sha1_name: warning ambiguous refs.
[git.git] / combine-diff.c
index 44931b2..a23894d 100644 (file)
@@ -8,8 +8,6 @@ static int uninteresting(struct diff_filepair *p)
 {
        if (diff_unmodified_pair(p))
                return 1;
-       if (!S_ISREG(p->one->mode) || !S_ISREG(p->two->mode))
-               return 1;
        return 0;
 }
 
@@ -28,15 +26,20 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
                                continue;
                        path = q->queue[i]->two->path;
                        len = strlen(path);
-
-                       p = xmalloc(sizeof(*p) + len + 1 + num_parent * 20);
-                       p->path = (char*) &(p->parent_sha1[num_parent][0]);
+                       p = xmalloc(combine_diff_path_size(num_parent, len));
+                       p->path = (char*) &(p->parent[num_parent]);
                        memcpy(p->path, path, len);
                        p->path[len] = 0;
                        p->len = len;
                        p->next = NULL;
+                       memset(p->parent, 0,
+                              sizeof(p->parent[0]) * num_parent);
+
                        memcpy(p->sha1, q->queue[i]->two->sha1, 20);
-                       memcpy(p->parent_sha1[n], q->queue[i]->one->sha1, 20);
+                       p->mode = q->queue[i]->two->mode;
+                       memcpy(p->parent[n].sha1, q->queue[i]->one->sha1, 20);
+                       p->parent[n].mode = q->queue[i]->one->mode;
+                       p->parent[n].status = q->queue[i]->status;
                        *tail = p;
                        tail = &p->next;
                }
@@ -57,8 +60,10 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
                        len = strlen(path);
                        if (len == p->len && !memcmp(path, p->path, len)) {
                                found = 1;
-                               memcpy(p->parent_sha1[n],
+                               memcpy(p->parent[n].sha1,
                                       q->queue[i]->one->sha1, 20);
+                               p->parent[n].mode = q->queue[i]->one->mode;
+                               p->parent[n].status = q->queue[i]->status;
                                break;
                        }
                }
@@ -68,6 +73,7 @@ static struct combine_diff_path *intersect_paths(struct combine_diff_path *curr,
        return curr;
 }
 
+/* Lines lost from parent */
 struct lline {
        struct lline *next;
        int len;
@@ -75,11 +81,17 @@ struct lline {
        char line[FLEX_ARRAY];
 };
 
+/* Lines surviving in the merge result */
 struct sline {
        struct lline *lost_head, **lost_tail;
        char *bol;
        int len;
+       /* bit 0 up to (N-1) are on if the parent has this line (i.e.
+        * we did not change it).
+        * bit N is used for "interesting" lines, including context.
+        */
        unsigned long flag;
+       unsigned long *p_lno;
 };
 
 static char *grab_blob(const unsigned char *sha1, unsigned long *size)
@@ -204,22 +216,25 @@ static void append_lost(struct sline *sline, int n, const char *line)
 }
 
 static void combine_diff(const unsigned char *parent, const char *ourtmp,
-                        struct sline *sline, int cnt, int n)
+                        struct sline *sline, int cnt, int n, int num_parent)
 {
        FILE *in;
        char parent_tmp[TMPPATHLEN];
        char cmd[TMPPATHLEN * 2 + 1024];
        char line[MAXLINELEN];
-       unsigned int lno, ob, on, nb, nn;
-       unsigned long pmask = ~(1UL << n);
+       unsigned int lno, ob, on, nb, nn, p_lno;
+       unsigned long nmask = (1UL << n);
        struct sline *lost_bucket = NULL;
 
+       if (!cnt)
+               return; /* result deleted */
+
        write_temp_blob(parent_tmp, parent);
        sprintf(cmd, "diff --unified=0 -La/x -Lb/x '%s' '%s'",
                parent_tmp, ourtmp);
        in = popen(cmd, "r");
        if (!in)
-               return;
+               die("cannot spawn %s", cmd);
 
