Fix ambiguous call in ranges::count & std::count for vector<bool>::iterator

Author: winner245

libcxx/include/__algorithm/count.h

@@ -55,18 +55,18 @@ __count_bool(__bit_iterator<_Cp, _IsConst> __first, typename __size_difference_t
   if (__first.__ctz_ != 0) {
     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
     __storage_type __dn    = std::min(__clz_f, __n);
-    __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
-    __r                    = std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
+    __storage_type __m     = std::__middle_mask<__storage_type>(__clz_f - __dn, __first.__ctz_);
+    __r                    = std::__popcount(__storage_type(std::__invert_if<!_ToCount>(*__first.__seg_) & __m));
     __n -= __dn;
     ++__first.__seg_;
   }
   // do middle whole words
   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
-    __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_));
+    __r += std::__popcount(__storage_type(std::__invert_if<!_ToCount>(*__first.__seg_)));
   // do last partial word
   if (__n > 0) {
-    __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
-    __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
+    __storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
+    __r += std::__popcount(__storage_type(std::__invert_if<!_ToCount>(*__first.__seg_) & __m));
   }
   return __r;
 }

libcxx/include/__bit/popcount.h

@@ -15,6 +15,7 @@
 #include <__bit/rotate.h>
 #include <__concepts/arithmetic.h>
 #include <__config>
+#include <__type_traits/is_unsigned.h>
 #include <limits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -38,31 +39,44 @@ inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __libcpp_popcount(unsigned lo
   return __builtin_popcountll(__x);
 }
 
-#if _LIBCPP_STD_VER >= 20
-
-template <__libcpp_unsigned_integer _Tp>
-[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
-#  if __has_builtin(__builtin_popcountg)
-  return __builtin_popcountg(__t);
-#  else  // __has_builtin(__builtin_popcountg)
-  if (sizeof(_Tp) <= sizeof(unsigned int))
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR int __popcount(_Tp __t) _NOEXCEPT {
+  static_assert(is_unsigned<_Tp>::value, "__popcount only works with unsigned types");
+  if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned int)) {
     return std::__libcpp_popcount(static_cast<unsigned int>(__t));
-  else if (sizeof(_Tp) <= sizeof(unsigned long))
+  } else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long)) {
     return std::__libcpp_popcount(static_cast<unsigned long>(__t));
-  else if (sizeof(_Tp) <= sizeof(unsigned long long))
+  } else if _LIBCPP_CONSTEXPR (sizeof(_Tp) <= sizeof(unsigned long long)) {
     return std::__libcpp_popcount(static_cast<unsigned long long>(__t));
-  else {
+  } else {
+#if _LIBCPP_STD_VER == 11
+    // A recursive constexpr implementation for C++11
+    return __t != 0 ? std::__libcpp_popcount(static_cast<unsigned long long>(__t)) +
+                          std::__popcount<_Tp>(__t >> numeric_limits<unsigned long long>::digits)
+                    : 0;
+#else
     int __ret = 0;
     while (__t != 0) {
       __ret += std::__libcpp_popcount(static_cast<unsigned long long>(__t));
-      __t >>= numeric_limits<unsigned long long>::digits;
+      __t >>= std::numeric_limits<unsigned long long>::digits;
     }
     return __ret;
+#endif
   }
-#  endif // __has_builtin(__builtin_popcountg)
 }
 
-#endif // _LIBCPP_STD_VER >= 20
+#if _LIBCPP_STD_VER >= 20
+
+template <__libcpp_unsigned_integer _Tp>
+[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int popcount(_Tp __t) noexcept {
+#  if __has_builtin(__builtin_popcountg)
+  return __builtin_popcountg(__t);
+#  else
+  return std::__popcount(__t);
+#  endif
+}
+
+#endif
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__bit_reference

@@ -62,6 +62,19 @@ struct __size_difference_type_traits<_Cp, __void_t<typename _Cp::difference_type
   using size_type       = typename _Cp::size_type;
 };
 
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __trailing_mask(unsigned __clz) {
+  static_assert(is_unsigned<_StorageType>::value, "__trailing_mask only works with unsigned types");
+  return static_cast<_StorageType>(static_cast<_StorageType>(~static_cast<_StorageType>(0)) >> __clz);
+}
+
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __middle_mask(unsigned __clz, unsigned __ctz) {
+  static_assert(is_unsigned<_StorageType>::value, "__middle_mask only works with unsigned types");
+  return static_cast<_StorageType>(static_cast<_StorageType>(~static_cast<_StorageType>(0)) << __ctz) &
+         std::__trailing_mask<_StorageType>(__clz);
+}
+
 // This function is designed to operate correctly even for smaller integral types like `uint8_t`, `uint16_t`,
 // or `unsigned short`. Casting back to _StorageType is crucial to prevent undefined behavior that can arise
 // from integral promotions.
@@ -74,8 +87,7 @@ __fill_masked_range(_StoragePointer __word, unsigned __clz, unsigned __ctz, bool
   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");
-  _StorageType __m = static_cast<_StorageType>(static_cast<_StorageType>(~static_cast<_StorageType>(0)) >> __clz) &
-                     static_cast<_StorageType>(static_cast<_StorageType>(~static_cast<_StorageType>(0)) << __ctz);
+  _StorageType __m = std::__middle_mask<_StorageType>(__clz, __ctz);
   if (__fill_val)
     *__word |= __m;
   else

libcxx/include/__fwd/bit_reference.h

@@ -30,6 +30,12 @@ template <class _StoragePointer>
 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void
 __fill_masked_range(_StoragePointer __word, unsigned __ctz, unsigned __clz, bool __fill_val);
 
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __trailing_mask(unsigned __clz);
+
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __middle_mask(unsigned __clz, unsigned __ctz);
+
 _LIBCPP_END_NAMESPACE_STD
 
 #endif // _LIBCPP___FWD_BIT_REFERENCE_H

libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp

@@ -15,12 +15,14 @@
 
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=20000000
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=80000000
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
 
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <vector>
 
+#include "sized_allocator.h"
 #include "test_macros.h"
 #include "test_iterators.h"
 #include "type_algorithms.h"
@@ -36,6 +38,29 @@ struct Test {
   }
 };
 
+TEST_CONSTEXPR_CXX20 void test_bit_iterator_with_custom_sized_types() {
+  {
+    using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+    std::vector<bool, Alloc> in(100, true, Alloc(1));
+    assert(std::count(in.begin(), in.end(), true) == 100);
+  }
+  {
+    using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+    std::vector<bool, Alloc> in(199, true, Alloc(1));
+    assert(std::count(in.begin(), in.end(), true) == 199);
+  }
+  {
+    using Alloc = sized_allocator<bool, std::uint32_t, std::int32_t>;
+    std::vector<bool, Alloc> in(200, true, Alloc(1));
+    assert(std::count(in.begin(), in.end(), true) == 200);
+  }
+  {
+    using Alloc = sized_allocator<bool, std::uint64_t, std::int64_t>;
+    std::vector<bool, Alloc> in(257, true, Alloc(1));
+    assert(std::count(in.begin(), in.end(), true) == 257);
+  }
+}
+
 TEST_CONSTEXPR_CXX20 bool test() {
   types::for_each(types::cpp17_input_iterator_list<const int*>(), Test());
 
@@ -51,6 +76,8 @@ TEST_CONSTEXPR_CXX20 bool test() {
     }
   }
 
+  test_bit_iterator_with_custom_sized_types();
+
   return true;
 }