Re: [PATCH 1/5] chainlint: match arbitrary here-docs tags rather than hard-coded names

On Wed, Aug 8, 2018 at 6:50 PM Jeff King [off-list ref] wrote:

On Tue, Aug 07, 2018 at 04:21:31AM -0400, Eric Sunshine wrote:

quoted

+# Swallowing here-docs with arbitrary tags requires a bit of finesse. When a
+# line such as "cat <<EOF >out" is seen, the here-doc tag is moved to the front
+# of the line enclosed in angle brackets as a sentinel, giving "<EOF>cat >out".

Gross, but OK, as long as we would not get confused by a line that
actually started with <EOF> at the start.

It can't get confused by such a line. There here-doc swallower
prepends that when it starts the swallowing process and removes it add
the end. Even if a line actually started with that, it would become
"<EOF><EOF>cmd" while swallowing the here-doc, and be restored to
"<EOF>cmd" at the end. Stripping the "<EOF>" is done non-greedily, so
it wouldn't remove both of them. Likewise, non-greedy matching is used
for pulling the "EOF" out of the "<...>" when trying to match against
the terminating "EOF" line, so there can be no confusion.

quoted

+/<<[         ]*[-\\]*[A-Z0-9_][A-Z0-9_]*/ {
+     s/^\(.*\)<<[    ]*[-\\]*\([A-Z0-9_][A-Z0-9_]*\)/<\2>\1<</
+     s/[     ]*<<//

Here-docs can use lowercase, too, though I'd personally frown on that
from a style perspective.

Yeah, I was going with the tighter uppercase-only which Jonathan
suggested[1], but I guess it wouldn't hurt to re-roll to allow
lowercase too.

[1]: https://public-inbox.org/git/20180730205914.GE156463@aiede.svl.corp.google.com/

It looks like this doesn't catch:

  cat <<'EOF'
  EOF

either. I think we prefer the backslash style, but there are quite a few
<<-'EOF' hits. Is it covered somewhere else?

No. I've gotten so used to \EOF in this codebase that it didn't occur
to me to even think about 'EOF', but a re-roll could add that, as
well.