Remove unrelated changes

Let's adjust tests and implementation
in a seperate PR.

libcxx/docs/ReleaseNotes/20.rst

@@ -64,8 +64,8 @@ Deprecations and Removals
   removed in language modes prior to C++20. If you are using these features prior to C++20, you will need to
   update to ``-std=c++20``.
 
-- The relational operators for ``std::chrono::weekday`` are removed entirely, and the
-  ``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension is
+- TODO: The relational operators for ``std::chrono::weekday`` will be removed entirely, and the
+  ``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro that was used to re-enable this extension will be
   ignored in LLVM 20.
 
 - The ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro no longer has any effect. ``std::allocator<const T>`` is not

libcxx/include/__chrono/weekday.h

@@ -79,6 +79,25 @@ _LIBCPP_HIDE_FROM_ABI inline constexpr bool operator==(const weekday& __lhs, con
   return __lhs.c_encoding() == __rhs.c_encoding();
 }
 
+// TODO(LLVM 20): Remove the escape hatch
+#  ifdef _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
+_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<(const weekday& __lhs, const weekday& __rhs) noexcept {
+  return __lhs.c_encoding() < __rhs.c_encoding();
+}
+
+_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>(const weekday& __lhs, const weekday& __rhs) noexcept {
+  return __rhs < __lhs;
+}
+
+_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator<=(const weekday& __lhs, const weekday& __rhs) noexcept {
+  return !(__rhs < __lhs);
+}
+
+_LIBCPP_HIDE_FROM_ABI inline constexpr bool operator>=(const weekday& __lhs, const weekday& __rhs) noexcept {
+  return !(__lhs < __rhs);
+}
+#  endif // _LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS
+
 _LIBCPP_HIDE_FROM_ABI inline constexpr weekday operator+(const weekday& __lhs, const days& __rhs) noexcept {
   auto const __mu = static_cast<long long>(__lhs.c_encoding()) + __rhs.count();
   auto const __yr = (__mu >= 0 ? __mu : __mu - 6) / 7;

libcxx/include/__type_traits/promote.h

@@ -13,12 +13,20 @@
 #include <__type_traits/integral_constant.h>
 #include <__type_traits/is_arithmetic.h>
 
+#if defined(_LIBCPP_CLANG_VER) && _LIBCPP_CLANG_VER == 1700
+#  include <__type_traits/is_same.h>
+#  include <__utility/declval.h>
+#endif
+
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
 #endif
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
+// TODO(LLVM-20): Remove this workaround
+#if !defined(_LIBCPP_CLANG_VER) || _LIBCPP_CLANG_VER != 1700
+
 template <class... _Args>
 class __promote {
   static_assert((is_arithmetic<_Args>::value && ...));
@@ -42,6 +50,79 @@ class __promote {
   using type = decltype((__test(_Args()) + ...));
 };
 
+#else
+
+template <class _Tp>
+struct __numeric_type {
+  static void __test(...);
+  static float __test(float);
+  static double __test(char);
+  static double __test(int);
+  static double __test(unsigned);
+  static double __test(long);
+  static double __test(unsigned long);
+  static double __test(long long);
+  static double __test(unsigned long long);
+#  ifndef _LIBCPP_HAS_NO_INT128
+  static double __test(__int128_t);
+  static double __test(__uint128_t);
+#  endif
+  static double __test(double);
+  static long double __test(long double);
+
+  typedef decltype(__test(std::declval<_Tp>())) type;
+  static const bool value = _IsNotSame<type, void>::value;
+};
+
+template <>
+struct __numeric_type<void> {
+  static const bool value = true;
+};
+
+template <class _A1,
+          class _A2 = void,
+          class _A3 = void,
+          bool      = __numeric_type<_A1>::value && __numeric_type<_A2>::value && __numeric_type<_A3>::value>
+class __promote_imp {
+public:
+  static const bool value = false;
+};
+
+template <class _A1, class _A2, class _A3>
+class __promote_imp<_A1, _A2, _A3, true> {
+private:
+  typedef typename __promote_imp<_A1>::type __type1;
+  typedef typename __promote_imp<_A2>::type __type2;
+  typedef typename __promote_imp<_A3>::type __type3;
+
+public:
+  typedef decltype(__type1() + __type2() + __type3()) type;
+  static const bool value = true;
+};
+
+template <class _A1, class _A2>
+class __promote_imp<_A1, _A2, void, true> {
+private:
+  typedef typename __promote_imp<_A1>::type __type1;
+  typedef typename __promote_imp<_A2>::type __type2;
+
+public:
+  typedef decltype(__type1() + __type2()) type;
+  static const bool value = true;
+};
+
+template <class _A1>
+class __promote_imp<_A1, void, void, true> {
+public:
+  typedef typename __numeric_type<_A1>::type type;
+  static const bool value = true;
+};
+
+template <class _A1, class _A2 = void, class _A3 = void>
+class __promote : public __promote_imp<_A1, _A2, _A3> {};
+
+#endif // !defined(_LIBCPP_CLANG_VER) || _LIBCPP_CLANG_VER >= 1700
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___TYPE_TRAITS_PROMOTE_H

