The behaviour of \w shouldn't change based on whether it's in a char class or not.

But running with -Dr shows that these regexes compiled differently. And it looks like the problem is not in IO, I've tried the following: 

#use locale;
use utf8;
$a = 'é';
$a =~ m/\w/ and print "first re match\n"; 
$a =~ m/[\w]/ and print "second re match\n";

[download]
if use locale is commented out it outputs: 
first re match
second re match

[download]
if use locale uncommented only: 
second re match

[download]
My locale en_US.UTF-8 BTW.

debugperl -Dr shows the following: 

Without locale:
Compiling REx "\w"
Final program:
   1: ALNUM (2)
   2: END (0)
stclass ALNUM minlen 1 
Compiling REx "[\w]"
Final program:
   1: ANYOF[0-9A-Z_a-z+utf8::IsWord] (13)
  13: END (0)
stclass ANYOF[0-9A-Z_a-z+utf8::IsWord] minlen 1 

with locale:
Compiling REx "\w"
Final program:
   1: ALNUML (2)
   2: END (0)
stclass ALNUML minlen 1 
Compiling REx "[\w]"
Final program:
   1: ANYOF{loc}[\w+utf8::IsWord] (13)
  13: END (0)
stclass ANYOF{loc}[\w+utf8::IsWord] minlen 1

[download]

I don't really understand this output very well, but it looks like it treats this regexes differently.

In reply to Re^3: use locale behavior depends on charset of locale? by zwon
in thread use locale behavior depends on charset of locale? by Anonymous Monk

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