT_OPTARG,
@@ -5411,10 +5527,6 @@ static void prep_parse_options(struct diff_options *options)
 int diff_opt_parse(struct diff_options *options,
                   const char **av, int ac, const char *prefix)
 {
-       const char *arg = av[0];
-       const char *optarg;
-       int argcount;
-
        if (!prefix)
                prefix = "";
 
@@ -5425,52 +5537,7 @@ int diff_opt_parse(struct diff_options *options,
                           PARSE_OPT_ONE_SHOT |
                           PARSE_OPT_STOP_AT_NON_OPTION);
 
-       if (ac)
-               return ac;
-
-       /* flags options */
-       if (!strcmp(arg, "--color-moved")) {
-               if (diff_color_moved_default)
-                       options->color_moved = diff_color_moved_default;
-               if (options->color_moved == COLOR_MOVED_NO)
-                       options->color_moved = COLOR_MOVED_DEFAULT;
-       } else if (!strcmp(arg, "--no-color-moved"))
-               options->color_moved = COLOR_MOVED_NO;
-       else if (skip_prefix(arg, "--color-moved=", &arg)) {
-               int cm = parse_color_moved(arg);
-               if (cm < 0)
-                       return error("bad --color-moved argument: %s", arg);
-               options->color_moved = cm;
-       } else if (skip_prefix(arg, "--color-moved-ws=", &arg)) {
-               unsigned cm = parse_color_moved_ws(arg);
-               if (cm & COLOR_MOVED_WS_ERROR)
-                       return -1;
-               options->color_moved_ws_handling = cm;
-       }
-
-       /* misc options */
-       else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
-               options->a_prefix = optarg;
-               return argcount;
-       }
-       else if ((argcount = parse_long_opt("line-prefix", av, &optarg))) {
-               options->line_prefix = optarg;
-               options->line_prefix_length = strlen(options->line_prefix);
-               graph_setup_line_prefix(options);
-               return argcount;
-       }
-       else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
-               options->b_prefix = optarg;
-               return argcount;
-       }
-       else if (!strcmp(arg, "--no-prefix"))
-               options->a_prefix = options->b_prefix = "";
-       else if (opt_arg(arg, '\0', "inter-hunk-context",
-                        &options->interhunkcontext))
-               ;
-       else
-               return 0;
-       return 1;
+       return ac;
 }
 
 int parse_rename_score(const char **cp_p)
@@ -5923,6 +5990,22 @@ static int remove_space(char *line, int len)
        return dst - line;
 }
 
+void flush_one_hunk(struct object_id *result, git_SHA_CTX *ctx)
+{
+       unsigned char hash[GIT_MAX_RAWSZ];
+       unsigned short carry = 0;
+       int i;
+
+       git_SHA1_Final(hash, ctx);
+       git_SHA1_Init(ctx);
+       /* 20-byte sum, with carry */
+       for (i = 0; i < GIT_SHA1_RAWSZ; ++i) {
+               carry += result->hash[i] + hash[i];
+               result->hash[i] = carry;
+               carry >>= 8;
+       }
+}
+
 static void patch_id_consume(void *priv, char *line, unsigned long len)
 {
        struct patch_id_t *data = priv;
@@ -5947,8 +6030,8 @@ static void patch_id_add_mode(git_SHA_CTX *ctx, unsigned mode)
        git_SHA1_Update(ctx, buf, len);
 }
 
-/* returns 0 upon success, and writes result into sha1 */
-static int diff_get_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only)
+/* returns 0 upon success, and writes result into oid */
+static int diff_get_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only, int stable)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
        int i;
@@ -5958,6 +6041,7 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
        git_SHA1_Init(&ctx);
        memset(&data, 0, sizeof(struct patch_id_t));
        data.ctx = &ctx;
+       oidclr(oid);
 
        for (i = 0; i < q->nr; i++) {
                xpparam_t xpp;
@@ -6033,17 +6117,22 @@ static int diff_get_patch_id(struct diff_options *options, struct object_id *oid
                                  patch_id_consume, &data, &xpp, &xecfg))
                        return error("unable to generate patch-id diff for %s",
                                     p->one->path);
+
+               if (stable)
+                       flush_one_hunk(oid, &ctx);
        }
 
-       git_SHA1_Final(oid->hash, &ctx);
+       if (!stable)
+               git_SHA1_Final(oid->hash, &ctx);
+
        return 0;
 }
 
-int diff_flush_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only)
+int diff_flush_patch_id(struct diff_options *options, struct object_id *oid, int diff_header_only, int stable)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
        int i;
-       int result = diff_get_patch_id(options, oid, diff_header_only);
+       int result = diff_get_patch_id(options, oid, diff_header_only, stable);
 
        for (i = 0; i < q->nr; i++)
                diff_free_filepair(q->queue[i]);
@@ -6145,8 +6234,10 @@ static void diff_flush_patch_all_file_pairs(struct diff_options *o)
 
                for (i = 0; i < esm.nr; i++)
                        free((void *)esm.buf[i].line);
+               esm.nr = 0;
+
+               o->emitted_symbols = NULL;
        }
-       esm.nr = 0;
 }
 
 void diff_flush(struct diff_options *options)
@@ -6405,14 +6496,47 @@ static int diffnamecmp(const void *a_, const void *b_)
        return strcmp(name_a, name_b);
 }
 
-void diffcore_fix_diff_index(struct diff_options *options)
+void diffcore_fix_diff_index(void)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
        QSORT(q->queue, q->nr, diffnamecmp);
 }
 
+static void add_if_missing(struct repository *r,
+                          struct oid_array *to_fetch,
+                          const struct diff_filespec *filespec)
+{
+       if (filespec && filespec->oid_valid &&
+           oid_object_info_extended(r, &filespec->oid, NULL,
+                                    OBJECT_INFO_FOR_PREFETCH))
+               oid_array_append(to_fetch, &filespec->oid);
+}
+
 void diffcore_std(struct diff_options *options)
 {
+       if (options->repo == the_repository &&
+           repository_format_partial_clone) {
+               /*
+                * Prefetch the diff pairs that are about to be flushed.
+                */
+               int i;
+               struct diff_queue_struct *q = &diff_queued_diff;
+               struct oid_array to_fetch = OID_ARRAY_INIT;
+
+               for (i = 0; i < q->nr; i++) {
+                       struct diff_filepair *p = q->queue[i];
+                       add_if_missing(options->repo, &to_fetch, p->one);
+                       add_if_missing(options->repo, &to_fetch, p->two);
+               }
+               if (to_fetch.nr)
+                       /*
+                        * NEEDSWORK: Consider deduplicating the OIDs sent.
+                        */
+                       fetch_objects(repository_format_partial_clone,
+                                     to_fetch.oid, to_fetch.nr);
+               oid_array_clear(&to_fetch);
+       }
+
        /* NOTE please keep the following in sync with diff_tree_combined() */
        if (options->skip_stat_unmatch)
                diffcore_skip_stat_unmatch(options);