        lno = 1;
        while (fgets(line, sizeof(line), in) != NULL) {
@@ -229,29 +244,64 @@ static void combine_diff(const unsigned char *parent, const char *ourtmp,
                                              &ob, &on, &nb, &nn))
                                break;
                        lno = nb;
-                       if (!nb) {
+                       if (!nb)
                                /* @@ -1,2 +0,0 @@ to remove the
                                 * first two lines...
                                 */
                                nb = 1;
-                       }
-                       lost_bucket = &sline[nb-1]; /* sline is 0 based */
+                       if (nn == 0)
+                               /* @@ -X,Y +N,0 @@ removed Y lines
+                                * that would have come *after* line N
+                                * in the result.  Our lost buckets hang
+                                * to the line after the removed lines,
+                                */
+                               lost_bucket = &sline[nb];
+                       else
+                               lost_bucket = &sline[nb-1];
+                       if (!sline[nb-1].p_lno)
+                               sline[nb-1].p_lno =
+                                       xcalloc(num_parent,
+                                               sizeof(unsigned long));
+                       sline[nb-1].p_lno[n] = ob;
                        continue;
                }
                if (!lost_bucket)
-                       continue;
+                       continue; /* not in any hunk yet */
                switch (line[0]) {
                case '-':
                        append_lost(lost_bucket, n, line+1);
                        break;
                case '+':
-                       sline[lno-1].flag &= pmask;
+                       sline[lno-1].flag |= nmask;
                        lno++;
                        break;
                }
        }
        fclose(in);
        unlink(parent_tmp);
+
+       /* Assign line numbers for this parent.
+        *
+        * sline[lno].p_lno[n] records the first line number
+        * (counting from 1) for parent N if the final hunk display
+        * started by showing sline[lno] (possibly showing the lost
+        * lines attached to it first).
+        */
+       for (lno = 0,  p_lno = 1; lno < cnt; lno++) {
+               struct lline *ll;
+               sline[lno].p_lno[n] = p_lno;
+
+               /* How many lines would this sline advance the p_lno? */
+               ll = sline[lno].lost_head;
+               while (ll) {
+                       if (ll->parent_map & nmask)
+                               p_lno++; /* '-' means parent had it */
+                       ll = ll->next;
+               }
+               if (!(sline[lno].flag & nmask))
+                       p_lno++; /* no '+' means parent had it */
+       }
+       sline[lno].p_lno[n] = p_lno; /* trailer */
 }
 
 static unsigned long context = 3;
@@ -259,7 +309,10 @@ static char combine_marker = '@';
 
 static int interesting(struct sline *sline, unsigned long all_mask)
 {
-       return ((sline->flag & all_mask) != all_mask || sline->lost_head);
+       /* If some parents lost lines here, or if we have added to
+        * some parent, it is interesting.
+        */
+       return ((sline->flag & all_mask) || sline->lost_head);
 }
 
 static unsigned long adjust_hunk_tail(struct sline *sline,
@@ -267,28 +320,35 @@ static unsigned long adjust_hunk_tail(struct sline *sline,
                                      unsigned long hunk_begin,
                                      unsigned long i)
 {
-       /* i points at the first uninteresting line.
-        * If the last line of the hunk was interesting
-        * only because it has some deletion, then
-        * it is not all that interesting for the
-        * purpose of giving trailing context lines.
+       /* i points at the first uninteresting line.  If the last line
+        * of the hunk was interesting only because it has some
+        * deletion, then it is not all that interesting for the
+        * purpose of giving trailing context lines.  This is because
+        * we output '-' line and then unmodified sline[i-1] itself in
+        * that case which gives us one extra context line.
         */
-       if ((hunk_begin + 1 <= i) &&
-           ((sline[i-1].flag & all_mask) == all_mask))
+       if ((hunk_begin + 1 <= i) && !(sline[i-1].flag & all_mask))
                i--;
        return i;
 }
 
-static unsigned long next_interesting(struct sline *sline,
-                                     unsigned long mark,
-                                     unsigned long i,
-                                     unsigned long cnt,
-                                     int uninteresting)
+static unsigned long find_next(struct sline *sline,
+                              unsigned long mark,
+                              unsigned long i,
+                              unsigned long cnt,
+                              int uninteresting)
 {
+       /* We have examined up to i-1 and are about to look at i.
+        * Find next interesting or uninteresting line.  Here,
+        * "interesting" does not mean interesting(), but marked by
+        * the give_context() function below (i.e. it includes context
+        * lines that are not interesting to interesting() function
+        * that are surrounded by interesting() ones.
+        */
        while (i < cnt)
-               if (uninteresting ?
-                   !(sline[i].flag & mark) :
-                   (sline[i].flag & mark))
+               if (uninteresting
+                   ? !(sline[i].flag & mark)
+                   (sline[i].flag & mark))
                        return i;
                else
                        i++;
@@ -301,23 +361,37 @@ static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
        unsigned long mark = (1UL<<num_parent);
        unsigned long i;
 
