[perl #72090] unitialized variable name wrong with no strict refs

$ ./perl -we '$a = @$a > 0'
Use of uninitialized value $a in array dereference at -e line 1.
Use of uninitialized value $a in numeric gt (>) at -e line 1.

S_find_uninit_var was not taking into account that rv2*v could return
undef. So it merrily looked at the child ops to find one that named
a variable.

This commit makes it skip any rv2av/rv2hv that does not have an OP_GV
as its child op.

In other words, it skips @{...} and %{...} (including the shorthand
forms @$foo and %$foo), but not @foo or %foo.

sv.c

@@ -14031,6 +14031,12 @@ S_find_uninit_var(pTHX_ const OP *const obase, const SV *const uninit_sv,
 		if ( (type == OP_CONST && SvOK(cSVOPx_sv(kid)))
 		  || (type == OP_NULL  && ! (kid->op_flags & OPf_KIDS))
 		  || (type == OP_PUSHMARK)
+		  || (
+		      /* @$a and %$a, but not @a or %a */
+		        (type == OP_RV2AV || type == OP_RV2HV)
+		     && cUNOPx(kid)->op_first
+		     && cUNOPx(kid)->op_first->op_type != OP_GV
+		     )
 		)
 		continue;
 	    }

t/lib/warnings/sv

@@ -209,6 +209,13 @@ 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 $a in concatenation (.) or string at - line 6.
 ########
+# [perl #72090]
+use warnings 'uninitialized';
+$a = @$a > 0;
+EXPECT
+Use of uninitialized value $a in array dereference at - line 3.
+Use of uninitialized value in numeric gt (>) at - line 3.
+########
 # sv.c 
 use warnings 'numeric' ;
 sub TIESCALAR{bless[]} ;