Merge branch 'jk/reflog-walk' into maint

Numerous bugs in walking of reflogs via "log -g" and friends have
been fixed.

* jk/reflog-walk:
  reflog-walk: apply --since/--until to reflog dates
  reflog-walk: stop using fake parents
  rev-list: check reflog_info before showing usage
  get_revision_1(): replace do-while with an early return
  log: do not free parents when walking reflog
  log: clarify comment about reflog cycles
  revision: disallow reflog walking with revs->limited
  t1414: document some reflog-walk oddities

3 files changed, 136 insertions, 12 deletions

diff --git a/t/t1411-reflog-show.sh b/t/t1411-reflog-show.sh
index b9cb76654b..6ac7734d79 100755
--- a/t/t1411-reflog-show.sh
+++ b/t/t1411-reflog-show.sh
@@ -171,14 +171,4 @@ test_expect_success 'reflog exists works' '
 	! git reflog exists refs/heads/nonexistent
 '
 
-# The behavior with two reflogs is buggy and the output is in flux; for now
-# we're just checking that the program works at all without segfaulting.
-test_expect_success 'showing multiple reflogs works' '
-	git log -g HEAD HEAD >actual
-'
-
-test_expect_success 'showing multiple reflogs with an old date' '
-	git log -g HEAD@{1979-01-01} HEAD >actual
-'
-
 test_done
diff --git a/t/t1414-reflog-walk.sh b/t/t1414-reflog-walk.sh
new file mode 100755
index 0000000000..feb1efd8ff
--- /dev/null
+++ b/t/t1414-reflog-walk.sh
@@ -0,0 +1,135 @@
+#!/bin/sh
+
+test_description='various tests of reflog walk (log -g) behavior'
+. ./test-lib.sh
+
+test_expect_success 'set up some reflog entries' '
+	test_commit one &&
+	test_commit two &&
+	git checkout -b side HEAD^ &&
+	test_commit three &&
+	git merge --no-commit master &&
+	echo evil-merge-content >>one.t &&
+	test_tick &&
+	git commit --no-edit -a
+'
+
+do_walk () {
+	git log -g --format="%gd %gs" "$@"
+}
+
+sq="'"
+test_expect_success 'set up expected reflog' '
+	cat >expect.all <<-EOF
+	HEAD@{0} commit (merge): Merge branch ${sq}master${sq} into side
+	HEAD@{1} commit: three
+	HEAD@{2} checkout: moving from master to side
+	HEAD@{3} commit: two
+	HEAD@{4} commit (initial): one
+	EOF
+'
+
+test_expect_success 'reflog walk shows expected logs' '
+	do_walk >actual &&
+	test_cmp expect.all actual
+'
+
+test_expect_success 'reflog can limit with --no-merges' '
+	grep -v merge expect.all >expect &&
+	do_walk --no-merges >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'reflog can limit with pathspecs' '
+	grep two expect.all >expect &&
+	do_walk -- two.t >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pathspec limiting handles merges' '
+	# we pick up:
+	#   - the initial commit of one
+	#   - the checkout back to commit one
+	#   - the evil merge which touched one
+	sed -n "1p;3p;5p" expect.all >expect &&
+	do_walk -- one.t >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--parents shows true parents' '
+	# convert newlines to spaces
+	echo $(git rev-parse HEAD HEAD^1 HEAD^2) >expect &&
+	git rev-list -g --parents -1 HEAD >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'walking multiple reflogs shows all' '
+	# We expect to see all entries for all reflogs, but interleaved by
+	# date, with order on the command line breaking ties. We
+	# can use "sort" on the separate lists to generate this,
+	# but note two tricks:
+	#
+	#   1. We use "{" as the delimiter, which lets us skip to the reflog
+	#      date specifier as our second field, and then our "-n" numeric
+	#      sort ignores the bits after the timestamp.
+	#
+	#   2. POSIX leaves undefined whether this is a stable sort or not. So
+	#      we use "-k 1" to ensure that we see HEAD before master before
+	#      side when breaking ties.
+	{
+		do_walk --date=unix HEAD &&
+		do_walk --date=unix side &&
+		do_walk --date=unix master
+	} >expect.raw &&
+	sort -t "{" -k 2nr -k 1 <expect.raw >expect &&
+	do_walk --date=unix HEAD master side >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'date-limiting does not interfere with other logs' '
+	do_walk HEAD@{1979-01-01} HEAD >actual &&
+	test_cmp expect.all actual
+'
+
+test_expect_success 'min/max age uses entry date to limit' '
+	# Flip between commits one and two so each ref update actually
+	# does something (and does not get optimized out). We know
+	# that the timestamps of those commits will be before our "min".
+
+	git update-ref -m before refs/heads/minmax one &&
+
+	test_tick &&
+	min=$test_tick &&
+	git update-ref -m min refs/heads/minmax two &&
+
+	test_tick &&
+	max=$test_tick &&
+	git update-ref -m max refs/heads/minmax one &&
+
+	test_tick &&
+	git update-ref -m after refs/heads/minmax two &&
+
+	cat >expect <<-\EOF &&
+	max
+	min
+	EOF
+	git log -g --since=$min --until=$max --format=%gs minmax >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'walk prefers reflog to ref tip' '
+	head=$(git rev-parse HEAD) &&
+	one=$(git rev-parse one) &&
+	ident="$GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE" &&
+	echo "$head $one $ident	broken reflog entry" >>.git/logs/HEAD &&
+
+	echo $one >expect &&
+	git log -g --format=%H -1 >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'rev-list -g complains when there are no reflogs' '
+	test_must_fail git rev-list -g
+'
+
+test_done
diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index dd37ac47c5..9d707d2a40 100755
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -166,10 +166,9 @@ test_expect_success 'resulting reflog can be shown by log -g' '
 	oid=$(git rev-parse HEAD) &&
 	cat >expect <<-EOF &&
 	HEAD@{0} $oid $msg
-	HEAD@{1} $oid $msg
 	HEAD@{2} $oid checkout: moving from foo to baz
 	EOF
-	git log -g --format="%gd %H %gs" -3 HEAD >actual &&
+	git log -g --format="%gd %H %gs" -2 HEAD >actual &&
 	test_cmp expect actual
 '