Problem with "perl -MExtUtils::Embed -e ldopts"

Problem with "perl -MExtUtils::Embed -e ldopts"

[Pierre A. Humblet]

I have a package that uses perl itself to configure a makefile to
use perl libraries. The command and its output are
 
> perl  -MExtUtils::Embed -e ldopts
Note (probably harmless): No library found for -lperl
 -s  -s -L/usr/local/lib
/usr/lib/perl5/5.6.1/cygwin-multi/auto/DynaLoader/DynaLoader.a
-L/usr/lib/perl5/5.6.1/cygwin-multi/CORE -lcrypt

3 observations:
1) The "harmless note" suggests that the perl library is not where expected.
   Should it be -lperl5_6_1 or is there a missing link? 
2) The -s causes the linker to drop the symbol table [when the command 
   output is blindly used in a makefile]. Not nice while debugging!
3) why list /usr/local/lib?

While not a show stopper, can this be fixed in future releases? 
Thanks.

Pierre


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Re: Problem with "perl -MExtUtils::Embed -e ldopts"

[Gerrit P. Haase @ cygwin]

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Hallo Pierre,

Am 2001-12-08 um 22:28 schriebst du:

> I have a package that uses perl itself to configure a makefile to
> use perl libraries. The command and its output are
 
>> perl  -MExtUtils::Embed -e ldopts
> Note (probably harmless): No library found for -lperl
>  -s  -s -L/usr/local/lib
> /usr/lib/perl5/5.6.1/cygwin-multi/auto/DynaLoader/DynaLoader.a
> -L/usr/lib/perl5/5.6.1/cygwin-multi/CORE -lcrypt

> 3 observations:
> 1) The "harmless note" suggests that the perl library is not where expected.
>    Should it be -lperl5_6_1 or is there a missing link? 
> 2) The -s causes the linker to drop the symbol table [when the command 
>    output is blindly used in a makefile]. Not nice while debugging!
> 3) why list /usr/local/lib?

> While not a show stopper, can this be fixed in future releases? 
> Thanks.

1.
This is from ExtUtils::Embed::ldopts:
    my $libperl;
    if ($^O eq 'MSWin32') {
        $libperl = $Config{libperl};
    }
    else {
        $libperl = (grep(/^-l\w*perl\w*$/, @link_args))[0] || "-lperl";
    }

It seems that it doesn't work as it should.
I have patched this for now (attached), I'll look to get this in perl
included if it is still broken in bleadperl.

$ perl  -MExtUtils::Embed -e ldopts
 -s  -s -L/usr/local/lib /usr/lib/perl5/5.6.1/cygwin-multi/auto/DynaLoader/DynaLoader.a -L/usr/lib/perl5/5.6.1/cygwin-multi/CORE -lperl5_6_1 -lcrypt

Alternative: create a symlink libperl.a -> libperl5_6_1.a

2. Cygwin Perl is built with -s flag, that strips the binaries, if you want
to have symbols in your module you will need symbols in perl, that means
you will have to rebuild perl yourself with symbols, that is: change nothing
at the source and do: ./Configure -Doptimize='-g' which turns on DEBUGGING.
(Note that Cygwin Perl is also build with '-Dmultiplicity').

I really don'y know why the '-s' flag is passed twice here.
Probable because there are several flags involved (ldflags & ccdlflags)

3. I didn't add /usr/local/lib to the linkline, it is done somewhere automagically.

You may change the values in Config.pm.
ldflags=''
then you get:
$ perl  -MExtUtils::Embed -e ldopts
 -s  /usr/lib/perl5/5.6.1/cygwin-multi/auto/DynaLoader/DynaLoader.a -L/usr/lib/perl5/5.6.1/cygwin-multi/CORE -lperl5_6_1 -lcrypt

ccdlflags=''
$ perl  -MExtUtils::Embed -e ldopts
  /usr/lib/perl5/5.6.1/cygwin-multi/auto/DynaLoader/DynaLoader.a -L/usr/lib/perl5/5.6.1/cygwin-multi/CORE -lperl5_6_1 -lcrypt

but as stated above I don't know if it is sufficient, maybe you need to
rebuild perl to get the symbols.

Ciao,

Gerrit P. Haase                                   mailto:gp@familiehaase.de
-- 
=^..^=

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--- perl5/5.6.1/ExtUtils/Embed.pm.orig	Sun Dec  9 15:23:22 2001
+++ perl5/5.6.1/ExtUtils/Embed.pm	Sun Dec  9 15:22:41 2001
@@ -207,9 +207,13 @@
     if ($^O eq 'MSWin32') {
 	$libperl = $Config{libperl};
     }
+    elsif ($^O eq 'cygwin') {
+	$libperl = "-lperl5_6_1";     
+    }
     else {
 	$libperl = (grep(/^-l\w*perl\w*$/, @link_args))[0] || "-lperl";
     }
+
 
     my $lpath = File::Spec->catdir($Config{archlibexp}, 'CORE');
     $lpath = qq["$lpath"] if $^O eq 'MSWin32';
--- perl5/5.6.1/cygwin-multi/ExtUtils/Embed.pm.orig	Sun Dec  9 15:23:10 2001
+++ perl5/5.6.1/cygwin-multi/ExtUtils/Embed.pm	Sun Dec  9 15:22:47 2001
@@ -207,6 +207,9 @@
     if ($^O eq 'MSWin32') {
 	$libperl = $Config{libperl};
     }
+    elsif ($^O eq 'cygwin') {
+	$libperl = "-lperl5_6_1";     
+    }
     else {
 	$libperl = (grep(/^-l\w*perl\w*$/, @link_args))[0] || "-lperl";
     }

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