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

Message ID AANLkTi=sbmtgJGU_j63E9tEdY=YEpL3iuMFLwCL1EwyA@mail.gmail.com
State New
Headers show

Commit Message

Jonathan Wakely Jan. 1, 2011, 10:36 p.m. UTC 
On 24 December 2010 00:31, Jonathan Wakely wrote:
> Merry Pingmas, one and all.

And a pingy new year.

Still hoping for this patch to be reviewed...

> On 21 December 2010 15:25, Jonathan Wakely wrote:
>> Here's my attempt to fix PR c++/18016 so that we get a warning from
>>
>> struct S {
>>  int i;
>>  S() : i(i) { }
>> };
>>
>> -Winit-self is broken for C++ (PR c++/34772) so I made this warn with
>> -Wuninitialized.  If you want to suppress the warning just don't put a
>> mem-initializer in the constructor (which will work at least until
>> someone fixes PR c++/2972)
>>
>> cp/ChangeLog:
>>
>>        PR c++/18016
>>        * init.c (perform_member_init): Check for self-initialization.
>>
>>
>> testsuite/ChangeLog:
>>
>>        PR c++/18016
>>        * g++.dg/warn/pr18016.C: New.
>>
>>
>> tested x86_64-linux with no regressions, ok for trunk?
>>
>
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Patch

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" }