Include variable names in "Use of uninitialized value" warnings

p4raw-id: //depot/perl@22741

34 files changed, 1939 insertions, 148 deletions

diff --git a/MANIFEST b/MANIFEST
index 706275ce53..1e5a1c0284 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -2733,6 +2733,7 @@ t/lib/warnings/6default		Tests default warnings
 t/lib/warnings/7fatal		Tests fatal warnings
 t/lib/warnings/8signal		Tests warnings + __WARN__ and __DIE__
 t/lib/warnings/9enabled		Tests warnings
+t/lib/warnings/9uninit		Tests "Use of uninitialized" warnings
 t/lib/warnings/av		Tests for av.c for warnings.t
 t/lib/warnings/doio		Tests for doio.c for warnings.t
 t/lib/warnings/doop		Tests for doop.c for warnings.t
diff --git a/doio.c b/doio.c
index 760e8f1329..98e7204768 100644
--- a/doio.c
+++ b/doio.c
@@ -1270,7 +1270,7 @@ Perl_do_print(pTHX_ register SV *sv, PerlIO *fp)
     switch (SvTYPE(sv)) {
     case SVt_NULL:
 	if (ckWARN(WARN_UNINITIALIZED))
-	    report_uninit();
+	    report_uninit(sv);
 	return TRUE;
     case SVt_IV:
 	if (SvIOK(sv)) {
diff --git a/embed.fnc b/embed.fnc
index 8e0b5caae7..1ee63c37b7 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -845,7 +845,7 @@ p	|U32	|parse_unicode_opts|char **popt
 p	|U32	|seed
 p	|UV	|get_hash_seed
 p	|void	|report_evil_fh	|GV *gv|IO *io|I32 op
-pd	|void	|report_uninit
+pd	|void	|report_uninit	|SV* uninit_sv
 Afpd	|void	|warn		|const char* pat|...
 Ap	|void	|vwarn		|const char* pat|va_list* args
 Afp	|void	|warner		|U32 err|const char* pat|...
@@ -1403,6 +1403,9 @@ Apd	|void	|hv_clear_placeholders|HV* hb
 
 Apd	|SV*	|hv_scalar	|HV* hv|
 p	|SV*	|magic_scalarpack|HV* hv|MAGIC*	mg
+#ifdef PERL_IN_SV_C
+sMd	|SV*	|find_uninit_var|OP* obase|SV* uninit_sv|bool top
+#endif
 
 #ifdef PERL_NEED_MY_HTOLE16
 np	|U16	|my_htole16	|U16 n
diff --git a/embed.h b/embed.h
index 3de8118b02..4eef0bf740 100644
--- a/embed.h
+++ b/embed.h
@@ -2155,6 +2155,11 @@
 #ifdef PERL_CORE
 #define magic_scalarpack	Perl_magic_scalarpack
 #endif
+#ifdef PERL_IN_SV_C
+#ifdef PERL_CORE
+#define find_uninit_var		S_find_uninit_var
+#endif
+#endif
 #ifdef PERL_NEED_MY_HTOLE16
 #ifdef PERL_CORE
 #define my_htole16		Perl_my_htole16
@@ -3745,7 +3750,7 @@
 #define report_evil_fh(a,b,c)	Perl_report_evil_fh(aTHX_ a,b,c)
 #endif
 #ifdef PERL_CORE
-#define report_uninit()		Perl_report_uninit(aTHX)
+#define report_uninit(a)	Perl_report_uninit(aTHX_ a)
 #endif
 #define vwarn(a,b)		Perl_vwarn(aTHX_ a,b)
 #define vwarner(a,b,c)		Perl_vwarner(aTHX_ a,b,c)
@@ -4770,6 +4775,11 @@
 #ifdef PERL_CORE
 #define magic_scalarpack(a,b)	Perl_magic_scalarpack(aTHX_ a,b)
 #endif
+#ifdef PERL_IN_SV_C
+#ifdef PERL_CORE
+#define find_uninit_var(a,b,c)	S_find_uninit_var(aTHX_ a,b,c)
+#endif
+#endif
 #ifdef PERL_NEED_MY_HTOLE16
 #ifdef PERL_CORE
 #define my_htole16		Perl_my_htole16
diff --git a/ext/DB_File/DB_File.pm b/ext/DB_File/DB_File.pm
index a965e82d41..b9fb63a224 100644
--- a/ext/DB_File/DB_File.pm
+++ b/ext/DB_File/DB_File.pm
@@ -165,7 +165,7 @@ our ($db_version, $use_XSLoader, $splice_end_array);
 use Carp;
 
 
-$VERSION = "1.808_01" ;
+$VERSION = "1.808_02" ;
 
 {
     local $SIG{__WARN__} = sub {$splice_end_array = "@_";};
diff --git a/ext/DB_File/t/db-recno.t b/ext/DB_File/t/db-recno.t
index 4ab0aebe4a..8bd637942f 100755
--- a/ext/DB_File/t/db-recno.t
+++ b/ext/DB_File/t/db-recno.t
@@ -1313,6 +1313,8 @@ sub test_splice {
     foreach ($s_error, @s_warnings) {
 	chomp;
 	s/ at \S+ line \d+\.$//;
+	# only built-in splice identifies name of uninit value
+	s/(uninitialized value) \$\w+/$1/;
     }
 
     # Now do the same for DB_File's version of splice
diff --git a/lib/Math/BigInt.pm b/lib/Math/BigInt.pm
index 7393b12d24..220920e5e1 100644
--- a/lib/Math/BigInt.pm
+++ b/lib/Math/BigInt.pm
@@ -18,7 +18,7 @@ package Math::BigInt;
 my $class = "Math::BigInt";
 require 5.005;
 
-$VERSION = '1.70';
+$VERSION = '1.70_01';
 use Exporter;
 @ISA =       qw( Exporter );
 @EXPORT_OK = qw( objectify bgcd blcm); 
diff --git a/lib/Math/BigInt/t/mbimbf.inc b/lib/Math/BigInt/t/mbimbf.inc
index b9c94c4900..51fea643d2 100644
--- a/lib/Math/BigInt/t/mbimbf.inc
+++ b/lib/Math/BigInt/t/mbimbf.inc
@@ -398,10 +398,10 @@ my $warn = ''; $SIG{__WARN__} = sub { $warn = shift; };
 # these should warn, since '3.17' is a NaN in BigInt and thus >= returns undef
 $warn = ''; eval "\$z = 3.17 <= \$y"; ok ($z, 1);
 print "# Got: '$warn'\n" unless
-ok ($warn =~ /^Use of uninitialized value (in numeric le \(<=\) |)at/);	
+ok ($warn =~ /^Use of uninitialized value (\$y )?(in numeric le \(<=\) |)at/);	
 $warn = ''; eval "\$z = \$y >= 3.17"; ok ($z, 1);
 print "# Got: '$warn'\n" unless
-ok ($warn =~ /^Use of uninitialized value (in numeric ge \(>=\) |)at/);	
+ok ($warn =~ /^Use of uninitialized value (\$y )?(in numeric ge \(>=\) |)at/);	
 
 # XXX TODO breakage:
 # $z = $y->copy()->bmul($u,2,0,'odd'); ok ($z,31000);
diff --git a/lib/Tie/RefHash.t b/lib/Tie/RefHash.t
index 52e3a2d5e9..55fde141a0 100644
--- a/lib/Tie/RefHash.t
+++ b/lib/Tie/RefHash.t
@@ -208,6 +208,7 @@ sub runtests {
             s/ at .+ line \d+\.$//mg;
             s/ at .+ line \d+, at .*//mg;
             s/ at .+ line \d+, near .*//mg;
+	    s/(uninitialized value)( within)? [\$@%].*? in /$1 in /g;
         }
 
         my (@warnings, %seen);
diff --git a/lib/charnames.t b/lib/charnames.t
index 34fe56d3dd..3502b74d5b 100644
--- a/lib/charnames.t
+++ b/lib/charnames.t
@@ -399,7 +399,7 @@ Only HASH reference supported as argument to :alias at
 use charnames ":short", ":alias" => { e_ACUTE => "LATIN:e WITH ACUTE", "a_ACUTE" };
 "Here: \N{e_ACUTE}\N{a_ACUTE}!\n";
 EXPECT
-Use of uninitialized value in string eq at
+Use of uninitialized value
 ########
 # alias with hashref two aliases
 use charnames ":short", ":alias" => {
diff --git a/mg.c b/mg.c
index d86e22d7dd..d162cd31ff 100644
--- a/mg.c
+++ b/mg.c
@@ -491,12 +491,12 @@ Perl_magic_len(pTHX_ SV *sv, MAGIC *mg)
 	    }
 	    else {
 		if (ckWARN(WARN_UNINITIALIZED))
-		    report_uninit();
+		    report_uninit(sv);
 	    }
 	}
 	else {
 	    if (ckWARN(WARN_UNINITIALIZED))
-		report_uninit();
+		report_uninit(sv);
 	}
 	return 0;
     case '+':
diff --git a/perl.h b/perl.h
index 7b9a51ad7d..1ee475664f 100644
--- a/perl.h
+++ b/perl.h
@@ -3237,7 +3237,7 @@ START_EXTERN_C
 
 /* handy constants */
 EXTCONST char PL_warn_uninit[]
-  INIT("Use of uninitialized value%s%s");
+  INIT("Use of uninitialized value%s%s%s");
 EXTCONST char PL_warn_nosemi[]
   INIT("Semicolon seems to be missing");
 EXTCONST char PL_warn_reserved[]
diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 94fc18901a..923d0ab448 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -4388,13 +4388,14 @@ arguments.  See L<perlsec>.
 defined.  It was interpreted as a "" or a 0, but maybe it was a mistake.
 To suppress this warning assign a defined value to your variables.
 
-To help you figure out what was undefined, perl tells you what operation
-you used the undefined value in.  Note, however, that perl optimizes your
-program and the operation displayed in the warning may not necessarily
-appear literally in your program.  For example, C<"that $foo"> is
-usually optimized into C<"that " . $foo>, and the warning will refer to
-the C<concatenation (.)> operator, even though there is no C<.> in your
-program.
+To help you figure out what was undefined, perl will try to tell you the
+name of the variable (if any) that was undefined. In some cases it cannot
+do this, so it also tells you what operation you used the undefined value
+in.  Note, however, that perl optimizes your program and the operation
+displayed in the warning may not necessarily appear literally in your
+program.  For example, C<"that $foo"> is usually optimized into C<"that "
+. $foo>, and the warning will refer to the C<concatenation (.)> operator,
+even though there is no C<.> in your program.
 
 =item Using a hash as a reference is deprecated
 
diff --git a/pod/perlintern.pod b/pod/perlintern.pod
index e12c271213..e79923191c 100644
--- a/pod/perlintern.pod
+++ b/pod/perlintern.pod
@@ -791,11 +791,32 @@ Found in file pp.h
 
 =over 8
 
+=item find_uninit_var
+
+Find the name of the undefined variable (if any) that caused the operator o
+to issue a "Use of uninitialized value" warning.
+If match is true, only return a name if it's value matches uninit_sv.
+So roughly speaking, if a unary operator (such as OP_COS) generates a
+warning, then following the direct child of the op may yield an
+OP_PADSV or OP_GV that gives the name of the undefined variable. On the
+other hand, with OP_ADD there are two branches to follow, so we only print
+the variable name if we get an exact match.
+
+The name is returned as a mortal SV.
+
+Assumes that PL_op is the op that originally triggered the error, and that
+PL_comppad/PL_curpad points to the currently executing pad.
+
+	SV*	find_uninit_var(OP* obase, SV* uninit_sv, bool top)
+
+=for hackers
+Found in file sv.c
+
 =item report_uninit
 
 Print appropriate "Use of uninitialized variable" warning
 
-	void	report_uninit()
+	void	report_uninit(SV* uninit_sv)
 
 =for hackers
 Found in file sv.c
diff --git a/pp.c b/pp.c
index 0bf02fa41d..6a17ece5c7 100644
--- a/pp.c
+++ b/pp.c
@@ -177,7 +177,7 @@ PP(pp_rv2gv)
 		    PL_op->op_private & HINT_STRICT_REFS)
 		    DIE(aTHX_ PL_no_usym, "a symbol");
 		if (ckWARN(WARN_UNINITIALIZED))
-		    report_uninit();
+		    report_uninit(sv);
 		RETSETUNDEF;
 	    }
 	    sym = SvPV(sv,len);
@@ -238,7 +238,7 @@ PP(pp_rv2sv)
 		    PL_op->op_private & HINT_STRICT_REFS)
 		    DIE(aTHX_ PL_no_usym, "a SCALAR");
 		if (ckWARN(WARN_UNINITIALIZED))
-		    report_uninit();
+		    report_uninit(sv);
 		RETSETUNDEF;
 	    }
 	    sym = SvPV(sv, len);
diff --git a/pp_hot.c b/pp_hot.c
index 452c3a91b8..d02bf96d0e 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -725,7 +725,7 @@ PP(pp_rv2av)
 		      PL_op->op_private & HINT_STRICT_REFS)
 			DIE(aTHX_ PL_no_usym, "an ARRAY");
 		    if (ckWARN(WARN_UNINITIALIZED))
-			report_uninit();
+			report_uninit(sv);
 		    if (GIMME == G_ARRAY) {
 			(void)POPs;
 			RETURN;
@@ -856,7 +856,7 @@ PP(pp_rv2hv)
 		      PL_op->op_private & HINT_STRICT_REFS)
 			DIE(aTHX_ PL_no_usym, "a HASH");
 		    if (ckWARN(WARN_UNINITIALIZED))
-			report_uninit();
+			report_uninit(sv);
 		    if (gimme == G_ARRAY) {
 			SP--;
 			RETURN;
diff --git a/proto.h b/proto.h
index b72fede18e..9dcf1c8b07 100644
--- a/proto.h
+++ b/proto.h
@@ -805,7 +805,7 @@ PERL_CALLCONV U32	Perl_parse_unicode_opts(pTHX_ char **popt);
 PERL_CALLCONV U32	Perl_seed(pTHX);
 PERL_CALLCONV UV	Perl_get_hash_seed(pTHX);
 PERL_CALLCONV void	Perl_report_evil_fh(pTHX_ GV *gv, IO *io, I32 op);
-PERL_CALLCONV void	Perl_report_uninit(pTHX);
+PERL_CALLCONV void	Perl_report_uninit(pTHX_ SV* uninit_sv);
 PERL_CALLCONV void	Perl_warn(pTHX_ const char* pat, ...)
 	__attribute__format__(__printf__,pTHX_1,pTHX_2);
 PERL_CALLCONV void	Perl_vwarn(pTHX_ const char* pat, va_list* args);
@@ -1344,6 +1344,9 @@ PERL_CALLCONV void	Perl_hv_clear_placeholders(pTHX_ HV* hb);
 
