Strawberry Perl warning Subroutine Config::STORE redefined from perl libs?

Question

I'm maintaining a few Perl scripts and recently I noticed that many of them output Subroutine ... redefined warnings from some "system" stuff, that is not from any code we've written.

A stripped down example I could come up now is:

#!perl -W

use strict;
use warnings;
use 5.14.0;

# These work without warnings:
use Carp;
use URI;
use POSIX;

# Any of these will generate warnings:
# use LWP; # Subroutine Config::STORE redefined at C:/local/Perl-5.32.1-64bit-portable/perl/vendor/lib/Portable/Config.pm line 68.
# use XML::LibXML; # Subroutine Config::STORE redefined at C:/local/Perl-5.32.1-64bit-portable/perl/vendor/lib/Portable/Config.pm line 68.
# use Win32::Service; # Subroutine Win32::GetCwd redefined at C:/local/Perl-5.32.1-64bit-portable/perl/lib/DynaLoader.pm line 210. (and 20!! more)
# ...

say "Hello world.";

Using Strawberry Perl 5.32.1 x64 ZIP/Portable on Windows 10. Also tested with Strawberry 5.14. Run via portableshell.bat -> perl testscript.pl

I find it strange that so many "system" modules should generate these warnings, especially since I can't recall seeing these a few months back when I last did some maintenance work.

• Should I just suppress these warning?
• Is there anything else I can check?

---

C:\local\Perl-5.32.1-64bit-portable>perl -V
Summary of my perl5 (revision 5 version 32 subversion 1) configuration:

  Platform:
    osname=MSWin32
    osvers=10.0.19042.746
    archname=MSWin32-x64-multi-thread
    uname='Win32 strawberry-perl 5.32.1.1 #1 Sun Jan 24 15:00:15 2021 x64'
    config_args='undef'
    hint=recommended
    useposix=true
    d_sigaction=undef
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=undef
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='gcc'
    ccflags =' -DWIN32 -DWIN64 -D__USE_MINGW_ANSI_STDIO -DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -fwrapv -fno-strict-aliasing -mms-bitfields'
    optimize='-s -O2'
    cppflags='-DWIN32'
    ccversion=''
    gccversion='8.3.0'
    gccosandvers=''
    intsize=4
    longsize=4
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='long long'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='g++.exe'
    ldflags ='-s -L"C:\local\Perl-5.32.1-64bit-portable\perl\lib\CORE" -L"C:\local\Perl-5.32.1-64bit-portable\c\lib"'
    libpth=C:\local\Perl-5.32.1-64bit-portable\c\lib C:\local\Perl-5.32.1-64bit-portable\c\x86_64-w64-mingw32\lib C:\local\Perl-5.32.1-64bit-portable\c\lib\gcc\x86_64-w64-mingw32\8.3.0
    libs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    perllibs= -lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
    libc=
    so=dll
    useshrplib=true
    libperl=libperl532.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_win32.xs
    dlext=xs.dll
    d_dlsymun=undef
    ccdlflags=' '
    cccdlflags=' '
    lddlflags='-mdll -s -L"C:\local\Perl-5.32.1-64bit-portable\perl\lib\CORE" -L"C:\local\Perl-5.32.1-64bit-portable\c\lib"'


Characteristics of this binary (from libperl):
  Compile-time options:
    HAS_TIMES
    HAVE_INTERP_INTERN
    MULTIPLICITY
    PERLIO_LAYERS
    PERL_COPY_ON_WRITE
    PERL_DONT_CREATE_GVSV
    PERL_IMPLICIT_CONTEXT
    PERL_IMPLICIT_SYS
    PERL_MALLOC_WRAP
    PERL_OP_PARENT
    PERL_PRESERVE_IVUV
    USE_64_BIT_INT
    USE_ITHREADS
    USE_LARGE_FILES
    USE_LOCALE
    USE_LOCALE_COLLATE
    USE_LOCALE_CTYPE
    USE_LOCALE_NUMERIC
    USE_LOCALE_TIME
    USE_PERLIO
    USE_PERL_ATOF
  Built under MSWin32
  Compiled at Jan 24 2021 15:05:42
  @INC:
    C:/local/Perl-5.32.1-64bit-portable/perl/site/lib
    C:/local/Perl-5.32.1-64bit-portable/perl/vendor/lib
    C:/local/Perl-5.32.1-64bit-portable/perl/lib

Answer 1

While trying to further narrow down my example script I finally figured this out:

Contrary to what I always believed, the shebang line in that specific form at the start of the script #!perl -W is interpreted even when running via perl script.pl from a Windows command prompt.

And there we have:

...
-W                enable all warnings
...

If I remove the line (not needed in our Windows environment) or change it to -w (lower case) then these warnings disappear.