fix optimizer bug in /^(?p{"a"})b/ (from Ilya Zakharevich)

p4raw-id: //depot/perl@5644

2 files changed, 6 insertions, 1 deletions

diff --git a/regcomp.c b/regcomp.c
index 9fbb3df20e..13fa36c201 100644
--- a/regcomp.c
+++ b/regcomp.c
@@ -1222,7 +1222,7 @@ S_study_chunk(pTHX_ regnode **scanp, I32 *deltap, regnode *last, scan_data_t *da
 		if (data)
 		    data->flags |= SF_HAS_EVAL;
 	}
-	else if (OP(scan) == LOGICAL && scan->flags == 2) { /* Embedded */
+	else if (OP(scan) == LOGICAL && scan->flags == 2) { /* Embedded follows */
 		if (flags & SCF_DO_SUBSTR) {
 		    scan_commit(data);
 		    data->longest = &(data->longest_float);
@@ -1230,6 +1230,7 @@ S_study_chunk(pTHX_ regnode **scanp, I32 *deltap, regnode *last, scan_data_t *da
 		is_inf = is_inf_internal = 1;
 		if (flags & SCF_DO_STCLASS_OR) /* Allow everything */
 		    cl_anything(data->start_class);
+		flags &= ~SCF_DO_STCLASS;
 	}
 	/* Else: zero-length, ignore. */
 	scan = regnext(scan);
diff --git a/t/op/pat.t b/t/op/pat.t
index 103e6132b5..7f20185e93 100755
--- a/t/op/pat.t
+++ b/t/op/pat.t
@@ -369,6 +369,10 @@ print "# ans='@ans'\n# expect='$expect'\nnot " if "@ans" ne $expect;
 print "ok $test\n";
 $test++;
 
+print "not " unless "abc" =~ /^(??{"a"})b/;
+print "ok $test\n";
+$test++;
+
 my $matched;
 $matched = qr/\((?:(?>[^()]+)|(??{$matched}))*\)/;