You may ignore this diagnostic message with my blessing.

The consensus is that you'll always want to develop under strict and warnings, but wait to use diagnostics until you find yourself needing the extra help.

If you have the time and motivation to understand why you got this diagnostic message, you'll want to try variations in which you omit some of the modules you are currently using, and track the errors, warnings, and diagnostics that result from each omission.

I searched the v.5.63 code for requires, and it does only two kinds of requires—one from a filename provided by find_filename, which seems explicitly to prevent itself from returning undef; and one require $path, which is executed only if (defined($path)). Could you post what's happening on line 92 of your AutoLoader.pm?

http://search.cpan.org/src/RGARCIA/perl-5.10.0/lib/diagnostics.pm

sub import {
    shift;
    $^W = 1; # yup, clobbered the global variable; 
         # tough, if you want diags, you want diags.
    return if defined $SIG{__WARN__} && ($SIG{__WARN__} eq \&warn_trap
+);
...
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perllexwarn

http://search.cpan.org/~gsar/perl-5.6.0/lib/AutoLoader.pm
http://search.cpan.org/~nwclark/perl-5.8.8/lib/AutoLoader.pm

I cannot reproduce the problem. Could it be related to DDSUtils? (I had to comment out that line.)

At the very least, tell us which version of Autoloader you have so we can identify the line where the warning originates.

Thank you both.

I can't get the answers till later - will get back a.s.a.p.

This signature will be ready by Christmas

This is indeed version 5.60 of Autoloader, running under perl 5.8.8.

The first few lines are:

package AutoLoader;

use strict;
use 5.006_001;

our($VERSION, $AUTOLOAD);

my $is_dosish;
my $is_epoc;
my $is_vms;
my $is_macos;

BEGIN {
    $is_dosish = $^O eq 'dos' || $^O eq 'os2' || $^O eq 'MSWin32' || $
+^O eq 'NetWare';
    $is_epoc = $^O eq 'epoc';
    $is_vms = $^O eq 'VMS';
    $is_macos = $^O eq 'MacOS';
    $VERSION = '5.60';
}

AUTOLOAD {
    my $sub = $AUTOLOAD;
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This is the same code as that cited by Anonymous Monk in http://search.cpan.org/~nwclark/perl-5.8.8/lib/AutoLoader.pm.

Lines 91-2 say:

    local $!; # Do not munge the value.
    eval { local $SIG{__DIE__}; require $filename };
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where the previous block (most of the AUTOLOAD sub, in fact) goes to great lengths to establish $filename.

ikegami, I don't believe DDSutils is involved. That just exports a couple of subs and some quasi-constants.No clever BEGIN/END stuff.

I observed that the Autoloader module does not itself use warnings; - I am reminded of another situation in the past where a CPAN module (I don't recall which) peppered my web server error log with warnings when my code ran under #!/usr/bin/perl -w because my invocation was imposing warningfulness on it. . That went away when I replaced #!/usr/bin/perl -w with use warnings; which kept my warnable condition to my own scope. I am just wondering whether something similar could be happening with regard to diagnostics but it seems rather far fetched.

Update: Forgot to say:

This is perl, v5.8.8 built for i486-linux-gnu-thread-multi ; out-of-the-box Ubuntu 8.04 LTS.

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I hope it is not considered poor etiquette to follow up on my own message - if so, please excuse this.

Just seen on perldoc's diagnostics (emphases are in the original):

(Note that this does enable perl's -w flag.)

So the throwaway comment on scoping turns out to be relevant after all. Once more the Universe says 'RTFM'.

I suspect that is probably about it...? Nothing further, your honour.

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diagnostics is causing the warning to appear, but it's not the cause of the warning. It appears that Autloader is doing require undef;. I'd wonder why.