[perl #52452] map isn't context aware in some cases

# New Ticket Created by  Stefan Wehinger 
# Please include the string:  [perl #52452]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=52452 >


This is a bug report for perl from stefan.wehinger@gmx.at,
generated with the help of perlbug 1.35 running under perl v5.8.8.


-----------------------------------------------------------------

map doesn't seem to be aware of its context when using it in void context
and only defining variables is done. Adding a simple command at the end 
makes it
context aware. Following three examples show the problem:
you could also use a "print" or anything else instead of the "defined"

This will fill your memory ... use with CAUTION!
================================================
#!/usr/bin/perl -w

use strict;

my %something;
my %somethingelse;
my %foo;

map {
    $something{$_} = $_;
    map {
        $somethingelse{$_} = $_;

        map {
            $foo{$_} = $_;
        } 1..999;
    } 1..999;
} 1..999999;
1;

This will fill your memory about 80-90MB
Not more!
========================================
#!/usr/bin/perl -w

use strict;

my %something;
my %somethingelse;
my %foo;

map {
    $something{$_} = $_;
    map {
        $somethingelse{$_} = $_;

        map {
            $foo{$_} = $_;
        } 1..999;
    } 1..999;
    defined $_;
} 1..999999;
1;

This won't be a problem at all (using about 40MB of memory)
==============================
#!/usr/bin/perl -w

use strict;

my %something;
my %somethingelse;
my %foo;

map {
    $something{$_} = $_;
    map {
        $somethingelse{$_} = $_;

        map {
            $foo{$_} = $_;
            defined $_;
        } 1..999;
        defined $_;
    } 1..999;
    defined $_;
} 1..999999;




[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=high
---
Site configuration information for perl v5.8.8:

Configured by Debian Project at Tue Dec  4 09:07:29 UTC 2007.

Summary of my perl5 (revision 5 version 8 subversion 8) configuration:
  Platform:
    osname=linux, osvers=2.6.15.7, archname=i486-linux-gnu-thread-multi
    uname='linux terranova 2.6.15.7 #1 smp thu jul 12 14:27:56 utc 2007 
i686 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN 
-Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -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/5.8.8 
-Dsitearch=/usr/local/lib/perl/5.8.8 -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.5.8.8 -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 -pipe -I/usr/local/include 
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN 
-fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.1.3 20070929 (prerelease) (Ubuntu 
4.1.2-16ubuntu2)', 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-2.6.1.so, so=so, useshrplib=true, 
libperl=libperl.so.5.8.8
    gnulibc_version='2.6.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:
    

---
@INC for perl v5.8.8:
    /etc/perl
    /usr/local/lib/perl/5.8.8
    /usr/local/share/perl/5.8.8
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.8
    /usr/share/perl/5.8
    /usr/local/lib/site_perl
    .

---
Environment for perl v5.8.8:
    HOME=/home/stiv
    LANG=en_US.UTF-8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

• [perl #52452] map isn't context aware in some cases by Stefan Wehinger
• Re: [perl #52452] map isn't context aware in some cases by David Nicol
• Re: [perl #52452] map isn't context aware in some cases by Jonathan Rockway
• Re: [perl #52452] map isn't context aware in some cases by David Nicol
• Re: [perl #52452] map isn't context aware in some cases by Nicholas Clark
• Re: [perl #52452] map isn't context aware in some cases by Ben Morrow