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[perl #37128] undefing *foo{CODE} does not fully work

From:
Ben Tilly
Date:
September 10, 2005 03:02
Subject:
[perl #37128] undefing *foo{CODE} does not fully work
Message ID:
rt-3.0.11-37128-120513.18.5957286616322@perl.org
# New Ticket Created by  Ben Tilly 
# Please include the string:  [perl #37128]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/rt3/Ticket/Display.html?id=37128 >



This is a bug report for perl from btilly@gmail.com,
generated with the help of perlbug 1.34 running under perl v5.8.3.


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

This problem has been seen on Perl 5.8.3 and 5.8.7.  I assume that
it happens under other versions as well.

If you try to undef the CODE slot of a glob, it only halfway works.
ref(*foo{CODE}) will still show that it is a code reference, and
UNIVERSAL::can still shows that it is a code reference.

This bug causes problems when Apache::Reload and Class::DBI are
used together.

The following code sample demonstrates what I am talking about

--------
#! /usr/bin/perl -l
print "Originally foo() is a " . ref(*foo{CODE});
print "Initializing foo()";
*foo = sub {print "hello"};
print "foo() is now a " . ref(*foo{CODE});
print "According to can, foo is " . main->can("foo");
print "Calling foo()";
foo();

print "Undefining foo()";
$x = *foo;
undef &$x;
print "foo() is now a " . ref(*foo{CODE});
print "According to can, foo is " . main->can("foo");
print "Calling foo()";
foo();

__END__
Originally foo() is a 
Initializing foo()
foo() is now a CODE
According to can, foo is CODE(0x8175b24)
Calling foo()
hello
Undefining foo()
foo() is now a CODE
According to can, foo is CODE(0x8175b24)
Calling foo()
--------

The way that this comes into play in the case that I mention is
that Apache::Reload attempts to undefine subroutines that have
been defined, but when Class::DBI tries to check whether they
are there it is told that they are, with disasterous results.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=medium
---
Site configuration information for perl v5.8.3:

Configured by Debian Project at Sun Feb 15 17:22:09 EST 2004.

Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
  Platform:
    osname=linux, osvers=2.4.22-xfs+ti1211, archname=i386-linux-thread-multi
    uname='linux kosh 2.4.22-xfs+ti1211 #1 sat oct 25 10:11:37 est 2003 i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr -Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.8.3 -Dsitearch=/usr/local/lib/perl/5.8.3 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dlibperl=libperl.so.5.8.3 -Dd_dosuid -des'
    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='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O3',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN -fno-strict-aliasing -I/usr/local/include'
    ccversion='', gccversion='3.3.3 20040125 (prerelease) (Debian)', 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 =' -L/usr/local/lib'
    libpth=/usr/local/lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so.5.8.3
    gnulibc_version='2.3.2'
  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 v5.8.3:
    /etc/perl
    /usr/local/lib/perl/5.8.3
    /usr/local/share/perl/5.8.3
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
    /usr/local/lib/perl/5.8.2
    /usr/local/share/perl/5.8.2
    /usr/local/lib/perl/5.8.1
    /usr/local/share/perl/5.8.1
    /usr/local/lib/perl/5.8.0
    /usr/local/share/perl/5.8.0
    .

---
Environment for perl v5.8.3:
    HOME=/home/btilly
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH=/usr/local/oracle/lib
    LOGDIR (unset)
    PATH=/home/btilly/cvs/bin:/home/btilly/cvs/lib/oracle/bin:/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games:/usr/share/games:~/cvs/bin:/usr/local/oracle/bin
    PERL_BADLANG (unset)
    SHELL=/bin/bash




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