fix for Exporter's $SIG{__WARN__} handler

Exporter's $SIG{__WARN__} handler is too zealous.  It fails here:

    $ cat t
    require Carp;
    package Foo;
	@ISA = qw(Exporter);
	@EXPORT_OK = @EXPORT_FAIL = qw(foo);
	sub export_fail {
	    my $self = shift;
	    Carp::carp("carp from export_fail");
	    return ();
	}
    package main;
	import Foo 'foo';
    $ perl5.00393 t
    carp from export_fail at t line 16
     at t line 16

This is because the carp() inside export_fail triggers Exporter's
__WARN__ handler which calls carp() a second time which adds the second
" at t line 16".

I was surprised to learn that carp() adds its string to an error message
which ends with a newline, I thought it followed warn()'s lead on that.
I checked 5.003 and it was the same there, too, though.

Also, shouldn't Exporter's __WARN__ handler increment $Carp::CarpLevel
rather than setting it to 1?  I didn't include that in the patch because
I'm not sure, but it seems the right thing to do to me.

p5p-msgid: 2282.858296451@eeyore.ibcinc.com

diff --git a/lib/Exporter.pm b/lib/Exporter.pm
index abdb1e7..72a1401 100644 (file)
--- a/lib/Exporter.pm
+++ b/lib/Exporter.pm
@@ -12,9 +12,13 @@ sub export {
     # First make import warnings look like they're coming from the "use".
     local $SIG{__WARN__} = sub {
        my $text = shift;
-       $text =~ s/ at \S*Exporter.pm line \d+.*\n//;
-       local $Carp::CarpLevel = 1;     # ignore package calling us too.
-       Carp::carp($text);
+       if ($text =~ s/ at \S*Exporter.pm line \d+.*\n//) {
+           local $Carp::CarpLevel = 1; # ignore package calling us too.
+           Carp::carp($text);
+       }
+       else {
+           warn $text;
+       }
     };
     local $SIG{__DIE__} = sub {
        Carp::croak("$_[0]Illegal null symbol in \@${1}::EXPORT")
@@ -246,7 +250,7 @@ In other files which wish to use ModuleName:
 =head1 DESCRIPTION
 
 The Exporter module implements a default C<import> method which
-many modules choose inherit rather than implement their own.
+many modules choose to inherit rather than implement their own.
 
 Perl automatically calls the C<import> method when processing a
 C<use> statement for a module. Modules and C<use> are documented