From @jimav

The program​:

  use Sys​::Hostname ();
  BEGIN { $hn = Sys​::Hostname​::hostname(); }
  BEGIN { $^W=1; } # or perl -w
  system("/bin/date");

generates a warning "Ambiguous call resolved as CORE​::system()..."

In the real application the code is not as strange as the above example​:
&hostname is called in the main body of a module which is use'd by another.

This is a new problem with 5.005_03. _02 does not have it.

-Jim Avera (jima@​hal.com)

Site configuration information for perl 5.00503​:

Configured by avera at Tue Oct 5 15​:28​:43 PDT 1999.

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
  Platform​:
  osname=solaris, osvers=2.6, archname=sun4-solaris
  uname='sunos membrane 5.6 generic_105181-11 sun4u sparc sunw,ultra-5_10 '
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  Compiler​:
  cc='/sim/caetools_ssd1/VCS/cctools/sun4-solaris/cc', optimize='-O', gccversion=2.8.1
  cppflags=''
  ccflags =''
  stdchar='unsigned char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries​:
  ld='/sim/caetools_ssd1/VCS/cctools/sun4-solaris/cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
  libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
  libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
  cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Locally applied patches​:
 

@​INC for perl 5.00503​:
  /sim/vcsperl/perl/5.005_03/lib/5.00503/sun4-solaris
  /sim/vcsperl/perl/5.005_03/lib/5.00503
  /sim/vcsperl/perl/5.005_03/lib/site_perl/5.005/sun4-solaris
  /sim/vcsperl/perl/5.005_03/lib/site_perl/5.005
  .

Environment for perl 5.00503​:
  HOME=/u/avera
  LANG=en_US
  LANGUAGE (unset)
  LC_COLLATE=en_US
  LC_CTYPE=en_US
  LC_MESSAGES=C
  LC_MONETARY=en_US
  LC_NUMERIC=en_US
  LC_TIME=en_US
  LD_LIBRARY_PATH=/usr/is/lib​:/usr/lib​:/usr/openwin/lib​:/usr/ucblib
  LOGDIR (unset)
  PATH=/sim/vcsperl/perl/new/bin​:/u/avera/bin​:/u/avera/bin/misc​:/usr/is/bin​:/usr/ccs/bin​:/usr/is/gnu/bin​:/usr/bin​:/usr/sbin​:/sbin​:/opt/SUNWspro-5.1/bin​:/usr/ucb​:.​:/sim/avera/cvshome/bin​:/u/avera/bin/hal​:/sim/tools/current/bin​:/usr/dt/bin​:/usr/openwin/bin/.​:/usr/openwin/bin​:/sim/lb/current/bin​:/tools/all/qa/current/bin​:/tools/all/bin​:/u/avera/bin/ssdhosts​:/u/avera/bin/ws​:/distrib/SunOS__5.6__sun4m/frame-5.5.6/bin
  PERL_BADLANG (unset)
  SHELL=/usr/is/gnu/bin/bash

From @gsar

On Tue, 05 Oct 1999 16​:08​:46 PDT, Jim Avera wrote​:

The program​:

use Sys​::Hostname ();
BEGIN { $hn = Sys​::Hostname​::hostname(); }
BEGIN { $^W=1; } # or perl -w
system("/bin/date");

generates a warning "Ambiguous call resolved as CORE​::system()..."

In the real application the code is not as strange as the above example​:
&hostname is called in the main body of a module which is use'd by another.

This is a new problem with 5.005_03. _02 does not have it.

Can't reproduce this on my copy of Solaris (see config below). Sounds
like you have a local syscall.ph with C<sub system { ... }> or similar
in it.

Sarathy
gsar@​activestate.com

---
Site configuration information for perl 5.00503​:

Configured by avera at Tue Oct 5 15​:28​:43 PDT 1999.

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
Platform​:
osname=solaris, osvers=2.6, archname=sun4-solaris
uname='sunos membrane 5.6 generic_105181-11 sun4u sparc sunw,ultra-5_10 '
hint=recommended, useposix=true, d_sigaction=define
usethreads=undef useperlio=undef d_sfio=undef
Compiler​:
cc='/sim/caetools_ssd1/VCS/cctools/sun4-solaris/cc', optimize='-O', gccversion=2.8.1
cppflags=''
ccflags =''
stdchar='unsigned char', d_stdstdio=define, usevfork=false
intsize=4, longsize=4, ptrsize=4, doublesize=8
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
alignbytes=8, usemymalloc=y, prototype=define
Linker and Libraries​:
ld='/sim/caetools_ssd1/VCS/cctools/sun4-solaris/cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
Dynamic Linking​:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Locally applied patches​:

---
@​INC for perl 5.00503​:
/sim/vcsperl/perl/5.005_03/lib/5.00503/sun4-solaris
/sim/vcsperl/perl/5.005_03/lib/5.00503
/sim/vcsperl/perl/5.005_03/lib/site_perl/5.005/sun4-solaris
/sim/vcsperl/perl/5.005_03/lib/site_perl/5.005
.

