[PATCH 1/2] git-format-patch: Print a diagnostic message when ignoring commits

[Ramkumar Ramachandra <artagnon@gmail.com>]

Earlier, git-format-patch used to silently skip over commits that it
didn't intend to make patches out of. As a consequence, a command like
'git-format-patch -3' would just do nothing and print nothing if the
topmost three commits were merge commits. Instead, print a useful
message similar to "Skipping: Merge branch ..." when ignoring a
commit.

Suggested-by: Jakub Narebski <jnareb@gmail.com>
Cc: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/log.c |   42 +++++++++++++++++++++++++++++++-----------
 1 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 0151d2f..b64de7c 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1090,7 +1090,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct commit **list = NULL;
 	struct rev_info rev;
 	struct setup_revision_opt s_r_opt;
-	int nr = 0, total, i;
+	int nr = 0, nr_i = 0, total, i;
 	int use_stdout = 0;
 	int start_number = -1;
 	int numbered_files = 0;		/* _just_ numbers */
@@ -1098,6 +1098,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	int cover_letter = 0;
 	int boundary_count = 0;
 	int no_binary_diff = 0;
+	int *list_i = NULL;
 	struct commit *origin = NULL, *head = NULL;
 	const char *in_reply_to = NULL;
 	struct patch_ids ids;
@@ -1342,19 +1343,22 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
-		/* ignore merges */
-		if (commit->parents && commit->parents->next)
-			continue;
-
-		if (ignore_if_in_upstream &&
-				has_commit_patch_id(commit, &ids))
-			continue;
+		/* ignore merge commits and optionally ignore commits
+		   already in upstream */
+		if ((commit->parents && commit->parents->next) ||
+		    (ignore_if_in_upstream &&
+		     has_commit_patch_id(commit, &ids))) {
+			/* Store the nr of the ignored commits in list_i */
+			nr_i++;
+			list_i = xrealloc(list_i, nr_i * sizeof(list_i[0]));
+			list_i[nr_i - 1] = nr;
+		}
 
 		nr++;
 		list = xrealloc(list, nr * sizeof(list[0]));
 		list[nr - 1] = commit;
 	}
-	total = nr;
+	total = nr - nr_i;
 	if (!keep_subject && auto_number && total > 1)
 		numbered = 1;
 	if (numbered)
@@ -1376,10 +1380,25 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		start_number--;
 	}
 	rev.add_signoff = add_signoff;
-	while (0 <= --nr) {
+	for (i = nr - nr_i; --nr >= 0;) {
 		int shown;
 		commit = list[nr];
-		rev.nr = total - nr + (start_number - 1);
+
+		/* Ignore commits in list whose index is list_i */
+		if (list_i[nr_i - 1] == nr) {
+			struct strbuf commit_msg = STRBUF_INIT;
+			struct pretty_print_context ctx = {0};
+			format_commit_message(commit, "%s", &commit_msg, &ctx);
+			fprintf(realstdout, "Skipping: %s\n",
+				commit_msg.buf);
+			strbuf_release(&buf);
+			--nr_i;
+			continue;
+		}
+		else
+			--i;
+
+		rev.nr = total - i + (start_number - 1);
 		/* Make the second and subsequent mails replies to the first */
 		if (thread) {
 			/* Have we already had a message ID? */
@@ -1443,6 +1462,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			fclose(stdout);
 	}
 	free(list);
+	free(list_i);
 	string_list_clear(&extra_to, 0);
 	string_list_clear(&extra_cc, 0);
 	string_list_clear(&extra_hdr, 0);
-- 
1.7.2.2.409.gdbb11.dirty