-       i = next_interesting(sline, mark, 0, cnt, 0);
+       /* Two groups of interesting lines may have a short gap of
+        * unintersting lines.  Connect such groups to give them a
+        * bit of context.
+        *
+        * We first start from what the interesting() function says,
+        * and mark them with "mark", and paint context lines with the
+        * mark.  So interesting() would still say false for such context
+        * lines but they are treated as "interesting" in the end.
+        */
+       i = find_next(sline, mark, 0, cnt, 0);
        if (cnt <= i)
                return 0;
 
        while (i < cnt) {
                unsigned long j = (context < i) ? (i - context) : 0;
                unsigned long k;
+
+               /* Paint a few lines before the first interesting line. */
                while (j < i)
                        sline[j++].flag |= mark;
 
        again:
-               j = next_interesting(sline, mark, i, cnt, 1);
+               /* we know up to i is to be included.  where does the
+                * next uninteresting one start?
+                */
+               j = find_next(sline, mark, i, cnt, 1);
                if (cnt <= j)
                        break; /* the rest are all interesting */
 
                /* lookahead context lines */
-               k = next_interesting(sline, mark, j, cnt, 0);
+               k = find_next(sline, mark, j, cnt, 0);
                j = adjust_hunk_tail(sline, all_mask, i, j);
 
                if (k < j + context) {
@@ -331,7 +405,8 @@ static int give_context(struct sline *sline, unsigned long cnt, int num_parent)
                }
 
                /* j is the first uninteresting line and there is
-                * no overlap beyond it within context lines.
+                * no overlap beyond it within context lines.  Paint
+                * the trailing edge a bit.
                 */
                i = k;
                k = (j + context < cnt) ? j + context : cnt;
@@ -397,12 +472,28 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
                hunk_end = j;
 
                /* [i..hunk_end) are interesting.  Now is it really
-                * interesting?
+                * interesting?  We check if there are only two versions
+                * and the result matches one of them.  That is, we look
+                * at:
+                *   (+) line, which records lines added to which parents;
+                *       this line appears in the result.
+                *   (-) line, which records from what parents the line
+                *       was removed; this line does not appear in the result.
+                * then check the set of parents the result has difference
+                * from, from all lines.  If there are lines that has
+                * different set of parents that the result has differences
+                * from, that means we have more than two versions.
+                *
+                * Even when we have only two versions, if the result does
+                * not match any of the parents, the it should be considered
+                * interesting.  In such a case, we would have all '+' line.
+                * After passing the above "two versions" test, that would
+                * appear as "the same set of parents" to be "all parents".
                 */
                same_diff = 0;
                has_interesting = 0;
                for (j = i; j < hunk_end && !has_interesting; j++) {
-                       unsigned long this_diff = ~sline[j].flag & all_mask;
+                       unsigned long this_diff = sline[j].flag & all_mask;
                        struct lline *ll = sline[j].lost_head;
                        if (this_diff) {
                                /* This has some changes.  Is it the
@@ -429,7 +520,7 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
                        }
                }
 
-               if (!has_interesting) {
+               if (!has_interesting && same_diff != all_mask) {
                        /* This hunk is not that interesting after all */
                        for (j = hunk_begin; j < hunk_end; j++)
                                sline[j].flag &= ~mark;
@@ -441,11 +532,21 @@ static int make_hunks(struct sline *sline, unsigned long cnt,
        return has_interesting;
 }
 
