Re: [patch] fix c++/18016 - warn about self-initialization in constructor init-list

[Jonathan Wakely <jwakely.gcc@gmail.com>]

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On 21 December 2010 17:11, Jonathan Wakely wrote:
> On 21 December 2010 17:04, Paolo Carlini wrote:
>> Hi,
>>
>> +  if (warn_uninitialized && init && init != NULL_TREE
>>
>> I think the last check in this line is redundant.
>
> Thanks, Paolo. I should have checked the definition of NULL_TREE.
>
> I'm re-testing with that change, but it shouldn't affect the results.

Updated patch, tested x86_64-linux

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Index: cp/init.c
===================================================================
--- cp/init.c	(revision 168023)
+++ cp/init.c	(working copy)
@@ -449,6 +449,17 @@ perform_member_init (tree member, tree i
   if (decl == error_mark_node)
     return;
 
+  if (warn_uninitialized && init && TREE_CODE (init) == TREE_LIST
+      && TREE_CHAIN (init) == NULL_TREE)
+    {
+      tree val = TREE_VALUE (init);
+      if (TREE_CODE (val) == COMPONENT_REF && TREE_OPERAND (val, 1) == member
+	  && TREE_OPERAND (val, 0) == current_class_ref)
+	warning_at (DECL_SOURCE_LOCATION (current_function_decl),
+	            OPT_Wuninitialized, "%qD is initialized with itself",
+		    member);
+    }
+
   if (init == void_type_node)
     {
       /* mem() means value-initialization.  */
Index: testsuite/g++.dg/warn/pr18016.C
===================================================================
--- testsuite/g++.dg/warn/pr18016.C	(revision 0)
+++ testsuite/g++.dg/warn/pr18016.C	(revision 0)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-Wuninitialized" } */
+
+class X {
+  int i;
+  X() : i(i) { }   // { dg-warning "initialized with itself" }
+  X(int i) : i(i) { }
+  X(const X& x) : i(x.i) { }
+};
+
+// { dg-prune-output "In constructor" }