Re: bug with check-ref-format outside of repository

[Jeff King <peff@peff.net>]

On Sat, Jul 08, 2017 at 03:17:32AM +0200, Marko Kungla wrote:

> As contrived e.g: if I have in my "workspace" sub directories mostly
> git repositories, but some not and if I exec,
> "for d in */ ; do (cd $d && git check-ref-format --branch @{-1});
> done" then I get 3 possible responses.
> 
> git version: 2.13.0
> 1. Valid branch name
> 2. fatal: '@{-1}' is not a valid branch name
> 3. fatal: BUG: setup_git_env called without repository
> 
> git version 2.13.2.915.ga9c46e097
> 1. Valid branch name
> 2. fatal: '@{-1}' is not a valid branch name
> 3. BUG: environment.c:178: git environment hasn't been setup

Thanks for the report. It's right to return an error, but obviously we
should never hit the BUG() in the lazy-setup code.

I think "check-ref-format --branch" is inherently a repository-only
operation, since its purpose is to look in the reflog with @{-1} and
similar branch-substitutions. Technically you can do:

  $ cd /not/a/git/repo
  $ git check-ref-format --branch 'refs/heads/foo'

but I'm not sure why you would want to. So I think the patch below is
probably the right direction. The other alternative is for
interpret_nth_prior_checkout() to detect the "not in a repo" case and
quietly return "nope, we couldn't find such a reflog entry".

+cc Jonathan, who added the original call in 49cc460d8 (Allow
"check-ref-format --branch" from subdirectory, 2010-08-05). That commit
message doesn't give any indication of why we used the gently form.
Looking back at the original thread[1], I suspect it was mostly out of
conservatism.

[1] https://public-inbox.org/git/20100806033922.GS22369@burratino/

---
diff --git a/builtin/check-ref-format.c b/builtin/check-ref-format.c
index eac499450..1e5f9835f 100644
--- a/builtin/check-ref-format.c
+++ b/builtin/check-ref-format.c
@@ -39,9 +39,8 @@ static char *collapse_slashes(const char *refname)
 static int check_ref_format_branch(const char *arg)
 {
 	struct strbuf sb = STRBUF_INIT;
-	int nongit;
 
-	setup_git_directory_gently(&nongit);
+	setup_git_directory();
 	if (strbuf_check_branch_ref(&sb, arg))
 		die("'%s' is not a valid branch name", arg);
 	printf("%s\n", sb.buf + 11);
diff --git a/t/t1402-check-ref-format.sh b/t/t1402-check-ref-format.sh
index 0790edf60..1674b061e 100755
--- a/t/t1402-check-ref-format.sh
+++ b/t/t1402-check-ref-format.sh
@@ -161,6 +161,10 @@ test_expect_success 'check-ref-format --branch from subdir' '
 	test "$refname" = "$sha1"
 '
 
+test_expect_success 'check-ref-format --branch from non-repo' '
+	test_must_fail nongit git check-ref-format --branch @{-1}
+'
+
 valid_ref_normalized() {
 	prereq=
 	case $1 in