-static void dump_sline(struct sline *sline, int cnt, int num_parent)
+static void show_parent_lno(struct sline *sline, unsigned long l0, unsigned long l1, unsigned long cnt, int n)
+{
+       l0 = sline[l0].p_lno[n];
+       l1 = sline[l1].p_lno[n];
+       printf(" -%lu,%lu", l0, l1-l0);
+}
+
+static void dump_sline(struct sline *sline, unsigned long cnt, int num_parent)
 {
        unsigned long mark = (1UL<<num_parent);
        int i;
-       int lno = 0;
+       unsigned long lno = 0;
+
+       if (!cnt)
+               return; /* result deleted */
 
        while (1) {
                struct sline *sl = &sline[lno];
@@ -458,12 +559,15 @@ static void dump_sline(struct sline *sline, int cnt, int num_parent)
                        if (!(sline[hunk_end].flag & mark))
                                break;
                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
-               printf(" +%d,%d ", lno+1, hunk_end-lno);
+               for (i = 0; i < num_parent; i++)
+                       show_parent_lno(sline, lno, hunk_end, cnt, i);
+               printf(" +%lu,%lu ", lno+1, hunk_end-lno);
                for (i = 0; i <= num_parent; i++) putchar(combine_marker);
                putchar('\n');
                while (lno < hunk_end) {
                        struct lline *ll;
                        int j;
+                       unsigned long p_mask;
                        sl = &sline[lno++];
                        ll = sl->lost_head;
                        while (ll) {
@@ -476,11 +580,13 @@ static void dump_sline(struct sline *sline, int cnt, int num_parent)
                                puts(ll->line);
                                ll = ll->next;
                        }
+                       p_mask = 1;
                        for (j = 0; j < num_parent; j++) {
-                               if ((1UL<<j) & sl->flag)
-                                       putchar(' ');
-                               else
+                               if (p_mask & sl->flag)
                                        putchar('+');
+                               else
+                                       putchar(' ');
+                               p_mask <<= 1;
                        }
                        printf("%.*s\n", sl->len, sl->bol);
                }
@@ -500,33 +606,41 @@ static void reuse_combine_diff(struct sline *sline, unsigned long cnt,
 
        for (lno = 0; lno < cnt; lno++) {
                struct lline *ll = sline->lost_head;
+               sline->p_lno[i] = sline->p_lno[j];
                while (ll) {
                        if (ll->parent_map & jmask)
                                ll->parent_map |= imask;
                        ll = ll->next;
                }
-               if (!(sline->flag & jmask))
-                       sline->flag &= ~imask;
+               if (sline->flag & jmask)
+                       sline->flag |= imask;
                sline++;
        }
+       /* the overall size of the file (sline[cnt]) */
+       sline->p_lno[i] = sline->p_lno[j];
 }
 
-int show_combined_diff(struct combine_diff_path *elem, int num_parent,
-                      int dense, const char *header, int show_empty)
+static int show_patch_diff(struct combine_diff_path *elem, int num_parent,
+                          int dense, const char *header,
+                          struct diff_options *opt)
 {
        unsigned long size, cnt, lno;
        char *result, *cp, *ep;
        struct sline *sline; /* survived lines */
+       int mode_differs = 0;
        int i, show_hunks, shown_header = 0;
        char ourtmp_buf[TMPPATHLEN];
        char *ourtmp = ourtmp_buf;
+       int working_tree_file = !memcmp(elem->sha1, null_sha1, 20);
+       int abbrev = opt->full_index ? 40 : DEFAULT_ABBREV;
 
        /* Read the result of merge first */
-       if (memcmp(elem->sha1, null_sha1, 20)) {
+       if (!working_tree_file) {
                result = grab_blob(elem->sha1, &size);
                write_to_temp_file(ourtmp, result, size);
        }
        else {
+               /* Used by diff-tree to read from the working tree */
                struct stat st;
                int fd;
                ourtmp = elem->path;
@@ -535,6 +649,7 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
                        int len = st.st_size;
                        int cnt = 0;
 
+                       elem->mode = DIFF_FILE_CANON_MODE(st.st_mode);
                        size = len;
                        result = xmalloc(len + 1);
                        while (cnt < len) {
@@ -550,6 +665,7 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
                else {
                        /* deleted file */
                        size = 0;
+                       elem->mode = 0;
                        result = xmalloc(1);
                        result[0] = 0;
                        ourtmp = "/dev/null";
@@ -562,55 +678,92 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
                if (*cp == '\n')
                        cnt++;
        }
-       if (result[size-1] != '\n')
+       if (size && result[size-1] != '\n')
                cnt++; /* incomplete line */
 