 PERL_CALLCONV SV*	Perl_hv_scalar(pTHX_ HV* hv);
 PERL_CALLCONV SV*	Perl_magic_scalarpack(pTHX_ HV* hv, MAGIC*	mg);
+#ifdef PERL_IN_SV_C
+STATIC SV*	S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool top);
+#endif
 
 #ifdef PERL_NEED_MY_HTOLE16
 PERL_CALLCONV U16	Perl_my_htole16(U16 n);
diff --git a/sv.c b/sv.c
index c4aa66cd69..5e4bf727f2 100644
--- a/sv.c
+++ b/sv.c
@@ -602,6 +602,458 @@ Perl_sv_free_arenas(pTHX)
     PL_sv_root = 0;
 }
 
+/* ---------------------------------------------------------------------
+ *
+ * support functions for report_uninit()
+ */
+
+/* the maxiumum size of array or hash where we will scan looking
+ * for the undefined element that triggered the warning */
+
+#define FUV_MAX_SEARCH_SIZE 1000
+
+/* Look for an entry in the hash whose value has the same SV as val;
+ * If so, return a mortal copy of the key. */
+
+STATIC SV*
+S_find_hash_subscript(pTHX_ HV *hv, SV* val)
+{
+    register HE **array;
+    register HE *entry;
+    I32 i;
+
+    if (!hv || SvMAGICAL(hv) || !HvARRAY(hv) ||
+			(HvTOTALKEYS(hv) > FUV_MAX_SEARCH_SIZE))
+	return Nullsv;
+
+    array = HvARRAY(hv);
+
+    for (i=HvMAX(hv); i>0; i--) {
+	for (entry = array[i]; entry; entry = HeNEXT(entry)) {
+	    if (HeVAL(entry) != val)
+		continue;
+	    if (    HeVAL(entry) == &PL_sv_undef ||
+		    HeVAL(entry) == &PL_sv_placeholder)
+		continue;
+	    if (!HeKEY(entry))
+		return Nullsv;
+	    if (HeKLEN(entry) == HEf_SVKEY)
+		return sv_mortalcopy(HeKEY_sv(entry));
+	    return sv_2mortal(newSVpvn(HeKEY(entry), HeKLEN(entry)));
+	}
+    }
+    return Nullsv;
+}
+
+/* Look for an entry in the array whose value has the same SV as val;
+ * If so, return the index, otherwise return -1. */
+
+STATIC I32
+S_find_array_subscript(pTHX_ AV *av, SV* val)
+{
+    SV** svp;
+    I32 i;
+    if (!av || SvMAGICAL(av) || !AvARRAY(av) ||
+			(AvFILLp(av) > FUV_MAX_SEARCH_SIZE))
+	return -1;
+
+    svp = AvARRAY(av);
+    for (i=AvFILLp(av); i>=0; i--) {
+	if (svp[i] == val && svp[i] != &PL_sv_undef)
+	    return i;
+    }
+    return -1;
+}
+
+/* S_varname(): return the name of a variable, optionally with a subscript.
+ * If gv is non-zero, use the name of that global, along with gvtype (one
+ * of "$", "@", "%"); otherwise use the name of the lexical at pad offset
+ * targ.  Depending on the value of the subscript_type flag, return:
+ */
+
+#define FUV_SUBSCRIPT_NONE	1	/* "@foo"          */
+#define FUV_SUBSCRIPT_ARRAY	2	/* "$foo[aindex]"  */
+#define FUV_SUBSCRIPT_HASH	3	/* "$foo{keyname}" */
+#define FUV_SUBSCRIPT_WITHIN	4	/* "within @foo"   */
+
+STATIC SV*
+S_varname(pTHX_ GV *gv, char *gvtype, PADOFFSET targ,
+	SV* keyname, I32 aindex, int subscript_type)
+{
+    AV *av;
+
+    SV *sv, *name;
+
+    name = sv_newmortal();
+    if (gv) {
+
+	/* simulate gv_fullname4(), but add literal '^' for $^FOO names
+	 * XXX get rid of all this if gv_fullnameX() ever supports this
+	 * directly */
+
+	char *p;
+	HV *hv = GvSTASH(gv);
+	sv_setpv(name, gvtype);
+	if (!hv)
+	    p = "???";
+	else if (!HvNAME(hv))
+	    p = "__ANON__";
+	else 
+	    p = HvNAME(hv);
+	if (strNE(p, "main")) {
+	    sv_catpv(name,p);
+	    sv_catpvn(name,"::", 2);
+	}
+	if (GvNAMELEN(gv)>= 1 &&
+	    ((unsigned int)*GvNAME(gv)) <= 26)
+	{ /* handle $^FOO */
+	    Perl_sv_catpvf(aTHX_ name,"^%c", *GvNAME(gv) + 'A' - 1);
+	    sv_catpvn(name,GvNAME(gv)+1,GvNAMELEN(gv)-1);
+	}
+	else
+	    sv_catpvn(name,GvNAME(gv),GvNAMELEN(gv));
+    }
+    else {
+	U32 u;
+	CV *cv = find_runcv(&u);
+	if (!cv || !CvPADLIST(cv))
+	    return Nullsv;;
+	av = (AV*)(*av_fetch(CvPADLIST(cv), 0, FALSE));
+	sv = *av_fetch(av, targ, FALSE);
+	/* SvLEN in a pad name is not to be trusted */
+	sv_setpv(name, SvPV_nolen(sv));
+    }
+
+    if (subscript_type == FUV_SUBSCRIPT_HASH) {
+	*SvPVX(name) = '$';
+	sv = NEWSV(0,0);
+	Perl_sv_catpvf(aTHX_ name, "{%s}",
+	    pv_display(sv,SvPVX(keyname), SvCUR(keyname), 0, 32));
+	SvREFCNT_dec(sv);
+    }
+    else if (subscript_type == FUV_SUBSCRIPT_ARRAY) {
+	*SvPVX(name) = '$';
+	Perl_sv_catpvf(aTHX_ name, "[%"IVdf"]", aindex);
+    }
+    else if (subscript_type == FUV_SUBSCRIPT_WITHIN)
+	sv_insert(name, 0, 0,  "within ", 7);
+
+    return name;
+}
+
+
+/*
+=for apidoc find_uninit_var
+
+Find the name of the undefined variable (if any) that caused the operator o
+to issue a "Use of uninitialized value" warning.
+If match is true, only return a name if it's value matches uninit_sv.
+So roughly speaking, if a unary operator (such as OP_COS) generates a
+warning, then following the direct child of the op may yield an
+OP_PADSV or OP_GV that gives the name of the undefined variable. On the
+other hand, with OP_ADD there are two branches to follow, so we only print
+the variable name if we get an exact match.
+
+The name is returned as a mortal SV.
+
+Assumes that PL_op is the op that originally triggered the error, and that
+PL_comppad/PL_curpad points to the currently executing pad.
+
+=cut
+*/
+
+STATIC SV *
+S_find_uninit_var(pTHX_ OP* obase, SV* uninit_sv, bool match)
+{
+    SV *sv;
+    AV *av;
+    SV **svp;
+    GV *gv;
+    OP *o, *o2, *kid;
+
+    if (!obase || (match && (!uninit_sv || uninit_sv == &PL_sv_undef ||
+			    uninit_sv == &PL_sv_placeholder)))
+	return Nullsv;
+
+    switch (obase->op_type) {
+
+    case OP_RV2AV:
+    case OP_RV2HV:
+    case OP_PADAV:
+    case OP_PADHV:
+      {
+	bool pad  = (obase->op_type == OP_PADAV || obase->op_type == OP_PADHV);
+	bool hash = (obase->op_type == OP_PADHV || obase->op_type == OP_RV2HV);
+	I32 index;
+	SV *keysv;
+	int subscript_type = FUV_SUBSCRIPT_WITHIN;
+
+	if (pad) { /* @lex, %lex */
+	    sv = PAD_SVl(obase->op_targ);
+	    gv = Nullgv;
+	}
+	else {
+	    if (cUNOPx(obase)->op_first->op_type == OP_GV) {
+	    /* @global, %global */
+		gv = cGVOPx_gv(cUNOPx(obase)->op_first);
+		if (!gv)
+		    break;
+		sv = hash ? (SV*)GvHV(gv): (SV*)GvAV(gv);
+	    }
+	    else /* @{expr}, %{expr} */
+		return find_uninit_var(cUNOPx(obase)->op_first,
+						    uninit_sv, match);
+	}
+
+	/* attempt to find a match within the aggregate */
+	if (hash) {
+	    keysv = S_find_hash_subscript(aTHX_ (HV*)sv, uninit_sv);
+	    if (keysv)
+		subscript_type = FUV_SUBSCRIPT_HASH;
+	}
+	else {
+	    index = S_find_array_subscript(aTHX_ (AV*)sv, uninit_sv);
+	    if (index >= 0)
+		subscript_type = FUV_SUBSCRIPT_ARRAY;
+	}
+
+	if (match && subscript_type == FUV_SUBSCRIPT_WITHIN)
+	    break;
+
+	return S_varname(aTHX_ gv, hash ? "%" : "@", obase->op_targ,
+				    keysv, index, subscript_type);
+      }
+
+    case OP_PADSV:
+	if (match && PAD_SVl(obase->op_targ) != uninit_sv)
+	    break;
+	return S_varname(aTHX_ Nullgv, "$", obase->op_targ,
+				    Nullsv, 0, FUV_SUBSCRIPT_NONE);
+
+    case OP_GVSV:
+	gv = cGVOPx_gv(obase);
+	if (!gv || (match && GvSV(gv) != uninit_sv))
+	    break;
+	return S_varname(aTHX_ gv, "$", 0, Nullsv, 0, FUV_SUBSCRIPT_NONE);
+
+    case OP_AELEMFAST:
+	if (obase->op_flags & OPf_SPECIAL) { /* lexical array */
+	    if (match) {
+		av = (AV*)PAD_SV(obase->op_targ);
+		if (!av || SvRMAGICAL(av))
+		    break;
+		svp = av_fetch(av, (I32)obase->op_private, FALSE);
+		if (!svp || *svp != uninit_sv)
+		    break;
+	    }
+	    return S_varname(aTHX_ Nullgv, "$", obase->op_targ,
+		    Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
+	}
+	else {
+	    gv = cGVOPx_gv(obase);
+	    if (!gv)
+		break;
+	    if (match) {
+		av = GvAV(gv);
+		if (!av || SvRMAGICAL(av))
+		    break;
+		svp = av_fetch(av, (I32)obase->op_private, FALSE);
+		if (!svp || *svp != uninit_sv)
+		    break;
+	    }
+	    return S_varname(aTHX_ gv, "$", 0,
+		    Nullsv, (I32)obase->op_private, FUV_SUBSCRIPT_ARRAY);
+	}
+	break;
+
+    case OP_EXISTS:
+	o = cUNOPx(obase)->op_first;
+	if (!o || o->op_type != OP_NULL ||
+		! (o->op_targ == OP_AELEM || o->op_targ == OP_HELEM))
+	    break;
+	return find_uninit_var(cBINOPo->op_last, uninit_sv, match);
+
+    case OP_AELEM:
+    case OP_HELEM:
+	if (PL_op == obase)
+	    /* $a[uninit_expr] or $h{uninit_expr} */
+	    return find_uninit_var(cBINOPx(obase)->op_last, uninit_sv, match);
+
+	gv = Nullgv;
+	o = cBINOPx(obase)->op_first;
+	kid = cBINOPx(obase)->op_last;
+
+	/* get the av or hv, and optionally the gv */
+	sv = Nullsv;
+	if  (o->op_type == OP_PADAV || o->op_type == OP_PADHV) {
+	    sv = PAD_SV(o->op_targ);
+	}
+	else if ((o->op_type == OP_RV2AV || o->op_type == OP_RV2HV)
+		&& cUNOPo->op_first->op_type == OP_GV)
+	{
+	    gv = cGVOPx_gv(cUNOPo->op_first);
+	    if (!gv)
+		break;
+	    sv = o->op_type == OP_RV2HV ? (SV*)GvHV(gv) : (SV*)GvAV(gv);
+	}
+	if (!sv)
+	    break;
+
+	if (kid && kid->op_type == OP_CONST && SvOK(cSVOPx_sv(kid))) {
+	    /* index is constant */
+	    if (match) {
+		if (SvMAGICAL(sv))
+		    break;
+		if (obase->op_type == OP_HELEM) {
+		    HE* he = hv_fetch_ent((HV*)sv, cSVOPx_sv(kid), 0, 0);
+		    if (!he || HeVAL(he) != uninit_sv)
+			break;
+		}
+		else {
+		    svp = av_fetch((AV*)sv, SvIV(cSVOPx_sv(kid)), FALSE);
+		    if (!svp || *svp != uninit_sv)
+			break;
+		}
+	    }
+	    if (obase->op_type == OP_HELEM)
+		return S_varname(aTHX_ gv, "%", o->op_targ,
+			    cSVOPx_sv(kid), 0, FUV_SUBSCRIPT_HASH);
+	    else
+		return S_varname(aTHX_ gv, "@", o->op_targ, Nullsv,
+			    SvIV(cSVOPx_sv(kid)), FUV_SUBSCRIPT_ARRAY);
+	    ;
+	}
+	else  {
+	    /* index is an expression;
+	     * attempt to find a match within the aggregate */
+	    if (obase->op_type == OP_HELEM) {
+		SV *keysv = S_find_hash_subscript(aTHX_ (HV*)sv, uninit_sv);
+		if (keysv)
+		    return S_varname(aTHX_ gv, "%", o->op_targ,
+						keysv, 0, FUV_SUBSCRIPT_HASH);
+	    }
+	    else {
+		I32 index = S_find_array_subscript(aTHX_ (AV*)sv, uninit_sv);
+		if (index >= 0)
+		return S_varname(aTHX_ gv, "@", o->op_targ,
+					Nullsv, index, FUV_SUBSCRIPT_ARRAY);
+	    }
+	    if (match)
+		break;
+	    return S_varname(aTHX_ gv,
+		(o->op_type == OP_PADAV || o->op_type == OP_RV2AV)
+		? "@" : "%",
+		o->op_targ, Nullsv, 0, FUV_SUBSCRIPT_WITHIN);
+	}
+
+	break;
+
+    case OP_AASSIGN:
+	/* only examine RHS */
+	return find_uninit_var(cBINOPx(obase)->op_first, uninit_sv, match);
+
+    case OP_OPEN:
+	o = cUNOPx(obase)->op_first;
+	if (o->op_type == OP_PUSHMARK)
+	    o = o->op_sibling;
+
+	if (!o->op_sibling) {
+	    /* one-arg version of open is highly magical */
+
+	    if (o->op_type == OP_GV) { /* open FOO; */
+		gv = cGVOPx_gv(o);
+		if (match && GvSV(gv) != uninit_sv)
+		    break;
+		return S_varname(aTHX_ gv, "$", 0, 
+			    Nullsv, 0, FUV_SUBSCRIPT_NONE);
+	    }
+	    /* other possibilities not handled are:
+	     * open $x; or open my $x;	should return '${*$x}'
+	     * open expr;		should return '$'.expr ideally
+	     */
+	     break;
+	}
+	goto do_op;
+
+    /* ops where $_ may be an implicit arg */
+    case OP_TRANS:
+    case OP_SUBST:
+    case OP_MATCH:
+	if ( !(obase->op_flags & OPf_STACKED)) {
+	    if (uninit_sv == ((obase->op_private & OPpTARGET_MY)
+				 ? PAD_SVl(obase->op_targ)
+				 : DEFSV))
+	    {
+		sv = sv_newmortal();
+		sv_setpv(sv, "$_");
+		return sv;
+	    }
+	}
+	goto do_op;
+
+    case OP_PRTF:
+    case OP_PRINT:
+	/* skip filehandle as it can't produce 'undef' warning  */
+	o = cUNOPx(obase)->op_first;
+	if ((obase->op_flags & OPf_STACKED) && o->op_type == OP_PUSHMARK)
+	    o = o->op_sibling->op_sibling;
+	goto do_op2;
+
+
+    case OP_CUSTOM:
+    case OP_ENTERSUB:
+	match = 1; /* XS or custom code could trigger random warnings */
+	goto do_op;
+
+    case OP_SCHOMP:
+    case OP_CHOMP:
+	if (SvROK(PL_rs) && uninit_sv == SvRV(PL_rs))
+	    return sv_2mortal(newSVpv("${$/}", 0));
+	/* FALL THROUGH */
+
+    default:
+    do_op:
+	if (!(obase->op_flags & OPf_KIDS))
+	    break;
+	o = cUNOPx(obase)->op_first;
+	
+    do_op2:
+	if (!o)
+	    break;
+
+	/* if all except one arg are constant, or have no side-effects,
+	 * or are optimized away, then it's unambiguous */
+	o2 = Nullop;
+	for (kid=o; kid; kid = kid->op_sibling) {
+	    if (kid &&
+		(    (kid->op_type == OP_CONST && SvOK(cSVOPx_sv(kid)))
+		  || (kid->op_type == OP_NULL  && ! (kid->op_flags & OPf_KIDS))
+		  || (kid->op_type == OP_PUSHMARK)
+		)
+	    )
+		continue;
+	    if (o2) { /* more than one found */
+		o2 = Nullop;
+		break;
+	    }
+	    o2 = kid;
+	}
+	if (o2)
+	    return find_uninit_var(o2, uninit_sv, match);
+
+	/* scan all args */
+	while (o) {
+	    sv = find_uninit_var(o, uninit_sv, 1);
+	    if (sv)
+		return sv;
+	    o = o->op_sibling;
+	}
+	break;
+    }
+    return Nullsv;
+}
+
+
 /*
 =for apidoc report_uninit
 
