'my' with 'if 0' retains old value

p5pRT commented 18 years ago

Migrated from rt.perl.org#37315 (status was 'rejected')

Searchable as RT37315$

p5pRT commented 18 years ago

From herington_dean@emc.com

This is a bug report for perl from herington_dean@emc.com \mailto:herington\_dean@emc\.com \, generated with the help of perlbug 1.35 running under perl v5.8.4.

Running the following program outputs: Perl 5.008004 undef undef undef 2 but it should output: Perl 5.008004 undef undef undef undef

#!/usr/bin/perl -w

print "Perl $]\n";

sub show { my ($val) = @_; if (! defined $val) { print "undef\n"; } else { print "$val\n"; } }

sub sb {

my $v1; $v1 = -1 if 0;

my $v2 = -2 if 0;

show $v1; show $v2;

$v1 = 1; $v2 = 2;

}

sb; sb;

Flags: category=core severity=high

Site configuration information for perl v5.8.4:

Summary of my perl5 (revision 5 version 8 subversion 4) configuration: Platform: osname=solaris\, osvers=2.10\, archname=sun4-solaris-64int uname='sunos localhost 5.10 sun4u sparc SUNW\,Ultra-2' config_args='' hint=recommended\, useposix=true\, d_sigaction=define usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef useperlio=define d_sfio=undef uselargefiles=define usesocks=undef use64bitint=define use64bitall=undef uselongdouble=undef usemymalloc=n\, bincompat5005=undef Compiler: cc='cc'\, ccflags ='-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -xarch=v8 -D_TS_ERRNO'\, optimize='-xO3 -xspace -xildoff'\, cppflags='' ccversion='Sun WorkShop'\, gccversion=''\, gccosandvers='' intsize=4\, longsize=4\, ptrsize=4\, doublesize=8\, byteorder=87654321 d_longlong=define\, longlongsize=8\, d_longdbl=define\, longdblsize=16 ivtype='long long'\, ivsize=8\, nvtype='double'\, nvsize=8\, Off_t='off_t'\, lseeksize=8 alignbytes=8\, prototype=define Linker and Libraries: ld='cc'\, ldflags ='' libpth=/lib /usr/lib /usr/ccs/lib libs=-lsocket -lnsl -ldl -lm -lc perllibs=-lsocket -lnsl -ldl -lm -lc libc=/lib/libc.so\, so=so\, useshrplib=true\, libperl=libperl.so gnulibc_version='' Dynamic Linking: dlsrc=dl_dlopen.xs\, dlext=so\, d_dlsymun=undef\, ccdlflags='-R /usr/perl5/5.8.4/lib/sun4-solaris-64int/CORE' cccdlflags='-KPIC'\, lddlflags='-G'

Locally applied patches: 22667 The optree builder was looping when constructing the ops ... 22715 Upgrade to FileCache 1.04 22733 Missing copyright in the README. 22746 fix a coredump caused by rv2gv not fully converting a PV ... 22755 Fix 29149 - another UTF8 cache bug hit by substr. 22774 [perl #28938] split could leave an array without ... 22775 [perl #29127] scalar delete of empty slice returned garbage 22776 [perl #28986] perl -e \"open m\" crashes Perl 22777 add test for change #22776 (\"open m\" crashes Perl) 22778 add test for change #22746 ([perl #29102] Crash on assign ... 22781 [perl #29340] Bizarre copy of ARRAY make sure a pad op's ... 22796 [perl #29346] Double warning for int(undef) and abs(undef) ... 22818 BOM-marked and (BOMless) UTF-16 scripts not working 22823 [perl #29581] glob() misses a lot of matches 22827 Smoke [5.9.2] 22818 FAIL(F) MSWin32 WinXP/.Net SP1 (x86/1 cpu) 22830 [perl #29637] Thread creation time is hypersensitive 22831 improve hashing algorithm for ptr tables in perl_clone: ... 22839 [perl #29790] Optimization busted: '@a \mailto:'@a = \"b\"\, sort @a' ... 22850 [PATCH] 'perl -v' fails if local_patches contains code snippets 22852 TEST needs to ignore SCM files 22886 Pod::Find should ignore SCM files and dirs 22888 Remove redundant %SIG assignments from FileCache 23006 [perl #30509] use encoding and \"eq\" cause memory leak 23074 Segfault using HTML::Entities 23106 Numeric comparison operators mustn't compare addresses of ... 23320 [perl #30066] Memory leak in nested shared data structures ... 23321 [perl #31459] Bug in read()

@INC for perl v5.8.4: /usr/perl5/5.8.4/lib/sun4-solaris-64int /usr/perl5/5.8.4/lib /usr/perl5/site_perl/5.8.4/sun4-solaris-64int /usr/perl5/site_perl/5.8.4 /usr/perl5/site_perl /usr/perl5/vendor_perl/5.8.4/sun4-solaris-64int /usr/perl5/vendor_perl/5.8.4 /usr/perl5/vendor_perl .

Environment for perl v5.8.4: HOME=/emc/dheringt LANG (unset) LANGUAGE (unset) LC_COLLATE=en_US.ISO8859-1 LC_CTYPE=en_US.ISO8859-1 LC_MESSAGES=C LC_MONETARY=en_US.ISO8859-1 LC_NUMERIC=en_US.ISO8859-1 LC_TIME=en_US.ISO8859-1 LD_LIBRARY_PATH (unset) LOGDIR (unset)

PATH=.:/emc/dheringt/bin:/usr/local/project/pp/tools/sparc_solaris/bin:/usr/ bin:/usr/local/bin:/usr/ucb:/usr/bin: PERL_BADLANG (unset) SHELL=/bin/csh

p5pRT commented 18 years ago

From charles.e.derykus@boeing.com

This is a bug report for perl from herington_dean@emc.com \mailto:herington\_dean@emc\.com \, generated with the help of > > perlbug 1.35 running under perl v5.8.4.

Use of 'my $v if 0' is deprecated. Please see:

http://groups.google.com/group/perl.perl5.porters/browse_frm/thread/e665 bd4eefa7771c/7f2a47223bb7cecf?lnk=st&q=%22if+0%22+group:*perl*&rnum=1&hl =en#7f2a47223bb7cecf

-- Charles DeRykus

p5pRT commented 18 years ago

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

p5pRT commented 18 years ago

From sts@accognoscere.org

On Fri\, Sep 30\, 2005 at 09:45:27AM -0700\, herington\, dean wrote:

Running the following program outputs: Perl 5.008004 undef undef undef 2 but it should output: Perl 5.008004 undef undef undef undef

#!/usr/bin/perl -w

print "Perl $]\n";

sub show { my ($val) = @_; if (! defined $val) { print "undef\n"; } else { print "$val\n"; } }

sub sb {
my $v1;
$v1 = \-1 if 0;

my $v2 = \-2 if 0;

show $v1;
show $v2;

$v1 = 1;
$v2 = 2;
}

sb; sb;

MJD (Mark-Jason Dominus) gave an explanation which is located at: http://www.perl.com/pub/a/2000/05/p5pdigest/THISWEEK-20000521.html#my_x_if_0%3B_Trick

The according thread on p5p: http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2000-05/msg00621.html

p5pRT commented 16 years ago

p5p@spam.wizbit.be - Status changed from 'open' to 'rejected'

Perl / perl5