-       sline = xcalloc(cnt, sizeof(*sline));
+       sline = xcalloc(cnt+1, sizeof(*sline));
        ep = result;
        sline[0].bol = result;
+       for (lno = 0; lno <= cnt; lno++) {
+               sline[lno].lost_tail = &sline[lno].lost_head;
+               sline[lno].flag = 0;
+       }
        for (lno = 0, cp = result; cp - result < size; cp++) {
                if (*cp == '\n') {
-                       sline[lno].lost_tail = &sline[lno].lost_head;
                        sline[lno].len = cp - sline[lno].bol;
-                       sline[lno].flag = (1UL<<num_parent) - 1;
                        lno++;
                        if (lno < cnt)
                                sline[lno].bol = cp + 1;
                }
        }
-       if (result[size-1] != '\n') {
-               sline[cnt-1].lost_tail = &sline[cnt-1].lost_head;
+       if (size && result[size-1] != '\n')
                sline[cnt-1].len = size - (sline[cnt-1].bol - result);
-               sline[cnt-1].flag = (1UL<<num_parent) - 1;
-       }
+
+       sline[0].p_lno = xcalloc((cnt+1) * num_parent, sizeof(unsigned long));
+       for (lno = 0; lno < cnt; lno++)
+               sline[lno+1].p_lno = sline[lno].p_lno + num_parent;
 
        for (i = 0; i < num_parent; i++) {
                int j;
                for (j = 0; j < i; j++) {
-                       if (!memcmp(elem->parent_sha1[i],
-                                   elem->parent_sha1[j], 20)) {
+                       if (!memcmp(elem->parent[i].sha1,
+                                   elem->parent[j].sha1, 20)) {
                                reuse_combine_diff(sline, cnt, i, j);
                                break;
                        }
                }
                if (i <= j)
-                       combine_diff(elem->parent_sha1[i], ourtmp, sline,
-                                    cnt, i);
+                       combine_diff(elem->parent[i].sha1, ourtmp, sline,
+                                    cnt, i, num_parent);
+               if (elem->parent[i].mode != elem->mode)
+                       mode_differs = 1;
        }
 
        show_hunks = make_hunks(sline, cnt, num_parent, dense);
 
-       if (header && (show_hunks || show_empty)) {
-               shown_header++;
-               puts(header);
-       }
-       if (show_hunks) {
+       if (show_hunks || mode_differs || working_tree_file) {
+               const char *abb;
+
+               if (header) {
+                       shown_header++;
+                       printf("%s%c", header, opt->line_termination);
+               }
                printf("diff --%s ", dense ? "cc" : "combined");
                if (quote_c_style(elem->path, NULL, NULL, 0))
                        quote_c_style(elem->path, NULL, stdout, 0);
                else
                        printf("%s", elem->path);
                putchar('\n');
+               printf("index ");
+               for (i = 0; i < num_parent; i++) {
+                       abb = find_unique_abbrev(elem->parent[i].sha1,
+                                                abbrev);
+                       printf("%s%s", i ? "," : "", abb);
+               }
+               abb = find_unique_abbrev(elem->sha1, abbrev);
+               printf("..%s\n", abb);
+
+               if (mode_differs) {
+                       int added = !!elem->mode;
+                       for (i = 0; added && i < num_parent; i++)
+                               if (elem->parent[i].status !=
+                                   DIFF_STATUS_ADDED)
+                                       added = 0;
+                       if (added)
+                               printf("new file mode %06o", elem->mode);
+                       else {
+                               if (!elem->mode)
+                                       printf("deleted file ");
+                               printf("mode ");
+                               for (i = 0; i < num_parent; i++) {
+                                       printf("%s%06o", i ? "," : "",
+                                              elem->parent[i].mode);
+                               }
+                               if (elem->mode)
+                                       printf("..%06o", elem->mode);
+                       }
+                       putchar('\n');
+               }
                dump_sline(sline, cnt, num_parent);
        }
        if (ourtmp == ourtmp_buf)
@@ -627,13 +780,97 @@ int show_combined_diff(struct combine_diff_path *elem, int num_parent,
                        }
                }
        }
+       free(sline[0].p_lno);
        free(sline);
        return shown_header;
 }
 
