git branch --merged and git branch --verbose do not combine

dak@lola:/usr/local/tmp/lilypond$ ../git/git branch --merged --verbose
fatal: malformed object name --verbose
dak@lola:/usr/local/tmp/lilypond$ ../git/git branch --verbose --merged
* (detached from 5b2267a) 1c23f39 Merge branch 'issue4097' into HEAD
  issue346                8cf033e Issue 346: monochord issues
dak@lola:/usr/local/tmp/lilypond$ ../git/git branch --merged
* (detached from 5b2267a)
  issue346
  issue3855
  issue4030
  issue4083
  issue4092
  issue4096
  issue4097
  removelyr
  test-master
  test-staging

So depending on the order of --verbose and --merged, one gets an incomplete list (basically ignoring --merged) or an error message.

Since both behavior and naming of the --verbose option is more or less orthogonal to other listing options, it would make sense to allow it to combine with them.

David Kastrup

Only at the very end of the command line if you omit something that is required, Git helps by defaulting the missing rev to HEAD. You can be a bit more explicit in the middle, i.e. instead of asking "Which are branches that already has been merged in --verbose?", you can ask "branch --merged HEAD --verbose", meaning "What are branhes that already has been merged in HEAD, please give me a verbose answer?" perhaps?

This gives the same result as

git branch --verbose --merged

namely _only_ listing the current branch verbosely. Use of --verbose kills any effect of --merged: instead of branches merged to the named branch (or to the default of HEAD), _only_ the named branch (or the default of HEAD) gets listed.

So no.

David Kastrup

Hmph. Then that is a different issue. As I never use --merged myself, even though I use "git branch [--verbose] --no-merged pu" quite often to check the list of topics that I received but not yet merged anywhere in my tree, I wouldn't be entirely surprised that the combination does not work, but with a quick glance of the code, especially how matches_merge_filter() uses "--[no-]merged", I cannot offhand imagine how --no-merged would work and --merged break.

Ugh. The bug is caused by a failure to clean up the global flag state. I am really tempted to try converting the revision walker to keep its flags in a commit_slab so that this sort of thing can never bite us again.

But here is the minimal fix.

-- >8 --
Subject: branch: clean up commit flags after merge-filter walk

When we run branch --merged, we use prepare_revision_walk with the merge-filter marked as UNINTERESTING. Any branch tips that are marked UNINTERESTING after it returns must be ancestors of that commit. As we iterate through the list of refs to show, we check item->commit->object.flags to see whether it was marked.

This interacts badly with --verbose, which will do a separate walk to find the ahead/behind information for each branch. There are two bad things that can happen:

1. The ahead/behind walk may get the wrong results, because it can see a bogus UNINTERESTING flag leftover from the merge-filter walk.

2. We may omit some branches if their tips are involved in the ahead/behind traversal of a branch shown earlier. The ahead/behind walk carefully cleans up its commit flags, meaning it may also erase the UNINTERESTING flag that we expect to check later.

We can solve this by moving the merge-filter state for each ref into its "struct ref_item" as soon as we finish the merge-filter walk. That fixes (2). Then we are free to clear the commit flags we used in the walk, fixing (1).

Note that we actually do away with the matches_merge_filter helper entirely here, and inline it between the revision walk and the flag-clearing. This ensures that nobody accidentally calls it at the wrong time (it is only safe to check in that instant between the setting and clearing of the global flag).

---
 builtin/branch.c           | 33 +++++++++++++++++++--------------
 t/t3201-branch-contains.sh | 29 +++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 14 deletions(-)

index ced422b..9e4666f 100644
@@ -280,6 +280,7 @@ struct ref_item {
 	char *dest;
 	unsigned int kind, width;
 	struct commit *commit;
+	int ignore;
 };
 
 struct ref_list {

@@ -385,6 +386,7 @@ static int append_ref(const char *refname, const unsigned char *sha1, int flags,
 	newitem->commit = commit;
 	newitem->width = utf8_strwidth(refname);
 	newitem->dest = resolve_symref(orig_refname, prefix);
+	newitem->ignore = 0;
 	/* adjust for "remotes/" */
 	if (newitem->kind == REF_REMOTE_BRANCH &&
 	    ref_list->kinds != REF_REMOTE_BRANCH)

