t6023: merge-file fails to output anything for a degenerate merge

diff --git a/builtin-diff.c b/builtin-diff.c
index faaa85a1d45ce6c5f398a44b1241f6325430918b..375a0d33022dc5ce137ef46feff0486eee92e675 100644 (file)
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -122,6 +122,8 @@ static int builtin_diff_index(struct rev_info *revs,
                        usage(builtin_diff_usage);
                argv++; argc--;
        }
+       if (!cached)
+               setup_work_tree();
        /*
         * Make sure there is one revision (i.e. pending object),
         * and there is no revision filtering parameters.
@@ -173,10 +175,8 @@ static int builtin_diff_combined(struct rev_info *revs,
        if (!revs->dense_combined_merges && !revs->combine_merges)
                revs->dense_combined_merges = revs->combine_merges = 1;
        parent = xmalloc(ents * sizeof(*parent));
-       /* Again, the revs are all reverse */
        for (i = 0; i < ents; i++)
-               hashcpy((unsigned char *)(parent + i),
-                       ent[ents - 1 - i].item->sha1);
+               hashcpy((unsigned char *)(parent + i), ent[i].item->sha1);
        diff_tree_combined(parent[0], parent + 1, ents - 1,
                           revs->dense_combined_merges, revs);
        return 0;
@@ -221,10 +221,17 @@ static int builtin_diff_files(struct rev_info *revs, int argc, const char **argv
                argv++; argc--;
        }
 
-       if (revs->max_count == -1 &&
+       /*
+        * "diff --base" should not combine merges because it was not
+        * asked to.  "diff -c" should not densify (if the user wants
+        * dense one, --cc can be explicitly asked for, or just rely
+        * on the default).
+        */
+       if (revs->max_count == -1 && !revs->combine_merges &&
            (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
                revs->combine_merges = revs->dense_combined_merges = 1;
 
+       setup_work_tree();
        if (read_cache() < 0) {
                perror("read_cache");
                return -1;
@@ -281,6 +288,9 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
        /* Otherwise, we are doing the usual "git" diff */
        rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;
 
+       /* Default to let external be used */
+       DIFF_OPT_SET(&rev.diffopt, ALLOW_EXTERNAL);
+
        if (nongit)
                die("Not a git repository");
        argc = setup_revisions(argc, argv, &rev, NULL);
@@ -289,14 +299,15 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
                if (diff_setup_done(&rev.diffopt) < 0)
                        die("diff_setup_done failed");
        }
-       DIFF_OPT_SET(&rev.diffopt, ALLOW_EXTERNAL);
+
        DIFF_OPT_SET(&rev.diffopt, RECURSIVE);
 
        /*
         * If the user asked for our exit code then don't start a
         * pager or we would end up reporting its exit code instead.
         */
-       if (!DIFF_OPT_TST(&rev.diffopt, EXIT_WITH_STATUS))
+       if (!DIFF_OPT_TST(&rev.diffopt, EXIT_WITH_STATUS) &&
+           check_pager_config("diff") != 0)
                setup_pager();
 
        /*