From 1219f94d0f79f336b2d09a64e01564c4d73cfe66 Mon Sep 17 00:00:00 2001
From: Johannes Schindelin <johasc@microsoft.com>
Date: Tue, 28 May 2019 21:48:08 +0200
Subject: [PATCH] backwards-compatibility: support the post-indexchanged hook

When our patches to support that hook were upstreamed, the hook's name
was eliciting some reviewer suggestions, and it was renamed to
`post-index-change`. These patches (with the new name) made it into
v2.22.0.

However, VFSforGit users may very well have checkouts with that hook
installed under the original name.

To support this, let's just introduce a hack where we look a bit more
closely when we just failed to find the `post-index-change` hook, and
allow any `post-indexchanged` hook to run instead (if it exists).
---
 hook.c                            | 14 +++++++++++++-
 t/t7113-post-index-change-hook.sh | 30 ++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/hook.c b/hook.c
index 4f6ad1499e..3bd788d1df 100644
--- a/hook.c
+++ b/hook.c
@@ -178,7 +178,7 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 		.hook_name = hook_name,
 		.options = options,
 	};
-	const char *const hook_path = find_hook(hook_name);
+	const char *hook_path = find_hook(hook_name);
 	int ret = 0;
 	const struct run_process_parallel_opts opts = {
 		.tr2_category = "hook",
@@ -194,6 +194,18 @@ int run_hooks_opt(const char *hook_name, struct run_hooks_opt *options)
 		.data = &cb_data,
 	};
 
+	/*
+	 * Backwards compatibility hack in VFS for Git: when originally
+	 * introduced (and used!), it was called `post-indexchanged`, but this
+	 * name was changed during the review on the Git mailing list.
+	 *
+	 * Therefore, when the `post-index-change` hook is not found, let's
+	 * look for a hook with the old name (which would be found in case of
+	 * already-existing checkouts).
+	 */
+	if (!hook_path && !strcmp(hook_name, "post-index-change"))
+		hook_path = find_hook("post-indexchanged");
+
 	if (!options)
 		BUG("a struct run_hooks_opt must be provided to run_hooks");
 
diff --git a/t/t7113-post-index-change-hook.sh b/t/t7113-post-index-change-hook.sh
index 58e55a7c77..455c61a925 100755
--- a/t/t7113-post-index-change-hook.sh
+++ b/t/t7113-post-index-change-hook.sh
@@ -16,6 +16,36 @@ test_expect_success 'setup' '
 	git commit -m "initial"
 '
 
+test_expect_success 'post-indexchanged' '
+	mkdir -p .git/hooks &&
+	test_when_finished "rm -f .git/hooks/post-indexchanged marker" &&
+	write_script .git/hooks/post-indexchanged <<-\EOF &&
+	: >marker
+	EOF
+
+	: make sure -changed is called if -change does not exist &&
+	test_when_finished "echo testing >dir1/file2.txt && git status" &&
+	echo changed >dir1/file2.txt &&
+	: force index to be dirty &&
+	test-tool chmtime -60 .git/index &&
+	git status &&
+	test_path_is_file marker &&
+
+	test_when_finished "rm -f .git/hooks/post-index-change marker2" &&
+	write_script .git/hooks/post-index-change <<-\EOF &&
+	: >marker2
+	EOF
+
+	: make sure -changed is not called if -change exists &&
+	rm -f marker marker2 &&
+	echo testing >dir1/file2.txt &&
+	: force index to be dirty &&
+	test-tool chmtime -60 .git/index &&
+	git status &&
+	test_path_is_missing marker &&
+	test_path_is_file marker2
+'
+
 test_expect_success 'test status, add, commit, others trigger hook without flags set' '
 	test_hook post-index-change <<-\EOF &&
 		if test "$1" -eq 1; then