@@ -484,17 +486,6 @@ static void fill_tracking_info(struct strbuf *stat, const char *branch_name,
 	free(ref);
 }
 
-static int matches_merge_filter(struct commit *commit)
-{
-	int is_merged;
-
-	if (merge_filter == NO_FILTER)
-		return 1;
-
-	is_merged = !!(commit->object.flags & UNINTERESTING);
-	return (is_merged == (merge_filter == SHOW_MERGED));
-}
-
 static void add_verbose_info(struct strbuf *out, struct ref_item *item,
 			     int verbose, int abbrev)
 {

@@ -522,10 +513,9 @@ static void print_ref_item(struct ref_item *item, int maxwidth, int verbose,
 {
 	char c;
 	int color;
-	struct commit *commit = item->commit;
 	struct strbuf out = STRBUF_INIT, name = STRBUF_INIT;
 
-	if (!matches_merge_filter(commit))
+	if (item->ignore)
 		return;
 
 	switch (item->kind) {

@@ -575,7 +565,7 @@ static int calc_maxwidth(struct ref_list *refs)
 {
 	int i, w = 0;
 	for (i = 0; i < refs->index; i++) {
-		if (!matches_merge_filter(refs->list[i].commit))
+		if (refs->list[i].ignore)
 			continue;
 		if (refs->list[i].width > w)
 			w = refs->list[i].width;

@@ -618,6 +608,7 @@ static void show_detached(struct ref_list *ref_list)
 		item.kind = REF_LOCAL_BRANCH;
 		item.dest = NULL;
 		item.commit = head_commit;
+		item.ignore = 0;
 		if (item.width > ref_list->maxwidth)
 			ref_list->maxwidth = item.width;
 		print_ref_item(&item, ref_list->maxwidth, ref_list->verbose, ref_list->abbrev, 1, "");

@@ -656,6 +647,20 @@ static int print_ref_list(int kinds, int detached, int verbose, int abbrev, stru
 
 		if (prepare_revision_walk(&ref_list.revs))
 			die(_("revision walk setup failed"));
+
+		for (i = 0; i < ref_list.index; i++) {
+			struct ref_item *item = &ref_list.list[i];
+			struct commit *commit = item->commit;
+			int is_merged = !!(commit->object.flags & UNINTERESTING);
+			item->ignore = is_merged != (merge_filter == SHOW_MERGED);
+		}
+
+		for (i = 0; i < ref_list.index; i++) {
+			struct ref_item *item = &ref_list.list[i];
+			clear_commit_marks(item->commit, ALL_REV_FLAGS);
+		}
+		clear_commit_marks(filter, ALL_REV_FLAGS);
+
 		if (verbose)
 			ref_list.maxwidth = calc_maxwidth(&ref_list);
 	}

index 141b061..912a663 100755
@@ -130,4 +130,33 @@ test_expect_success 'implicit --list conflicts with modification options' '
 
 '
 
+# We want to set up a case where the walk for the tracking info
+# of one branch crosses the tip of another branch (and make sure
+# that the latter walk does not mess up our flag to see if it was
+# merged).
+#
+# Here "topic" tracks "master" with one extra commit, and "zzz" points to the
+# same tip as master The name "zzz" must come alphabetically after "topic"
+# as we process them in that order.
+test_expect_success 'branch --merged with --verbose' '
+	git branch --track topic master &&
+	git branch zzz topic &&
+	git checkout topic &&
+	test_commit foo &&
+	git branch --merged topic >actual &&
+	cat >expect <<-\EOF &&
+	  master
+	* topic
+	  zzz
+	EOF
+	test_cmp expect actual &&
+	git branch --verbose --merged topic >actual &&
+	cat >expect <<-\EOF &&
+	  master c77a0a9 second on master
+	* topic  2c939f4 [ahead 1] foo
+	  zzz    c77a0a9 second on master
+	EOF
+	test_cmp expect actual
+'
+
 test_done

2.1.0.486.g83bb229