@@ -611,13 +1063,22 @@ Print appropriate "Use of uninitialized variable" warning
 */
 
 void
-Perl_report_uninit(pTHX)
+Perl_report_uninit(pTHX_ SV* uninit_sv)
 {
-    if (PL_op)
+    if (PL_op) {
+	SV* varname;
+	if (uninit_sv) {
+	    varname = find_uninit_var(PL_op, uninit_sv,0);
+	    if (varname)
+		sv_insert(varname, 0, 0, " ", 1);
+	}
 	Perl_warner(aTHX_ packWARN(WARN_UNINITIALIZED), PL_warn_uninit,
-		    " in ", OP_DESC(PL_op));
+		varname ? SvPV_nolen(varname) : "",
+		" in ", OP_DESC(PL_op));
+    }
     else
-	Perl_warner(aTHX_ packWARN(WARN_UNINITIALIZED), PL_warn_uninit, "", "");
+	Perl_warner(aTHX_ packWARN(WARN_UNINITIALIZED), PL_warn_uninit,
+		    "", "", "");
 }
 
 /* grab a new IV body from the free list, allocating more if necessary */
@@ -2091,7 +2552,7 @@ Perl_sv_2iv_flags(pTHX_ register SV *sv, I32 flags)
 	if (!SvROK(sv)) {
 	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
 		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
-		    report_uninit();
+		    report_uninit(sv);
 	    }
 	    return 0;
 	}
@@ -2109,7 +2570,7 @@ Perl_sv_2iv_flags(pTHX_ register SV *sv, I32 flags)
 	}
 	if (SvREADONLY(sv) && !SvOK(sv)) {
 	    if (ckWARN(WARN_UNINITIALIZED))
-		report_uninit();
+		report_uninit(sv);
 	    return 0;
 	}
     }
@@ -2351,7 +2812,7 @@ Perl_sv_2iv_flags(pTHX_ register SV *sv, I32 flags)
 	}
     } else  {
 	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
-	    report_uninit();
+	    report_uninit(sv);
 	if (SvTYPE(sv) < SVt_IV)
 	    /* Typically the caller expects that sv_any is not NULL now.  */
 	    sv_upgrade(sv, SVt_IV);
@@ -2399,7 +2860,7 @@ Perl_sv_2uv_flags(pTHX_ register SV *sv, I32 flags)
 	if (!SvROK(sv)) {
 	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
 		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
-		    report_uninit();
+		    report_uninit(sv);
 	    }
 	    return 0;
 	}
@@ -2417,7 +2878,7 @@ Perl_sv_2uv_flags(pTHX_ register SV *sv, I32 flags)
 	}
 	if (SvREADONLY(sv) && !SvOK(sv)) {
 	    if (ckWARN(WARN_UNINITIALIZED))
-		report_uninit();
+		report_uninit(sv);
 	    return 0;
 	}
     }
@@ -2640,7 +3101,7 @@ Perl_sv_2uv_flags(pTHX_ register SV *sv, I32 flags)
     else  {
 	if (!(SvFLAGS(sv) & SVs_PADTMP)) {
 	    if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
-		report_uninit();
+		report_uninit(sv);
 	}
 	if (SvTYPE(sv) < SVt_IV)
 	    /* Typically the caller expects that sv_any is not NULL now.  */
@@ -2687,7 +3148,7 @@ Perl_sv_2nv(pTHX_ register SV *sv)
         if (!SvROK(sv)) {
 	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
 		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
-		    report_uninit();
+		    report_uninit(sv);
 	    }
             return 0;
         }
@@ -2705,7 +3166,7 @@ Perl_sv_2nv(pTHX_ register SV *sv)
 	}
 	if (SvREADONLY(sv) && !SvOK(sv)) {
 	    if (ckWARN(WARN_UNINITIALIZED))
-		report_uninit();
+		report_uninit(sv);
 	    return 0.0;
 	}
     }
@@ -2836,7 +3297,7 @@ Perl_sv_2nv(pTHX_ register SV *sv)
     }
     else  {
 	if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
-	    report_uninit();
+	    report_uninit(sv);
 	if (SvTYPE(sv) < SVt_NV)
 	    /* Typically the caller expects that sv_any is not NULL now.  */
 	    /* XXX Ilya implies that this is a bug in callers that assume this
@@ -3016,7 +3477,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
         if (!SvROK(sv)) {
 	    if (!(SvFLAGS(sv) & SVs_PADTMP)) {
 		if (ckWARN(WARN_UNINITIALIZED) && !PL_localizing)
-		    report_uninit();
+		    report_uninit(sv);
 	    }
             *lp = 0;
             return "";
@@ -3166,7 +3627,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
 	}
 	if (SvREADONLY(sv) && !SvOK(sv)) {
 	    if (ckWARN(WARN_UNINITIALIZED))
-		report_uninit();
+		report_uninit(sv);
 	    *lp = 0;
 	    return "";
 	}
@@ -3226,7 +3687,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *sv, STRLEN *lp, I32 flags)
     else {
 	if (ckWARN(WARN_UNINITIALIZED)
 	    && !PL_localizing && !(SvFLAGS(sv) & SVs_PADTMP))
-	    report_uninit();
+	    report_uninit(sv);
 	*lp = 0;
 	if (SvTYPE(sv) < SVt_PV)
 	    /* Typically the caller expects that sv_any is not NULL now.  */
diff --git a/t/lib/warnings/1global b/t/lib/warnings/1global
index 0af80221b2..9de457da0f 100644
--- a/t/lib/warnings/1global
+++ b/t/lib/warnings/1global
@@ -43,7 +43,7 @@ EXPECT
 $^W = 1 ;
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 4.
+Use of uninitialized value $b in scalar chop at - line 4.
 ########
 
 # warnings enabled at compile time, disabled at run time
@@ -59,7 +59,7 @@ BEGIN { $^W = 0 }
 $^W = 1 ;
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 5.
+Use of uninitialized value $b in scalar chop at - line 5.
 ########
 -w
 --FILE-- abcd
@@ -68,7 +68,7 @@ my $b ; chop $b ;
 --FILE-- 
 require "./abcd";
 EXPECT
-Use of uninitialized value in scalar chop at ./abcd line 1.
+Use of uninitialized value $b in scalar chop at ./abcd line 1.
 ########
 
 --FILE-- abcd
@@ -78,7 +78,7 @@ my $b ; chop $b ;
 #! perl -w
 require "./abcd";
 EXPECT
-Use of uninitialized value in scalar chop at ./abcd line 1.
+Use of uninitialized value $b in scalar chop at ./abcd line 1.
 ########
 
 --FILE-- abcd
@@ -88,7 +88,7 @@ my $b ; chop $b ;
 $^W =1 ;
 require "./abcd";
 EXPECT
-Use of uninitialized value in scalar chop at ./abcd line 1.
+Use of uninitialized value $b in scalar chop at ./abcd line 1.
 ########
 
 --FILE-- abcd
@@ -110,28 +110,28 @@ $^W =0 ;
 require "./abcd";
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $b in scalar chop at - line 3.
 ########
 
 $^W = 1;
 eval 'my $b ; chop $b ;' ;
 print $@ ;
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 1.
+Use of uninitialized value $b in scalar chop at (eval 1) line 1.
 ########
 
 eval '$^W = 1;' ;
 print $@ ;
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 4.
+Use of uninitialized value $b in scalar chop at - line 4.
 ########
 
 eval {$^W = 1;} ;
 print $@ ;
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 4.
+Use of uninitialized value $b in scalar chop at - line 4.
 ########
 
 {
@@ -149,7 +149,7 @@ my $a ; chop $a ;
 }
 my $c ; chop $c ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 5.
+Use of uninitialized value $b in scalar chop at - line 5.
 ########
 -w
 -e undef
@@ -186,4 +186,4 @@ sub fred { my $b ; chop $b ;}
   fred() ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 2.
+Use of uninitialized value $b in scalar chop at - line 2.
diff --git a/t/lib/warnings/2use b/t/lib/warnings/2use
index b700ef70dc..7810287a3a 100644
--- a/t/lib/warnings/2use
+++ b/t/lib/warnings/2use
@@ -42,7 +42,7 @@ use warnings 'uninitialized' ;
 }
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check runtime scope of pragma
@@ -53,7 +53,7 @@ no warnings ;
 }
 my $b ; chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check runtime scope of pragma
@@ -64,7 +64,7 @@ no warnings ;
 }
 &$a ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 use warnings 'syntax' ;
@@ -103,7 +103,7 @@ require "./abc";
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at ./abc line 2.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 
 --FILE-- abc.pm
@@ -116,7 +116,7 @@ use abc;
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at abc.pm line 2.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 
 # Check scope of pragma with eval
@@ -143,7 +143,7 @@ use warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check scope of pragma with eval
@@ -156,8 +156,8 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 7.
-Use of uninitialized value in scalar chop at - line 9.
+Use of uninitialized value $b in scalar chop at - line 7.
+Use of uninitialized value $b in scalar chop at - line 9.
 ########
 
 # Check scope of pragma with eval
@@ -171,7 +171,7 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 
 # Check scope of pragma with eval
@@ -253,7 +253,7 @@ use warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 3.
+Use of uninitialized value $b in scalar chop at (eval 1) line 3.
 ########
 
 # Check scope of pragma with eval
@@ -266,8 +266,8 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 2.
-Use of uninitialized value in scalar chop at - line 9.
+Use of uninitialized value $b in scalar chop at (eval 1) line 2.
+Use of uninitialized value $b in scalar chop at - line 9.
 ########
 
 # Check scope of pragma with eval
@@ -281,7 +281,7 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 
 # Check scope of pragma with eval
@@ -351,4 +351,4 @@ no warnings 'syntax' ;
 $a =+ 1 ;
 EXPECT
 Reversed += operator at - line 6.
-Use of uninitialized value in scalar chop at - line 9.
+Use of uninitialized value $c in scalar chop at - line 9.
diff --git a/t/lib/warnings/3both b/t/lib/warnings/3both
index a4d9ba806d..733261cf3b 100644
--- a/t/lib/warnings/3both
+++ b/t/lib/warnings/3both
@@ -13,7 +13,7 @@ sub fred {
 }
 
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -27,7 +27,7 @@ sub fred {
 }
 
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -64,7 +64,7 @@ $^W = 1 ;
 my $b ; 
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -73,7 +73,7 @@ use warnings ;
 my $b ; 
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -107,7 +107,7 @@ use warnings ;
 my $b ; 
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 5.
+Use of uninitialized value $b in scalar chop at - line 5.
 ########
 
 # Check interaction of $^W and use warnings
@@ -119,7 +119,7 @@ sub fred {
 BEGIN {  $^W = 0 }
 fred() ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -141,7 +141,7 @@ BEGIN {  $^W = 1 }
 my $b ; 
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -150,7 +150,7 @@ use warnings ;
 my $b ; 
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check interaction of $^W and use warnings
@@ -181,7 +181,7 @@ BEGIN {  $^W = 1 }
 my $b ;
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 
 # Check interaction of $^W and use warnings
@@ -194,7 +194,7 @@ BEGIN {  $^W = 0 }
 my $b ;
 chop $b ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 7.
+Use of uninitialized value $b in scalar chop at - line 7.
 ########
 
 # Check scope of pragma with eval
@@ -222,7 +222,7 @@ use warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 3.
+Use of uninitialized value $b in scalar chop at (eval 1) line 3.
 ########
 
 # Check scope of pragma with eval
@@ -235,8 +235,8 @@ BEGIN {  $^W = 0 }
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 2.
-Use of uninitialized value in scalar chop at - line 9.
+Use of uninitialized value $b in scalar chop at (eval 1) line 2.
+Use of uninitialized value $b in scalar chop at - line 9.
 ########
 