libcxx/test/libcxx/atomics/diagnose_invalid_memory_order.verify.cpp

@@ -9,7 +9,7 @@
 // This test fails with Clang <18 because diagnose_if doesn't emit all of the
 // diagnostics when -fdelayed-template-parsing is enabled, like it is in MSVC
 // mode.
-// XFAIL: msvc
+// XFAIL: msvc && clang-17
 
 // REQUIRES: diagnose-if-support
 

libcxx/test/libcxx/clang_tidy.gen.py

@@ -27,6 +27,9 @@
 // The GCC compiler flags are not always compatible with clang-tidy.
 // UNSUPPORTED: gcc
 
+// Clang 17 has false positives.
+// UNSUPPORTED: clang-17
+
 {lit_header_restrictions.get(header, '')}
 
 // TODO: run clang-tidy with modules enabled once they are supported

libcxx/test/libcxx/gdb/gdb_pretty_printer_test.sh.cpp

@@ -12,7 +12,7 @@
 // UNSUPPORTED: c++03
 
 // TODO: Investigate these failures which break the CI.
-// UNSUPPORTED: clang-18, clang-19
+// UNSUPPORTED: clang-17, clang-18, clang-19
 
 // The Android libc++ tests are run on a non-Android host, connected to an
 // Android device over adb. gdb needs special support to make this work (e.g.

libcxx/test/libcxx/ranges/range.adaptors/range.lazy.split/no_unique_address.compile.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc
+// XFAIL: msvc && clang-17
 
 // class lazy_split_view {
 //   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();

libcxx/test/libcxx/ranges/range.adaptors/range.split/no_unique_address.compile.pass.cpp

@@ -7,7 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc
+// XFAIL: msvc && clang-17
 
 // class split_view {
 //   _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();

libcxx/test/libcxx/ranges/range.factories/range.istream.view/no_unique_address.compile.pass.cpp

@@ -8,7 +8,7 @@
 
 // UNSUPPORTED: no-localization
 // UNSUPPORTED: c++03, c++11, c++14, c++17
-// XFAIL: msvc
+// XFAIL: msvc && clang-17
 
 // Test the libc++ extension that the value stored in `std::ranges::istream_view` has been marked
 // as _LIBCPP_NO_UNIQUE_ADDRESS

libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp

@@ -6,6 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+// Clang-18 fixed some spurious clang diagnostics. Once clang-18 is the
+// minimum required version these obsolete tests can be removed.
+// TODO(LLVM-20) remove spurious clang diagnostic tests.
+
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
 // With clang-cl, some warnings have a 'which is a Microsoft extension' suffix
@@ -55,12 +59,12 @@ void test() {
   {
     std::expected<int, int> e;
     e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
     // expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}
 
     e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
     // expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}
   }
@@ -69,27 +73,27 @@ void test() {
   {
     const std::expected<int, int> e;
     e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
   }
 
   // Test && overload
   {
     std::expected<int, int> e;
     std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
   }
 
   // Test const&& overload
   {
     const std::expected<int, int> e;
     std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
   }
 }
 // clang-format on

libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp

@@ -6,6 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
+// Clang-18 fixed some spurious clang diagnostics. Once clang-18 is the
+// minumum required version these obsolete tests can be removed.
+// TODO(LLVM-20) remove spurious clang diagnostic tests.
+
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
 
 // With clang-cl, some warnings have a 'which is a Microsoft extension' suffix
@@ -56,13 +60,13 @@ void test() {
   {
     std::expected<void, int> e;
     e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
-    // expected-error-re@*:* {{call to deleted constructor of {{.*}}}}
+    // expected-error-re@*:* 0-1 {{call to deleted constructor of {{.*}}}}
     // expected-error-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}}}
 
     e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     // expected-error-re@*:* {{static assertion failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
     // expected-warning-re@*:* 0-1 {{union member {{.*}} has reference type {{.*}}, which is a Microsoft extension}}
   }
@@ -71,28 +75,28 @@ void test() {
   {
     const std::expected<void, int> e;
     e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
-    // expected-error-re@*:* {{call to deleted constructor of {{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{call to deleted constructor of {{.*}}}}
   }
 
