libstdc++: Fixes for feature test macros (PR 91480)

Remove the non-standard __cpp_lib_allocator_is_always_equal macro and
add the missing macros for P1032R1.

	PR libstdc++/91480
	* include/bits/allocator.h (__cpp_lib_allocator_is_always_equal):
	Remove non-standard macro.
	* include/bits/stl_iterator.h (__cpp_lib_constexpr_iterator): Define
	to indicate P1032R1 support.
	* include/bits/stl_pair.h (__cpp_lib_constexpr_utility): Likewise.
	* include/std/string_view (__cpp_lib_constexpr_string_view): Likewise.
	* include/std/tuple (__cpp_lib_constexpr_tuple): Likewise.
	* include/std/version (__cpp_lib_allocator_is_always_equal): Remove.
	(__cpp_lib_constexpr_iterator, __cpp_lib_constexpr_string_view)
	(__cpp_lib_constexpr_tuple, __cpp_lib_constexpr_utility): Define.
	* testsuite/20_util/function_objects/constexpr_searcher.cc: Check
	feature test macro.
	* testsuite/20_util/tuple/cons/constexpr_allocator_arg_t.cc: Likewise.
	* testsuite/21_strings/basic_string_view/operations/copy/char/
	constexpr.cc: Likewise.
	* testsuite/24_iterators/insert_iterator/constexpr.cc: Likewise.

libstdc++-v3/ChangeLog

 2020-04-28  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/91480
+	* include/bits/allocator.h (__cpp_lib_allocator_is_always_equal):
+	Remove non-standard macro.
+	* include/bits/stl_iterator.h (__cpp_lib_constexpr_iterator): Define
+	to indicate P1032R1 support.
+	* include/bits/stl_pair.h (__cpp_lib_constexpr_utility): Likewise.
+	* include/std/string_view (__cpp_lib_constexpr_string_view): Likewise.
+	* include/std/tuple (__cpp_lib_constexpr_tuple): Likewise.
+	* include/std/version (__cpp_lib_allocator_is_always_equal): Remove.
+	(__cpp_lib_constexpr_iterator, __cpp_lib_constexpr_string_view)
+	(__cpp_lib_constexpr_tuple, __cpp_lib_constexpr_utility): Define.
+	* testsuite/20_util/function_objects/constexpr_searcher.cc: Check
+	feature test macro.
+	* testsuite/20_util/tuple/cons/constexpr_allocator_arg_t.cc: Likewise.
+	* testsuite/21_strings/basic_string_view/operations/copy/char/
+	constexpr.cc: Likewise.
+	* testsuite/24_iterators/insert_iterator/constexpr.cc: Likewise.
+
 	PR libstdc++/94831
 	* include/bits/alloc_traits.h (_S_construct): Restore placement
 	new-expression for C++11/14/17 and call std::construct_at directly

libstdc++-v3/include/bits/allocator.h

@@ -50,9 +50,6 @@
 #endif
 
 #define __cpp_lib_incomplete_container_elements 201505
-#if __cplusplus >= 201103L
-# define __cpp_lib_allocator_is_always_equal 201411
-#endif
 
 namespace std _GLIBCXX_VISIBILITY(default)
 {

libstdc++-v3/include/bits/stl_iterator.h

@@ -71,6 +71,7 @@
 
 #if __cplusplus > 201703L
 # define __cpp_lib_array_constexpr 201811L
+# define __cpp_lib_constexpr_iterator 201811L
 #elif __cplusplus == 201703L
 # define __cpp_lib_array_constexpr 201803L
 #endif

libstdc++-v3/include/bits/stl_pair.h

@@ -63,6 +63,7 @@
 #endif
 #if __cplusplus > 201703L
 # include <compare>
+# define __cpp_lib_constexpr_utility 201811L
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)

libstdc++-v3/include/std/string_view

@@ -48,7 +48,10 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-#define __cpp_lib_string_view 201803
+# define __cpp_lib_string_view 201803L
+#if __cplusplus > 201703L
+# define __cpp_lib_constexpr_string_view 201811L
+#endif
 
