use warnings FATAL => 'all' causes wrong syntax error diagnostics #14235

p5pRT · 2014-11-13T07:45:15Z

Migrated from rt.perl.org#123195 (status was 'open')

Searchable as RT123195$

p5pRT · 2014-11-13T07:45:15Z

From @jimav

Created by @jimav

This is a bug report for perl from jim.avera@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.20.1.

-----------------------------------------------------------------
If a script using 'strict' also has "use warnings FATAL => 'all';"
then referencing an undeclared $variable often results in a wildly
inappropriate diagnostic from the parser (diagnosing correct code
later in the program), and NO mention of the actual error.
Usually the bogus diagnostic points to code far, far away from the
mis-spelled variable reference, making it a pain to track down.

I never noticed this until now, and I recently upgraded from
5.18 to 5.20.1, so it *might* be a regression.

The following script produces _only_ the bogus diagnostic

Number found where operator expected at test.pl line 17, near "myfunc 1"

However, if the FATAL => 'all' is removed, then the reference to
an undeclared variable is diagnosed correctly (in addition to the
bogus error, which is not a problem because the actual error
is also mentioned).

#!/usr/bin/perl
use strict; use warnings;
use warnings FATAL => 'all'; # comment this to allow correct diagnostic

$misspelled = @ARGV;

#.
#.
#.
# thousands of lines of valid code here
#.
#.
#.

sub myfunc(@) { }

sub bar { myfunc 1,2,3 ; };

Perl Info


Flags:
    category=core
    severity=low

Site configuration information for perl 5.20.1:

Configured by Debian Project at Fri Oct 10 14:16:26 UTC 2014.

Summary of my perl5 (revision 5 version 20 subversion 1) configuration:
   
  Platform:
    osname=linux, osvers=3.2.0-37-generic, archname=x86_64-linux-gnu-thread-multi
    uname='linux batsu 3.2.0-37-generic #58-ubuntu smp thu jan 24 15:28:10 utc 2013 x86_64 x86_64 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-Bsymbolic-functions -Wl,-z,relro -Dlddlflags=-shared -Wl,-Bsymbolic-functions -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.20 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.20 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.20 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.20.1 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.20.1 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.20.1 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.9.1', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=libc-2.19.so, so=so, useshrplib=true, libperl=libperl.so.5.20
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -fstack-protector'

Locally applied patches:
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - http://bugs.debian.org/340047 Remove overly restrictive DB_File version check.
    DEBPKG:debian/doc_info - Replace generic man(1) instructions with Debian-specific information.
    DEBPKG:debian/enc2xs_inc - http://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
    DEBPKG:debian/libperl_embed_doc - http://bugs.debian.org/186778 Note that libperl-dev package is required for embedded linking
    DEBPKG:fixes/respect_umask - Respect umask during installation
    DEBPKG:debian/writable_site_dirs - Set umask approproately for site install directories
    DEBPKG:debian/extutils_set_libperl_path - EU:MM: set location of libperl.a under /usr/lib
    DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor
    DEBPKG:debian/prefix_changes - Fiddle with *PREFIX and variables written to the makefile
    DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to the binary targets.
    DEBPKG:debian/instmodsh_doc - Debian policy doesn't install .packlist files for core or vendor.
    DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH as per Debian policy.
    DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to /etc/perl/Net as /usr may not be writable.
    DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
    DEBPKG:debian/module_build_man_extensions - http://bugs.debian.org/479460 Adjust Module::Build manual page extensions for the Debian Perl policy
    DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
    DEBPKG:fixes/net_smtp_docs - [rt.cpan.org #36038] http://bugs.debian.org/100195 Document the Net::SMTP 'Port' option
    DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
    DEBPKG:debian/deprecate-with-apt - http://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules
    DEBPKG:debian/squelch-locale-warnings - http://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
    DEBPKG:debian/skip-upstream-git-tests - Skip tests specific to the upstream Git repository
    DEBPKG:debian/patchlevel - http://bugs.debian.org/567489 List packaged patches for 5.20.1-1 in patchlevel.h
    DEBPKG:debian/skip-kfreebsd-crash - http://bugs.debian.org/628493 [perl #96272] Skip a crashing test case in t/op/threads.t on GNU/kFreeBSD
    DEBPKG:fixes/document_makemaker_ccflags - http://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}
    DEBPKG:debian/find_html2text - http://bugs.debian.org/640479 Configure CPAN::Distribution with correct name of html2text
    DEBPKG:debian/perl5db-x-terminal-emulator.patch - http://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl
    DEBPKG:debian/cpan-missing-site-dirs - http://bugs.debian.org/688842 Fix CPAN::FirstTime defaults with nonexisting site dirs if a parent is writable
    DEBPKG:fixes/memoize_storable_nstore - [rt.cpan.org #77790] http://bugs.debian.org/587650 Memoize::Storable: respect 'nstore' option not respected
    DEBPKG:debian/regen-skip - Skip a regeneration check in unrelated git repositories
    DEBPKG:fixes/regcomp-mips-optim - [perl #122817] http://bugs.debian.org/754054 Downgrade the optimization of regcomp.c on mips and mipsel due to a gcc-4.9 bug
    DEBPKG:debian/makemaker-pasthru - http://bugs.debian.org/758471 Pass LD settings through to subdirectories
    DEBPKG:fixes/perldoc-less-R - [rt.cpan.org #98636] http://bugs.debian.org/758689 Tell the 'less' pager to allow terminal escape sequences
    DEBPKG:fixes/hurd_test_todo_socket.t - [perl #122657] http://bugs.debian.org/758718 Disable failing GNU/Hurd test in t/io/socket.t
    DEBPKG:fixes/pod_man_reproducible_date - http://bugs.debian.org/759405 Support POD_MAN_DATE in Pod::Man for the left-hand footer
    DEBPKG:fixes/data_dump_infinite_recurse - [19be3be] don't recurse infinitely in Data::Dumper


