Bug#654387: perl debugger dies for PDL scripts with "Can't return a temporary from lvalue subroutine"

[Bryan Jurish]

Package: perl
Version: 5.10.1-17squeeze2
Severity: normal
Tags: upstream patch

Perl Data Language ("PDL", debian package "pdl") exploits what is normally a
non-harmful, non-useful case in Perl 5; a roadblock added in Perl 5.10.1 kills
that case, gutting PDL functionality under the perl debugger, which makes it
virtually impossible to debug PDL scripts.   Under perl-5.10.1, the perl
debugger aborts for common PDL constructions with the error message:

Can't return a temporary from lvalue subroutine

This issue has been discussed on the perlbug list as item 71172:
  https://rt.perl.org/rt3/Public/Bug/Display.html?id=71172

... and on the Pdl-porters list as the thread "New lvalue subroutine roadblock
in 5.10.1 breaks important functionality":
http://mailman.jach.hawaii.edu/pipermail/pdl-porters/2010-February/001789.html

A patch which successfully fixes the problem was submitted by Doug Hunt; I have
attached it here; the original is available at:
https://rt.perl.org/rt3/Ticket/Attachment/656478/313038/lvalue_71172.patch

I would be very grateful if this patch could be added to debian's perl package.



-- System Information:
Debian Release: 6.0.3
  APT prefers stable
  APT policy: (990, 'stable'), (500, 'stable-updates')
Architecture: i386 (i686)

Kernel: Linux 2.6.38-bpo.2-686-bigmem (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages perl depends on:
ii  libbz2-1.0             1.0.5-6           high-quality block-sorting file co
ii  libc6                  2.11.2-10         Embedded GNU C Library: Shared lib
ii  libdb4.7               4.7.25-9          Berkeley v4.7 Database Libraries [
ii  libgdbm3               1.8.3-9           GNU dbm database routines (runtime
ii  perl-base              5.10.1-17squeeze2 minimal Perl system
ii  perl-modules           5.10.1-17squeeze2 Core Perl modules
ii  zlib1g                 1:1.2.3.4.dfsg-3  compression library - runtime

Versions of packages perl recommends:
ii  netbase                       4.45       Basic TCP/IP networking system

Versions of packages perl suggests:
ii  libterm-readline-gnu-p 1.20-1            Perl extension for the GNU ReadLin
ii  make                   3.81-8            An utility for Directing compilati
ii  perl-doc               5.10.1-17squeeze2 Perl documentation
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