 # Check scope of pragma with eval
@@ -250,7 +250,7 @@ BEGIN {  $^W = 0 }
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 
 # Check scope of pragma with eval
diff --git a/t/lib/warnings/4lint b/t/lib/warnings/4lint
index 805bd98905..5b46ce4ec5 100644
--- a/t/lib/warnings/4lint
+++ b/t/lib/warnings/4lint
@@ -68,7 +68,7 @@ use abc;
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at abc.pm line 4.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 -W
 --FILE-- abc
@@ -83,7 +83,7 @@ require "./abc";
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at ./abc line 4.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 -W
 --FILE-- abc.pm
@@ -98,7 +98,7 @@ use abc;
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at abc.pm line 4.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 -W
 --FILE-- abc
@@ -112,7 +112,7 @@ require "./abc";
 my $a ; chop $a ;
 EXPECT
 Reversed += operator at ./abc line 3.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 -W
 # Check scope of pragma with eval
@@ -124,8 +124,8 @@ Use of uninitialized value in scalar chop at - line 3.
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 2.
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at (eval 1) line 2.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 -W
 # Check scope of pragma with eval
@@ -139,8 +139,8 @@ use warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 3.
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at (eval 1) line 3.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 -W
 # Check scope of pragma with eval
@@ -153,8 +153,8 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 2.
-Use of uninitialized value in scalar chop at - line 9.
+Use of uninitialized value $b in scalar chop at (eval 1) line 2.
+Use of uninitialized value $b in scalar chop at - line 9.
 ########
 -W
 # Check scope of pragma with eval
@@ -168,8 +168,8 @@ no warnings;
     my $b ; chop $b ;
 }
 EXPECT
-Use of uninitialized value in scalar chop at (eval 1) line 3.
-Use of uninitialized value in scalar chop at - line 10.
+Use of uninitialized value $b in scalar chop at (eval 1) line 3.
+Use of uninitialized value $b in scalar chop at - line 10.
 ########
 -W
 # Check scope of pragma with eval
diff --git a/t/lib/warnings/7fatal b/t/lib/warnings/7fatal
index a3e70f8d50..1ad7658f74 100644
--- a/t/lib/warnings/7fatal
+++ b/t/lib/warnings/7fatal
@@ -35,7 +35,7 @@ use warnings FATAL => 'uninitialized' ;
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check runtime scope of pragma
@@ -47,7 +47,7 @@ use warnings FATAL => 'all' ;
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check runtime scope of pragma
@@ -59,7 +59,7 @@ no warnings ;
 &$a ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 # Check runtime scope of pragma
@@ -71,7 +71,7 @@ no warnings ;
 &$a ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 6.
+Use of uninitialized value $b in scalar chop at - line 6.
 ########
 
 --FILE-- abc
@@ -105,7 +105,7 @@ my $a ; chop $a ;
 print STDERR "The End.\n" ;
 EXPECT
 Reversed += operator at ./abc line 2.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 
 --FILE-- abc.pm
@@ -119,7 +119,7 @@ my $a ; chop $a ;
 print STDERR "The End.\n" ;
 EXPECT
 Reversed += operator at abc.pm line 2.
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $a in scalar chop at - line 3.
 ########
 
 # Check scope of pragma with eval
@@ -131,7 +131,7 @@ eval {
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
--- Use of uninitialized value in scalar chop at - line 6.
+-- Use of uninitialized value $b in scalar chop at - line 6.
 The End.
 ########
 
@@ -143,8 +143,8 @@ eval {
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
--- Use of uninitialized value in scalar chop at - line 5.
-Use of uninitialized value in scalar chop at - line 7.
+-- Use of uninitialized value $b in scalar chop at - line 5.
+Use of uninitialized value $b in scalar chop at - line 7.
 ########
 
 # Check scope of pragma with eval
@@ -156,7 +156,7 @@ eval {
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check scope of pragma with eval
@@ -214,7 +214,7 @@ eval q[
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
--- Use of uninitialized value in scalar chop at (eval 1) line 3.
+-- Use of uninitialized value $b in scalar chop at (eval 1) line 3.
 The End.
 ########
 
@@ -226,8 +226,8 @@ eval '
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
--- Use of uninitialized value in scalar chop at (eval 1) line 2.
-Use of uninitialized value in scalar chop at - line 7.
+-- Use of uninitialized value $b in scalar chop at (eval 1) line 2.
+Use of uninitialized value $b in scalar chop at - line 7.
 ########
 
 # Check scope of pragma with eval
@@ -239,7 +239,7 @@ eval '
 my $b ; chop $b ;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 8.
 ########
 
 # Check scope of pragma with eval
@@ -324,8 +324,8 @@ use warnings FATAL => 'all';
 my $b ; chop $b;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
-Use of uninitialized value in scalar chop at - line 11.
+Use of uninitialized value $b in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 11.
 ########
 
 use warnings FATAL => 'all';
@@ -340,8 +340,8 @@ use warnings FATAL => 'all';
 my $b ; chop $b;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 8.
-Use of uninitialized value in scalar chop at - line 11.
+Use of uninitialized value $b in scalar chop at - line 8.
+Use of uninitialized value $b in scalar chop at - line 11.
 ########
 
 use warnings FATAL => 'all';
@@ -355,7 +355,7 @@ use warnings FATAL => 'all';
 my $b ; chop $b;
 print STDERR "The End.\n" ;
 EXPECT
-Use of uninitialized value in scalar chop at - line 7.
+Use of uninitialized value $b in scalar chop at - line 7.
 ########
 
 use warnings FATAL => 'syntax', NONFATAL => 'void' ;
@@ -383,7 +383,7 @@ length "abc";
 print STDERR "The End.\n" ;
 EXPECT
 Useless use of length in void context at - line 5.
-Use of uninitialized value in scalar chomp at - line 4.
+Use of uninitialized value $a in scalar chomp at - line 4.
 ########
 