@INC for perl 5.20.1:
    /home/jima/lib/perl
    /home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi
    /home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi
    /home/jima/perl5/lib/perl5
    /etc/perl
    /usr/local/lib/x86_64-linux-gnu/perl/5.20.1
    /usr/local/share/perl/5.20.1
    /usr/lib/x86_64-linux-gnu/perl5/5.20
    /usr/share/perl5
    /usr/lib/x86_64-linux-gnu/perl/5.20
    /usr/share/perl/5.20
    /usr/local/lib/site_perl
    .


Environment for perl 5.20.1:
    HOME=/home/jima
    LANG=en_US.UTF-8
    LANGUAGE=en_US
    LD_LIBRARY_PATH=/home/jima/local/lib
    LOGDIR (unset)
    PATH=/home/jima/perl5/bin:/home/jima/bin:/home/jima/local/bin:/home/jima/jima_tools/x86_64/bin:/home/jima/jima_tools/bin:/opt/Adobe/Reader9/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/bin/X11:/usr/local/bin:/usr/local/sbin:/usr/games:/usr/local/games:/usr/lib/jvm/java-7-oracle/bin:/usr/lib/jvm/java-7-oracle/db/bin:/usr/lib/jvm/java-7-oracle/jre/bin:.
    PERL5LIB=/home/jima/lib/perl:/home/jima/perl5/lib/perl5/x86_64-linux-gnu-thread-multi:/home/jima/perl5/lib/perl5
    PERL_BADLANG (unset)
    PERL_LOCAL_LIB_ROOT=/home/jima/perl5
    PERL_MB_OPT=--install_base /home/jima/perl5
    PERL_MM_OPT=INSTALL_BASE=/home/jima/perl5
    SHELL=/bin/bash

p5pRT · 2014-11-13T12:41:19Z

From @cpansprout

On Wed Nov 12 23:45:15 2014, jim.avera@gmail.com wrote:

This is a bug report for perl from jim.avera@gmail.com,
generated with the help of perlbug 1.40 running under perl 5.20.1.

-----------------------------------------------------------------
If a script using 'strict' also has "use warnings FATAL => 'all';"
then referencing an undeclared $variable often results in a wildly
inappropriate diagnostic from the parser (diagnosing correct code
later in the program), and NO mention of the actual error.
Usually the bogus diagnostic points to code far, far away from the
mis-spelled variable reference, making it a pain to track down.

I never noticed this until now, and I recently upgraded from
5.18 to 5.20.1, so it *might* be a regression.

The following script produces _only_ the bogus diagnostic

Number found where operator expected at test.pl line 17, near "myfunc
1"

However, if the FATAL => 'all' is removed, then the reference to
an undeclared variable is diagnosed correctly (in addition to the
bogus error, which is not a problem because the actual error
is also mentioned).

#!/usr/bin/perl
use strict; use warnings;
use warnings FATAL => 'all'; # comment this to allow correct
diagnostic

$misspelled = @ARGV;

#.
#.
#.
# thousands of lines of valid code here
#.
#.
#.

sub myfunc(@) { }

sub bar { myfunc 1,2,3 ; };

$ pbpaste|perl5.8.7
Global symbol "$misspelled" requires explicit package name at - line 5.
Execution of - aborted due to compilation errors.
$ pbpaste|perl5.14.4
Global symbol "$misspelled" requires explicit package name at - line 5.
Execution of - aborted due to compilation errors.
$ pbpaste|perl5.18.1
Number found where operator expected at - line 17, near "myfunc 1"
$ pbpaste|perl5.20.1
Number found where operator expected at - line 17, near "myfunc 1"
$ pbpaste|perl5.21.5
Global symbol "$misspelled" requires explicit package name (did you forget to declare "my $misspelled"?) at - line 5.
(Do you need to predeclare myfunc?)
syntax error at - line 17, near "myfunc 1"
Execution of - aborted due to compilation errors.

