tree.c (handle_nodiscard_attribute): Do not warn about nodiscard applied to a constructor.

/cp
2019-08-02  Paolo Carlini  <paolo.carlini@oracle.com>

	* tree.c (handle_nodiscard_attribute): Do not warn about nodiscard
	applied to a constructor.

/testsuite
2019-08-02  Paolo Carlini  <paolo.carlini@oracle.com>

	* g++.dg/cpp1z/nodiscard6.C: New.

From-SVN: r274002

gcc/cp/ChangeLog

+2019-08-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* tree.c (handle_nodiscard_attribute): Do not warn about nodiscard
+	applied to a constructor.
+
 2019-08-02  Martin Liska  <mliska@suse.cz>
 
 	* decl.c (grok_op_properties):

gcc/cp/tree.c

@@ -4361,7 +4361,8 @@ handle_nodiscard_attribute (tree *node, tree name, tree /*args*/,
 {
   if (TREE_CODE (*node) == FUNCTION_DECL)
     {
-      if (VOID_TYPE_P (TREE_TYPE (TREE_TYPE (*node))))
+      if (VOID_TYPE_P (TREE_TYPE (TREE_TYPE (*node)))
+	  && !DECL_CONSTRUCTOR_P (*node))
 	warning_at (DECL_SOURCE_LOCATION (*node),
 		    OPT_Wattributes, "%qE attribute applied to %qD with void "
 		    "return type", name, *node);

gcc/testsuite/ChangeLog

+2019-08-02  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	* g++.dg/cpp1z/nodiscard6.C: New.
+
 2019-08-02  Senthil Kumar Selvaraj  <senthilkumar.selvaraj@microchip.com>
 
 	* gcc.dg/torture/ssa-fre-5.c: Add dg-require-effective-target int32.

gcc/testsuite/g++.dg/cpp1z/nodiscard6.C

+// { dg-do compile { target c++11 } }
+
+struct A
+{
+  [[nodiscard]] A();
+};
+
+void foo()
+{
+  A();  // { dg-warning "ignoring return value" }
+}