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[perl #77360] Aliased @ISA does not work

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Father Chrysostomos
August 22, 2010 12:20
[perl #77360] Aliased @ISA does not work
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# New Ticket Created by  Father Chrysostomos 
# Please include the string:  [perl #77360]
# in the subject line of all future correspondence about this issue. 
# <URL: >

If the same @ISA variable is assigned to multiple packages, inheritance does not work properly. It used to work in 5.8. Here is an example:

{package parent}
*right::ISA = \@left'ISA;
push right::ISA, parent;
print right->isa('parent'),"\n"; # prints nothing in 5.10; 1 in 5.8
print left->isa('parent'),"\n";  # prints 1 regardless of perl version

This is a known problem, as this comment in mg.c, which was added in 70cd14a, shows:
    /* XXX Once it's possible, we need to
       detect that our @ISA is aliased in
       other stashes, and act on the stashes
       of all of the aliases */

But I’m creating this ticket so it’s not forgotten. (And now I see there’s a test commented out in t/mro/basic.t for it.)

Site configuration information for perl 5.13.3:

Configured by sprout at Sat Jul 31 05:50:29 PDT 2010.

Summary of my perl5 (revision 5 version 13 subversion 3 patch v5.13.3-140-g79504a3) configuration:
  Snapshot of: 79504a3e595470dc0a74cb78989091a8e9f7b0ce
    osname=darwin, osvers=10.4.0, archname=darwin-2level
    uname='darwin pint.local 10.4.0 darwin kernel version 10.4.0: fri apr 23 18:28:53 pdt 2010; root:xnu-1504.7.4~1release_i386 i386 '
    config_args='-de -Dusedevel'
    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
    cc='cc', ccflags ='-fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include',
    cppflags='-no-cpp-precomp -fno-common -DPERL_DARWIN -no-cpp-precomp -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.2.1 (Apple Inc. build 5664)', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib
    libs=-ldbm -ldl -lm -lutil -lc
    perllibs=-ldl -lm -lutil -lc
    libc=/usr/lib/libc.dylib, so=dylib, useshrplib=false, libperl=libperl.a
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
    cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/usr/local/lib -fstack-protector'

Locally applied patches:

@INC for perl 5.13.3:

Environment for perl 5.13.3:
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PERL_BADLANG (unset)

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