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[perl #58480] Assigning *a = \&a drops a reference

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From:
Nicholas Clark
Date:
August 31, 2008 12:06
Subject:
[perl #58480] Assigning *a = \&a drops a reference
Message ID:
rt-3.6.HEAD-29759-1220194938-928.58480-75-0@perl.org
# New Ticket Created by  Nicholas Clark 
# Please include the string:  [perl #58480]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=58480 >


This is a bug report for perl from nick@ccl4.org,
generated with the help of perlbug 1.35 running under perl 5.9.4.


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

Assigning something to its own typeglob leaks a reference:

$ ./perl -lwe 'sub a {warn "a"}; *a = \&a; eval "a"'
a at -e line 1.
$ ./perl -lwe 'sub a {warn "a"}; eval "*a = \&a"; eval "a"'
a at -e line 1.
Unquoted string "a" may clash with future reserved word at (eval 2) line 2.

$ ./perl -lwe 'eval "%h = (1,2)"; eval "*h = \%h"; eval "print keys %h"'

$ ./perl -lwe 'eval "%h = (1,2)"; *h = \%h; eval "print keys %h"'
1

Note that when the assignment isn't in the string eval, an extra reference
to &a and %h exists via the optree, so they don't get cleared up.

The bug is caused by lax code recently moved from perl_sv_setsv_flags to
S_pvgv_assign. I think that I can see how to fix this, but TODO regression
tests welcome if I don't get there first.

Nicholas Clark

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.9.4:

Configured by nick at Sun Feb  5 22:04:16 GMT 2006.

Summary of my perl5 (revision 5 version 9 subversion 4) configuration:
  Platform:
    osname=freebsd, osvers=5.3-release-p25, archname=i386-freebsd-thread-multi
    uname='freebsd saigo.etla.org 5.3-release-p25 freebsd 5.3-release-p25 #0: mon jan 30 21:09:14 gmt 2006 root@saigo.etla.org:usrobjusrsrcsyssaigo i386 '
    config_args='-Dusedevel=y -Dcc=ccache gcc -Dld=gcc -Ubincompat5005 -Uinstallusrbinperl -Dcf_email=nick@ccl4.org -Dperladmin=nick@ccl4.org -Dinc_version_list=  -Dinc_version_list_init=0 -Doptimize=-g -Dusethreads -Uuse64bitint -Uusemymalloc -Duseperlio -Dprefix=~/Sandpit/snap5.9.x-27097 -Dinstallman1dir=none -Dinstallman3dir=none -de'
    hint=recommended, useposix=true, d_sigaction=define
    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='ccache gcc', ccflags ='-DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include',
    optimize='-g',
    cppflags='-DHAS_FPSETMASK -DHAS_FLOATINGPOINT_H -DDEBUGGING -fno-strict-aliasing -pipe -Wdeclaration-after-statement -I/usr/local/include'
    ccversion='', gccversion='3.4.2 [FreeBSD] 20040728', 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='gcc', ldflags ='-Wl,-E  -L/usr/local/lib'
    libpth=/usr/lib /usr/local/lib
    libs=-lm -lcrypt -lutil -lc_r
    perllibs=-lm -lcrypt -lutil -lc_r
    libc=, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version=''
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags=' '
    cccdlflags='-DPIC -fPIC', lddlflags='-shared  -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl 5.9.4:
    lib
    /home/nick/Sandpit/snap5.9.x-27097/lib/perl5/5.9.4/i386-freebsd-thread-multi
    /home/nick/Sandpit/snap5.9.x-27097/lib/perl5/5.9.4
    /home/nick/Sandpit/snap5.9.x-27097/lib/perl5/site_perl/5.9.4/i386-freebsd-thread-multi
    /home/nick/Sandpit/snap5.9.x-27097/lib/perl5/site_perl/5.9.4
    /home/nick/Sandpit/snap5.9.x-27097/lib/perl5/site_perl
    .

---
Environment for perl 5.9.4:
    HOME=/home/nick
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/nick/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/games:/usr/local/sbin:/usr/local/bin:/usr/X11R6/bin:/home/nick/bin:/usr/local/sbin:/sbin:/usr/sbin
    PERL_BADLANG (unset)
    SHELL=/usr/local/bin/bash


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