regcomp.c These tests have been moved to t/re/reg_mesg.t except for those that explicitly test line numbers. __END__ use warnings 'regexp'; $r=qr/(??{ q"\\b+" })/; "a" =~ /a$r/; # warning should come from this line EXPECT \b+ matches null string many times in regex; marked by <-- HERE in m/\b+ <-- HERE / at - line 3.