p5pRT
commented
6 years ago From @jimav
Created by @jimav
This is a bug report for perl from jim.avera@gmail.com\, generated with the help of perlbug 1.40 running under perl 5.26.0.
----------------------------------------------------------------- If $1 is passed as an arg to a function\, and that function internally performs a regex match\, then the argument seen from inside the func is corrupted.
I'm guessing this is because the localization of $1 does not also localize aliases to $1 such as in @_. This is a nasty trap\, and it would be great if perl could at least diagnose it if it happens (the passed-in $1 is\, after all\, nominally read-only and a direct assignment results in a a fatal "Modification of a read-only value attempted"; so one could argue that any operation which similarly could modify that argument should be flagged as well).
If not fixable or catchable\, then I'd like to suggest adding an explicit mention of this trap to the docs\, e.g. «perlsub».
#!/usr/bin/perl use strict; use warnings;
sub func($) { my $saved = $_[0]; if ($_[0] =~ /(\d+)/) { } warn "\$_[0] MUTATED from '$saved' to '$_[0]'\n" if $_[0] ne $saved; }
func "a123b"; if ("c456d" =~ /(.*)/) { func($1) }
Migrated from rt.perl.org#132647 (status was 'open')
Searchable as RT132647$