[libc++] Fix failures with GCC 14 (#92663)

Fixes #91831

Author: philnik777

libcxx/include/__string/constexpr_c_functions.h

@@ -123,7 +123,7 @@ __constexpr_memcmp_equal(const _Tp* __lhs, const _Up* __rhs, __element_count __n
     }
     return true;
   } else {
-    return __builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp)) == 0;
+    return ::__builtin_memcmp(__lhs, __rhs, __count * sizeof(_Tp)) == 0;
   }
 }
 

libcxx/include/__type_traits/remove_pointer.h

@@ -23,8 +23,13 @@ struct remove_pointer {
   using type _LIBCPP_NODEBUG = __remove_pointer(_Tp);
 };
 
+#  ifdef _LIBCPP_COMPILER_GCC
+template <class _Tp>
+using __remove_pointer_t = typename remove_pointer<_Tp>::type;
+#  else
 template <class _Tp>
 using __remove_pointer_t = __remove_pointer(_Tp);
+#  endif
 #else
 // clang-format off
 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS remove_pointer                      {typedef _LIBCPP_NODEBUG _Tp type;};

libcxx/include/bitset

@@ -375,8 +375,11 @@ template <size_t _N_words, size_t _Size>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long
 __bitset<_N_words, _Size>::to_ullong(true_type, true_type) const {
   unsigned long long __r = __first_[0];
+  _LIBCPP_DIAGNOSTIC_PUSH
+  _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wshift-count-overflow")
   for (size_t __i = 1; __i < sizeof(unsigned long long) / sizeof(__storage_type); ++__i)
     __r |= static_cast<unsigned long long>(__first_[__i]) << (sizeof(__storage_type) * CHAR_BIT);
+  _LIBCPP_DIAGNOSTIC_POP
   return __r;
 }
 

libcxx/test/std/time/time.zone/time.zone.leap/nonmembers/comparison.pass.cpp

@@ -9,8 +9,8 @@
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // UNSUPPORTED: no-filesystem, no-localization, no-tzdb
 
-// TODO TZDB test whether this can be enabled with gcc 14.
-// UNSUPPORTED: gcc-13
+// TODO TZDB investigate why this fails with GCC
+// UNSUPPORTED: gcc-13, gcc-14
 
 // XFAIL: libcpp-has-no-experimental-tzdb
 // XFAIL: availability-tzdb-missing

libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp

@@ -10,7 +10,7 @@
 
 // GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
 // please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333
-// XFAIL: gcc-13
+// XFAIL: gcc-13, gcc-14
 
 // <expected>
 

libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp

@@ -10,7 +10,7 @@
 
 // GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
 // please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333.
-// XFAIL: gcc-13
+// XFAIL: gcc-13, gcc-14
 
 // <expected>
 

libcxx/test/std/utilities/expected/expected.void/monadic/transform_error.pass.cpp

@@ -10,7 +10,7 @@
 
 // GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
 // please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333
-// XFAIL: gcc-13
+// XFAIL: gcc-13, gcc-14
 
 // <expected>
 

libcxx/test/std/utilities/format/format.formatter/format.formatter.spec/formatter.char_array.pass.cpp

@@ -7,7 +7,7 @@
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
 // TODO FMT __builtin_memcpy isn't constexpr in GCC
-// UNSUPPORTED: gcc-13
+// UNSUPPORTED: gcc-13, gcc-14
 
 // <format>
 

libcxx/test/std/utilities/tuple/tuple.tuple/tuple.cnstr/PR31384.pass.cpp

@@ -8,6 +8,9 @@
 
 // UNSUPPORTED: c++03
 
+// FIXME: Why does this start to fail with GCC 14?
+// XFAIL: gcc-14
+
 // See https://llvm.org/PR31384.
 
 #include <tuple>

libcxx/test/std/utilities/variant/variant.visit.member/visit_return_type.pass.cpp

@@ -34,6 +34,9 @@ struct overloaded : Ts... {
   using Ts::operator()...;
 };
 
+template <class... Ts>
+overloaded(Ts...) -> overloaded<Ts...>;
+
 void test_overload_ambiguity() {
   using V = std::variant<float, long, std::string>;
   using namespace std::string_literals;