libstdc++: Adjust testcase for constexpr placement new [PR115744]

This test now fails in C++26 mode because the declaration in <new> is
constexpr and the one in the test isn't. Add constexpr to the test.

libstdc++-v3/ChangeLog:

	PR libstdc++/115744
	* testsuite/18_support/headers/new/synopsis.cc [C++26]: Add
	constexpr to placement operator new and operator new[].

diff --git a/libstdc++-v3/testsuite/18_support/headers/new/synopsis.cc b/libstdc++-v3/testsuite/18_support/headers/new/synopsis.cc
index 5c83956b5845c934944512c7464089731239ac04..479f0df12b5df8d72d8c116c08f0c713e2ceec80 100644 (file)
--- a/libstdc++-v3/testsuite/18_support/headers/new/synopsis.cc
+++ b/libstdc++-v3/testsuite/18_support/headers/new/synopsis.cc
@@ -46,8 +46,13 @@ void* operator new[](std::size_t size, const std::nothrow_t&) throw();
 void  operator delete[](void* ptr) throw();
 void  operator delete[](void* ptr, const std::nothrow_t&) throw();
 
-void* operator new  (std::size_t size, void* ptr) throw();
-void* operator new[](std::size_t size, void* ptr) throw();
+#if __cplusplus > 202302L
+# define CXX26_CONSTEXPR constexpr
+#else
+# define CXX26_CONSTEXPR
+#endif
+CXX26_CONSTEXPR void* operator new  (std::size_t size, void* ptr) throw();
+CXX26_CONSTEXPR void* operator new[](std::size_t size, void* ptr) throw();
 void  operator delete  (void* ptr, void*) throw();
 void  operator delete[](void* ptr, void*) throw();