 use warnings FATAL => 'void', NONFATAL => 'void' ;
diff --git a/t/lib/warnings/9uninit b/t/lib/warnings/9uninit
new file mode 100644
index 0000000000..67139c3b6b
--- /dev/null
+++ b/t/lib/warnings/9uninit
@@ -0,0 +1,1288 @@
+DAPM 4/2004.
+
+Test the appearance of variable names in "Use of uninitialized value"
+warnings.
+
+The following ops aren't tested, mainly because they do IO or non-portable
+stuff:
+
+    send recv bind conect listen accept shutdown chdir chown chroot unlink
+    chmod utime rename link symlink readlink mkdir rmdir opendir seekdir
+    system exec kill getpgrp alarm sleep dofile require gethostbyname
+    gethostbyaddr getnetbyname getnetbyaddr getprotobyname getprotobynumber
+    getservbyname getservbyport sethostent setnetent setprotoent setservent
+    getpwnam getpwuid getgrnam getgrgid waitpid setpgrp setpriority
+    getpriority syscall dbmopen ioctl fcntl truncate getsockopt setsockopt
+    semctl semop semget msgget msgctl msgsnd msgrcv shmget shmctl shmread
+    shmwrite
+
+    ---------------------------------------------------
+
+
+__END__
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+
+$v = $m1 + 10;
+$v = 22 + $m2;
+$v = $m1 + $m2;
+EXPECT
+Use of uninitialized value $m1 in addition (+) at - line 4.
+Use of uninitialized value $m2 in addition (+) at - line 5.
+Use of uninitialized value $m2 in addition (+) at - line 6.
+Use of uninitialized value $m1 in addition (+) at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1, $g2);
+
+$v = $g1 + 21;
+$v = 31 + $g2;
+$v = $g1 + $g2;
+$v = $m1 + $g2;
+EXPECT
+Use of uninitialized value $g1 in addition (+) at - line 5.
+Use of uninitialized value $g2 in addition (+) at - line 6.
+Use of uninitialized value $g2 in addition (+) at - line 7.
+Use of uninitialized value $g1 in addition (+) at - line 7.
+Use of uninitialized value $g2 in addition (+) at - line 8.
+Use of uninitialized value $m1 in addition (+) at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1, @ma, $v);
+
+$v = $ma[5] + 45;
+$v = 56 + $ma[6];
+$v = $ma[7] + $m1;
+$v = $ma[8] + $ma[9];
+$v = $ma[-1] + $ma[-2];
+EXPECT
+Use of uninitialized value $ma[5] in addition (+) at - line 4.
+Use of uninitialized value $ma[6] in addition (+) at - line 5.
+Use of uninitialized value $m1 in addition (+) at - line 6.
+Use of uninitialized value in addition (+) at - line 6.
+Use of uninitialized value in addition (+) at - line 7.
+Use of uninitialized value in addition (+) at - line 7.
+Use of uninitialized value in addition (+) at - line 8.
+Use of uninitialized value in addition (+) at - line 8.
+########
+use warnings 'uninitialized';
+my ($v);
+my @mau = (undef) x 258;
+my %mhu = ('foo', undef, 'bar', undef);
+
+$v = $mau[5] + 23;
+$v = $mau[-5] + 45;
+$v = 56 + $mau[6];
+$v = 78 + $mau[-6];
+$v = $mau[7] + $mau[8];
+$v = $mau[256] + $mau[257];
+$v = $mau[-1] + $mau[-2];
+$v = $mhu{foo} + $mhu{bar};
+EXPECT
+Use of uninitialized value $mau[5] in addition (+) at - line 6.
+Use of uninitialized value $mau[-5] in addition (+) at - line 7.
+Use of uninitialized value $mau[6] in addition (+) at - line 8.
+Use of uninitialized value $mau[-6] in addition (+) at - line 9.
+Use of uninitialized value $mau[8] in addition (+) at - line 10.
+Use of uninitialized value $mau[7] in addition (+) at - line 10.
+Use of uninitialized value $mau[257] in addition (+) at - line 11.
+Use of uninitialized value $mau[256] in addition (+) at - line 11.
+Use of uninitialized value $mau[-2] in addition (+) at - line 12.
+Use of uninitialized value $mau[-1] in addition (+) at - line 12.
+Use of uninitialized value $mhu{"bar"} in addition (+) at - line 13.
+Use of uninitialized value $mhu{"foo"} in addition (+) at - line 13.
+########
+use warnings 'uninitialized';
+my ($v);
+our (@ga);
+
+$v = $ga[8] + 21;
+$v = $ga[-8] + 46;
+$v = 57 + $ga[9];
+$v = 58 + $ga[-9];
+$v = $ga[10] + $ga[11];
+$v = $ga[-10] + $ga[-11];
+EXPECT
+Use of uninitialized value $ga[8] in addition (+) at - line 5.
+Use of uninitialized value $ga[-8] in addition (+) at - line 6.
+Use of uninitialized value $ga[9] in addition (+) at - line 7.
+Use of uninitialized value $ga[-9] in addition (+) at - line 8.
+Use of uninitialized value in addition (+) at - line 9.
+Use of uninitialized value in addition (+) at - line 9.
+Use of uninitialized value in addition (+) at - line 10.
+Use of uninitialized value in addition (+) at - line 10.
+########
+use warnings 'uninitialized';
+my ($v);
+our @gau = (undef) x 258;
+our %ghu = ('foo', undef, 'bar', undef);
+
+$v = $gau[8] + 46;
+$v = $gau[-8] + 47;
+$v = 57 + $gau[9];
+$v = 57 + $gau[-9];
+$v = $gau[10] + $gau[11];
+$v = $gau[256] + $gau[257];
+$v = $gau[-1] + $gau[-2];
+$v = $ghu{foo} + $ghu{bar};
+EXPECT
+Use of uninitialized value $gau[8] in addition (+) at - line 6.
+Use of uninitialized value $gau[-8] in addition (+) at - line 7.
+Use of uninitialized value $gau[9] in addition (+) at - line 8.
+Use of uninitialized value $gau[-9] in addition (+) at - line 9.
+Use of uninitialized value $gau[11] in addition (+) at - line 10.
+Use of uninitialized value $gau[10] in addition (+) at - line 10.
+Use of uninitialized value $gau[257] in addition (+) at - line 11.
+Use of uninitialized value $gau[256] in addition (+) at - line 11.
+Use of uninitialized value $gau[-2] in addition (+) at - line 12.
+Use of uninitialized value $gau[-1] in addition (+) at - line 12.
+Use of uninitialized value $ghu{"bar"} in addition (+) at - line 13.
+Use of uninitialized value $ghu{"foo"} in addition (+) at - line 13.
+########
+use warnings 'uninitialized';
+my ($v);
+our @gau = (undef) x 258;
+our %ghu = ('foo', undef, 'bar', undef);
+my @mau = (undef) x 258;
+my %mhu = ('foo', undef, 'bar', undef);
+
+my $i1 = 10;
+my $i2 = 20;
+my $i3 = 2000;
+my $k1 = 'foo';
+my $k2 = 'bar';
+my $k3 = 'baz';
+$v = $mau[$i1] + $mau[$i2];
+$v = $gau[$i1] + $gau[$i2];
+$v = $gau[$i1] + $gau[$i3];
+$v = $mhu{$k1} + $mhu{$k2};
+$v = $ghu{$k1} + $ghu{$k2};
+$v = $ghu{$k1} + $ghu{$k3};
+EXPECT
+Use of uninitialized value $mau[20] in addition (+) at - line 14.
+Use of uninitialized value $mau[10] in addition (+) at - line 14.
+Use of uninitialized value $gau[20] in addition (+) at - line 15.
+Use of uninitialized value $gau[10] in addition (+) at - line 15.
+Use of uninitialized value in addition (+) at - line 16.
+Use of uninitialized value $gau[10] in addition (+) at - line 16.
+Use of uninitialized value $mhu{"bar"} in addition (+) at - line 17.
+Use of uninitialized value $mhu{"foo"} in addition (+) at - line 17.
+Use of uninitialized value $ghu{"bar"} in addition (+) at - line 18.
+Use of uninitialized value $ghu{"foo"} in addition (+) at - line 18.
+Use of uninitialized value in addition (+) at - line 19.
+Use of uninitialized value $ghu{"foo"} in addition (+) at - line 19.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, @ma, %mh, $v);
+our ($g1, $g2, @ga, %gh);
+
+$v = $ma[$m1];
+$v = $ma[$g1];
+$v = $ga[$m2];
+$v = $ga[$g2];
+
+$v = $mh{$m1};
+$v = $mh{$g1};
+$v = $gh{$m2};
+$v = $gh{$g2};
+
+$v = $m1+($m2-$g1);
+$v = $ma[$ga[3]];
+$v = $ga[$ma[4]];
+EXPECT
+Use of uninitialized value $m1 in array element at - line 5.
+Use of uninitialized value $g1 in array element at - line 6.
+Use of uninitialized value $m2 in array element at - line 7.
+Use of uninitialized value $g2 in array element at - line 8.
+Use of uninitialized value $m1 in hash element at - line 10.
+Use of uninitialized value $g1 in hash element at - line 11.
+Use of uninitialized value $m2 in hash element at - line 12.
+Use of uninitialized value $g2 in hash element at - line 13.
+Use of uninitialized value $g1 in subtraction (-) at - line 15.
+Use of uninitialized value $m2 in subtraction (-) at - line 15.
+Use of uninitialized value $m1 in addition (+) at - line 15.
+Use of uninitialized value $ga[3] in array element at - line 16.
+Use of uninitialized value $ma[4] in array element at - line 17.
+########
+use warnings 'uninitialized';
+my (@ma, %mh, $v);
+our (@ga, %gh);
+
+$v = sin $ga[1000];
+$v = sin $ma[1000];
+$v = sin $gh{foo};
+$v = sin $mh{bar};
+
+$v = sin $ga[$$];
+$v = sin $ma[$$];
+$v = sin $gh{$$};
+$v = sin $mh{$$};
+EXPECT
+Use of uninitialized value $ga[1000] in sin at - line 5.
+Use of uninitialized value $ma[1000] in sin at - line 6.
+Use of uninitialized value $gh{"foo"} in sin at - line 7.
+Use of uninitialized value $mh{"bar"} in sin at - line 8.
+Use of uninitialized value within @ga in sin at - line 10.
+Use of uninitialized value within @ma in sin at - line 11.
+Use of uninitialized value within %gh in sin at - line 12.
+Use of uninitialized value within %mh in sin at - line 13.
+########
+use warnings 'uninitialized';
+my (@mat, %mht, $v);
+sub X::TIEARRAY { bless [], 'X' }
+sub X::TIEHASH { bless [], 'X' }
+sub X::FETCH { undef }
+tie @mat, 'X';
+tie %mht, 'X';
+my $key1 = 'akey';
+my $key2 = 'bkey';
+my $index1 = 33;
+my $index2 = 55;
+
+$v = sin $mat[0];
+$v = $mat[0] + $mat[1];
+$v = sin $mat[1000];
+$v = $mat[1000] + $mat[1001];
+
+$v = sin $mat[$index1];
+$v = $mat[$index1] + $mat[$index2];
+
+$v = sin $mht{foo};
+$v = $mht{foo} + $mht{bar};
+
+$v = sin $mht{$key1};
+$v = $mht{$key1} + $mht{$key2};
+
+$v = $1+1;
+EXPECT
+Use of uninitialized value $mat[0] in sin at - line 13.
+Use of uninitialized value in addition (+) at - line 14.
+Use of uninitialized value in addition (+) at - line 14.
+Use of uninitialized value $mat[1000] in sin at - line 15.
+Use of uninitialized value in addition (+) at - line 16.
+Use of uninitialized value in addition (+) at - line 16.
+Use of uninitialized value within @mat in sin at - line 18.
+Use of uninitialized value in addition (+) at - line 19.
+Use of uninitialized value in addition (+) at - line 19.
+Use of uninitialized value $mht{"foo"} in sin at - line 21.
+Use of uninitialized value in addition (+) at - line 22.
+Use of uninitialized value in addition (+) at - line 22.
+Use of uninitialized value within %mht in sin at - line 24.
+Use of uninitialized value in addition (+) at - line 25.
+Use of uninitialized value in addition (+) at - line 25.
+Use of uninitialized value $1 in addition (+) at - line 27.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1, @ga);
+
+print $ga[1000];
+print STDERR $ga[1000];
+print STDERR $m1, $g1, $ga[1],$m2;
+print STDERR "", $ga[1],"";
+EXPECT
+Use of uninitialized value $ga[1000] in print at - line 5.
+Use of uninitialized value $ga[1000] in print at - line 6.
+Use of uninitialized value $m1 in print at - line 7.
+Use of uninitialized value $g1 in print at - line 7.
+Use of uninitialized value in print at - line 7.
+Use of uninitialized value $m2 in print at - line 7.
+Use of uninitialized value $ga[1] in print at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1);
+
+close $m1;	# exercises rv2gv
+close $g1;	# exercises rv2gv
+EXPECT
+Use of uninitialized value $m1 in ref-to-glob cast at - line 5.
+Use of uninitialized value $g1 in ref-to-glob cast at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+our ($g1, $g2);
+
+$v = $$m1;
+$v = $$g1;
+
+$v = @$m1;
+$v = @$g1;
+$v = %$m2;
+$v = %$g2;
+EXPECT
+Use of uninitialized value $m1 in scalar dereference at - line 5.
+Use of uninitialized value $g1 in scalar dereference at - line 6.
+Use of uninitialized value $m1 in array dereference at - line 8.
+Use of uninitialized value $g1 in array dereference at - line 9.
+Use of uninitialized value $m2 in hash dereference at - line 10.
+Use of uninitialized value $g2 in hash dereference at - line 11.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = $m1 | $m2;
+$v = $m1 & $m2;
+$v = $m1 ^ $m2;
+$v = ~$m1;
+
+$v = $g1 | $g2;
+$v = $g1 & $g2;
+$v = $g1 ^ $g2;
+$v = ~$g1;
+EXPECT
+Use of uninitialized value $m1 in bitwise or (|) at - line 5.
+Use of uninitialized value $m2 in bitwise or (|) at - line 5.
+Use of uninitialized value $m1 in bitwise and (&) at - line 6.
+Use of uninitialized value $m2 in bitwise and (&) at - line 6.
+Use of uninitialized value $m1 in bitwise xor (^) at - line 7.
+Use of uninitialized value $m2 in bitwise xor (^) at - line 7.
+Use of uninitialized value $m1 in 1's complement (~) at - line 8.
+Use of uninitialized value $g1 in bitwise or (|) at - line 10.
+Use of uninitialized value $g2 in bitwise or (|) at - line 10.
+Use of uninitialized value $g1 in bitwise and (&) at - line 11.
+Use of uninitialized value $g2 in bitwise and (&) at - line 11.
+Use of uninitialized value $g1 in bitwise xor (^) at - line 12.
+Use of uninitialized value $g2 in bitwise xor (^) at - line 12.
+Use of uninitialized value $g1 in 1's complement (~) at - line 13.
+########
+use warnings 'uninitialized';
+my ($v);
+
+my  $tmp1; $v = $tmp1++; # (doesn't warn)
+our $tmp2; $v = $tmp2++; # (doesn't warn)
+my  $tmp3; $v = ++$tmp1; # (doesn't warn)
+our $tmp4; $v = ++$tmp2; # (doesn't warn)
+
+my  $tmp5; $v = $tmp5--; # (doesn't warn)
+our $tmp6; $v = $tmp6--; # (doesn't warn)
+my  $tmp7; $v = --$tmp7; # (doesn't warn)
+our $tmp8; $v = --$tmp8; # (doesn't warn)
+EXPECT
+########
+use warnings 'uninitialized';
+
+my $s1; chomp $s1;
+my $s2; chop  $s2;
+my ($s3,$s4); chomp ($s3,$s4);
+my ($s5,$s6); chop  ($s5,$s6);
+EXPECT
+Use of uninitialized value $s1 in scalar chomp at - line 3.
+Use of uninitialized value $s2 in scalar chop at - line 4.
+Use of uninitialized value $s4 in chomp at - line 5.
+Use of uninitialized value $s3 in chomp at - line 5.
+Use of uninitialized value $s5 in chop at - line 6.
+Use of uninitialized value $s6 in chop at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1);
+
+local $/ =\$m1;
+my $x = "abc";
+chomp $x; chop $x;
+my $y;
+chomp ($x, $y); chop ($x, $y);
+EXPECT
+Use of uninitialized value ${$/} in scalar chomp at - line 6.
+Use of uninitialized value ${$/} in chomp at - line 8.
+Use of uninitialized value $y in chomp at - line 8.
+Use of uninitialized value ${$/} in chomp at - line 8.
+Use of uninitialized value $y in chop at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1, @ma, %mh);
+our ($g1);
+
+delete $ma[$m1];
+delete @ma[$m1, $g1];
+delete $mh{$m1};
+delete @mh{$m1, $g1};
+EXPECT
+Use of uninitialized value $m1 in delete at - line 5.
+Use of uninitialized value $m1 in delete at - line 6.
+Use of uninitialized value $g1 in delete at - line 6.
+Use of uninitialized value $m1 in delete at - line 7.
+Use of uninitialized value $m1 in delete at - line 8.
+Use of uninitialized value $g1 in delete at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1, @ma, %mh);
