From gerard@ggoossen.net

This is a bug report for perl from gerard@​ggoossen.net,
generated with the help of perlbug 1.39 running under perl 5.15.2.

From 15850133545e13d0450e92c1f2ec0cbb0891c085 Mon Sep 17 00​:00​:00 2001
From​: Gerard Goossen <gerard@​ggoossen.net>
Date​: Sat, 3 Sep 2011 12​:28​:45 +0200
Subject​: [PATCH] Include negative index of array in warnings about an
unitialized value wen constant folding isn't done.

When constant folding isn't done OP_NEGATE isn't merged with
a constant, and the index isn't detected when warning about
unintialized values. This patch adds special handling for OP_NEGATE to
the index detection.

sv.c | 27 +++++++++++++++++++++++----
1 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/sv.c b/sv.c
index ea78558..f555e44 100644
--- a/sv.c
+++ b/sv.c
@@ -13909,6 +13909,9 @@ S_find_uninit_var(pTHX_ const OP *const obase, const SV *const uninit_sv,
 
     case OP_AELEM:
     case OP_HELEM:
+    {
+	bool negate = FALSE;
+
 	if (PL_op == obase)
 	    /* $a[uninit_expr] or $h{uninit_expr} */
 	    return find_uninit_var(cBINOPx(obase)->op_last, uninit_sv, match);
@@ -13934,28 +13937,43 @@ S_find_uninit_var(pTHX_ const OP *const obase, const SV *const uninit_sv,
 	if (!sv)
 	    break;
 
+	if (kid && kid->op_type == OP_NEGATE) {
+	    negate = TRUE;
+	    kid = cUNOPx(kid)->op_first;
+	}
+
 	if (kid && kid->op_type == OP_CONST && SvOK(cSVOPx_sv(kid))) {
 	    /* index is constant */
+	    SV* kidsv;
+	    if (negate) {
+		kidsv = sv_2mortal(newSVpvs("-"));
+		sv_catsv(kidsv, cSVOPx_sv(kid));
+	    }
+	    else
+		kidsv = cSVOPx_sv(kid);
 	    if (match) {
 		if (SvMAGICAL(sv))
 		    break;
 		if (obase->op_type == OP_HELEM) {
-		    HE* he = hv_fetch_ent(MUTABLE_HV(sv), cSVOPx_sv(kid), 0, 0);
+		    HE* he = hv_fetch_ent(MUTABLE_HV(sv), kidsv, 0, 0);
 		    if (!he || HeVAL(he) != uninit_sv)
 			break;
 		}
 		else {
-		    SV * const * const svp = av_fetch(MUTABLE_AV(sv), SvIV(cSVOPx_sv(kid)), FALSE);
+		    SV * const * const svp = av_fetch(MUTABLE_AV(sv),
+			negate ? - SvIV(cSVOPx_sv(kid)) : SvIV(cSVOPx_sv(kid)),
+			FALSE);
 		    if (!svp || *svp != uninit_sv)
 			break;
 		}
 	    }
 	    if (obase->op_type == OP_HELEM)
 		return varname(gv, '%', o->op_targ,
-			    cSVOPx_sv(kid), 0, FUV_SUBSCRIPT_HASH);
+			    kidsv, 0, FUV_SUBSCRIPT_HASH);
 	    else
 		return varname(gv, '@', o->op_targ, NULL,
-			    SvIV(cSVOPx_sv(kid)), FUV_SUBSCRIPT_ARRAY);
+		    negate ? - SvIV(cSVOPx_sv(kid)) : SvIV(cSVOPx_sv(kid)),
+		    FUV_SUBSCRIPT_ARRAY);
 	}
 	else  {
 	    /* index is an expression;
@@ -13981,6 +13999,7 @@ S_find_uninit_var(pTHX_ const OP *const obase, const SV *const uninit_sv,
 		o->op_targ, NULL, 0, FUV_SUBSCRIPT_WITHIN);
 	}
 	break;
+    }
 
     case OP_AASSIGN:
 	/* only examine RHS */
-- 

Flags​:
  category=core
  severity=low

Site configuration information for perl 5.15.2​:

Configured by gerard at Sun Sep 4 13​:21​:43 CEST 2011.

Summary of my perl5 (revision 5 version 15 subversion 2) configuration​:
  Commit id​: 15850133545e13d0450e92c1f2ec0cbb0891c085
  Platform​:
  osname=linux, osvers=3.0.0-1-686-pae, archname=i686-linux-thread-multi
  uname='linux zeus 3.0.0-1-686-pae #1 smp sun jul 24 14​:27​:32 utc 2011 i686 gnulinux '
  config_args='-des -Dusethreads -Dnoextensions= -Doptimize=-O3 -g3 -DDEBUGGING -Dusedevel -Dprefix=/home/gerard/perl/inst/blead-codegen'
  hint=recommended, useposix=true, d_sigaction=define
  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 -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
  optimize='-O3 -g3',
  cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBUGGING -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
  ccversion='', gccversion='4.6.1', 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 =' -fstack-protector -L/usr/local/lib'
  libpth=/usr/local/lib /lib /usr/lib /usr/lib/i386-linux-gnu /usr/lib64
  libs=-lnsl -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
  perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
  libc=, so=so, useshrplib=false, libperl=libperl.a
  gnulibc_version='2.13'
  Dynamic Linking​:
  dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
  cccdlflags='-fPIC', lddlflags='-shared -O3 -g3 -L/usr/local/lib -fstack-protector'

Locally applied patches​:
 

@​INC for perl 5.15.2​:
  lib
  /home/gerard/perl/inst/blead-codegen/lib/site_perl/5.15.2/i686-linux-thread-multi
  /home/gerard/perl/inst/blead-codegen/lib/site_perl/5.15.2
  /home/gerard/perl/inst/blead-codegen/lib/5.15.2/i686-linux-thread-multi
  /home/gerard/perl/inst/blead-codegen/lib/5.15.2
  /home/gerard/perl/inst/blead-codegen/lib/site_perl
  .

Environment for perl 5.15.2​:
  HOME=/home/gerard
  LANG=en_US.UTF-8
  LANGUAGE (unset)
  LD_LIBRARY_PATH (unset)
  LOGDIR (unset)
  PATH=/usr/lib/ccache​:/home/gerard/bin​:/usr/local/bin​:/usr/bin​:/bin​:/usr/games
  PERL_BADLANG (unset)
  SHELL=/bin/bash

From @cpansprout

On Sun Sep 04 04​:27​:02 2011, ggoossen wrote​:

This is a bug report for perl from gerard@​ggoossen.net,
generated with the help of perlbug 1.39 running under perl 5.15.2.

From 15850133545e13d0450e92c1f2ec0cbb0891c085 Mon Sep 17 00​:00​:00 2001
From​: Gerard Goossen <gerard@​ggoossen.net>
Date​: Sat, 3 Sep 2011 12​:28​:45 +0200
Subject​: [PATCH] Include negative index of array in warnings about an
unitialized value wen constant folding isn't done.

When constant folding isn't done OP_NEGATE isn't merged with
a constant, and the index isn't detected when warning about
unintialized values. This patch adds special handling for OP_NEGATE to
the index detection.

Thank you. Applied as e6c60e7.

The RT System itself - Status changed from 'new' to 'open'

@cpansprout - Status changed from 'open' to 'resolved'