[PATCH 12/14] format-patch: teach --range-diff to respect -v/--reroll-count

[Eric Sunshine]

The --range-diff option announces the embedded range-diff generically
as "Range-diff:", however, we can do better when --reroll-count is
specified by emitting "Range-diff against v{n}:" instead.

Signed-off-by: Eric Sunshine <sunsh...@sunshineco.com>
---
 builtin/log.c | 7 ++++++-
 revision.h    | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/builtin/log.c b/builtin/log.c
index 4f937aad15..fdb2180d7e 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1091,7 +1091,7 @@ static void make_cover_letter(struct rev_info *rev, int 
use_stdout,
        }
 
        if (rev->rdiff1) {
-               fprintf_ln(rev->diffopt.file, "%s", _("Range-diff:"));
+               fprintf_ln(rev->diffopt.file, "%s", rev->rdiff_title);
                show_range_diff(rev->rdiff1, rev->rdiff2,
                                rev->creation_factor, 1, &rev->diffopt);
        }
@@ -1496,6 +1496,7 @@ int cmd_format_patch(int argc, const char **argv, const 
char *prefix)
        const char *rdiff_prev = NULL;
        struct strbuf rdiff1 = STRBUF_INIT;
        struct strbuf rdiff2 = STRBUF_INIT;
+       struct strbuf rdiff_title = STRBUF_INIT;
 
        const struct option builtin_format_patch_options[] = {
                { OPTION_CALLBACK, 'n', "numbered", &numbered, NULL,
@@ -1815,6 +1816,9 @@ int cmd_format_patch(int argc, const char **argv, const 
char *prefix)
                rev.rdiff1 = rdiff1.buf;
                rev.rdiff2 = rdiff2.buf;
                rev.creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
+               rev.rdiff_title = diff_title(&rdiff_title, reroll_count,
+                                            _("Range-diff:"),
+                                            _("Range-diff against v%d:"));
        }
 
        if (!signature) {
@@ -1942,6 +1946,7 @@ int cmd_format_patch(int argc, const char **argv, const 
char *prefix)
        strbuf_release(&idiff_title);
        strbuf_release(&rdiff1);
        strbuf_release(&rdiff2);
+       strbuf_release(&rdiff_title);
        return 0;
 }
 
diff --git a/revision.h b/revision.h
index 11159416dc..cd0873b575 100644
--- a/revision.h
+++ b/revision.h
@@ -221,6 +221,7 @@ struct rev_info {
        const char *rdiff1;
        const char *rdiff2;
        int creation_factor;
+       const char *rdiff_title;
 
        /* commit counts */
        int count_left;
-- 
2.18.0.345.g5c9ce644c3