   // Test && overload
   {
     std::expected<void, int> e;
     std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
   }
 
   // Test const&& overload
   {
     const std::expected<void, int> e;
     std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
     std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{static assertion failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
-    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* 0-1 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
   }
 }
 // clang-format on

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_add.pass.cpp

@@ -10,7 +10,7 @@
 
 // Older versions of clang have a bug with atomic builtins affecting double and long double.
 // Fixed by 5fdd0948.
-// XFAIL: target=powerpc-ibm-{{.*}} && clang-18
+// XFAIL: target=powerpc-ibm-{{.*}} && (clang-17 || clang-18)
 
 // https://github.com/llvm/llvm-project/issues/72893
 // XFAIL: target={{x86_64-.*}} && tsan

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/fetch_sub.pass.cpp

@@ -10,7 +10,7 @@
 
 // Older versions of clang have a bug with atomic builtins affecting double and long double.
 // Fixed by 5fdd0948.
-// XFAIL: target=powerpc-ibm-{{.*}} && clang-18
+// XFAIL: target=powerpc-ibm-{{.*}} && (clang-17 || clang-18)
 
 // https://github.com/llvm/llvm-project/issues/72893
 // XFAIL: target={{x86_64-.*}} && tsan

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.minus_equals.pass.cpp

@@ -10,7 +10,7 @@
 
 // Older versions of clang have a bug with atomic builtins affecting double and long double.
 // Fixed by 5fdd0948.
-// XFAIL: target=powerpc-ibm-{{.*}} && clang-18
+// XFAIL: target=powerpc-ibm-{{.*}} && (clang-17 || clang-18)
 
 // floating-point-type operator-=(floating-point-type) volatile noexcept;
 // floating-point-type operator-=(floating-point-type) noexcept;

libcxx/test/std/atomics/atomics.types.generic/atomics.types.float/operator.plus_equals.pass.cpp

@@ -10,7 +10,7 @@
 
 // Older versions of clang have a bug with atomic builtins affecting double and long double.
 // Fixed by 5fdd0948.
-// XFAIL: target=powerpc-ibm-{{.*}} && clang-18
+// XFAIL: target=powerpc-ibm-{{.*}} && (clang-17 || clang-18)
 
 // floating-point-type operator+=(floating-point-type) volatile noexcept;
 // floating-point-type operator+=(floating-point-type) noexcept;

libcxx/test/std/experimental/simd/simd.class/simd_copy.pass.cpp

@@ -10,7 +10,7 @@
 
 // Older versions of clang may encounter a backend error (see 0295c2ad):
 //   Pass-by-value arguments with alignment greater than register width are not supported.
-// XFAIL: target=powerpc{{.*}}-ibm-{{.*}} clang-18
+// XFAIL: target=powerpc{{.*}}-ibm-{{.*}} && (clang-17 || clang-18)
 
 // <experimental/simd>
 //

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array14.pass.cpp

@@ -9,7 +9,7 @@
 // test sized operator delete[] replacement.
 
 // These compiler versions don't enable sized deallocation by default.
-// UNSUPPORTED: clang-18
+// UNSUPPORTED: clang-17, clang-18
 
 // UNSUPPORTED: sanitizer-new-delete, c++03, c++11
 // XFAIL: apple-clang

libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete14.pass.cpp

@@ -9,7 +9,7 @@
 // Test sized operator delete replacement.
 
 // These compiler versions do not enable sized deallocation by default.
-// UNSUPPORTED: clang-18
+// UNSUPPORTED: clang-17, clang-18
 
 // UNSUPPORTED: sanitizer-new-delete, c++03, c++11
 // XFAIL: apple-clang

libcxx/test/std/numerics/c.math/signbit.pass.cpp

@@ -12,7 +12,7 @@
 // UNSUPPORTED: windows
 
 // These compilers don't support constexpr `__builtin_signbit` yet.
-// UNSUPPORTED: clang-18, clang-19, apple-clang-15, apple-clang-16
+// UNSUPPORTED: clang-17, clang-18, clang-19, apple-clang-15, apple-clang-16
 
 #include <cassert>
 #include <cmath>