+our ($g1);
+
+my @a = @ma[$m1, $g1];
+@a = (4,5)[$m1, $g1];
+@a = @mh{$m1, $g1};
+EXPECT
+Use of uninitialized value $m1 in array slice at - line 5.
+Use of uninitialized value $g1 in array slice at - line 5.
+Use of uninitialized value $m1 in list slice at - line 6.
+Use of uninitialized value $g1 in list slice at - line 6.
+Use of uninitialized value $m1 in hash slice at - line 7.
+Use of uninitialized value $g1 in hash slice at - line 7.
+########
+use warnings 'uninitialized';
+my ($m1, @ma, %mh, $v);
+our ($g1, @ga, %gh);
+
+$v = exists $ma[$m1];
+$v = exists $ga[$g1];
+$v = exists $mh{$m1};
+$v = exists $gh{$g1};
+EXPECT
+Use of uninitialized value $m1 in exists at - line 5.
+Use of uninitialized value $g1 in exists at - line 6.
+Use of uninitialized value $m1 in exists at - line 7.
+Use of uninitialized value $g1 in exists at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+my ($x1,$x2);
+$v = $x1 << $m1;
+$v = $x2 << $g1;
+EXPECT
+Use of uninitialized value $m1 in left bitshift (<<) at - line 6.
+Use of uninitialized value $x1 in left bitshift (<<) at - line 6.
+Use of uninitialized value $g1 in left bitshift (<<) at - line 7.
+Use of uninitialized value $x2 in left bitshift (<<) at - line 7.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+our ($g1, $g2);
+
+use integer;
+$v = $m1 + $g1;
+$v = $m1 - $g1;
+$v = $m1 * $g1;
+eval {$v = $m1 / $g1};
+$v = $m2 / 2;
+eval {$v = $m1 % $g1};
+$v = $m2 % 2;
+$v = $m1 < $g1;
+$v = $m1 > $g1;
+$v = $m1 <= $g1;
+$v = $m1 >= $g1;
+$v = $m1 == $g1;
+$v = $m1 != $g1;
+$v = $m1 <=> $g1;
+$v = -$m1;
+EXPECT
+Use of uninitialized value $g1 in integer addition (+) at - line 6.
+Use of uninitialized value $m1 in integer addition (+) at - line 6.
+Use of uninitialized value $g1 in integer subtraction (-) at - line 7.
+Use of uninitialized value $m1 in integer subtraction (-) at - line 7.
+Use of uninitialized value $g1 in integer multiplication (*) at - line 8.
+Use of uninitialized value $m1 in integer multiplication (*) at - line 8.
+Use of uninitialized value $g1 in integer division (/) at - line 9.
+Use of uninitialized value $m2 in integer division (/) at - line 10.
+Use of uninitialized value $g1 in integer modulus (%) at - line 11.
+Use of uninitialized value $m1 in integer modulus (%) at - line 11.
+Use of uninitialized value $m2 in integer modulus (%) at - line 12.
+Use of uninitialized value $g1 in integer lt (<) at - line 13.
+Use of uninitialized value $m1 in integer lt (<) at - line 13.
+Use of uninitialized value $g1 in integer gt (>) at - line 14.
+Use of uninitialized value $m1 in integer gt (>) at - line 14.
+Use of uninitialized value $g1 in integer le (<=) at - line 15.
+Use of uninitialized value $m1 in integer le (<=) at - line 15.
+Use of uninitialized value $g1 in integer ge (>=) at - line 16.
+Use of uninitialized value $m1 in integer ge (>=) at - line 16.
+Use of uninitialized value $g1 in integer eq (==) at - line 17.
+Use of uninitialized value $m1 in integer eq (==) at - line 17.
+Use of uninitialized value $g1 in integer ne (!=) at - line 18.
+Use of uninitialized value $m1 in integer ne (!=) at - line 18.
+Use of uninitialized value $g1 in integer comparison (<=>) at - line 19.
+Use of uninitialized value $m1 in integer comparison (<=>) at - line 19.
+Use of uninitialized value $m1 in integer negation (-) at - line 20.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+our ($g1, $g2);
+
+$v = int($g1);
+$v = abs($g2);
+EXPECT
+Use of uninitialized value $g1 in int at - line 5.
+Use of uninitialized value $g1 in int at - line 5.
+Use of uninitialized value $g2 in abs at - line 6.
+Use of uninitialized value $g2 in abs at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+our ($g1);
+
+$v = pack $m1;
+$v = pack "i*", $m2, $g1, $g2;
+my @unpack = unpack $m1, $m2;
+EXPECT
+Use of uninitialized value $m1 in pack at - line 5.
+Use of uninitialized value $m2 in pack at - line 6.
+Use of uninitialized value $g1 in pack at - line 6.
+Use of uninitialized value $g2 in pack at - line 6.
+Use of uninitialized value $m1 in unpack at - line 7.
+Use of uninitialized value $m2 in unpack at - line 7.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1);
+
+my @sort;
+@sort = sort $m1, $g1;
+@sort = sort {$a <=> $b} $m1, $g1;
+sub sortf {$a-1 <=> $b-1};
+@sort = sort  &sortf, $m1, $g1;
+EXPECT
+Use of uninitialized value $m1 in sort at - line 6.
+Use of uninitialized value $g1 in sort at - line 6.
+Use of uninitialized value $m1 in sort at - line 6.
+Use of uninitialized value $g1 in sort at - line 6.
+Use of uninitialized value $m1 in sort at - line 7.
+Use of uninitialized value $g1 in sort at - line 7.
+Use of uninitialized value $m1 in sort at - line 7.
+Use of uninitialized value $g1 in sort at - line 7.
+Use of uninitialized value $a in subtraction (-) at - line 8.
+Use of uninitialized value $b in subtraction (-) at - line 8.
+Use of uninitialized value $m1 in sort at - line 9.
+Use of uninitialized value $g1 in sort at - line 9.
+Use of uninitialized value $m1 in sort at - line 9.
+Use of uninitialized value $m1 in sort at - line 9.
+Use of uninitialized value $g1 in sort at - line 9.
+Use of uninitialized value $g1 in sort at - line 9.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, $v);
+our ($g1);
+
+eval { $v = $m1 / $g1 };
+$v = $m2 / 2;
+eval { $v = $m1 % $g1 };
+$v = $m2 % 2;
+$v = $m1 == $g1;
+$v = $m1 >= $g1;
+$v = $m1 >  $g1;
+$v = $m1 <= $g1;
+$v = $m1 <  $g1;
+$v = $m1 *  $g1;
+$v = $m1 <=>$g1;
+$v = $m1 != $g1;
+$v = $m1   -$g1;
+$v = $m1 ** $g1;
+$v = $m1 +  $g1;
+$v = $m1 -  $g1;
+EXPECT
+Use of uninitialized value $g1 in division (/) at - line 5.
+Use of uninitialized value $m1 in division (/) at - line 5.
+Use of uninitialized value $m2 in division (/) at - line 6.
+Use of uninitialized value $g1 in modulus (%) at - line 7.
+Use of uninitialized value $m1 in modulus (%) at - line 7.
+Use of uninitialized value $m2 in modulus (%) at - line 8.
+Use of uninitialized value $g1 in numeric eq (==) at - line 9.
+Use of uninitialized value $m1 in numeric eq (==) at - line 9.
+Use of uninitialized value $g1 in numeric ge (>=) at - line 10.
+Use of uninitialized value $m1 in numeric ge (>=) at - line 10.
+Use of uninitialized value $g1 in numeric gt (>) at - line 11.
+Use of uninitialized value $m1 in numeric gt (>) at - line 11.
+Use of uninitialized value $g1 in numeric le (<=) at - line 12.
+Use of uninitialized value $m1 in numeric le (<=) at - line 12.
+Use of uninitialized value $g1 in numeric lt (<) at - line 13.
+Use of uninitialized value $m1 in numeric lt (<) at - line 13.
+Use of uninitialized value $g1 in multiplication (*) at - line 14.
+Use of uninitialized value $m1 in multiplication (*) at - line 14.
+Use of uninitialized value $g1 in numeric comparison (<=>) at - line 15.
+Use of uninitialized value $m1 in numeric comparison (<=>) at - line 15.
+Use of uninitialized value $g1 in numeric ne (!=) at - line 16.
+Use of uninitialized value $m1 in numeric ne (!=) at - line 16.
+Use of uninitialized value $g1 in subtraction (-) at - line 17.
+Use of uninitialized value $m1 in subtraction (-) at - line 17.
+Use of uninitialized value $g1 in exponentiation (**) at - line 18.
+Use of uninitialized value $m1 in exponentiation (**) at - line 18.
+Use of uninitialized value $g1 in addition (+) at - line 19.
+Use of uninitialized value $m1 in addition (+) at - line 19.
+Use of uninitialized value $g1 in subtraction (-) at - line 20.
+Use of uninitialized value $m1 in subtraction (-) at - line 20.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = *global1{$m1};
+$v = prototype $g1;
+$v = bless [], $g1;
+$v = `$m1`;
+
+$v = $m1 . $g1;
+EXPECT
+Use of uninitialized value $m1 in glob elem at - line 5.
+Use of uninitialized value $g1 in subroutine prototype at - line 6.
+Use of uninitialized value $g1 in bless at - line 7.
+Use of uninitialized value $m1 in quoted execution (``, qx) at - line 8.
+Use of uninitialized value $g1 in concatenation (.) or string at - line 10.
+Use of uninitialized value $m1 in concatenation (.) or string at - line 10.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1, $g2);
+
+/y/;
+/$m1/;
+/$g1/;
+
+s/y/z/;		undef $_;
+s/$m1/z/;	undef $_;
+s//$g1/;	undef $_;
+s/$m1/$g1/;	undef $_;
+tr/x/y/;	undef $_;
+
+my $_; 
+/y/;
+/$m1/;
+/$g1/;
+s/y/z/;		undef $_;
+s/$m1/z/;	undef $_;
+s//$g1/;	undef $_;
+s/$m1/$g1/;	undef $_;
+tr/x/y/;	undef $_;
+
+$g2 =~ /y/;
+$g2 =~ /$m1/;
+$g2 =~ /$g1/;
+$g2 =~ s/y/z/;		undef $g2;
+$g2 =~ s/$m1/z/;	undef $g2;
+$g2 =~ s//$g1/;		undef $g2;
+$g2 =~ s/$m1/$g1/;	undef $g2;
+$g2 =~ tr/x/y/;		undef $g2; # XXX can't extract var name yet
+
+my $foo = "abc";
+$foo =~ /$m1/;
+$foo =~ /$g1/;
+$foo =~ s/y/z/;
+$foo =~ s/$m1/z/;
+$foo =~ s//$g1/;
+$foo =~ s/$m1/$g1/;
+$foo =~ s/./$m1/e;
+EXPECT
+Use of uninitialized value $_ in pattern match (m//) at - line 5.
+Use of uninitialized value $m1 in regexp compilation at - line 6.
+Use of uninitialized value $_ in pattern match (m//) at - line 6.
+Use of uninitialized value $g1 in regexp compilation at - line 7.
+Use of uninitialized value $_ in pattern match (m//) at - line 7.
+Use of uninitialized value $_ in substitution (s///) at - line 9.
+Use of uninitialized value $m1 in regexp compilation at - line 10.
+Use of uninitialized value $_ in substitution (s///) at - line 10.
+Use of uninitialized value $_ in substitution (s///) at - line 10.
+Use of uninitialized value $_ in substitution (s///) at - line 11.
+Use of uninitialized value $g1 in substitution (s///) at - line 11.
+Use of uninitialized value $_ in substitution (s///) at - line 11.
+Use of uninitialized value $g1 in substitution (s///) at - line 11.
+Use of uninitialized value $m1 in regexp compilation at - line 12.
+Use of uninitialized value $_ in substitution (s///) at - line 12.
+Use of uninitialized value $_ in substitution (s///) at - line 12.
+Use of uninitialized value $g1 in substitution iterator at - line 12.
+Use of uninitialized value $_ in transliteration (tr///) at - line 13.
+Use of uninitialized value $_ in pattern match (m//) at - line 16.
+Use of uninitialized value $m1 in regexp compilation at - line 17.
+Use of uninitialized value $_ in pattern match (m//) at - line 17.
+Use of uninitialized value $g1 in regexp compilation at - line 18.
+Use of uninitialized value $_ in pattern match (m//) at - line 18.
+Use of uninitialized value $_ in substitution (s///) at - line 19.
+Use of uninitialized value $m1 in regexp compilation at - line 20.
+Use of uninitialized value $_ in substitution (s///) at - line 20.
+Use of uninitialized value $_ in substitution (s///) at - line 20.
+Use of uninitialized value $_ in substitution (s///) at - line 21.
+Use of uninitialized value $g1 in substitution (s///) at - line 21.
+Use of uninitialized value $_ in substitution (s///) at - line 21.
+Use of uninitialized value $g1 in substitution (s///) at - line 21.
+Use of uninitialized value $m1 in regexp compilation at - line 22.
+Use of uninitialized value $_ in substitution (s///) at - line 22.
+Use of uninitialized value $_ in substitution (s///) at - line 22.
+Use of uninitialized value $g1 in substitution iterator at - line 22.
+Use of uninitialized value $_ in transliteration (tr///) at - line 23.
+Use of uninitialized value $g2 in pattern match (m//) at - line 25.
+Use of uninitialized value $m1 in regexp compilation at - line 26.
+Use of uninitialized value $g2 in pattern match (m//) at - line 26.
+Use of uninitialized value $g1 in regexp compilation at - line 27.
+Use of uninitialized value $g2 in pattern match (m//) at - line 27.
+Use of uninitialized value $g2 in substitution (s///) at - line 28.
+Use of uninitialized value $m1 in regexp compilation at - line 29.
+Use of uninitialized value $g2 in substitution (s///) at - line 29.
+Use of uninitialized value $g2 in substitution (s///) at - line 29.
+Use of uninitialized value $g2 in substitution (s///) at - line 30.
+Use of uninitialized value $g1 in substitution (s///) at - line 30.
+Use of uninitialized value $g2 in substitution (s///) at - line 30.
+Use of uninitialized value $g1 in substitution (s///) at - line 30.
+Use of uninitialized value $m1 in regexp compilation at - line 31.
+Use of uninitialized value $g2 in substitution (s///) at - line 31.
+Use of uninitialized value $g2 in substitution (s///) at - line 31.
+Use of uninitialized value $g1 in substitution iterator at - line 31.
+Use of uninitialized value in transliteration (tr///) at - line 32.
+Use of uninitialized value $m1 in regexp compilation at - line 35.
+Use of uninitialized value $g1 in regexp compilation at - line 36.
+Use of uninitialized value $m1 in regexp compilation at - line 38.
+Use of uninitialized value $g1 in substitution (s///) at - line 39.
+Use of uninitialized value $m1 in regexp compilation at - line 40.
+Use of uninitialized value $g1 in substitution iterator at - line 40.
+Use of uninitialized value $m1 in substitution iterator at - line 41.
+########
+use warnings 'uninitialized';
+my ($m1);
+
+{ my $foo = "abc"; (substr($foo,0,0)) = ($m1) }
+EXPECT
+Use of uninitialized value $m1 in list assignment at - line 4.
+########
+use warnings 'uninitialized';
+our ($g1);
+
+study;
+study $g1;
+EXPECT
+Use of uninitialized value $_ in study at - line 4.
+Use of uninitialized value $g1 in study at - line 5.
+########
+use warnings 'uninitialized';
+my ($m1);
+
+pos()=0;
+pos($m1)=0;
+EXPECT
+Use of uninitialized value $_ in scalar assignment at - line 4.
+Use of uninitialized value $m1 in scalar assignment at - line 5.
+########
+use warnings 'uninitialized';
+my ($m1);
+
+{ my $x = "a" x $m1 }		# NB LHS of repeat does not warn
+{ my @x = ("a") x $m1 }
+EXPECT
+Use of uninitialized value $m1 in repeat (x) at - line 4.
+Use of uninitialized value $m1 in repeat (x) at - line 5.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = "$m1";
+
+$v = $m1 lt $g1;
+$v = $m1 le $g1;
+$v = $m1 gt $g1;
+$v = $m1 ge $g1;
+$v = $m1 eq $g1;
+$v = $m1 ne $g1;
+$v = $m1 cmp $g1;
+EXPECT
+Use of uninitialized value $m1 in string at - line 5.
+Use of uninitialized value $m1 in string lt at - line 7.
+Use of uninitialized value $g1 in string lt at - line 7.
+Use of uninitialized value $m1 in string le at - line 8.
+Use of uninitialized value $g1 in string le at - line 8.
+Use of uninitialized value $m1 in string gt at - line 9.
+Use of uninitialized value $g1 in string gt at - line 9.
