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Make it a (default) warning to use % between two refs #14890

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p5pRT opened this issue Sep 4, 2015 · 6 comments
Open

Make it a (default) warning to use % between two refs #14890

p5pRT opened this issue Sep 4, 2015 · 6 comments

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@p5pRT
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@p5pRT p5pRT commented Sep 4, 2015

Migrated from rt.perl.org#125983 (status was 'open')

Searchable as RT125983$

@p5pRT
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@p5pRT p5pRT commented Sep 4, 2015

From mark@markandruth.co.uk

Created by mark@markandruth.co.uk

This is a bug report for perl from mark@​markandruth.co.uk,
generated with the help of perlbug 1.39 running under perl 5.18.2.

-----------------------------------------------------------------

use strict;
use warnings;
use Data​::Dumper;

my $a = { foo => 1 };

my $t = {
  bar => { foo => 1 }
  %$a
};
warn Dumper $t;

rather surprisingly outputs​:

$VAR1 = { 'bar' => 121656 };

due to the typo. I find it hard to believe that this is not a warning,
perhaps
'warn if there is a % between two refs' would be a good warning to add? I
can't see of any reason to be doing this other than a typo, unless of
course %
operator was overloaded.

Obviously using %{$a} produces a warning but I'm guessing not too many
people
do that.

Perl Info

Flags:
     category=core
     severity=low

Site configuration information for perl 5.18.2:

Configured by Debian Project at Thu Mar 27 18:28:21 UTC 2014.

Summary of my perl5 (revision 5 version 18 subversion 2) configuration:

   Platform:
     osname=linux, osvers=3.2.0-58-generic, 
archname=x86_64-linux-gnu-thread-multi
     uname='linux brownie 3.2.0-58-generic #88-ubuntu smp tue dec 3 
17:37:58 utc 2013 x86_64 x86_64 x86_64 gnulinux '
     config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN 
-D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4 
-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/5.18 -Darchlib=/usr/lib/perl/5.18 
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local 
-Dsitelib=/usr/local/share/perl/5.18.2 
-Dsitearch=/usr/local/lib/perl/5.18.2 -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.5.18.2 -des'
     hint=recommended, useposix=true, d_sigaction=define
     useithreads=define, usemultiplicity=define
     useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
     use64bitint=define, use64bitall=define, uselongdouble=undef
     usemymalloc=n, bincompat5005=undef
   Compiler:
     cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN 
-fstack-protector -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 -fstack-protector 
-fno-strict-aliasing -pipe -I/usr/local/include'
     ccversion='', gccversion='4.8.2', 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 /lib/x86_64-linux-gnu /lib/../lib 
/usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
     libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
     perllibs=-ldl -lm -lpthread -lc -lcrypt
     libc=, so=so, useshrplib=true, libperl=libperl.so.5.18.2
     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 to /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/cpanplus_definstalldirs - 
http://bugs.debian.org/533707 Configure CPANPLUS to use the site 
directories by default.
     DEBPKG:debian/cpanplus_config_path - Save local versions of 
CPANPLUS::Config::System into /etc/perl.
     DEBPKG:debian/deprecate-with-apt - http://bugs.debian.org/702096 
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 5.18.2-2ubuntu1 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/hurd_test_skip_stack - http://bugs.debian.org/650175 
Disable failing GNU/Hurd tests dist/threads/t/stack.t
     DEBPKG:fixes/manpage_name_Test-Harness - 
http://bugs.debian.org/650451 [rt.cpan.org #73399] cpan/Test-Harness: 
add NAME headings in modules with POD
     DEBPKG:debian/makemaker-pasthru - http://bugs.debian.org/660195 
[rt.cpan.org #28632] Make EU::MM pass LD through to recursive 
Makefile.PL invocations
     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:fixes/net_ftp_failed_command - [rt.cpan.org #37700] 
http://bugs.debian.org/491062 Net::FTP: cope gracefully with a failed 
command
     DEBPKG:fixes/perlbug-patchlist - [3541c11] 
http://bugs.debian.org/710842 [perl #118433] Make perlbug look up the 
list of local patches at run time
     DEBPKG:fixes/module_metadata_security_doc - [68cdd4b] CVE-2013-1437 
documentation fix
     DEBPKG:fixes/module_metadata_taint_fix - [bff978f] 
http://bugs.debian.org/722210 [rt.cpan.org #88576] untaint version, if 
needed, in Module::Metadata
     DEBPKG:fixes/IPC-SysV-spelling - http://bugs.debian.org/730558 
[rt.cpan.org #86736] Fix spelling of IPC_CREAT in IPC-SysV documentation
     DEBPKG:fixes/fix-undef-source -


@INC for perl 5.18.2:
     /etc/perl
     /usr/local/lib/perl/5.18.2
     /usr/local/share/perl/5.18.2
     /usr/lib/perl5
     /usr/share/perl5
     /usr/lib/perl/5.18
     /usr/share/perl/5.18
     /usr/local/lib/site_perl
     .


