[perl #74290] [PATCH] Regression in 5.12: labelled string eval

# New Ticket Created by  Father Chrysostomos 
# Please include the string:  [perl #74290]
# in the subject line of all future correspondence about this issue. 
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=74290 >


http://www.nntp.perl.org/group/perl.perl5.porters/2010/04/msg158760.html

This was broken by change 33656 (http://perl5.git.perl.org/perl.git/commitdiff/dca6062a863d0 
) moves labels to the hints hash.

Here’s another example of the same bug, which shows that that it has  
nothing to do with $_:

perl5.12.0 -le 'F1:++$x and eval q"print qq/x is $x/;  exit if ++$y ==  
10; goto q/F1/;"'
x is 1
x is 1
x is 1
x is 1
x is 1
x is 1
x is 1
x is 1
x is 1
x is 1

In short,
	Foo: eval "goto Foo"
doesn’t go to Foo, but simply repeats the eval.

I tried making S_dofindlabel skip any op that == PL_eval_start, but  
that prevents eval "Foo: print q/foo/; goto Foo" from working.

In other words, the goto inside the eval cannot tell the difference  
between
	Foo: eval " ... "
and
	eval "Foo: ... "

It seems to have something to do with %^H not being synchronised with  
the equivalent internal structure, because putting BEGIN{ delete $^H 
{anything} } at the beginning of the evalled code fixes it.

The attached patch is perhaps not the best fix, but works around the  
bug in a way that can’t cause any negative side-effects.

Use of uninitialized value $category in concatenation (.) or string  
at /usr/local/bin/perlbug5.12.0 line 645.
Use of uninitialized value $severity in concatenation (.) or string  
at /usr/local/bin/perlbug5.12.0 line 645.
---
Flags:
     category=core
     severity=medium
---
Site configuration information for perl 5.12.0:

Configured by sprout at Tue Apr  6 15:41:56 PDT 2010.

Summary of my perl5 (revision 5 version 12 subversion 0 patch v5.12.0- 
RC3-6-g8c57606) configuration:
   Snapshot of: 431be7b35e7448c1ced59444d6bdcfa11c5f83c7
   Platform:
     osname=darwin, osvers=10.0.0, archname=darwin-2level
     uname='darwin pint.local 10.0.0 darwin kernel version 10.0.0: fri  
jul 31 22:47:34 pdt 2009; root:xnu-1456.1.25~1release_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
   Compiler:
     cc='cc', ccflags ='-fno-common -DPERL_DARWIN -no-cpp-precomp -fno- 
strict-aliasing -pipe -fstack-protector -I/usr/local/include',
     optimize='-O3',
     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 5646)',  
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
     gnulibc_version=''
   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:
     RC5

---
@INC for perl 5.12.0:
     /usr/local/lib/perl5/site_perl/5.12.0/darwin-2level
     /usr/local/lib/perl5/site_perl/5.12.0
     /usr/local/lib/perl5/5.12.0/darwin-2level
     /usr/local/lib/perl5/5.12.0
     /usr/local/lib/perl5/site_perl
     .

---
Environment for perl 5.12.0:
     DYLD_LIBRARY_PATH (unset)
     HOME=/Users/sprout
     LANG=en_US.UTF-8
     LANGUAGE (unset)
     LD_LIBRARY_PATH (unset)
     LOGDIR (unset)
     PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/ 
usr/local/bin
     PERL_BADLANG (unset)
     SHELL=/bin/bash

• [perl #74290] [PATCH] Regression in 5.12: labelled string eval by Father Chrysostomos
• Re: [perl #74290] [PATCH] Regression in 5.12: labelled string eval by Nicholas Clark
• Re: [perl #74290] [PATCH] Regression in 5.12: labelled string eval by Nicholas Clark