goto() from an if to an else doesn't undo local() changes

[p5pRT]

Migrated from rt.perl.org#43403 (status was 'open')

Searchable as RT43403$

[p5pRT]

From jsailor@jesnetplus.com

Created by jsailor@jesnetplus.com

Here's a weird interaction of goto, if, and else​:

#!/usr/bin/perl -w
use strict;
our $global = "unmodified";
if ($global) { # true but not constant-folded
  local $global = "modified";
  goto ELSE;
} else {
  ELSE​: print "$global\n";
}

You'd expect the goto to leave the if{} block, thereby undoing the local($global),
so the code prints "unmodified\n". But instead, the localization isn't undone until
after perl leaves the else{}, so the code prints "modified\n".

Perl Info

Flags:
    category=core
    severity=low

Site configuration information for perl v5.8.8:

Configured by Gentoo at Mon May 29 13:57:46 EDT 2006.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=linux, osvers=2.6.16-gentoo-r3+bsdreiser2_1, archname=i686-linux-thread-multi
    uname='linux gentoo.grakker.jesnetplus.com 2.6.16-gentoo-r3+bsdreiser2_1 #1 thu apr 27 19:48:03 edt 2006 i686 amd athlon(tm) xp 2800+ gnulinux '
    config_args='-des -Darchname=i686-linux-thread -Dcccdlflags=-fPIC -Dccdlflags=-rdynamic -Dcc=i686-pc-linux-gnu-gcc -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr -Dlocincpth=  -Doptimize=-march=athlon-xp -O2 -fomit-frame-pointer -pipe -Duselargefiles -Dd_semctl_semun -Dscriptdir=/usr/bin -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dinstallman1dir=/usr/share/man/man1 -Dinstallman3dir=/usr/share/man/man3 -Dman1ext=1 -Dman3ext=3pm -Dinc_version_list=5.8.0 5.8.0/i686-linux-thread-multi 5.8.2 5.8.2/i686-linux-thread-multi 5.8.4 5.8.4/i686-linux-thread-multi 5.8.5 5.8.5/i686-linux-thread-multi 5.8.6 5.8.6/i686-linux-thread-multi 5.8.7 5.8.7/i686-linux-thread-multi  -Dcf_by=Gentoo -Ud_csh -Dusenm -Dusethreads -Di_ndbm -Di_gdbm -Di_db'
    hint=recommended, useposix=true, d_sigaction=define
    usethreads=define use5005threads=undef useithreads=define usemultiplicity=define
    useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
    use64bitint=undef use64bitall=undef uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='i686-pc-linux-gnu-gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -fno-strict-aliasing -pipe -Wdeclaration-after-statement -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-march=athlon-xp -O2 -fomit-frame-pointer -pipe',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -fno-strict-aliasing -pipe -Wdeclaration-after-statement'
    ccversion='', gccversion='3.4.5 (Gentoo 3.4.5-r1, ssp-3.4.5-1.0, pie-8.7.9)', 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='i686-pc-linux-gnu-gcc', ldflags =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lpthread -lnsl -lndbm -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.3.6.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.3.6'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    


@INC for perl v5.8.8:
    /etc/perl
    /usr/lib/perl5/vendor_perl/5.8.8/i686-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.8
    /usr/lib/perl5/vendor_perl/5.8.5
    /usr/lib/perl5/vendor_perl/5.8.5/i686-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.6
    /usr/lib/perl5/vendor_perl/5.8.6/i686-linux-thread-multi
    /usr/lib/perl5/vendor_perl/5.8.7
    /usr/lib/perl5/vendor_perl/5.8.7/i686-linux-thread-multi
    /usr/lib/perl5/vendor_perl
    /usr/lib/perl5/site_perl/5.8.8/i686-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.8
    /usr/lib/perl5/site_perl/5.8.4
    /usr/lib/perl5/site_perl/5.8.4/i686-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.5
    /usr/lib/perl5/site_perl/5.8.5/i686-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.6
    /usr/lib/perl5/site_perl/5.8.6/i686-linux-thread-multi
    /usr/lib/perl5/site_perl/5.8.7
    /usr/lib/perl5/site_perl/5.8.7/i686-linux-thread-multi
    /usr/lib/perl5/site_perl
    /usr/lib/perl5/5.8.8/i686-linux-thread-multi
    /usr/lib/perl5/5.8.8
    /usr/local/lib/site_perl
    .


Environment for perl v5.8.8:
    HOME=/home/jsailor
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/usr/local/bin:/usr/bin:/bin:/opt/bin:/usr/i686-pc-linux-gnu/gcc-bin/3.4.6:/opt/blackdown-jdk-1.4.2.03/bin:/opt/blackdown-jdk-1.4.2.03/jre/bin:/usr/games/bin
    PERLIO=stdio
    PERL_BADLANG (unset)
    SHELL=/bin/bash

[p5pRT]

From @smpeters

On Wed Jun 27 16​:37​:17 2007, jsailor wrote​:

This is a bug report for perl from jsailor <!-- x --> at jesnetplus.com,
generated with the help of perlbug 1.35 running under perl v5.8.8.

-----------------------------------------------------------------
[Please enter your report here]

Here's a weird interaction of goto, if, and else​:

#!/usr/bin/perl -w
use strict;
our $global = "unmodified";
if ($global) { # true but not constant-folded
local $global = "modified";
goto ELSE;
} else {
ELSE​: print "$global\n";
}

You'd expect the goto to leave the if{} block, thereby undoing the
local($global),
so the code prints "unmodified\n". But instead, the localization isn't
undone until
after perl leaves the else{}, so the code prints "modified\n".

This problem still exists in bleadperl. I've added the following TODO
test case for this problem.

Change 31494 by stevep@​stevep-kirk on 2007/06/28 20​:33​:32

  Add a TODO test cases RT# 43403.

Affected files ...

... //depot/perl/t/op/goto.t#32 edit

Differences ...

==== //depot/perl/t/op/goto.t#32 (xtext) ====

@​@​ -10,7 +10,8 @​@​

use warnings;
use strict;
-plan tests => 57;
+plan tests => 58;
+our $TODO;

our $foo;
while ($?) {
@​@​ -446,3 +447,16 @​@​
  );
  like($r, qr/bar/, "goto &foo in warn");
}
+
+TODO​: {
+ local $TODO = "[perl #43403] goto() from an if to an else doesn't
undo local
+() changes";
+ our $global = "unmodified";
+ if ($global) { # true but not constant-folded
+ local $global = "modified";
+ goto ELSE;
+ } else {
+ ELSE​: is($global, "unmodified");
+ }
+}
+

[p5pRT]

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