Fix bug #109206: ANCH_MBOL with while /.*/g

We had a fencepost error when ANCH_MBOL was enabled that meant we
did not "see" matches at the end of string. This fixes the problem
and adds tests.

2 files changed, 15 insertions, 3 deletions

diff --git a/regexec.c b/regexec.c
index 6bd8b20b60..b84dcbd8b7 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2245,8 +2245,8 @@ Perl_regexec_flags(pTHX_ REGEXP * const rx, char *stringarg, register char *stre
                     /*XXX: The s-- is almost definitely wrong here under unicode - demeprhq*/
 		    s--;
 		}
-                /* We can use a more efficient search as newlines are the same in unicode as they are in latin */
-		while (s < end) {
+		/* We can use a more efficient search as newlines are the same in unicode as they are in latin */
+		while (s <= end) { /* note it could be possible to match at the end of the string */
 		    if (*s++ == '\n') {	/* don't need PL_utf8skip here */
 			if (regtry(&reginfo, &s))
 			    goto got_it;
diff --git a/t/re/pat.t b/t/re/pat.t
index 8ea531c63f..b4b7ac477f 100644
--- a/t/re/pat.t
+++ b/t/re/pat.t
@@ -21,7 +21,7 @@ BEGIN {
     require './test.pl';
 }
 
-plan tests => 466;  # Update this when adding/deleting tests.
+plan tests => 469;  # Update this when adding/deleting tests.
 
 run_tests() unless caller;
 
@@ -1241,6 +1241,18 @@ EOP
 	is "@refs", "Regexp", '/$o$qr/ passes qr ref to cat overload meth';
     }
 
+    {
+        my $count=0;
+        my $str="\n";
+        $count++ while $str=~/.*/g;
+        is $count, 2, 'test that ANCH_MBOL works properly. We should get 2 from $count++ while "\n"=~/.*/g';
+        my $class_count= 0;
+        $class_count++ while $str=~/[^\n]*/g;
+        is $class_count, $count, 'while "\n"=~/.*/g and while "\n"=~/[^\n]*/g should behave the same';
+        my $anch_count= 0;
+        $anch_count++ while $str=~/^.*/mg;
+        is $anch_count, 1, 'while "\n"=~/^.*/mg should match only once';
+    }
 } # End of sub run_tests
 
 1;