---
Environment for perl 5.00503​:
HOME=/u/avera
LANG=en_US
LANGUAGE (unset)
LC_COLLATE=en_US
LC_CTYPE=en_US
LC_MESSAGES=C
LC_MONETARY=en_US
LC_NUMERIC=en_US
LC_TIME=en_US
LD_LIBRARY_PATH=/usr/is/lib​:/usr/lib​:/usr/openwin/lib​:/usr/ucblib
LOGDIR (unset)
PATH=/sim/vcsperl/perl/new/bin​:/u/avera/bin​:/u/avera/bin/misc​:/usr/is/bin​:/usr/ccs/b
in​:/usr/is/gnu/bin​:/usr/bin​:/usr/sbin​:/sbin​:/opt/SUNWspro-5.1/bin​:/usr/ucb​:.​:/sim/avera/
cvshome/bin​:/u/avera/bin/hal​:/sim/tools/current/bin​:/usr/dt/bin​:/usr/openwin/bin/.​:/usr/
openwin/bin​:/sim/lb/current/bin​:/tools/all/qa/current/bin​:/tools/all/bin​:/u/avera/bin/ss
dhosts​:/u/avera/bin/ws​:/distrib/SunOS__5.6__sun4m/frame-5.5.6/bin
  PERL_BADLANG (unset)
SHELL=/usr/is/gnu/bin/bash

Summary of my perl5 (5.0 patchlevel 5 subversion 3) configuration​:
  Platform​:
  osname=solaris, osvers=2.6, archname=sun4-solaris
  uname='sunos sparc26.activestate.com 5.6 generic sun4m sparc sunw,sparcstation-5 '
  hint=recommended, useposix=true, d_sigaction=define
  usethreads=undef useperlio=undef d_sfio=undef
  Compiler​:
  cc='cc', optimize='-O', gccversion=2.7.2.3
  cppflags='-I/usr/local/include'
  ccflags ='-I/usr/local/include'
  stdchar='unsigned char', d_stdstdio=define, usevfork=false
  intsize=4, longsize=4, ptrsize=4, doublesize=8
  d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
  alignbytes=8, usemymalloc=y, prototype=define
  Linker and Libraries​:
  ld='cc', ldflags =' -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /usr/ccs/lib
  libs=-lsocket -lnsl -ldl -lm -lc -lcrypt
  libc=/lib/libc.so, so=so, useshrplib=false, libperl=libperl.a
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
  cccdlflags='-fPIC', lddlflags='-G -L/usr/local/lib'

Characteristics of this binary (from libperl)​:
  Built under solaris
  Compiled at Apr 4 1999 16​:29​:37
  @​INC​:
  /usr/local/pdperl/lib/5.00503/sun4-solaris
  /usr/local/pdperl/lib/5.00503
  /usr/local/pdperl/lib/site_perl/5.005/sun4-solaris
  /usr/local/pdperl/lib/site_perl/5.005
  .

From [Unknown Contact. See original ticket]

I was a little quick on the h2ph as possible solution as I ran it and was
still able to generate the error. However, the following does not generate
the error;

use Sys​::Hostname;
$host = hostname;
print "$host\n";
system("/bin/date");

and produces the output as expected.

use Sys​::Hostname ();
BEGIN { $hn = Sys​::Hostname​::hostname(); }
BEGIN { $^W=1; } # or perl -w
print "$hn\n";
system("/bin/date");

is the original example.

Now, if I change the original snippet to

#!/usr/local/bin/perl -w

use Sys​::Hostname ();
$hn = Sys​::Hostname​::hostname();
print "$hn\n";
system("/bin/date");

it works without the warning.

as does

#!/usr/local/bin/perl -w

use Sys​::Hostname();
BEGIN { $hn = Sys​::Hostname​::hostname();
  print "$hn\n";
  system("/bin/date");
  }

This strikes me as odd, but I imagine I'm missing something here.

e.

From @tamias

On Wed, Oct 06, 1999 at 10​:57​:24AM -0500, Elaine -HFB- Ashton wrote​:

I was a little quick on the h2ph as possible solution as I ran it and was
still able to generate the error. However, the following does not generate
the error;

use Sys​::Hostname;
$host = hostname;
print "$host\n";
system("/bin/date");

and produces the output as expected.

use Sys​::Hostname ();
BEGIN { $hn = Sys​::Hostname​::hostname(); }
BEGIN { $^W=1; } # or perl -w
print "$hn\n";
system("/bin/date");

is the original example.

Now, if I change the original snippet to

#!/usr/local/bin/perl -w

use Sys​::Hostname ();
$hn = Sys​::Hostname​::hostname();
print "$hn\n";
system("/bin/date");

it works without the warning.

as does

#!/usr/local/bin/perl -w

use Sys​::Hostname();
BEGIN { $hn = Sys​::Hostname​::hostname();
print "$hn\n";
system("/bin/date");
}

This strikes me as odd, but I imagine I'm missing something here.

