quiet "Complex regular subexpression recursion limit" warnings

These seem mostly harmless since Perl will just truncate the
match and start a new one on a newline boundary in our case.
The only downside is we'd end up with redundant <span> tags in
HTML.

Limiting the number of line matched ourselves with `{1,$NUM}'
doesn't seem prudent since lines vary in length, so we continue
to defer the job of limiting matches to the Perl regexp engine.

I've noticed this warning in practice on 100K+ line patches to
locale data.

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/PublicInbox/ViewDiff.pm b/lib/PublicInbox/ViewDiff.pm
index d22c80b9..5d391a13 100644
--- a/lib/PublicInbox/ViewDiff.pm
+++ b/lib/PublicInbox/ViewDiff.pm
@@ -202,6 +202,17 @@ sub flush_diff ($$$) {
                         $dctx = diff_header($dst, \$x, $ctx, \@top);
                 } elsif ($dctx) {
                         my $after = '';
+
+                        # Quiet "Complex regular subexpression recursion limit"
+                        # warning.  Perl will truncate matches upon hitting
+                        # that limit, giving us more (and shorter) scalars than
+                        # would be ideal, but otherwise it's harmless.
+                        #
+                        # We could replace the `+' metacharacter with `{1,100}'
+                        # to limit the matches ourselves to 100, but we can
+                        # let Perl do it for us, quietly.
+                        no warnings 'regexp';
+
                         for my $s (split(/((?:(?:^\+[^\n]*\n)+)|
                                         (?:(?:^-[^\n]*\n)+)|
                                         (?:^@@ [^\n]+\n))/xsm, $x)) {