I have hit this error several time lately (since the advent of 5.6.0 ?). A Google search produced 7 problem reports, btw Jun 2000 and now, with a variety of Perl modules, including PPM and ExtUtils::Installed. It can crop up easily on Win32 if you use the native pathnames containing '\' path separator. Here are examples:

#! perl -w
use strict;


# 1: no problem (even on Win32)
#
my $root = 'C:/perl';
my $podfile = 'C:/Perl/lib/Config.pm';
print "$podfile   $root   $1   $2\n" if $podfile =~ m!$root/(.*)/(\w+)
+\.p.+$!i;


# 2: causes error
#
my $rootb = 'C:\perl';
my $podfileb = 'C:\Perl\lib\Config.pm';
print "$podfileb   $rootb   $1   $2\n" if $podfileb =~ m!$rootb/(.*)/(
+\w+)\.p.+$!i;


# 3: simplified, causes error
#
print "yo\n" if 'perl' =~ m|\perl|;


__END__
[download]

It turns out that the problem is related to the recently added regex feature, mentioned briefly in perlre like so

In addition, Perl defines the following:

...

    \pP Match P, named property.  Use \p{Prop} for longer names.

    \PP Match non-P
[download]

Apparently,  m|\perl| means: match a property named 'e' which might be defined in a script or in the main module - but it is not defined, in my case.

On Win2k you can easily get a pathname containing '\p' or '\P' from a module such as File::Find or Config

print "==$Config{installprefix}==\n";    # prints ==C:\Perl==
[download]

The workaround is to replace backslashes by slashes before using such paths in a matching operation

$podfileb =~ s!\\!/!g;
$rootb =~ s!\\!/!g;
[download]

However, if a path containing backslashes is being passed between code inside a module, you might have to dig deeply if you want to fix it.

Questions to wise Monks:

• Could anyone explain the purpose and use of the Unicode named properties?
  
  
• Could or would anyone recommend a modification to published Perl modules (Config.pm to begin with), to use '/' as the path separator also on Win32?
  AFAIK '/' always works inside Perl code. The only time you have to use '\' as path separator on Win32 is when you hand the path to a native command shell, perhaps as an argument to an utility invoked with system() or qx().
  
  
• Are my observations mostly correct, or am I missing anything?
  
  

Rudif

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