Remove inactive code branches

Author: frederick-vs-ja

libcxx/include/__type_traits/reference_constructs_from_temporary.h

@@ -33,14 +33,10 @@ _LIBCPP_NO_SPECIALIZATIONS inline constexpr bool reference_constructs_from_tempo
 #if __has_builtin(__reference_constructs_from_temporary)
 template <class _Tp, class _Up>
 inline const bool __reference_constructs_from_temporary_v = __reference_constructs_from_temporary(_Tp, _Up);
-#elif __has_builtin(__reference_binds_to_temporary)
-// TODO: Remove this once all support compilers have __reference_constructs_from_temporary implemented.
-template <class _Tp, class _Up>
-inline const bool __reference_constructs_from_temporary_v = __reference_binds_to_temporary(_Tp, _Up);
 #else
-// TODO: Remove this once https://github.com/llvm/llvm-project/issues/111477 no longer affects supported compilers.
+// TODO(LLVM 22): Remove this as all support compilers should have __reference_constructs_from_temporary implemented.
 template <class _Tp, class _Up>
-inline const bool __reference_constructs_from_temporary_v = false;
+inline const bool __reference_constructs_from_temporary_v = __reference_binds_to_temporary(_Tp, _Up);
 #endif
 
 _LIBCPP_END_NAMESPACE_STD

libcxx/test/libcxx/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.verify.cpp

@@ -38,16 +38,7 @@ template <class T> struct CannotDeduce {
 template <class ...Args>
 void F(typename CannotDeduce<std::tuple<Args...>>::type const&) {}
 
-#if TEST_HAS_BUILTIN(__reference_constructs_from_temporary)
-#  define TEST_HAS_REFERENCE_BINDING_TRAIT 1
-#elif TEST_HAS_BUILTIN(__reference_binds_to_temporary)
-#  define TEST_HAS_REFERENCE_BINDING_TRAIT 1
-#else
-#  define TEST_HAS_REFERENCE_BINDING_TRAIT 0
-#endif
-
 void f() {
-#if TEST_HAS_REFERENCE_BINDING_TRAIT
   // Test that we emit our diagnostic from the library.
   // expected-error@tuple:* 8 {{Attempted construction of reference element binds to a temporary whose lifetime has ended}}
 
@@ -80,8 +71,4 @@ void f() {
     std::tuple<std::string &&> t2("hello"); // expected-note {{requested here}}
     std::tuple<std::string &&> t3(std::allocator_arg, alloc, "hello"); // expected-note {{requested here}}
   }
-#else
-#error force failure
-// expected-error@-1 {{force failure}}
-#endif
 }

libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR20855_tuple_ref_binding_diagnostics.pass.cpp

@@ -22,12 +22,10 @@
 #  define ASSERT_REFERENCE_BINDS_TEMPORARY(...) static_assert(__reference_constructs_from_temporary(__VA_ARGS__), "")
 #  define ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(...)                                                                    \
     static_assert(!__reference_constructs_from_temporary(__VA_ARGS__), "")
-#elif TEST_HAS_BUILTIN(__reference_binds_to_temporary)
+#else
+// TODO(LLVM 22): Remove this as all support compilers should have __reference_constructs_from_temporary implemented.
 #  define ASSERT_REFERENCE_BINDS_TEMPORARY(...) static_assert(__reference_binds_to_temporary(__VA_ARGS__), "")
 #  define ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(...) static_assert(!__reference_binds_to_temporary(__VA_ARGS__), "")
-#else
-#  define ASSERT_REFERENCE_BINDS_TEMPORARY(...) static_assert(true, "")
-#  define ASSERT_NOT_REFERENCE_BINDS_TEMPORARY(...) static_assert(true, "")
 #endif
 
 template <class Tp>