re PR c++/35602 (Bogus warning with -Wsign-conversion)

2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	PR c++/35602
	* c-common.c (conversion_warning): Do not warn for artificial
	expressions.
testsuite/
	* g++.dg/warn/pr35602.C: New.

From-SVN: r139328

gcc/ChangeLog

+2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR c++/35602
+	* c-common.c (conversion_warning): Do not warn for artificial
+	expressions.
+
 2008-08-20  Richard Guenther  <rguenther@suse.de>
 
 	* tree-vrp.c (op_with_constant_singleton_value_range): New function.

gcc/c-common.c

@@ -1556,11 +1556,22 @@ conversion_warning (tree type, tree expr)
 {
   bool give_warning = false;
 
+  int i;
+  const int expr_num_operands = TREE_OPERAND_LENGTH (expr);
   tree expr_type = TREE_TYPE (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 (DECL_P (op) && DECL_ARTIFICIAL (op))
+	return;
+    }
+
   switch (TREE_CODE (expr))
     {
     case EQ_EXPR:

gcc/testsuite/ChangeLog

+2008-08-20  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	PR c++/35602
+	* g++.dg/warn/pr35602.C: New.
+
 2008-08-20  Richard Guenther  <rguenther@suse.de>
 
 	* gcc.dg/tree-ssa/pr21829.c: Scan optimized and cddce2 dumps

gcc/testsuite/g++.dg/warn/pr35602.C

+// PR 35602 Bogus warning with -Wsign-conversion
+// { dg-do compile }
+// { dg-options "-Wconversion -Wsign-conversion" }
+struct c
+{
+  ~c();
+  c();
+};
+
+int
+
+main(const int,
+     const char * const * const)
+{
+  c x[0UL][0UL] =  // { dg-bogus "warning: conversion to .long unsigned int. from .long int. may change the sign of the result" }
+    {
+    };
+  
+  c y[0UL] =
+    {
+    };
+  
+  int z[0ul][0UL] =
+    {
+    };
+  
+  return 0;
+}