From mike@longenbach.com

Created by mike@longenbach.com

I have saved off STDERR to the file handle STDSAVE, and closed STDERR. Then
I open a new file handle (FILE) for output, which I believe receives file
handle 2. Then I have code which generates a runtime warning. The warning
text goes to the file handle FILE. This seems incorrect, as if the core is
hardcoded to send warning output to file handle 2 instead of STDERR. The
following is minimal code to generate the problem. Note the warning will
appear in the file "foo.file".

#!perl -w

open( STDSAVE, ">&STDERR" );
close STDERR;

open FILE, ">foo.file";

if( $foo eq '' ) { print "foo\n"; }; # this line generates a run time
warning

close FILE;

Flags:
    category=core
    severity=medium

Site configuration information for perl v5.6.1:

Configured by ActiveState at Mon Jun 17 21:32:50 2002.

Summary of my perl5 (revision 5 version 6 subversion 1) configuration:
  Platform:
    osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread
    uname=''
    config_args='undef'
    hint=recommended, useposix=true, d_sigaction=undef
    usethreads=undef use5005threads=undef useithreads=define
usemultiplicity=define
    useperlio=undef d_sfio=undef uselargefiles=undef usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
  Compiler:
    cc='cl', ccflags
='-nologo -O1 -MD -DNDEBUG -DWIN32 -D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT 
 -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DPERL_MSVCRT_READFIX',
    optimize='-O1 -MD -DNDEBUG',
    cppflags='-DWIN32'
    ccversion='', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=4
    alignbytes=8, usemymalloc=n, prototype=define
  Linker and Libraries:
    ld='link', ldflags
'-nologo -nodefaultlib -release  -libpath:"C:/Perl\lib\CORE"  -machine:x86'
    libpth="C:\Perl\lib\CORE"
    libs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib
uuid.lib wsock32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib
msvcrt.lib
    perllibs=  oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib  netapi32.lib
uuid.lib wsock32.lib mpr.lib winmm.lib  version.lib odbc32.lib odbccp32.lib
msvcrt.lib
    libc=msvcrt.lib, so=dll, useshrplib=yes, libperl=perl56.lib
  Dynamic Linking:
    dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ',
ddlflags='-dll -nologo -nodefaultlib -release  -libpath:"C:/Perl\lib\CORE"  
-machine:x86'

Locally applied patches:
    ACTIVEPERL_LOCAL_PATCHES_ENTRY


@INC for perl v5.6.1:
    C:/Perl/lib
    C:/Perl/site/lib
    .


Environment for perl v5.6.1:
    HOME (unset)
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)

PATH=C:\Perl\bin\;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:
\PROGRA~1\ULTRAE~1
    PERL_BADLANG (unset)
    SHELL (unset)

From @eserte

"mike@​longenbach.com (via RT)" <perlbug@​perl.org> writes​:

# New Ticket Created by mike@​longenbach.com
# Please include the string​: [perl #18099]
# in the subject line of all future correspondence about this issue.
# <URL​: http​://rt.perl.org/rt2/Ticket/Display.html?id=18099 >

This is a bug report for perl from mike@​longenbach.com,
generated with the help of perlbug 1.33 running under perl v5.6.1.

-----------------------------------------------------------------
[Please enter your report here]

I have saved off STDERR to the file handle STDSAVE, and closed STDERR. Then
I open a new file handle (FILE) for output, which I believe receives file
handle 2. Then I have code which generates a runtime warning. The warning
text goes to the file handle FILE. This seems incorrect, as if the core is
hardcoded to send warning output to file handle 2 instead of STDERR. The
following is minimal code to generate the problem. Note the warning will
appear in the file "foo.file".

#!perl -w

open( STDSAVE, ">&STDERR" );
close STDERR;

open FILE, ">foo.file";

if( $foo eq '' ) { print "foo\n"; }; # this line generates a run time
warning

close FILE;

The problem is still in 5.8.0. I guess the following define in perl.h​:

# define Perl_error_log (PL_stderrgv \
  && isGV(PL_stderrgv) \
  && GvIOp(PL_stderrgv) \
  && IoOFP(GvIOp(PL_stderrgv)) \
  ? IoOFP(GvIOp(PL_stderrgv)) \
  : PerlIO_stderr())

is responsible for this behavior​: if there is no valid STDERR, then
there is a fallback to PerlIO_stderr (always fd 2?). Possible
solutions​:

* Document this behavior. To workaround the problem, always reopen
  STDERR to /dev/null​:

  require File​::Spec;
  open(STDERR, ">" . File​::Spec->devnull);

* Instead of using PerlIO_stderr, use some magic filehandle which
  writes to /dev/null.

* Do not fallback but return NULL and change all occurrences (there
  are many) of Perl_error_log to check for the return value.

Regards,
  Slaven

--
Slaven Rezic - slaven.rezic@​berlin.de
  BBBike - route planner for cyclists in Berlin
  WWW version​: http​://www.bbbike.de
  Perl/Tk version for Unix and Windows​: http​://bbbike.sourceforge.net