Sys​::Hostname​::hostname() requires syscall.ph. If syscall.ph is required
at compile-time with respect to the system() expression, as in the original
example, you have ambiguity. In the latter two examples above, syscall.ph
is required at run-time with respect to the system() expression.

(If syscall.ph doesn't work, it tries requiring sys/syscall.ph and
sys/sysinfo.ph. According to the comments, this is needed on systems like
Solaris.)

Ronald

From @jimav

Elaine -HFB- Ashton <elaine@​chaos.wustl.edu> wrote​:
] I was a little quick on the h2ph as possible solution as I ran it and was
] still able to generate the error. However, the following does not generate
] the error;
]
] use Sys​::Hostname;
] $host = hostname;
] print "$host\n";
] system("/bin/date");

That's because &hostname is no longer called before the system("...") line
is compiled, as was the case when &hostname was called inside BEGIN {...}
or in another module which is use'd by the main module.

When hostname() is called it executes `` require "syscall.ph" '' in
package main; syscall.ph then require's "_h2ph_pre.ph", which defines
sub system() because 'system' is in Config{ccsymbols}.

--> h2ph "caused" the problem by creating a sub definition with the
  same name as a CORE function.

If the 'system' #define is never actually used then it can simply
be eliminated (not generated in_h2ph_pre.ph). The below patch does
this.

However, if it *is* ever needed, then it (and any other conflicting
symbols) could be put in a special H2ph package, and all references changed
to qualified references (e.g., H2ph​::system) in code extracted from the .h
files. You would not want to put all symbols in a special package,
because programs want to refer to constants in .h files with unqualified
names.

-Jim

P.S. This patch makes h2ph (5.005_03) omit functions from _h2ph_pre.ph
which have the same name as a Perl opcode.
This fixes the problem with 'system' being overloaded on Solaris 2.6.

*** h2ph Tue Oct 5 15​:33​:04 1999
--- h2ph.new Wed Oct 6 15​:14​:12 1999
***************
*** 6,11 ****
--- 6,17 ----
  use File​::Path qw(mkpath);
  use Getopt​::Std;
 
+ my %reserved_word;
+ use Opcode ();
+ BEGIN {
+ %reserved_word = map {($_,1)} Opcode​::opset_to_ops(Opcode​::full_opset);
+ }
+
  getopts('Dd​:rlhaQ');
  die "-r and -a options are mutually exclusive\n" if ($opt_r and $opt_a);
  @​inc_dirs = inc_dirs() if $opt_a;
***************
*** 494,500 ****
  sub build_preamble_if_necessary
  {
  # Increment $VERSION every time this function is modified​:
! my $VERSION = 1;
  my $preamble = "$Dest_dir/_h2ph_pre.ph";
 
  # Can we skip building the preamble file?
--- 500,506 ----
  sub build_preamble_if_necessary
  {
  # Increment $VERSION every time this function is modified​:
! my $VERSION = 2;
  my $preamble = "$Dest_dir/_h2ph_pre.ph";
 
  # Can we skip building the preamble file?
***************
*** 519,524 ****
--- 525,532 ----
  print PREAMBLE "# $_=$define{$_}\n";
  }
 
+ next if $reserved_word{$_};
+
  if ($define{$_} =~ /^\d+$/) {
  print PREAMBLE
  "unless (defined &$_) { sub $_() { $define{$_} } }\n\n";

From @gsar

On Wed, 06 Oct 1999 15​:22​:41 PDT, Jim Avera wrote​:

--> h2ph "caused" the problem by creating a sub definition with the
same name as a CORE function.

If the 'system' #define is never actually used then it can simply
be eliminated (not generated in_h2ph_pre.ph).

We don't know that for all keywords. But I guess removing them
doesn't hurt because they're useless as they are anyway.

                                          The below patch does

this.

However, if it *is* ever needed, then it (and any other conflicting
symbols) could be put in a special H2ph package, and all references changed
to qualified references (e.g., H2ph​::system) in code extracted from the .h
files. You would not want to put all symbols in a special package,
because programs want to refer to constants in .h files with unqualified
names.

-Jim

P.S. This patch makes h2ph (5.005_03) omit functions from _h2ph_pre.ph
which have the same name as a Perl opcode.
This fixes the problem with 'system' being overloaded on Solaris 2.6.

I think the better approach would be to rework h2ph to emit *.pm
files that can (selectively) @​EXPORT_OK their constants.

*** h2ph Tue Oct 5 15​:33​:04 1999
--- h2ph.new Wed Oct 6 15​:14​:12 1999
***************
*** 6,11 ****
--- 6,17 ----
use File​::Path qw(mkpath);
use Getopt​::Std;

+ my %reserved_word;
+ use Opcode ();
+ BEGIN {
+ %reserved_word = map {($_,1)} Opcode​::opset_to_ops(Opcode​::full_opset);

This won't do the correct thing. It reflects the names of the pp_*
functions, not Perl keywords. (gethostbyname() vs pp_ghbyname(),
for example.)

Sarathy
gsar@​activestate.com