Replace enable_if by static_assert

Author: winner245

libcxx/include/__bit_reference

@@ -63,10 +63,11 @@ struct __size_difference_type_traits<_Cp, __void_t<typename _Cp::difference_type
 // or `unsigned short`. Casting back to _StorageType is crucial to prevent undefined behavior that can arise
 // from integral promotions.
 // See https://github.com/llvm/llvm-project/pull/122410.
-template <class _StoragePointer,
-          __enable_if_t<is_unsigned<typename pointer_traits<_StoragePointer>::element_type>::value, int> >
+template <class _StoragePointer>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
 __fill_masked_range(_StoragePointer __word, unsigned __clz, unsigned __ctz, bool __fill_val) {
+  static_assert(is_unsigned<typename pointer_traits<_StoragePointer>::element_type>::value,
+                "__fill_masked_range must be called with unsigned type");
   using _StorageType = typename pointer_traits<_StoragePointer>::element_type;
   _LIBCPP_ASSERT_VALID_INPUT_RANGE(
       __ctz + __clz < sizeof(_StorageType) * CHAR_BIT, "__fill_masked_range called with invalid range");

libcxx/include/__fwd/bit_reference.h

@@ -26,8 +26,7 @@ class __bit_iterator;
 template <class, class = void>
 struct __size_difference_type_traits;
 
-template <class _StoragePointer,
-          __enable_if_t<is_unsigned<typename pointer_traits<_StoragePointer>::element_type>::value, int> = 0>
+template <class _StoragePointer>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
 __fill_masked_range(_StoragePointer __word, unsigned __ctz, unsigned __clz, bool __fill_val);
 

libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/fill.pass.cpp

@@ -47,6 +47,8 @@ struct Test {
   }
 };
 
+// Make sure std::fill behaves properly with std::vector<bool> iterators with custom size types.
+// See https://github.com/llvm/llvm-project/pull/122410.
 TEST_CONSTEXPR_CXX20 void test_bititer_with_custom_sized_types() {
   {
     using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;

libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/fill_n.pass.cpp

@@ -129,6 +129,8 @@ void test6() {
   std::fill_n(&foo[0], UDI(5), Storage());
 }
 
+// Make sure std::fill_n behaves properly with std::vector<bool> iterators with custom size types.
+// See https://github.com/llvm/llvm-project/pull/122410.
 TEST_CONSTEXPR_CXX20 void test_bititer_with_custom_sized_types() {
   {
     using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;

libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill.pass.cpp

@@ -78,8 +78,8 @@ constexpr void test_iterators() {
   }
 }
 
-// Make sure we behave properly with std::vector<bool> iterators with custom size types, see
-// https://github.com/llvm/llvm-project/pull/122410.
+// Make sure std::ranges::fill behaves properly with std::vector<bool> iterators with custom
+// size types. See https://github.com/llvm/llvm-project/pull/122410.
 //
 // The `ranges::{fill, fill_n}` algorithms require `vector<bool, Alloc>::iterator` to satisfy
 // the `std::indirectly_writable` concept when used with `vector<bool, Alloc>`, which is only

libcxx/test/std/algorithms/alg.modifying.operations/alg.fill/ranges.fill_n.pass.cpp

@@ -51,8 +51,8 @@ constexpr void test_iterators() {
   }
 }
 
-// Make sure we behave properly with std::vector<bool> iterators with custom size types, see
-// https://github.com/llvm/llvm-project/pull/122410.
+// Make sure std::ranges::fill_n behaves properly with std::vector<bool> iterators with custom
+// size types. See https://github.com/llvm/llvm-project/pull/122410.
 //
 // The `ranges::{fill, fill_n}` algorithms require `vector<bool, Alloc>::iterator` to satisfy
 // the `std::indirectly_writable` concept when used with `vector<bool, Alloc>`, which is only