regcomp.c	AOK

  %.*s matches null string many times   

	$a = "ABC123" ; $a =~ /(?=a)*/'

  Strange *+?{} on zero-length expression

	/(?=a)?/

  Character class syntax [: :] is reserved for future extensions
	/[a[:xyz:]b]/

  Character class syntax [. .] is reserved for future extensions
  Character class syntax [= =] is reserved for future extensions

__END__
# regcomp.c
use warning 'unsafe' ;
my $a = "ABC123" ; 
$a =~ /(?=a)*/ ;
EXPECT
(?=a)* matches null string many times at - line 4.
########
# regcomp.c
use warning 'unsafe' ;
$_ = "" ;
/(?=a)?/;
EXPECT
Strange *+?{} on zero-length expression at - line 4.
########
# regcomp.c
use warning 'unsafe' ;
$_ = "" ;
/[a[:xyz:]b]/;
/[a[.xyz.]b]/;
/[a[=xyz=]b]/;
EXPECT
Character class syntax [: :] is reserved for future extensions at - line 4.
Character class syntax [. .] is reserved for future extensions at - line 5.
Character class syntax [= =] is reserved for future extensions at - line 6.
########
# regcomp.c
use warning 'unsafe' ; 
# use utf8 ; # Note this line should be uncommented when utf8 gets fixed.
$_ = "" ;
/[a[:xyz:]b]/;
/[a[.xyz.]b]/;
/[a[=xyz=]b]/;
EXPECT
Character class syntax [: :] is reserved for future extensions at - line 5.
Character class syntax [. .] is reserved for future extensions at - line 6.
Character class syntax [= =] is reserved for future extensions at - line 7.