+Use of uninitialized value $m1 in string ge at - line 10.
+Use of uninitialized value $g1 in string ge at - line 10.
+Use of uninitialized value $m1 in string eq at - line 11.
+Use of uninitialized value $g1 in string eq at - line 11.
+Use of uninitialized value $m1 in string ne at - line 12.
+Use of uninitialized value $g1 in string ne at - line 12.
+Use of uninitialized value $m1 in string comparison (cmp) at - line 13.
+Use of uninitialized value $g1 in string comparison (cmp) at - line 13.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = atan2($m1,$g1);
+$v = sin $m1;
+$v = cos $m1;
+$v = rand $m1;
+$v = srand $m1;
+$v = exp $m1;
+$v = eval {log $m1};
+$v = sqrt $m1;
+$v = hex $m1;
+$v = oct $m1;
+$v = length $m1;
+$v = length;
+EXPECT
+Use of uninitialized value $g1 in atan2 at - line 5.
+Use of uninitialized value $m1 in atan2 at - line 5.
+Use of uninitialized value $m1 in sin at - line 6.
+Use of uninitialized value $m1 in cos at - line 7.
+Use of uninitialized value $m1 in rand at - line 8.
+Use of uninitialized value $m1 in srand at - line 9.
+Use of uninitialized value $m1 in exp at - line 10.
+Use of uninitialized value $m1 in log at - line 11.
+Use of uninitialized value $m1 in sqrt at - line 12.
+Use of uninitialized value $m1 in hex at - line 13.
+Use of uninitialized value $m1 in oct at - line 14.
+Use of uninitialized value $m1 in length at - line 15.
+Use of uninitialized value $_ in length at - line 16.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = substr $m1, $g1;
+$v = substr $m1, $g1, $m2;
+$v = substr $m1, $g1, $m2, $g2;	undef $m1;
+substr($m1, $g1) = $g2;		undef $m1; # NB global2
+substr($m1, $g1, $m2) = $g2;	undef $m1; # isn't identified
+
+$v = eval {vec ($m1, $g1, $m2)};
+eval {vec ($m1, $g1, $m2) = $g2};	undef $m1; # ditto
+
+$v = index  $m1, $m2;
+$v = index  $m1, $m2, $g1;
+$v = rindex $m1, $m2;
+$v = rindex $m1, $m2, $g1;
+EXPECT
+Use of uninitialized value $g1 in substr at - line 5.
+Use of uninitialized value $m1 in substr at - line 5.
+Use of uninitialized value $m2 in substr at - line 6.
+Use of uninitialized value $g1 in substr at - line 6.
+Use of uninitialized value $m1 in substr at - line 6.
+Use of uninitialized value $g2 in substr at - line 7.
+Use of uninitialized value $m2 in substr at - line 7.
+Use of uninitialized value $g1 in substr at - line 7.
+Use of uninitialized value $m1 in substr at - line 7.
+Use of uninitialized value $m1 in substr at - line 7.
+Use of uninitialized value $g1 in substr at - line 8.
+Use of uninitialized value $m1 in substr at - line 8.
+Use of uninitialized value in scalar assignment at - line 8.
+Use of uninitialized value $m2 in substr at - line 9.
+Use of uninitialized value $g1 in substr at - line 9.
+Use of uninitialized value $m1 in substr at - line 9.
+Use of uninitialized value in scalar assignment at - line 9.
+Use of uninitialized value $m2 in vec at - line 11.
+Use of uninitialized value $g1 in vec at - line 11.
+Use of uninitialized value $m1 in vec at - line 11.
+Use of uninitialized value $m2 in vec at - line 12.
+Use of uninitialized value $g1 in vec at - line 12.
+Use of uninitialized value $m1 in vec at - line 12.
+Use of uninitialized value $m1 in index at - line 14.
+Use of uninitialized value $m2 in index at - line 14.
+Use of uninitialized value $g1 in index at - line 15.
+Use of uninitialized value $m1 in index at - line 15.
+Use of uninitialized value $m2 in index at - line 15.
+Use of uninitialized value $m2 in rindex at - line 16.
+Use of uninitialized value $m1 in rindex at - line 16.
+Use of uninitialized value $g1 in rindex at - line 17.
+Use of uninitialized value $m2 in rindex at - line 17.
+Use of uninitialized value $m1 in rindex at - line 17.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = sprintf $m1;
+$v = sprintf '%d%d%d%d', $m1, $m2, $g1, $g2;
+eval {formline $m1 };	undef $m1;
+formline '@<<@<<@<<@<<', $m1, $m2, $g1, $g2;
+EXPECT
+Use of uninitialized value $m1 in sprintf at - line 5.
+Use of uninitialized value $m1 in sprintf at - line 6.
+Use of uninitialized value $m2 in sprintf at - line 6.
+Use of uninitialized value $g1 in sprintf at - line 6.
+Use of uninitialized value $g2 in sprintf at - line 6.
+Use of uninitialized value $m1 in formline at - line 7.
+Use of uninitialized value $m1 in formline at - line 8.
+Use of uninitialized value $m2 in formline at - line 8.
+Use of uninitialized value $g1 in formline at - line 8.
+Use of uninitialized value $g2 in formline at - line 8.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = crypt $m1, $g1;
+
+$v = ord;
+$v = ord $m1;
+$v = chr;
+$v = chr $m1;
+
+# XXX these functions don't warn!
+$v = ucfirst;
+$v = ucfirst $m1;
+$v = lcfirst;
+$v = lcfirst $m1;
+$v = uc;
+$v = uc $m1;
+$v = lc;
+$v = lc $m1;
+
+$v = quotemeta;
+$v = quotemeta $m1;
+EXPECT
+Use of uninitialized value $m1 in crypt at - line 5.
+Use of uninitialized value $g1 in crypt at - line 5.
+Use of uninitialized value $_ in ord at - line 7.
+Use of uninitialized value $m1 in ord at - line 8.
+Use of uninitialized value $_ in chr at - line 9.
+Use of uninitialized value $m1 in chr at - line 10.
+Use of uninitialized value $_ in quotemeta at - line 22.
+Use of uninitialized value $m1 in quotemeta at - line 23.
+########
+use warnings 'uninitialized';
+my ($m1, $v1, $v2, $v3, $v4);
+our ($g1);
+
+($v1,$v2,$v3,$v4) = split;
+($v1,$v2,$v3,$v4) = split $m1;
+($v1,$v2,$v3,$v4) = split $m1, $m2;
+($v1,$v2,$v3,$v4) = split $m1, $m2, $g1;
+
+$v1 = join $m1;
+$v2 = join $m1, $m2;
+$v3 = join $m1, $m2, $m3;
+EXPECT
+Use of uninitialized value $_ in split at - line 5.
+Use of uninitialized value $m1 in regexp compilation at - line 6.
+Use of uninitialized value $_ in split at - line 6.
+Use of uninitialized value $m1 in regexp compilation at - line 7.
+Use of uninitialized value $m2 in split at - line 7.
+Use of uninitialized value $m1 in regexp compilation at - line 8.
+Use of uninitialized value $g1 in split at - line 8.
+Use of uninitialized value $m2 in split at - line 8.
+Use of uninitialized value $m1 in join or string at - line 10.
+Use of uninitialized value $m1 in join or string at - line 11.
+Use of uninitialized value $m2 in join or string at - line 11.
+Use of uninitialized value $m1 in join or string at - line 12.
+Use of uninitialized value $m2 in join or string at - line 12.
+Use of uninitialized value $m3 in join or string at - line 12.
+########
+use warnings 'uninitialized';
+my ($m1, $m2, @ma, $v);
+
+our @foo1=(1,undef); chomp @foo1;
+my  @foo2=(1,undef); chomp @foo2;
+our @foo3=(1,undef); chop  @foo3;
+my  @foo4=(1,undef); chop  @foo4;
+our @foo5=(1,undef); $v = sprintf "%s%s",@foo5;
+my  @foo6=(1,undef); $v = sprintf "%s%s",@foo6;
+our %foo7=('foo'=>'bar','baz'=>undef); $v = sprintf "%s%s",%foo7;
+my  %foo8=('foo'=>'bar','baz'=>undef); $v = sprintf "%s%s",%foo8;
+our @foo9 =(1,undef); $v = sprintf "%s%s%s%s",$m1,@foo9, $ma[2];
+my  @foo10=(1,undef); $v = sprintf "%s%s%s%s",$m2,@foo10,$ma[2];
+our %foo11=('foo'=>'bar','baz'=>undef); $v = join '', %foo11;
+my  %foo12=('foo'=>'bar','baz'=>undef); $v = join '', %foo12;
+our %foo13=(1..2000,'foo'=>'bar','baz'=>undef); $v = join '', %foo13;
+my  %foo14=(1..2000,'foo'=>'bar','baz'=>undef); $v = join '', %foo14;
+EXPECT
+Use of uninitialized value $foo1[1] in chomp at - line 4.
+Use of uninitialized value $foo2[1] in chomp at - line 5.
+Use of uninitialized value $foo3[1] in chop at - line 6.
+Use of uninitialized value $foo4[1] in chop at - line 7.
+Use of uninitialized value $foo5[1] in sprintf at - line 8.
+Use of uninitialized value $foo6[1] in sprintf at - line 9.
+Use of uninitialized value $foo7{"baz"} in sprintf at - line 10.
+Use of uninitialized value $foo8{"baz"} in sprintf at - line 11.
+Use of uninitialized value $m1 in sprintf at - line 12.
+Use of uninitialized value $foo9[1] in sprintf at - line 12.
+Use of uninitialized value in sprintf at - line 12.
+Use of uninitialized value $m2 in sprintf at - line 13.
+Use of uninitialized value $foo10[1] in sprintf at - line 13.
+Use of uninitialized value in sprintf at - line 13.
+Use of uninitialized value $foo11{"baz"} in join or string at - line 14.
+Use of uninitialized value $foo12{"baz"} in join or string at - line 15.
+Use of uninitialized value within %foo13 in join or string at - line 16.
+Use of uninitialized value within %foo14 in join or string at - line 17.
+########
+use warnings 'uninitialized';
+my ($v);
+
+undef $^A; $v = $^A + ${^FOO}; # should output '^A' not chr(1)
+*GLOB1 = *GLOB2;
+$v = $GLOB1 + 1;
+$v = $GLOB2 + 1;
+EXPECT
+Use of uninitialized value $^FOO in addition (+) at - line 4.
+Use of uninitialized value $^A in addition (+) at - line 4.
+Use of uninitialized value $GLOB1 in addition (+) at - line 6.
+Use of uninitialized value $GLOB2 in addition (+) at - line 7.
+########
+use warnings 'uninitialized';
+my ($v);
+
+# check hash key is sanitised
+my %h = ("\0011\002\r\n\t\f\"\\abcdefghijklmnopqrstuvwxyz", undef);
+$v = join '', %h;
+EXPECT
+Use of uninitialized value $h{"\0011\2\r\n\t\f\"\\abcdefghijkl"...} in join or string at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = eval { \&$m1 };
+$v = eval { \&$g1 };
+
+my @a;
+@a = splice @a, $m1, $g1;
+$v = 1 + splice @a, $m1, $g1;
+
+my $x = bless [], 'Z';
+eval { $x->$m1() };
+
+eval { &$m1() };
+eval { &$g1() };
+
+warn $m1,$g1,"foo";
+
+eval { die $m1, $g1 };
+
+reset $m1;
+reset $g1;
+EXPECT
+Use of uninitialized value $m1 in subroutine dereference at - line 5.
+Use of uninitialized value $m1 in subroutine dereference at - line 5.
+Use of uninitialized value $g1 in subroutine dereference at - line 6.
+Use of uninitialized value $g1 in subroutine dereference at - line 6.
+Use of uninitialized value $m1 in splice at - line 9.
+Use of uninitialized value $g1 in splice at - line 9.
+Use of uninitialized value $m1 in splice at - line 10.
+Use of uninitialized value $g1 in splice at - line 10.
+Use of uninitialized value in addition (+) at - line 10.
+Use of uninitialized value $m1 in method lookup at - line 13.
+Use of uninitialized value $m1 in subroutine entry at - line 15.
+Use of uninitialized value $g1 in subroutine entry at - line 16.
+Use of uninitialized value $m1 in warn at - line 18.
+Use of uninitialized value $g1 in warn at - line 18.
+foo at - line 18.
+Use of uninitialized value $m1 in die at - line 20.
+Use of uninitialized value $g1 in die at - line 20.
+Use of uninitialized value $m1 in symbol reset at - line 22.
+Use of uninitialized value $g1 in symbol reset at - line 23.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1);
+
+open FOO;		# accesses $FOO
+my $foo = 'FO';
+open($foo."O");	# accesses $FOO
+open my $x;		# accesses ${*$x}
+open $foobar;	# accesses ${*$foobar}
+my $y;
+open $y, $m1;
+eval { open $y, $m1, $g1 };
+open $y, '<', $g1;
+
+sysopen $y, $m1, $m2;
+sysopen $y, $m1, $g1, $m2;
+
+my $old = umask;
+umask $m1;
+umask $g1;
+umask $old;
+
+binmode STDIN, $m1;
+EXPECT
+Use of uninitialized value $FOO in open at - line 5.
+Use of uninitialized value in open at - line 7.
+Use of uninitialized value in open at - line 8.
+Use of uninitialized value in open at - line 9.
+Use of uninitialized value $m1 in open at - line 11.
+Use of uninitialized value $m1 in open at - line 12.
+Use of uninitialized value $g1 in open at - line 13.
+Use of uninitialized value $m2 in sysopen at - line 15.
+Use of uninitialized value $m1 in sysopen at - line 15.
+Use of uninitialized value $m2 in sysopen at - line 16.
+Use of uninitialized value $g1 in sysopen at - line 16.
+Use of uninitialized value $m1 in sysopen at - line 16.
+Use of uninitialized value $m1 in umask at - line 19.
+Use of uninitialized value $g1 in umask at - line 20.
+Use of uninitialized value $m1 in binmode at - line 23.
+Use of uninitialized value $m1 in binmode at - line 23.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1);
+
+eval { my $x; tie $x, $m1 };
+
+eval { my $x; read    $m1, $x, $g1 };
+eval { my $x; read    $m1, $x, $g1, $g2 };
+eval { my $x; sysread $m1, $x, $g1 };
+eval { my $x; sysread $m1, $x, $g1, $g2 };
+EXPECT
+Use of uninitialized value $m1 in tie at - line 5.
+Use of uninitialized value $m1 in tie at - line 5.
+Use of uninitialized value $m1 in ref-to-glob cast at - line 7.
+Use of uninitialized value $g1 in read at - line 7.
+Use of uninitialized value $m1 in ref-to-glob cast at - line 8.
+Use of uninitialized value $g1 in read at - line 8.
+Use of uninitialized value $g2 in read at - line 8.
+Use of uninitialized value $m1 in ref-to-glob cast at - line 9.
+Use of uninitialized value $g1 in sysread at - line 9.
+Use of uninitialized value $m1 in ref-to-glob cast at - line 10.
+Use of uninitialized value $g1 in sysread at - line 10.
+Use of uninitialized value $g2 in sysread at - line 10.
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1, @ga);
+
+printf $m1;
+printf STDERR "%d%d%d%d\n", $m1, $m2, $g1, $g2;
+printf $ga[1000];
+printf STDERR "FOO1:%s\n", $ga[1000];
+printf STDERR "FOO2:%s%s%s%s\n", $m1, $g1, $ga[1],$m2;
+printf STDERR "FOO3:%s%s%s\n", "X", $ga[1],"Y";
+EXPECT
+Use of uninitialized value $m1 in printf at - line 5.
+Use of uninitialized value $m1 in printf at - line 6.
+Use of uninitialized value $m2 in printf at - line 6.
+Use of uninitialized value $g1 in printf at - line 6.
+Use of uninitialized value $g2 in printf at - line 6.
+0000
+Use of uninitialized value $ga[1000] in printf at - line 7.
+Use of uninitialized value $ga[1000] in printf at - line 8.
+FOO1:
+Use of uninitialized value $m1 in printf at - line 9.
+Use of uninitialized value $g1 in printf at - line 9.
+Use of uninitialized value in printf at - line 9.
+Use of uninitialized value $m2 in printf at - line 9.
+FOO2:
+Use of uninitialized value $ga[1] in printf at - line 10.
+FOO3:XY
+########
+use warnings 'uninitialized';
+my ($m1);
+our ($g1);
+
+eval { my $x; seek    $x,$m1, $g1 };
+eval { my $x; sysseek $x,$m1, $g1 };
+eval { syswrite $m1, $g1 };
+eval { syswrite STDERR, $m1 };
+eval { syswrite STDERR, $m1, $g1 };
+eval { syswrite STDERR, $m1, $g1, $m2 };
+eval { my $x; flock $x, $g1 };
+eval { my $x; socket $x, $m1, $g1, $m2 };
+eval { my ($x,$y); socketpair $x, $y, $m1, $g1, $m2 };
+EXPECT
+Use of uninitialized value $x in ref-to-glob cast at - line 5.
+Use of uninitialized value $g1 in seek at - line 5.
+Use of uninitialized value $m1 in seek at - line 5.
+Use of uninitialized value $x in ref-to-glob cast at - line 6.
+Use of uninitialized value $g1 in sysseek at - line 6.
