DB<164> p $_
__'abc'__"def"__
  DB<165> x / ( (['"]) [^\2]*? \2 ) /gx     # OK
0  '\'abc\''
1  '\''
2  '"def"'
3  '"'
  DB<166> x / ( (['"]) [^\2]*? \g-1 ) /gx   # OK
0  '\'abc\''
1  '\''
2  '"def"'
3  '"'
  DB<167> x / ( (['"]) [^\g-1]*? \g-1 ) /gx # OOPS
Invalid [] range "\g-1" in regex; marked by <-- HERE in m/ ( (['"]) [^\g-1 <-- HERE ]*? \g-1 ) / at (eval 179)[c:/St\
rawberry/perl/lib/perl5db.pl:738] line 2.
 at (eval 179)[c:/Strawberry/perl/lib/perl5db.pl:738] line 2.
        eval 'no strict; ($@, $!, $^E, $,, $/, $\\, $^W) = @DB::saved;package main; $^D = $^D | $DB::db_stop;
  / ( ([\'"]) [^\\g-1]*? \\g-1 ) /gx;
' called at c:/Strawberry/perl/lib/perl5db.pl line 738
        DB::eval called at c:/Strawberry/perl/lib/perl5db.pl line 3138
        DB::DB called at -e line 1
  DB<168> p $]
5.032001
  DB<169>