re PR c++/18313 (Missing warning for superfluous const's in return types)

2006-12-01  Dirk Mueller  <dmueller@suse.de>

        PR c++/18313
        * decl.c (grokdeclarator): Warn for type qualifiers on return
        type for non-dependent types.
        * pt.c (tsubst_function_type): Warn for type qualifiers on
        return type for dependent types.

        * g++.dg/warn/Wreturn-type-4.C: New testcase.

From-SVN: r119382

gcc/cp/ChangeLog

+2006-12-01  Dirk Mueller  <dmueller@suse.de>
+
+	PR c++/18313
+	* decl.c (grokdeclarator): Warn for type qualifiers on return
+	type for non-dependent types.
+	* pt.c (tsubst_function_type): Warn for type qualifiers on
+	return type for dependent types.
+
 2006-11-30  Geoffrey Keating  <geoffk@apple.com>
 
 	* rtti.c (get_tinfo_decl): Handle return value from

gcc/cp/decl.c

@@ -6895,6 +6895,7 @@ grokdeclarator (const cp_declarator *declarator,
   cp_storage_class storage_class;
   bool unsigned_p, signed_p, short_p, long_p, thread_p;
   bool type_was_error_mark_node = false;
+  bool set_no_warning = false;
 
   signed_p = declspecs->specs[(int)ds_signed];
   unsigned_p = declspecs->specs[(int)ds_unsigned];
@@ -7541,9 +7542,16 @@ grokdeclarator (const cp_declarator *declarator,
 	    /* Declaring a function type.
 	       Make sure we have a valid type for the function to return.  */
 
-	    /* We now know that the TYPE_QUALS don't apply to the
-	       decl, but to its return type.  */
-	    type_quals = TYPE_UNQUALIFIED;
+	    if (type_quals != TYPE_UNQUALIFIED)
+	      {
+		if (SCALAR_TYPE_P (type) || VOID_TYPE_P (type))
+		  warning (OPT_Wreturn_type,
+			   "type qualifiers ignored on function return type");
+		/* We now know that the TYPE_QUALS don't apply to the
+		   decl, but to its return type.  */
+		type_quals = TYPE_UNQUALIFIED;
+		set_no_warning = true;
+	      }
 
 	    /* Warn about some types functions can't return.  */
 
@@ -8623,6 +8631,9 @@ grokdeclarator (const cp_declarator *declarator,
     if (!processing_template_decl)
       cp_apply_type_quals_to_decl (type_quals, decl);
 
+    if (set_no_warning)
+        TREE_NO_WARNING (decl) = 1;
+
     return decl;
   }
 }

gcc/cp/pt.c

@@ -7133,6 +7133,13 @@ tsubst_function_type (tree t,
   if (arg_types == error_mark_node)
     return error_mark_node;
 
+  if (TYPE_QUALS (return_type) != TYPE_UNQUALIFIED
+      && in_decl != NULL_TREE
+      && !TREE_NO_WARNING (in_decl)
+      && (SCALAR_TYPE_P (return_type) || VOID_TYPE_P (return_type)))
+    warning (OPT_Wreturn_type,
+            "type qualifiers ignored on function return type");
+
   /* Construct a new type node and return it.  */
   if (TREE_CODE (t) == FUNCTION_TYPE)
     fntype = build_function_type (return_type, arg_types);

gcc/testsuite/ChangeLog

+2006-12-01  Dirk Mueller  <dmueller@suse.de>
+
+	* g++.dg/warn/Wreturn-type-4.C: New testcase.
+
 2006-11-30  Janis Johnson  <janis187@us.ibm.com>
 
 	* gcc.dg/dfp/convert-int-max.c: New test.

gcc/testsuite/g++.dg/warn/Wreturn-type-4.C

+/* PR c++/18313 */
+/* { dg-do compile } */
+/* { dg-options "-Wreturn-type" } */
+
+volatile void bar(); /* { dg-warning "type qualifiers ignored" } */
+
+struct A
+{
+    const int bla(); /* { dg-warning "type qualifiers ignored" } */
+    static const A getA(); /* { dg-bogus "type qualifiers" } */
+};
+
+template<typename T> const T getfoo(const T def) /* { dg-bogus "type qualifiers ignored" } */
+{ return def; } 
+
+template<typename T> class Pair
+{
+    public:
+        T getLeft() const { return T(); }   /* { dg-warning "type qualifiers ignored" } */
+        const T getRight() const { return T(); } /* { dg-bogus "type qualifiers ignored" } */
+};
+
+template <typename T> struct S {
+    const int f();                     /* { dg-warning "type qualifiers ignored" } */
+    const T g();                       /* { dg-bogus "type qualifiers ignored" } */
+    T h();
+};
+
+int* testtemplate()
+{
+    int i;
+
+    Pair<const int> a;
+
+    a.getLeft();
+    a.getRight();
+
+    S<bool> b;
+    b.h();              /* { dg-bogus "type qualifiers ignored" } */
+    b.g();              /* { dg-bogus "type qualifiers ignored" } */
+
+    return getfoo<int*>(&i);
+}