   // Helper for basic_string and basic_string_view members.
   constexpr size_t

libstdc++-v3/include/std/tuple

@@ -41,6 +41,7 @@
 #include <bits/invoke.h>
 #if __cplusplus > 201703L
 # include <compare>
+# define __cpp_lib_constexpr_tuple 201811L
 #endif
 
 namespace std _GLIBCXX_VISIBILITY(default)

libstdc++-v3/include/std/version

@@ -50,7 +50,6 @@
 #define __cpp_lib_result_of_sfinae 201210
 
 #if _GLIBCXX_HOSTED
-# define __cpp_lib_allocator_is_always_equal 201411
 # define __cpp_lib_allocator_traits_is_always_equal 201411
 # define __cpp_lib_shared_ptr_arrays 201611L
 #endif
@@ -157,7 +156,7 @@
 # define __cpp_lib_shared_mutex 201505
 #endif
 #define __cpp_lib_shared_ptr_weak_type 201606
-#define __cpp_lib_string_view 201803
+#define __cpp_lib_string_view 201803L
 // #define __cpp_lib_to_chars 201611L
 #define __cpp_lib_unordered_map_try_emplace 201411
 #define __cpp_lib_variant 201606L
@@ -201,8 +200,12 @@
 #define __cpp_lib_constexpr_complex 201711L
 #define __cpp_lib_constexpr_dynamic_alloc 201907L
 #define __cpp_lib_constexpr_functional 201907L
+# define __cpp_lib_constexpr_iterator 201811L
 #define __cpp_lib_constexpr_memory 201811L
 #define __cpp_lib_constexpr_numeric 201911L
+#define __cpp_lib_constexpr_string_view 201811L
+#define __cpp_lib_constexpr_tuple 201811L
+#define __cpp_lib_constexpr_utility 201811L
 #define __cpp_lib_erase_if 202002L
 #define __cpp_lib_interpolate 201902L
 #ifdef _GLIBCXX_HAS_GTHREADS

libstdc++-v3/testsuite/20_util/function_objects/constexpr_searcher.cc

@@ -19,6 +19,13 @@
 // { dg-do compile { target c++2a } }
 
 #include <functional>
+
+#ifndef __cpp_lib_constexpr_functional
+# error "Feature test macro for constexpr searcher is missing in <functional>"
+#elif __cpp_lib_constexpr_functional < 201811L
+# error "Feature test macro for constexpr searcher has wrong value in <functional>"
+#endif
+
 #include <string_view>
 
 const std::string_view

libstdc++-v3/testsuite/20_util/tuple/cons/constexpr_allocator_arg_t.cc

@@ -18,9 +18,16 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-#include <memory>
 #include <tuple>
 
+#ifndef __cpp_lib_constexpr_tuple
+# error "Feature test macro for constexpr allocator constructors is missing in <tuple>"
+#elif __cpp_lib_constexpr_tuple < 201811L
+# error "Feature test macro for constexpr allocator constructors has wrong value in <tuple>"
+#endif
+
+#include <memory>
+
 const std::allocator<int> alloc{};
 
 constexpr bool

libstdc++-v3/testsuite/21_strings/basic_string_view/operations/copy/char/constexpr.cc

@@ -20,6 +20,12 @@
 
 #include <string_view>
 
+#ifndef __cpp_lib_constexpr_string_view
+# error "Feature test macro for constexpr copy is missing in <string_view>"
+#elif __cpp_lib_constexpr_iterator < 201811L
+# error "Feature test macro for constexpr copy has wrong value in <string_view>"
+#endif
+
 constexpr bool
 test01()
 {

libstdc++-v3/testsuite/24_iterators/insert_iterator/constexpr.cc

@@ -20,6 +20,12 @@
 
 #include <iterator>
 
+#ifndef __cpp_lib_constexpr_iterator
+# error "Feature test macro for constexpr insert iterators is missing in <iterator>"
+#elif __cpp_lib_constexpr_iterator < 201811L
+# error "Feature test macro for constexpr insert iterators has wrong value in <iterator>"
+#endif
+
 struct container
 {
   using value_type = int;