Do not declare std::uses_allocator before C++11

	* include/bits/memoryfwd.h (uses_allocator): Do not declare for C++98.
	* testsuite/17_intro/names.cc: Check uses_allocator in C++98.

From-SVN: r277301

libstdc++-v3/ChangeLog

 2019-10-22  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/bits/memoryfwd.h (uses_allocator): Do not declare for C++98.
+	* testsuite/17_intro/names.cc: Check uses_allocator in C++98.
+
 	* include/bits/alloc_traits.h
 	(allocator_traits<allocator<T>>::allocate): Ignore hint for C++20.
 	(allocator_traits<allocator<T>>::construct): Perform placement new

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

@@ -68,9 +68,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     class allocator<void>;
 #endif
 
+#if __cplusplus >= 201103L
   /// Declare uses_allocator so it can be specialized in \<queue\> etc.
   template<typename, typename>
     struct uses_allocator;
+#endif
 
   /// @} group memory
 

libstdc++-v3/testsuite/17_intro/names.cc

@@ -103,6 +103,10 @@
 
 #define tmp (
 
+#if __cplusplus < 201103L
+#define uses_allocator  (
+#endif
+
 #if __cplusplus < 201703L
 // <charconv> defines to_chars_result::ptr and to_chars_result::ec
 #define ec (