-int diff_tree_combined_merge(const unsigned char *sha1,
-                            const char *header,
-                            int show_empty_merge, int dense)
+#define COLONS "::::::::::::::::::::::::::::::::"
+
+static void show_raw_diff(struct combine_diff_path *p, int num_parent, const char *header, struct diff_options *opt)
+{
+       int i, offset, mod_type = 'A';
+       const char *prefix;
+       int line_termination, inter_name_termination;
+
+       line_termination = opt->line_termination;
+       inter_name_termination = '\t';
+       if (!line_termination)
+               inter_name_termination = 0;
+
+       if (header)
+               printf("%s%c", header, line_termination);
+
+       for (i = 0; i < num_parent; i++) {
+               if (p->parent[i].mode)
+                       mod_type = 'M';
+       }
+       if (!p->mode)
+               mod_type = 'D';
+
+       if (opt->output_format == DIFF_FORMAT_RAW) {
+               offset = strlen(COLONS) - num_parent;
+               if (offset < 0)
+                       offset = 0;
+               prefix = COLONS + offset;
+
+               /* Show the modes */
+               for (i = 0; i < num_parent; i++) {
+                       printf("%s%06o", prefix, p->parent[i].mode);
+                       prefix = " ";
+               }
+               printf("%s%06o", prefix, p->mode);
+
+               /* Show sha1's */
+               for (i = 0; i < num_parent; i++)
+                       printf(" %s", diff_unique_abbrev(p->parent[i].sha1,
+                                                        opt->abbrev));
+               printf(" %s ", diff_unique_abbrev(p->sha1, opt->abbrev));
+       }
+
+       if (opt->output_format == DIFF_FORMAT_RAW ||
+           opt->output_format == DIFF_FORMAT_NAME_STATUS) {
+               for (i = 0; i < num_parent; i++)
+                       putchar(p->parent[i].status);
+               putchar(inter_name_termination);
+       }
+
+       if (line_termination) {
+               if (quote_c_style(p->path, NULL, NULL, 0))
+                       quote_c_style(p->path, NULL, stdout, 0);
+               else
+                       printf("%s", p->path);
+               putchar(line_termination);
+       }
+       else {
+               printf("%s%c", p->path, line_termination);
+       }
+}
+
+int show_combined_diff(struct combine_diff_path *p,
+                      int num_parent,
+                      int dense,
+                      const char *header,
+                      struct diff_options *opt)
+{
+       if (!p->len)
+               return 0;
+       switch (opt->output_format) {
+       case DIFF_FORMAT_RAW:
+       case DIFF_FORMAT_NAME_STATUS:
+       case DIFF_FORMAT_NAME:
+               show_raw_diff(p, num_parent, header, opt);
+               return 1;
+
+       default:
+       case DIFF_FORMAT_PATCH:
+               return show_patch_diff(p, num_parent, dense, header, opt);
+       }
+}
+
+const char *diff_tree_combined_merge(const unsigned char *sha1,
+                            const char *header, int dense,
+                            struct diff_options *opt)
 {
        struct commit *commit = lookup_commit(sha1);
        struct diff_options diffopts;
@@ -641,7 +878,7 @@ int diff_tree_combined_merge(const unsigned char *sha1,
        struct combine_diff_path *p, *paths = NULL;
        int num_parent, i, num_paths;
 
-       diff_setup(&diffopts);
+       diffopts = *opt;
        diffopts.output_format = DIFF_FORMAT_NO_OUTPUT;
        diffopts.recursive = 1;
 
@@ -658,6 +895,7 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                struct commit *parent = parents->item;
                diff_tree_sha1(parent->object.sha1, commit->object.sha1, "",
                               &diffopts);
+               diffcore_std(&diffopts);
                paths = intersect_paths(paths, i, num_parent);
                diff_flush(&diffopts);
        }
@@ -667,12 +905,10 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                if (p->len)
                        num_paths++;
        }
-       if (num_paths || show_empty_merge) {
+       if (num_paths) {
                for (p = paths; p; p = p->next) {
-                       if (!p->len)
-                               continue;
-                       if (show_combined_diff(p, num_parent, dense, header,
-                                              show_empty_merge))
+                       if (show_combined_diff(p, num_parent, dense,
+                                              header, opt))
                                header = NULL;
                }
        }
@@ -683,5 +919,5 @@ int diff_tree_combined_merge(const unsigned char *sha1,
                paths = paths->next;
                free(tmp);
        }
-       return 0;
+       return header;
 }