re PR c++/41779 (Wconversion cannot see throught real*integer promotions)

2010-02-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>

	PR 41779
	* c-common.c (conversion_warning): Remove widening conversions
	before checking the conversion of integers to reals.
testsuite/
	* c-c++-common/pr41779.c: New.

From-SVN: r156911

gcc/ChangeLog

+2010-02-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR 41779
+	* c-common.c (conversion_warning): Remove widening conversions
+	before checking the conversion of integers to reals.
+
 2010-02-19  Mike Stump  <mikestump@comcast.net>
 
 	PR objc/43061

gcc/c-common.c

@@ -2192,12 +2192,17 @@ conversion_warning (tree type, tree expr)
       else if (TREE_CODE (expr_type) == INTEGER_TYPE
                && TREE_CODE (type) == REAL_TYPE)
         {
-          tree type_low_bound = TYPE_MIN_VALUE (expr_type);
-          tree type_high_bound = TYPE_MAX_VALUE (expr_type);
-          REAL_VALUE_TYPE real_low_bound
-	    = real_value_from_int_cst (0, type_low_bound);
-          REAL_VALUE_TYPE real_high_bound
-	    = real_value_from_int_cst (0, type_high_bound);
+	  tree type_low_bound, type_high_bound;
+          REAL_VALUE_TYPE real_low_bound, real_high_bound;
+
+	  /* Don't warn about char y = 0xff; float x = (int) y;  */
+	  expr = get_unwidened (expr, 0);
+	  expr_type = TREE_TYPE (expr);
+
+          type_low_bound = TYPE_MIN_VALUE (expr_type);
+          type_high_bound = TYPE_MAX_VALUE (expr_type);
+          real_low_bound = real_value_from_int_cst (0, type_low_bound);
+          real_high_bound = real_value_from_int_cst (0, type_high_bound);
 
           if (!exact_real_truncate (TYPE_MODE (type), &real_low_bound)
               || !exact_real_truncate (TYPE_MODE (type), &real_high_bound))

gcc/testsuite/ChangeLog

+2010-02-19  Manuel López-Ibáñez  <manu@gcc.gnu.org>
+
+	PR 41779
+	* c-c++-common/pr41779.c: New.
+
 2010-02-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/43084

gcc/testsuite/c-c++-common/pr41779.c

+/* PR41779: Wconversion cannot see throught real*integer promotions. */
+/* { dg-do compile } */
+/* { dg-skip-if "doubles are floats" { "avr-*-*" } { "*" } { "" } } */
+/* { dg-options "-std=c99 -Wconversion" { target c } } */
+/* { dg-options "-Wconversion" { target c++ } } */
+/* { dg-require-effective-target large_double } */
+
+float f(float x, unsigned short y)
+{
+  return x * y;
+}
+
+float f(float x, short y)
+{
+  return x * y;
+}
+
+float f(float x, char y)
+{
+  return x * y;
+}
+
+float f(float x, unsigned char y)
+{
+  return x * y;
+}
+
+float f(float x, int y)
+{
+  return x * y; /* { dg-warning "conversion" } */
+}