Bug #48613 for Test-XML-Easy: $xml10_s_rx usage in Test::XML::Easy

Test::XML::Easy uses $xml10_s_rx (from XML::Easy::Syntax) slightly incorrectly. $xml10_s_rx matches a *sequence of one or more* whitespace chars, but you've treated it as if it matched *exactly one* whitespace char, risking exponential explosion in backtracking. Also, two of the three places that you do whitespace matching will match on an empty string and do a null substitution, whereas it would be more efficient to only match a non-empty string. Incidentally, you should be using the /o modifier to avoid repeated interpolation. So where you have $comp_got_text =~ s/ \A (?:$xml10_s_rx)* //x; you should instead have $comp_got_text =~ s/ \A $xml10_s_rx //ox; and likewise the other substitutions should be $comp_got_text =~ s/ $xml10_s_rx \z//ox; $comp_got_text =~ s/ $xml10_s_rx / /ogx; -zefram