re PR c++/84364 (-Weffc++ warns on "return *this" in template after r253599)

	PR c++/84364
	* typeck.c (check_return_expr): Don't emit -Weffc++ warning
	about return other than *this in assignment operators if
	retval is type dependent expression.

	* g++.dg/warn/effc4.C: New test.

From-SVN: r257640

gcc/cp/ChangeLog

+2018-02-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/84364
+	* typeck.c (check_return_expr): Don't emit -Weffc++ warning
+	about return other than *this in assignment operators if
+	retval is type dependent expression.
+
 2018-02-13  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/84333

gcc/cp/typeck.c

@@ -9232,7 +9232,8 @@ check_return_expr (tree retval, bool *no_warning)
 
   /* Effective C++ rule 15.  See also start_function.  */
   if (warn_ecpp
-      && DECL_NAME (current_function_decl) == assign_op_identifier)
+      && DECL_NAME (current_function_decl) == assign_op_identifier
+      && !type_dependent_expression_p (retval))
     {
       bool warn = true;
 

gcc/testsuite/ChangeLog

+2018-02-13  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/84364
+	* g++.dg/warn/effc4.C: New test.
+
 2018-02-13  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/84333

gcc/testsuite/g++.dg/warn/effc4.C

+// PR c++/84364
+// { dg-do compile }
+// { dg-options "-Weffc++" }
+
+template <typename T>
+struct A {
+  A &operator=(A<T>& f) {
+    return *this;	// { dg-bogus "should return a reference to" }
+  }
+};