PR c++/87357 - missing -Wconversion warning

	PR c++/87357 - missing -Wconversion warning
	* decl.c (grok_op_properties): Remove diagnostic parts mentioning
	a conversion to a reference to void.  Use
	same_type_ignoring_top_level_qualifiers_p rather than comparing types
	directly.

	* g++.dg/warn/Wconversion5.C: New test.

From-SVN: r264425

gcc/cp/ChangeLog

+2018-09-19  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/87357 - missing -Wconversion warning
+	* decl.c (grok_op_properties): Remove diagnostic parts mentioning
+	a conversion to a reference to void.  Use
+	same_type_ignoring_top_level_qualifiers_p rather than comparing types
+	directly.
+
 2018-09-18  Marek Polacek  <polacek@redhat.com>
 
 	P1064R0 - Allowing Virtual Function Calls in Constant Expressions

gcc/cp/decl.c

@@ -13553,15 +13553,11 @@ grok_op_properties (tree decl, bool complain)
 	t = TYPE_MAIN_VARIANT (TREE_TYPE (t));
 
       if (VOID_TYPE_P (t))
-	warning_at (loc, OPT_Wconversion,
-		    ref
-		    ? G_("conversion to a reference to void "
-			 "will never use a type conversion operator")
-		    : G_("conversion to void "
-			 "will never use a type conversion operator"));
+	warning_at (loc, OPT_Wconversion, "conversion to void "
+		    "will never use a type conversion operator");
       else if (class_type)
 	{
-	  if (t == class_type)
+	  if (same_type_ignoring_top_level_qualifiers_p (t, class_type))
 	    warning_at (loc, OPT_Wconversion,
 			ref
 			? G_("conversion to a reference to the same type "

gcc/testsuite/ChangeLog

+2018-09-19  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/87357 - missing -Wconversion warning
+	* g++.dg/warn/Wconversion5.C: New test.
+
 2018-09-19  Matthew Malcomson  <matthew.malcomson@arm.com>
 
 	* gcc.target/aarch64/atomic-store.c: New.

gcc/testsuite/g++.dg/warn/Wconversion5.C

+// PR c++/87357
+// { dg-do compile }
+// { dg-options "-Wconversion" }
+
+struct B { };
+
+struct X : public B {
+  operator X(); // { dg-warning "3:conversion to the same type will never use a type conversion operator" }
+  operator X&(); // { dg-warning "3:conversion to a reference to the same type will never use a type conversion operator" }
+  operator X() const; // { dg-warning "3:conversion to the same type will never use a type conversion operator" }
+  operator const X(); // { dg-warning "3:conversion to the same type will never use a type conversion operator" }
+
+  operator B(); // { dg-warning "3:conversion to a base class will never use a type conversion operator" }
+  operator B&(); // { dg-warning "3:conversion to a reference to a base class will never use a type conversion operator" }
+  operator B() const; // { dg-warning "3:conversion to a base class will never use a type conversion operator" }
+  operator const B(); // { dg-warning "3:conversion to a base class will never use a type conversion operator" }
+
+  operator void(); // { dg-warning "3:conversion to void will never use a type conversion operator" }
+  operator void() const; // { dg-warning "3:conversion to void will never use a type conversion operator" }
+};