+Use of uninitialized value $m1 in sysseek at - line 6.
+Use of uninitialized value $m1 in ref-to-glob cast at - line 7.
+Use of uninitialized value $g1 in syswrite at - line 7.
+Use of uninitialized value $m1 in syswrite at - line 8.
+Use of uninitialized value $m1 in syswrite at - line 8.
+Use of uninitialized value $g1 in syswrite at - line 9.
+Use of uninitialized value $m1 in syswrite at - line 9.
+Use of uninitialized value $g1 in syswrite at - line 10.
+Use of uninitialized value $m1 in syswrite at - line 10.
+Use of uninitialized value $m2 in syswrite at - line 10.
+Use of uninitialized value $x in ref-to-glob cast at - line 11.
+Use of uninitialized value $g1 in flock at - line 11.
+Use of uninitialized value $m2 in socket at - line 12.
+Use of uninitialized value $g1 in socket at - line 12.
+Use of uninitialized value $m1 in socket at - line 12.
+Use of uninitialized value $m2 in socketpair at - line 13.
+Use of uninitialized value $g1 in socketpair at - line 13.
+Use of uninitialized value $m1 in socketpair at - line 13.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+stat;
+lstat;
+stat $m1;
+lstat $g1;
+
+$v = -R $m1;
+$v = -W $m1;
+$v = -X $m1;
+$v = -r $m1;
+$v = -w $m1;
+$v = -x $m1;
+$v = -e $m1;
+$v = -O $m1;
+$v = -o $m1;
+$v = -z $m1;
+$v = -s $m1;
+$v = -M $m1;
+$v = -A $m1;
+$v = -C $m1;
+$v = -S $m1;
+$v = -c $m1;
+$v = -b $m1;
+$v = -f $m1;
+$v = -d $m1;
+$v = -p $m1;
+$v = -l $m1;
+$v = -u $m1;
+$v = -g $m1;
+$v = -k $m1;
+$v = -t $m1;
+$v = -T $m1;
+$v = -B $m1;
+EXPECT
+Use of uninitialized value $_ in stat at - line 5.
+Use of uninitialized value $_ in lstat at - line 6.
+Use of uninitialized value $m1 in stat at - line 7.
+Use of uninitialized value $g1 in lstat at - line 8.
+Use of uninitialized value $m1 in -R at - line 10.
+Use of uninitialized value $m1 in -W at - line 11.
+Use of uninitialized value $m1 in -X at - line 12.
+Use of uninitialized value $m1 in -r at - line 13.
+Use of uninitialized value $m1 in -w at - line 14.
+Use of uninitialized value $m1 in -x at - line 15.
+Use of uninitialized value $m1 in -e at - line 16.
+Use of uninitialized value $m1 in -o at - line 17.
+Use of uninitialized value $m1 in -O at - line 18.
+Use of uninitialized value $m1 in -z at - line 19.
+Use of uninitialized value $m1 in -s at - line 20.
+Use of uninitialized value $m1 in -M at - line 21.
+Use of uninitialized value $m1 in -A at - line 22.
+Use of uninitialized value $m1 in -C at - line 23.
+Use of uninitialized value $m1 in -S at - line 24.
+Use of uninitialized value $m1 in -c at - line 25.
+Use of uninitialized value $m1 in -b at - line 26.
+Use of uninitialized value $m1 in -f at - line 27.
+Use of uninitialized value $m1 in -d at - line 28.
+Use of uninitialized value $m1 in -p at - line 29.
+Use of uninitialized value $m1 in -l at - line 30.
+Use of uninitialized value $m1 in -l at - line 30.
+Use of uninitialized value $m1 in -u at - line 31.
+Use of uninitialized value $m1 in -g at - line 32.
+Use of uninitialized value $m1 in -k at - line 33.
+Use of uninitialized value $m1 in -t at - line 34.
+Use of uninitialized value $m1 in -T at - line 35.
+Use of uninitialized value $m1 in -B at - line 36.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+our ($g1);
+
+$v = localtime $m1;
+$v = gmtime $g1;
+EXPECT
+Use of uninitialized value $m1 in localtime at - line 5.
+Use of uninitialized value $g1 in gmtime at - line 6.
+########
+use warnings 'uninitialized';
+my ($m1, $v);
+
+$v = eval;
+$v = eval $m1;
+EXPECT
+Use of uninitialized value $_ in eval "string" at - line 4.
+Use of uninitialized value $_ in eval "string" at - line 4.
+Use of uninitialized value $_ in eval "string" at - line 4.
+Use of uninitialized value $m1 in eval "string" at - line 5.
+Use of uninitialized value $m1 in eval "string" at - line 5.
+Use of uninitialized value $m1 in eval "string" at - line 5.
+########
+use warnings 'uninitialized';
+my ($m1);
+
+exit $m1;
+EXPECT
+Use of uninitialized value $m1 in exit at - line 4.
diff --git a/t/lib/warnings/doio b/t/lib/warnings/doio
index 15d4c5e957..a4518460b4 100644
--- a/t/lib/warnings/doio
+++ b/t/lib/warnings/doio
@@ -143,7 +143,7 @@ print $a ;
 no warnings 'uninitialized' ;
 print $b ;
 EXPECT
-Use of uninitialized value in print at - line 3.
+Use of uninitialized value $a in print at - line 3.
 ########
 # doio.c [Perl_my_stat Perl_my_lstat]
 use warnings 'io' ;
diff --git a/t/lib/warnings/mg b/t/lib/warnings/mg
index f7c3ebf435..c6d7506be2 100644
--- a/t/lib/warnings/mg
+++ b/t/lib/warnings/mg
@@ -48,10 +48,10 @@ use warnings 'uninitialized';
 'foo' =~ /(foo)/;
 length $3;
 EXPECT
-Use of uninitialized value in length at - line 4.
+Use of uninitialized value $3 in length at - line 4.
 ########
 # mg.c
 use warnings 'uninitialized';
 length $3;
 EXPECT
-Use of uninitialized value in length at - line 3.
+Use of uninitialized value $3 in length at - line 3.
diff --git a/t/lib/warnings/pp b/t/lib/warnings/pp
index 5ed7aa0891..d1581446f0 100644
--- a/t/lib/warnings/pp
+++ b/t/lib/warnings/pp
@@ -59,7 +59,7 @@ $x = undef; $y = $$x;
 no warnings 'uninitialized' ;
 $u = undef; $v = $$u;
 EXPECT
-Use of uninitialized value in scalar dereference at - line 3.
+Use of uninitialized value $x in scalar dereference at - line 3.
 ########
 # pp.c
 use warnings 'misc' ;
diff --git a/t/lib/warnings/pp_ctl b/t/lib/warnings/pp_ctl
index 59ced2b446..d27e8963f4 100644
--- a/t/lib/warnings/pp_ctl
+++ b/t/lib/warnings/pp_ctl
@@ -219,7 +219,7 @@ EXPECT
 use warnings;
 eval 'print $foo';
 EXPECT
-Use of uninitialized value in print at (eval 1) line 1.
+Use of uninitialized value $foo in print at (eval 1) line 1.
 ########
 # pp_ctl.c
 use warnings 'portable';
diff --git a/t/lib/warnings/pp_hot b/t/lib/warnings/pp_hot
index 4e10627325..f5a580337c 100644
--- a/t/lib/warnings/pp_hot
+++ b/t/lib/warnings/pp_hot
@@ -145,7 +145,7 @@ my @b = @$a;
 no warnings 'uninitialized' ;
 my @c = @$a;
 EXPECT
-Use of uninitialized value in array dereference at - line 4.
+Use of uninitialized value $a in array dereference at - line 4.
 ########
 # pp_hot.c [pp_rv2hv]
 use warnings 'uninitialized' ;
@@ -154,7 +154,7 @@ my %b = %$a;
 no warnings 'uninitialized' ;
 my %c = %$a;
 EXPECT
-Use of uninitialized value in hash dereference at - line 4.
+Use of uninitialized value $a in hash dereference at - line 4.
 ########
 # pp_hot.c [pp_aassign]
 use warnings 'misc' ;
@@ -269,11 +269,11 @@ a($x . $y);	# should warn twice
 $x .= $y;	# should warn once
 $y .= $y;	# should warn once
 EXPECT
-Use of uninitialized value in concatenation (.) or string at - line 5.
-Use of uninitialized value in concatenation (.) or string at - line 6.
-Use of uninitialized value in concatenation (.) or string at - line 6.
-Use of uninitialized value in concatenation (.) or string at - line 7.
-Use of uninitialized value in concatenation (.) or string at - line 8.
+Use of uninitialized value $x in concatenation (.) or string at - line 5.
+Use of uninitialized value $y in concatenation (.) or string at - line 6.
+Use of uninitialized value $x in concatenation (.) or string at - line 6.
+Use of uninitialized value $y in concatenation (.) or string at - line 7.
+Use of uninitialized value $y in concatenation (.) or string at - line 8.
 ########
 # pp_hot.c [pp_concat]
 use warnings 'y2k';
diff --git a/t/lib/warnings/pp_pack b/t/lib/warnings/pp_pack
index 0f447c75b6..62ae3a9a89 100644
--- a/t/lib/warnings/pp_pack
+++ b/t/lib/warnings/pp_pack
@@ -28,7 +28,7 @@ my $b = $$a;
 no warnings 'uninitialized' ;
 my $c = $$a;
 EXPECT
-Use of uninitialized value in scalar dereference at - line 4.
+Use of uninitialized value $a in scalar dereference at - line 4.
 ########
 # pp_pack.c
 use warnings 'pack' ;
diff --git a/t/lib/warnings/sv b/t/lib/warnings/sv
index b38200d4c8..bf01657e21 100644
--- a/t/lib/warnings/sv
+++ b/t/lib/warnings/sv
@@ -58,7 +58,7 @@ $x = 1 + $a[0] ; # a
 no warnings 'uninitialized' ;
 $x = 1 + $b[0] ; # a
 EXPECT
-Use of uninitialized value in integer addition (+) at - line 4.
+Use of uninitialized value $a[0] in integer addition (+) at - line 4.
 ########
 # sv.c (sv_2iv)
 package fred ;
@@ -73,7 +73,7 @@ $A *= 2 ;
 no warnings 'uninitialized' ;
 $A *= 2 ;
 EXPECT
-Use of uninitialized value in integer multiplication (*) at - line 10.
+Use of uninitialized value $A in integer multiplication (*) at - line 10.
 ########
 # sv.c
 use integer ;
@@ -82,7 +82,7 @@ my $x *= 2 ; #b
 no warnings 'uninitialized' ;
 my $y *= 2 ; #b 
 EXPECT
-Use of uninitialized value in integer multiplication (*) at - line 4.
+Use of uninitialized value $x in integer multiplication (*) at - line 4.
 ########
 # sv.c (sv_2uv)
 package fred ;
@@ -98,7 +98,7 @@ no warnings 'uninitialized' ;
 $B = 0 ;
 $B |= $A ;
 EXPECT
-Use of uninitialized value in bitwise or (|) at - line 10.
+Use of uninitialized value $A in bitwise or (|) at - line 10.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -108,7 +108,7 @@ no warnings 'uninitialized' ;
 my $Y = 1 ; 
 $x = 1 | $b[$Y] ;
 EXPECT
-Use of uninitialized value in bitwise or (|) at - line 4.
+Use of uninitialized value within @a in bitwise or (|) at - line 4.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -118,7 +118,7 @@ no warnings 'uninitialized' ;
 my $Y = 1 ; 
 $x = 1 & $b[$Y] ;
 EXPECT
-Use of uninitialized value in bitwise and (&) at - line 4.
+Use of uninitialized value within @a in bitwise and (&) at - line 4.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -128,7 +128,7 @@ no warnings 'uninitialized' ;
 my $Y = 1 ; 
 $x = ~$b[$Y] ;
 EXPECT
-Use of uninitialized value in 1's complement (~) at - line 4.
+Use of uninitialized value within @a in 1's complement (~) at - line 4.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -136,7 +136,7 @@ my $x *= 1 ; # d
 no warnings 'uninitialized' ;
 my $y *= 1 ; # d
 EXPECT
-Use of uninitialized value in multiplication (*) at - line 3.
+Use of uninitialized value $x in multiplication (*) at - line 3.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -144,7 +144,7 @@ $x = 1 + $a[0] ; # e
 no warnings 'uninitialized' ;
 $x = 1 + $b[0] ; # e
 EXPECT
-Use of uninitialized value in addition (+) at - line 3.
+Use of uninitialized value $a[0] in addition (+) at - line 3.
 ########
 # sv.c (sv_2nv)
 package fred ;
@@ -158,7 +158,7 @@ $A *= 2 ;
 no warnings 'uninitialized' ;
 $A *= 2 ;
 EXPECT
-Use of uninitialized value in multiplication (*) at - line 9.
+Use of uninitialized value $A in multiplication (*) at - line 9.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -166,7 +166,7 @@ $x = $y + 1 ; # f
 no warnings 'uninitialized' ;
 $x = $z + 1 ; # f
 EXPECT
-Use of uninitialized value in addition (+) at - line 3.
+Use of uninitialized value $y in addition (+) at - line 3.
 ########
 # sv.c
 use warnings 'uninitialized' ;
@@ -182,7 +182,7 @@ $x = chop $y ; # h
 no warnings 'uninitialized' ;
 $x = chop $z ; # h
 EXPECT
-Use of uninitialized value in scalar chop at - line 3.
+Use of uninitialized value $y in scalar chop at - line 3.
 ########
 # sv.c (sv_2pv)
 package fred ;
@@ -198,7 +198,7 @@ no warnings 'uninitialized' ;
 $C = "" ;
 $C .= $A ;
 EXPECT
-Use of uninitialized value in concatenation (.) or string at - line 10.
+Use of uninitialized value $A in concatenation (.) or string at - line 10.
 ########
 # perlbug 20011116.125
 use warnings 'uninitialized';
@@ -207,9 +207,9 @@ $foo = join '', $a, "\n";
 $foo = "$a\n";
 $foo = "a:$a\n";
 EXPECT
-Use of uninitialized value in join or string at - line 4.
-Use of uninitialized value in concatenation (.) or string at - line 5.
-Use of uninitialized value in concatenation (.) or string at - line 6.
+Use of uninitialized value $a in join or string at - line 4.
+Use of uninitialized value $a in concatenation (.) or string at - line 5.
+Use of uninitialized value $a in concatenation (.) or string at - line 6.
 ########
 # sv.c 
 use warnings 'numeric' ;
diff --git a/t/lib/warnings/util b/t/lib/warnings/util
index 4e960c1ea1..e632d09e0d 100644
--- a/t/lib/warnings/util
+++ b/t/lib/warnings/util
@@ -115,7 +115,7 @@ if ($x) {
 }
 EXPECT
 Name "main::y" used only once: possible typo at - line 5.
-Use of uninitialized value in print at - line 5.
+Use of uninitialized value $y in print at - line 5.
 ########
 # util.c
 use warnings;
@@ -126,7 +126,7 @@ if ($x) {
 }
 EXPECT
 Name "main::y" used only once: possible typo at - line 6.
-Use of uninitialized value in print at - line 6.
+Use of uninitialized value $y in print at - line 6.
 ########
 # util.c
 use warnings;
@@ -140,7 +140,7 @@ if ($x) {
 }
 EXPECT
 Name "main::y" used only once: possible typo at - line 7.
-Use of uninitialized value in print at - line 7.
+Use of uninitialized value $y in print at - line 7.
 ########
 # util.c
 use warnings;
@@ -155,4 +155,4 @@ if ($x) {
 }
 EXPECT
 Name "main::y" used only once: possible typo at - line 8.
-Use of uninitialized value in print at - line 8.
+Use of uninitialized value $y in print at - line 8.
diff --git a/t/run/fresh_perl.t b/t/run/fresh_perl.t
index 0f5073dcaa..d47f27f6cc 100644
--- a/t/run/fresh_perl.t
+++ b/t/run/fresh_perl.t
@@ -510,7 +510,7 @@ else {
   if ($x == 0) { print "" } else { print $x }
 }
 EXPECT
-Use of uninitialized value in numeric eq (==) at - line 4.
+Use of uninitialized value $x in numeric eq (==) at - line 4.
 ########
 $x = sub {};
 foo();
diff --git a/t/run/runenv.t b/t/run/runenv.t
index df4a778b4d..1e36c99998 100644
--- a/t/run/runenv.t
+++ b/t/run/runenv.t
@@ -97,7 +97,7 @@ sub try {
 
 try({PERL5OPT => '-w'}, ['-e', 'print $::x'],
     "", 
-    qq{Name "main::x" used only once: possible typo at -e line 1.\nUse of uninitialized value in print at -e line 1.\n});
+    qq{Name "main::x" used only once: possible typo at -e line 1.\nUse of uninitialized value \$x in print at -e line 1.\n});
 
 try({PERL5OPT => '-Mstrict'}, ['-e', 'print $::x'],
     "", "");
@@ -116,7 +116,7 @@ try({PERL5OPT => '-w -Mstrict'}, ['-e', 'print $::x'],
     "", 
     <<ERROR
 Name "main::x" used only once: possible typo at -e line 1.
-Use of uninitialized value in print at -e line 1.
+Use of uninitialized value \$x in print at -e line 1.
 ERROR
     );
 
@@ -125,7 +125,7 @@ try({PERL5OPT => '-w -Mstrict'}, ['-e', 'print $::x'],
     "", 
     <<ERROR
 Name "main::x" used only once: possible typo at -e line 1.
-Use of uninitialized value in print at -e line 1.
+Use of uninitialized value \$x in print at -e line 1.
 ERROR
     );