Fix tests that fail in C++2a mode

The nested typedefs in std::reference_wrapper are no longer present in
C++2a mode, so skip the tests that check for them.

The addition of the [[nodiscard]] attribute to a few functions causes
some failures in tests that intentionally ignore the return value.
Casting the result to void suppresses the new warnings.

	* testsuite/20_util/reference_wrapper/result_type.cc: Disable for
	C++2a.
	* testsuite/20_util/reference_wrapper/typedefs-2.cc: Likewise.
	* testsuite/20_util/reference_wrapper/typedefs-3.cc: Likewise.
	* testsuite/20_util/reference_wrapper/typedefs.cc: Likewise.
	* testsuite/30_threads/async/54297.cc: Suppress nodiscard warning.
	* testsuite/ext/array_allocator/26875.cc: Likewise.
	* testsuite/ext/pool_allocator/allocate_chunk.cc: Likewise.
	* testsuite/util/replacement_memory_operators.h: Likewise.
	* testsuite/util/testsuite_allocator.h: Likewise.

From-SVN: r268355

libstdc++-v3/ChangeLog

 2019-01-29  Jonathan Wakely  <jwakely@redhat.com>
 
+	* testsuite/20_util/reference_wrapper/result_type.cc: Disable for
+	C++2a.
+	* testsuite/20_util/reference_wrapper/typedefs-2.cc: Likewise.
+	* testsuite/20_util/reference_wrapper/typedefs-3.cc: Likewise.
+	* testsuite/20_util/reference_wrapper/typedefs.cc: Likewise.
+	* testsuite/30_threads/async/54297.cc: Suppress nodiscard warning.
+	* testsuite/ext/array_allocator/26875.cc: Likewise.
+	* testsuite/ext/pool_allocator/allocate_chunk.cc: Likewise.
+	* testsuite/util/replacement_memory_operators.h: Likewise.
+	* testsuite/util/testsuite_allocator.h: Likewise.
+
 	* include/std/memory_resource (__pool_resource::_M_unpooled): Use
 	normal mode vector, even for debug mode.
 	* include/std/vector [_GLIBCXX_DEBUG] (_GLIBCXX_STD_C::pmr::vector):

libstdc++-v3/testsuite/20_util/reference_wrapper/result_type.cc

 // { dg-do compile { target c++11 } }
+// { dg-skip-if "result_type removed for C++20" { c++2a } }
 
 // 2010-10-06  Paolo Carlini  <paolo.carlini@oracle.com>
 

libstdc++-v3/testsuite/20_util/reference_wrapper/typedefs-2.cc

 // { dg-do compile { target c++11 } }
+// { dg-skip-if "argument_type removed for C++20" { c++2a } }
 
 // 2010-10-06  Paolo Carlini  <paolo.carlini@oracle.com>
 

libstdc++-v3/testsuite/20_util/reference_wrapper/typedefs-3.cc

 // { dg-do compile { target c++11 } }
+// { dg-skip-if "argument_type removed for C++20" { c++2a } }
 
 // Copyright (C) 2011-2019 Free Software Foundation, Inc.
 //

libstdc++-v3/testsuite/20_util/reference_wrapper/typedefs.cc

 // { dg-do compile { target c++11 } }
+// { dg-skip-if "result_type removed for C++20" { c++2a } }
 
 // Copyright (C) 2008-2019 Free Software Foundation, Inc.
 //

libstdc++-v3/testsuite/30_threads/async/54297.cc

@@ -45,5 +45,5 @@ struct Task
 
 int main()
 {
-  std::async(std::launch::async, Task());
+  (void) std::async(std::launch::async, Task());
 }

libstdc++-v3/testsuite/ext/array_allocator/26875.cc

@@ -33,8 +33,8 @@ int main()
 
   try
     {
-      Allocator1.allocate(1);
-      Allocator2.allocate(1);
+      (void) Allocator1.allocate(1);
+      (void) Allocator2.allocate(1);
     }
   catch (std::bad_alloc& ex)
     {

libstdc++-v3/testsuite/ext/pool_allocator/allocate_chunk.cc

@@ -48,13 +48,13 @@ void test01()
   using __gnu_cxx::__pool_alloc;
 
   __pool_alloc<big> alloc_big;
-  alloc_big.allocate(1);
+  (void) alloc_big.allocate(1);
 
   // The constant 20 comes from __pool_alloc_base::_M_refill. See
   // also __pool_alloc_base::_M_allocate_chunk.
   __pool_alloc<small> alloc_small;
   for (unsigned int i = 0; i < 20 * sizeof(big) / sizeof(small) + 1; ++i)
-    alloc_small.allocate(1);
+    (void) alloc_small.allocate(1);
 }
 
 int main()

libstdc++-v3/testsuite/util/replacement_memory_operators.h

@@ -64,7 +64,7 @@ namespace __gnu_test
     check_new(Alloc a = Alloc())
     {
       __gnu_test::counter::exceptions(false);
-      a.allocate(10);
+      (void) a.allocate(10);
       const bool __b((__gnu_test::counter::count() > 0) == uses_global_new);
       if (!__b)
 	throw std::logic_error("counter not incremented");

libstdc++-v3/testsuite/util/testsuite_allocator.h

@@ -245,7 +245,7 @@ namespace __gnu_test
       Alloc a;
       try
 	{
-	  a.allocate(a.max_size() + 1);
+	  (void) a.allocate(a.max_size() + 1);
 	}
       catch(std::bad_alloc&)
 	{