Environment for perl 5.18.2:
     HOME=/home/mark
     LANG=en_GB.UTF-8
     LANGUAGE=en_GB:en
     LD_LIBRARY_PATH (unset)
     LOGDIR (unset)
PATH=/home/mark/Downloads/android-sdk-linux/tools/:/home/mark/bin:/home/mark/Downloads/android-sdk-linux/tools/:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/sbin:/sbin:/home/mark/bin:/home/mark/.rvm/bin:/usr/sbin:/sbin:/home/mark/bin:/home/mark/.rvm/bin
     PERL_BADLANG (unset)
     SHELL=/bin/bash


@p5pRT
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@p5pRT p5pRT commented Sep 8, 2015

From @rgarcia

On 4 September 2015 at 07​:48, Mark Zealey <perlbug-followup@​perl.org> wrote​:

my $a = { foo => 1 };

my $t = {
bar => { foo => 1 }
%$a
};
warn Dumper $t;

rather surprisingly outputs​:

$VAR1 = { 'bar' => 121656 };

due to the typo. I find it hard to believe that this is not a warning,
perhaps
'warn if there is a % between two refs' would be a good warning to add? I
can't see of any reason to be doing this other than a typo, unless of
course %
operator was overloaded.

I see why % is a special case here, but with a bit more generality we could
even envision a warning for treating references as integers.

I remember an earlier proposal to warn when treating references as strings,
to detect outputs containing HASH(0x421789ab) faster. Or maybe that was
a new kind of stricture.

I'd personally like to have that kind of warning. The only real use cases I see
for treating references as non-references are (besides operator overloading)​:
- comparing pointers with ==
- producing stack traces or other debug messages.

@p5pRT
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@p5pRT p5pRT commented Sep 8, 2015

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

@p5pRT
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@p5pRT p5pRT commented Sep 8, 2015

From jjuran@gmail.com

On Sep 8, 2015, at 2​:25 AM, Rafael Garcia-Suarez <rgs@​consttype.org> wrote​:

On 4 September 2015 at 07​:48, Mark Zealey <perlbug-followup@​perl.org> wrote​:

my $a = { foo => 1 };

my $t = {
bar => { foo => 1 }
%$a
};
warn Dumper $t;

rather surprisingly outputs​:

$VAR1 = { 'bar' => 121656 };

due to the typo. I find it hard to believe that this is not a warning,
perhaps
'warn if there is a % between two refs' would be a good warning to add? I
can't see of any reason to be doing this other than a typo, unless of
course %
operator was overloaded.

I see why % is a special case here, but with a bit more generality we could
even envision a warning for treating references as integers.

I'd personally like to have that kind of warning. The only real use cases I see
for treating references as non-references are (besides operator overloading)​:
- comparing pointers with ==
- producing stack traces or other debug messages.

Perhaps `int $hashref` would yield the numeric address without warning.

Josh

@p5pRT
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@p5pRT p5pRT commented Sep 9, 2015

From @ysth

On Sep 8, 2015 3​:59 AM, "Josh Juran" <jjuran@​gmail.com> wrote​:

On Sep 8, 2015, at 2​:25 AM, Rafael Garcia-Suarez <rgs@​consttype.org>
wrote​:

I see why % is a special case here, but with a bit more generality we
could
even envision a warning for treating references as integers.

I'd personally like to have that kind of warning. The only real use
cases I see
for treating references as non-references are (besides operator
overloading)​:
- comparing pointers with ==
- producing stack traces or other debug messages.

Perhaps `int $hashref` would yield the numeric address without warning.

That or explicit 0+. Numeric printf formats should also get a pass.

@p5pRT
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@p5pRT p5pRT commented Sep 9, 2015

From @rgarcia

On 9 September 2015 at 04​:33, Yitzchak Scott-Thoennes
<sthoenna@​gmail.com> wrote​:

On Sep 8, 2015 3​:59 AM, "Josh Juran" <jjuran@​gmail.com> wrote​:

On Sep 8, 2015, at 2​:25 AM, Rafael Garcia-Suarez <rgs@​consttype.org>
wrote​:

I see why % is a special case here, but with a bit more generality we
could
even envision a warning for treating references as integers.

I'd personally like to have that kind of warning. The only real use
cases I see
for treating references as non-references are (besides operator
overloading)​:
- comparing pointers with ==
- producing stack traces or other debug messages.

Perhaps `int $hashref` would yield the numeric address without warning.

That or explicit 0+. Numeric printf formats should also get a pass.

Maybe just %p then.

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