invoke.texi (-Wconversion): Document warnings specific to C++.

2007-03-16  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>

	* doc/invoke.texi (-Wconversion): Document warnings specific to C++.
	* c-common.c (convert_and_check): Move warning logic to...
	(warnings_for_convert_and_check): ...here. Define.
	* c-common.h (warnings_for_convert_and_check): Declare.
cp/
	* cvt.c (cp_convert_and_check) : Define.
	* cp-tree.h (cp_convert_and_check): Declare.
	* call.c (convert_conversion_warnings): Rename to
	conversion_null_warnings.  The warning for floating-point to
	integer is handled by convert_and_check in convert_like_real.
	(convert_like_real): convert_conversion_warnings was renamed as
	conversion_null_warnings.
	* typeck.c (build_binary_op): Use cp_convert_and_check to warn for
	overflow and changes of value during conversion.
testsuite/
	* g++.dg/warn/Wconversion-integer.C: New
	* g++.dg/warn/Wconversion-real.C: New.
	* g++.dg/warn/Wconversion-real-integer.C: New.
	* g++.dg/warn/conv2.C: Updated.

From-SVN: r123005

5 files changed, 44 insertions, 18 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 730c59e..f5d26c0 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,15 @@
+2007-03-16  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
+
+	* cvt.c (cp_convert_and_check) : Define.
+	* cp-tree.h (cp_convert_and_check): Declare.
+	* call.c (convert_conversion_warnings): Rename to
+	conversion_null_warnings.  The warning for floating-point to
+	integer is handled by convert_and_check in convert_like_real.
+	(convert_like_real): convert_conversion_warnings was renamed as
+	conversion_null_warnings.
+	* typeck.c (build_binary_op): Use cp_convert_and_check to warn for
+	overflow and changes of value during conversion.
+
 2007-03-15  Manuel Lopez-Ibanez  <manu@gcc.gnu.org>
 
 	PR c++/30891
diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 9d25298..8218ed4 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -4245,11 +4245,12 @@ build_temp (tree expr, tree type, int flags,
   return expr;
 }
 
-/* Perform warnings about conversion of EXPR to type TOTYPE.
+/* Perform warnings about peculiar, but valid, conversions from/to NULL.
+   EXPR is implicitly converted to type TOTYPE.
    FN and ARGNUM are used for diagnostics.  */
 
 static void
-convert_conversion_warnings (tree totype, tree expr, tree fn, int argnum)
+conversion_null_warnings (tree totype, tree expr, tree fn, int argnum)
 {
   tree t = non_reference (totype);
 
@@ -4263,19 +4264,8 @@ convert_conversion_warnings (tree totype, tree expr, tree fn, int argnum)
 	warning (OPT_Wconversion, "converting to non-pointer type %qT from NULL", t);
     }
 
-  /* Warn about assigning a floating-point type to an integer type.  */
-  if (TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE
-      && TREE_CODE (t) == INTEGER_TYPE)
-    {
-      if (fn)
-	warning (OPT_Wconversion, "passing %qT for argument %P to %qD",
-		 TREE_TYPE (expr), argnum, fn);
-      else
-	warning (OPT_Wconversion, "converting to %qT from %qT", t, TREE_TYPE (expr));
-    }
-
   /* Issue warnings if "false" is converted to a NULL pointer */
-  if (expr == boolean_false_node && fn && POINTER_TYPE_P (t))
+  else if (expr == boolean_false_node && fn && POINTER_TYPE_P (t))
     warning (OPT_Wconversion,
 	     "converting %<false%> to pointer type for argument %P of %qD",
 	     argnum, fn);
@@ -4328,7 +4318,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
     }
 
   if (issue_conversion_warnings)
-    convert_conversion_warnings (totype, expr, fn, argnum);
+    conversion_null_warnings (totype, expr, fn, argnum);
 
   switch (convs->kind)
     {
@@ -4415,7 +4405,7 @@ convert_like_real (conversion *convs, tree expr, tree fn, int argnum,
 
   expr = convert_like_real (convs->u.next, expr, fn, argnum,
 			    convs->kind == ck_ref_bind ? -1 : 1,
-			    /*issue_conversion_warnings=*/false,
+			    convs->kind == ck_ref_bind ? issue_conversion_warnings : false, 
 			    c_cast_p);
   if (expr == error_mark_node)
     return error_mark_node;
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 7d6ebc7..b9b3500 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -4049,6 +4049,7 @@ extern tree convert_from_reference		(tree);
 extern tree force_rvalue			(tree);
 extern tree ocp_convert				(tree, tree, int, int);
 extern tree cp_convert				(tree, tree);
+extern tree cp_convert_and_check                (tree, tree);
 extern tree convert_to_void	(tree, const char */*implicit context*/);
 extern tree convert_force			(tree, tree, int);
 extern tree build_expr_type_conversion		(int, tree, bool);
diff --git a/gcc/cp/cvt.c b/gcc/cp/cvt.c
index 4e628a5..947f1f2 100644
--- a/gcc/cp/cvt.c
+++ b/gcc/cp/cvt.c
@@ -593,6 +593,29 @@ cp_convert (tree type, tree expr)
   return ocp_convert (type, expr, CONV_OLD_CONVERT, LOOKUP_NORMAL);
 }
 
+/* C++ equivalent of convert_and_check but using cp_convert as the
+   conversion function.
+
+   Convert EXPR to TYPE, warning about conversion problems with constants.
+   Invoke this function on every expression that is converted implicitly,
+   i.e. because of language rules and not because of an explicit cast.  */
+
+tree
+cp_convert_and_check (tree type, tree expr)
+{
+  tree result;
+
+  if (TREE_TYPE (expr) == type)
+    return expr;
+  
+  result = cp_convert (type, expr);
+
+  if (!skip_evaluation && !TREE_OVERFLOW_P (expr))
+    warnings_for_convert_and_check (type, expr, result);
+
+  return result;
+}
+
 /* Conversion...
 
    FLAGS indicates how we should behave.  */
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index ac6eb2b..6478b37 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -3837,9 +3837,9 @@ build_binary_op (enum tree_code code, tree orig_op0, tree orig_op1,
   if (! converted)
     {
       if (TREE_TYPE (op0) != result_type)
-	op0 = cp_convert (result_type, op0);
+	op0 = cp_convert_and_check (result_type, op0);
       if (TREE_TYPE (op1) != result_type)
-	op1 = cp_convert (result_type, op1);
+	op1 = cp_convert_and_check (result_type, op1);
 
       if (op0 == error_mark_node || op1 == error_mark_node)
 	return error_mark_node;