On Tue, Mar 28, 2023 at 10:37:02PM -0400, Jeff King wrote:

I just think chainlint.pl is doing a good enough job of catching it that
we can rely on it. I'll be curious if Eric has input there on whether it
can do even better, which would remove all of the caveats from the
commit message.

So I _think_ it's something like this:

diff --git a/t/chainlint.pl b/t/chainlint.pl
index e966412999a..6b8c1de5208 100755
--- a/t/chainlint.pl
+++ b/t/chainlint.pl

@@ -171,6 +171,9 @@ sub swallow_heredocs {
 		my $start = pos($$b);
 		my $indent = $tag =~ s/^\t// ? '\\s*' : '';
 		$$b =~ /(?:\G|\n)$indent\Q$tag\E(?:\n|\z)/gc;
+		if (pos($$b) == $start) {
+			die "oops, we did not find the end of the heredoc";
+		}
 		my $body = substr($$b, $start, pos($$b) - $start);
 		$self->{lineno} += () = $body =~ /\n/sg;
 	}

But I wasn't sure how to surface a clean error from here, since we're in
the Lexer. Maybe we just accumulate a "problems" array here, and then
roll those up via the TestParser? I'm not very familiar with the
arrangement of that part of the script.

And I say "think" because the thing I was worried about is that we'd do
this lexing at too high a level, and accidentally walk past the end of
the test. Which would mean getting fooled by;

  test_expect_success 'this one is broken' '
	cat >foo <<\EOF
	oops, we are missing our here-doc end
  '

  test_expect_success 'this one is ok' '
	cat >foo <<\EOF
	this one is OK, but we would not want to confuse
	its closing tag for the missing one
	EOF
  '

But it looks like Lexer::swallow_heredocs gets to see the individual
test snippets.

-Peff