libstdc++: Fix testsuite failures and warnings due to is_pod deprecation

With -std=gnu++2a and -Wsystem-headers the std::is_pod deprecation
causes some new diagnostics. This suppresses them.

	* include/experimental/type_traits (experimental::is_pod_v): Disable
	-Wdeprecated-declarations warnings around reference to std::is_pod.
	* include/std/type_traits (is_pod_v): Likewise.
	* testsuite/18_support/max_align_t/requirements/2.cc: Also check
	is_standard_layout and is_trivial. Do not check is_pod for C++20.
	* testsuite/20_util/is_pod/requirements/explicit_instantiation.cc:
	Add -Wno-deprecated for C++20.
	* testsuite/20_util/is_pod/requirements/typedefs.cc: Likewise.
	* testsuite/20_util/is_pod/value.cc: Likewise.
	* testsuite/experimental/type_traits/value.cc: Likewise.

From-SVN: r280066

libstdc++-v3/ChangeLog

+2020-01-09  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/experimental/type_traits (experimental::is_pod_v): Disable
+	-Wdeprecated-declarations warnings around reference to std::is_pod.
+	* include/std/type_traits (is_pod_v): Likewise.
+	* testsuite/18_support/max_align_t/requirements/2.cc: Also check
+	is_standard_layout and is_trivial. Do not check is_pod for C++20.
+	* testsuite/20_util/is_pod/requirements/explicit_instantiation.cc:
+	Add -Wno-deprecated for C++20.
+	* testsuite/20_util/is_pod/requirements/typedefs.cc: Likewise.
+	* testsuite/20_util/is_pod/value.cc: Likewise.
+	* testsuite/experimental/type_traits/value.cc: Likewise.
+
 2020-01-09  JeanHeyd "ThePhD" Meneide  <phdofthehouse@gmail.com>
 
 	* include/bits/c++config (_GLIBCXX20_DEPRECATED): Add new macro.

libstdc++-v3/include/experimental/type_traits

@@ -110,8 +110,11 @@ template <typename _Tp>
   constexpr bool is_trivially_copyable_v = is_trivially_copyable<_Tp>::value;
 template <typename _Tp>
   constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 template <typename _Tp>
   constexpr bool is_pod_v = is_pod<_Tp>::value;
+#pragma GCC diagnostic pop
 template <typename _Tp>
   constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
 template <typename _Tp>

libstdc++-v3/include/std/type_traits

@@ -3079,9 +3079,12 @@ template <typename _Tp>
     is_trivially_copyable<_Tp>::value;
 template <typename _Tp>
   inline constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 template <typename _Tp>
   _GLIBCXX20_DEPRECATED("use is_standard_layout_v && is_trivial_v instead")
   inline constexpr bool is_pod_v = is_pod<_Tp>::value;
+#pragma GCC diagnostic pop
 template <typename _Tp>
   inline constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
 template <typename _Tp>

libstdc++-v3/testsuite/18_support/max_align_t/requirements/2.cc

@@ -20,4 +20,8 @@
 #include <cstddef>
 #include <type_traits>
 
+#if __cplusplus <= 201703L
 static_assert (std::is_pod<std::max_align_t>::value, "");
+#endif
+static_assert (std::is_standard_layout<std::max_align_t>::value, "");
+static_assert (std::is_trivial<std::max_align_t>::value, "");

libstdc++-v3/testsuite/20_util/is_pod/requirements/explicit_instantiation.cc

 // { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-deprecated" { target { c++2a } } }
 // 2010-02-21  Paolo Carlini  <paolo.carlini@oracle.com>
 
 // Copyright (C) 2010-2020 Free Software Foundation, Inc.

libstdc++-v3/testsuite/20_util/is_pod/requirements/typedefs.cc

 // { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-deprecated" { target { c++2a } } }
 
 // 2010-02-21  Paolo Carlini  <paolo.carlini@oracle.com>
 //

libstdc++-v3/testsuite/20_util/is_pod/value.cc

 // { dg-do compile { target c++11 } }
+// { dg-additional-options "-Wno-deprecated" { target { c++2a } } }
 
 // 2010-02-21  Paolo Carlini  <pcarlini@suse.de>
 //

libstdc++-v3/testsuite/experimental/type_traits/value.cc

 // { dg-do compile { target c++14 } }
+// { dg-additional-options "-Wno-deprecated" { target { c++2a } } }
 
 // Copyright (C) 2014-2020 Free Software Foundation, Inc.
 //