diff mbox

[C++,/,RFC] PR 45385

Message ID 4EA19BB2.8050002@oracle.com
State New
Headers show

Commit Message

Paolo Carlini Oct. 21, 2011, 4:20 p.m. UTC 
On 10/21/2011 04:56 PM, Jason Merrill wrote:
> I think the fix for 35602 was wrong; instead of trying to suppress the 
> warning, we should avoid building expressions that trip it.  In this 
> case, the problem is a type mismatch in build_vec_init between 
> maxindex/iterator (ptrdiff_type_node) and array_type_nelts_total 
> (sizetype).  And indeed, converting (ptrdiff_t)-1 to unsigned changes 
> its sign.
>
> I think a better fix for 35602 would be to bail out of build_vec_init 
> exit early if maxindex is -1.
Ah great, thanks a lot. The below passes testing, if it's Ok I would be 
tempted to backport it to the 4_6-branch too after 4.6.2 is out..

Thanks again,
Paolo.

//////////////////////
/cp
2011-10-21  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/45385
	* init.c (build_vec_init): Early return error_mark_node if
	maxindex is -1.

/c-family
2011-10-21  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/45385
	* c-common.c (conversion_warning): Remove code looking for
	artificial operands.

/testsuite
2011-10-21  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/45385
	* g++.dg/warn/Wconversion4.C: New.

Comments

Jason Merrill Oct. 21, 2011, 6:17 p.m. UTC | #1 
On 10/21/2011 12:20 PM, Paolo Carlini wrote:
> +      || tree_int_cst_equal (maxindex, integer_minus_one_node))

Use integer_all_onesp instead.  OK with that change.

Jason
diff mbox

Patch

Index: c-family/c-common.c
===================================================================
--- c-family/c-common.c	(revision 180307)
+++ c-family/c-common.c	(working copy)
@@ -2121,23 +2121,12 @@  unsafe_conversion_p (tree type, tree expr, bool pr
 static void
 conversion_warning (tree type, tree expr)
 {
-  int i;
-  const int expr_num_operands = TREE_OPERAND_LENGTH (expr);
   tree expr_type = TREE_TYPE (expr);
   location_t loc = EXPR_LOC_OR_HERE (expr);
 
   if (!warn_conversion && !warn_sign_conversion)
     return;
 
-  /* If any operand is artificial, then this expression was generated
-     by the compiler and we do not warn.  */
-  for (i = 0; i < expr_num_operands; i++)
-    {
-      tree op = TREE_OPERAND (expr, i);
-      if (op && DECL_P (op) && DECL_ARTIFICIAL (op))
-	return;
-    }
-
   switch (TREE_CODE (expr))
     {
     case EQ_EXPR:
Index: testsuite/g++.dg/warn/Wconversion4.C
===================================================================
--- testsuite/g++.dg/warn/Wconversion4.C	(revision 0)
+++ testsuite/g++.dg/warn/Wconversion4.C	(revision 0)
@@ -0,0 +1,17 @@ 
+// PR c++/45385
+// { dg-options "-Wconversion" } 
+
+void foo(unsigned char);
+
+class Test
+{
+  void eval()
+  {
+    foo(bar());  // { dg-warning "may alter its value" }
+  }
+
+  unsigned int bar() const
+  {
+    return __INT_MAX__ * 2U + 1;
+  }
+};
Index: cp/init.c
===================================================================
--- cp/init.c	(revision 180307)
+++ cp/init.c	(working copy)
@@ -2998,7 +2998,8 @@  build_vec_init (tree base, tree maxindex, tree ini
   if (TREE_CODE (atype) == ARRAY_TYPE && TYPE_DOMAIN (atype))
     maxindex = array_type_nelts (atype);
 
-  if (maxindex == NULL_TREE || maxindex == error_mark_node)
+  if (maxindex == NULL_TREE || maxindex == error_mark_node
+      || tree_int_cst_equal (maxindex, integer_minus_one_node))
     return error_mark_node;
 
   if (explicit_value_init_p)