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[perl #118857] $_foo exempt from 'used only once' warnings
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From:
l . mai @ web . de
Date:
July 10, 2013 14:58
Subject:
[perl #118857] $_foo exempt from 'used only once' warnings
Message ID:
rt-3.6.HEAD-2552-1373468256-94.118857-75-0@perl.org
# New Ticket Created by l.mai@web.de
# Please include the string: [perl #118857]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=118857 >
This is a bug report for perl from l.mai@web.de,
generated with the help of perlbug 1.39 running under perl 5.18.0.
-----------------------------------------------------------------
[Please describe your issue here]
% perl -we '$_foo = 42; $bar = 42;'
Name "main::bar" used only once: possible typo at -e line 1.
Expected output:
Name "main::_foo" used only once: possible typo at -e line 1.
Name "main::bar" used only once: possible typo at -e line 1.
It looks like symbols starting with '_' are exempt from the "used only once"
check. I couldn't find any documentation for this.
It may be a feature because there's explicit code for it in
gv.c:Perl_gv_check:
else if ( *HeKEY(entry) != '_'
&& isIDFIRST_lazy_if(HeKEY(entry), HeUTF8(entry)) ) {
It may be a "feature" because I can't think of a good reason for it.
Either this special case should be removed, or it should be promoted to an
official feature (with documentation and tests).
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=low
---
This perlbug was built using Perl 5.12.1 - Thu Jun 3 20:09:15 CEST 2010
It is being executed now by Perl 5.18.0 - Fri May 24 23:20:48 CEST 2013.
Site configuration information for perl 5.18.0:
Configured by mauke at Fri May 24 23:20:48 CEST 2013.
Summary of my perl5 (revision 5 version 18 subversion 0) configuration:
Platform:
osname=linux, osvers=3.5.7-gentoo, archname=i686-linux
uname='linux nora 3.5.7-gentoo #5 preempt sat jan 26 16:46:10 cet 2013 i686 amd athlon(tm) 64 processor 3200+ authenticamd gnulinux '
config_args=''
hint=recommended, useposix=true, d_sigaction=define
useithreads=undef, usemultiplicity=undef
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=undef, use64bitall=undef, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -flto',
cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.8.0', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags ='-fstack-protector -L/usr/local/lib -O2 -flto'
libpth=/usr/local/lib /lib/../lib /usr/lib/../lib /lib /usr/lib
libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=/lib/libc-2.15.so, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.15'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -flto -L/usr/local/lib -fstack-protector'
Locally applied patches:
SAVEARGV0 - disable magic open in <ARGV>
---
@INC for perl 5.18.0:
/home/mauke/usr/local/lib/perl5/site_perl/5.18.0/i686-linux
/home/mauke/usr/local/lib/perl5/site_perl/5.18.0
/home/mauke/usr/local/lib/perl5/5.18.0/i686-linux
/home/mauke/usr/local/lib/perl5/5.18.0
.
---
Environment for perl 5.18.0:
HOME=/home/mauke
LANG=en_US.UTF-8
LANGUAGE (unset)
LC_COLLATE=POSIX
LD_LIBRARY_PATH=/home/mauke/usr/local/lib
LOGDIR (unset)
PATH=/home/mauke/usr/perlbrew/bin:/home/mauke/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/4.6.3:/opt/sun-jdk-1.4.2.13/bin:/opt/sun-jdk-1.4.2.13/jre/bin:/opt/sun-jdk-1.4.2.13/jre/javaws:/opt/dmd/bin:/usr/games/bin
PERLBREW_BASHRC_VERSION=0.43
PERLBREW_HOME=/home/mauke/.perlbrew
PERLBREW_PATH=/home/mauke/usr/perlbrew/bin
PERLBREW_ROOT=/home/mauke/usr/perlbrew
PERLBREW_VERSION=0.27
PERL_BADLANG (unset)
PERL_UNICODE=SAL
SHELL=/bin/bash
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