use utf8; $_="foo"; /\X/   # runs fine

[download]
As the utf8 manpage puts it,: 
       WARNING: The implementation of Unicode support in Perl is
       incomplete.  See the perlunicode manpage for the exact
       details.

[download]
And in the perlunicode perldoc: 
           WARNING:  As of the 5.6.1 release, the implementation of Un
+icode
           support in Perl is incomplete, and continues to be highly e
+xperimental.

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So, I guess there are problems using extended unicode and that's why it's marked experimental.

Aziz,,,

In reply to Re: Known bug? /\X/ by abstracts
in thread Known bug? /\X/ by MeowChow

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