It looks as though we have already addressed this. But I do wonder when ‘Number found’ disappeared. I am also surprised that it changed in 5.18.

Thank you for the report. This is an area that definitely needs more tests, so I’ll steal some of your code for that purpose. :-)

--

Father Chrysostomos

p5pRT · 2014-11-13T12:41:19Z

The RT System itself - Status changed from 'new' to 'open'

p5pRT · 2014-11-13T13:46:51Z

From @cpansprout

On Thu Nov 13 04:41:19 2014, sprout wrote:

On Wed Nov 12 23:45:15 2014, jim.avera@gmail.com wrote:

#!/usr/bin/perl
use strict; use warnings;
use warnings FATAL => 'all'; # comment this to allow correct
diagnostic

$misspelled = @ARGV;

#.
#.
#.
# thousands of lines of valid code here
#.
#.
#.

sub myfunc(@) { }

sub bar { myfunc 1,2,3 ; };

$ pbpaste|perl5.8.7
Global symbol "$misspelled" requires explicit package name at - line
5.
Execution of - aborted due to compilation errors.
$ pbpaste|perl5.14.4
Global symbol "$misspelled" requires explicit package name at - line
5.
Execution of - aborted due to compilation errors.
$ pbpaste|perl5.18.1
Number found where operator expected at - line 17, near "myfunc 1"
$ pbpaste|perl5.20.1
Number found where operator expected at - line 17, near "myfunc 1"
$ pbpaste|perl5.21.5
Global symbol "$misspelled" requires explicit package name (did you
forget to declare "my $misspelled"?) at - line 5.
(Do you need to predeclare myfunc?)
syntax error at - line 17, near "myfunc 1"
Execution of - aborted due to compilation errors.

That’s still not quite right. We can’t say ‘Global symbol $foo requires explicit package name, do you need to predeclare bar?’

The ‘Number found...’ should not be omitted if we are going to say ‘Do you need to predeclare?’

I have addressed that in b255a11.

It looks as though we have already addressed this. But I do wonder
when ‘Number found’ disappeared. I am also surprised that it changed
in 5.18.

It was most likely v5.17.1-23-ga73ef99 that changed it.

This bogus message is happening because we no longer allow sub declarations to have any effect after an error, as that can be a source of problems elsewhere:

$ perl5.14.4 -lMstrict -e 'eval q|$foo; sub myfunc {}|; print $::{myfunc} // "undef"'
*main::myfunc
$ perl5.18.1 -lMstrict -e 'eval q|$foo; sub myfunc {}|; print $::{myfunc} // "undef"'
undef

But that does lead to bogus warnings at compile time. So I wonder whether we should go back to leaving sub stubs outside of an eval.

--

Father Chrysostomos

p5pRT · 2014-11-13T17:56:40Z

From @karenetheridge

On Wed Nov 12 23:45:15 2014, jim.avera@gmail.com wrote:

If a script using 'strict' also has "use warnings FATAL => 'all';"
then referencing an undeclared $variable often results in a wildly
inappropriate diagnostic from the parser (diagnosing correct code
later in the program), and NO mention of the actual error.

I wonder if this is related to https://rt-archive.perl.org/perl5/Ticket/Display.html?id=121834.

p5pRT · 2014-11-13T22:49:46Z

From @cpansprout

On Thu Nov 13 09:56:40 2014, ether wrote:

On Wed Nov 12 23:45:15 2014, jim.avera@gmail.com wrote:

If a script using 'strict' also has "use warnings FATAL => 'all';"
then referencing an undeclared $variable often results in a wildly
inappropriate diagnostic from the parser (diagnosing correct code
later in the program), and NO mention of the actual error.

I wonder if this is related to
https://rt-archive.perl.org/perl5/Ticket/Display.html?id=121834.

No. #121834 is about ‘once’ warnings being delayed until after the main program has compiled, so the fatality is no longer in scope when the warning happens.

This bug is about fatal warnings during compilation suppressing the actual syntax error messages. We have mostly fixed that in blead, but the behaviour is still not quite satisfactory.

--

Father Chrysostomos

p5pRT added Severity Low distro-Linux type-core labels Oct 19, 2019

xenu removed the affects-5.20 label Nov 19, 2021

xenu removed the Severity Low label Dec 29, 2021

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use warnings FATAL => 'all' causes wrong syntax error diagnostics #14235

use warnings FATAL => 'all' causes wrong syntax error diagnostics #14235

Comments

p5pRT commented Nov 13, 2014

p5pRT commented Nov 13, 2014

From @jimav

Created by @jimav

p5pRT commented Nov 13, 2014

From @cpansprout

p5pRT commented Nov 13, 2014

p5pRT commented Nov 13, 2014

From @cpansprout

p5pRT commented Nov 13, 2014

From @karenetheridge

p5pRT commented Nov 13, 2014

From @cpansprout