[libcxx-commits] [libcxx] [libc++] Fix {std, ranges}::equal for vector<bool> with small storage types (PR #130394)
Peng Liu via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Mar 8 04:37:10 PST 2025
https://github.com/winner245 updated https://github.com/llvm/llvm-project/pull/130394
>From c56fb66c331b19065f5c949cb12cace2d1832676 Mon Sep 17 00:00:00 2001
From: Peng Liu <winner245 at hotmail.com>
Date: Fri, 7 Mar 2025 22:10:22 -0500
Subject: [PATCH] Fix ranges::equal for vector<bool> with small storage types
---
libcxx/include/__algorithm/equal.h | 36 ++---
libcxx/include/__bit_reference | 27 +++-
libcxx/include/__fwd/bit_reference.h | 9 ++
libcxx/include/__vector/comparison.h | 14 --
.../alg.nonmodifying/alg.equal/equal.pass.cpp | 86 ++++++++++++
.../alg.equal/ranges.equal.pass.cpp | 125 ++++++++++++++++--
.../bitset.members/left_shift_eq.pass.cpp | 2 +
7 files changed, 259 insertions(+), 40 deletions(-)
diff --git a/libcxx/include/__algorithm/equal.h b/libcxx/include/__algorithm/equal.h
index 4cac9652d55ed..5a8c9504ede1d 100644
--- a/libcxx/include/__algorithm/equal.h
+++ b/libcxx/include/__algorithm/equal.h
@@ -54,24 +54,27 @@ __equal_unaligned(__bit_iterator<_Cp, _IsConst1> __first1,
unsigned __clz_f = __bits_per_word - __first1.__ctz_;
difference_type __dn = std::min(static_cast<difference_type>(__clz_f), __n);
__n -= __dn;
- __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
+ __storage_type __m = std::__middle_mask<__storage_type>(__clz_f - __dn, __first1.__ctz_);
__storage_type __b = *__first1.__seg_ & __m;
unsigned __clz_r = __bits_per_word - __first2.__ctz_;
__storage_type __ddn = std::min<__storage_type>(__dn, __clz_r);
- __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __ddn));
+ __m = std::__middle_mask<__storage_type>(__clz_r - __ddn, __first2.__ctz_);
if (__first2.__ctz_ > __first1.__ctz_) {
- if ((*__first2.__seg_ & __m) != (__b << (__first2.__ctz_ - __first1.__ctz_)))
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) !=
+ static_cast<__storage_type>(__b << (__first2.__ctz_ - __first1.__ctz_)))
return false;
} else {
- if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ - __first2.__ctz_)))
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) !=
+ static_cast<__storage_type>(__b >> (__first1.__ctz_ - __first2.__ctz_)))
return false;
}
__first2.__seg_ += (__ddn + __first2.__ctz_) / __bits_per_word;
__first2.__ctz_ = static_cast<unsigned>((__ddn + __first2.__ctz_) % __bits_per_word);
__dn -= __ddn;
if (__dn > 0) {
- __m = ~__storage_type(0) >> (__bits_per_word - __dn);
- if ((*__first2.__seg_ & __m) != (__b >> (__first1.__ctz_ + __ddn)))
+ __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) !=
+ static_cast<__storage_type>(__b >> (__first1.__ctz_ + __ddn)))
return false;
__first2.__ctz_ = static_cast<unsigned>(__dn);
}
@@ -81,29 +84,30 @@ __equal_unaligned(__bit_iterator<_Cp, _IsConst1> __first1,
// __first1.__ctz_ == 0;
// do middle words
unsigned __clz_r = __bits_per_word - __first2.__ctz_;
- __storage_type __m = ~__storage_type(0) << __first2.__ctz_;
+ __storage_type __m = std::__leading_mask<__storage_type>(__first2.__ctz_);
for (; __n >= __bits_per_word; __n -= __bits_per_word, ++__first1.__seg_) {
__storage_type __b = *__first1.__seg_;
- if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) != static_cast<__storage_type>(__b << __first2.__ctz_))
return false;
++__first2.__seg_;
- if ((*__first2.__seg_ & ~__m) != (__b >> __clz_r))
+ if (static_cast<__storage_type>(*__first2.__seg_ & static_cast<__storage_type>(~__m)) !=
+ static_cast<__storage_type>(__b >> __clz_r))
return false;
}
// do last word
if (__n > 0) {
- __m = ~__storage_type(0) >> (__bits_per_word - __n);
+ __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
__storage_type __b = *__first1.__seg_ & __m;
__storage_type __dn = std::min(__n, static_cast<difference_type>(__clz_r));
- __m = (~__storage_type(0) << __first2.__ctz_) & (~__storage_type(0) >> (__clz_r - __dn));
- if ((*__first2.__seg_ & __m) != (__b << __first2.__ctz_))
+ __m = std::__middle_mask<__storage_type>(__clz_r - __dn, __first2.__ctz_);
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) != static_cast<__storage_type>(__b << __first2.__ctz_))
return false;
__first2.__seg_ += (__dn + __first2.__ctz_) / __bits_per_word;
__first2.__ctz_ = static_cast<unsigned>((__dn + __first2.__ctz_) % __bits_per_word);
__n -= __dn;
if (__n > 0) {
- __m = ~__storage_type(0) >> (__bits_per_word - __n);
- if ((*__first2.__seg_ & __m) != (__b >> __dn))
+ __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
+ if (static_cast<__storage_type>(*__first2.__seg_ & __m) != static_cast<__storage_type>(__b >> __dn))
return false;
}
}
@@ -128,7 +132,7 @@ __equal_aligned(__bit_iterator<_Cp, _IsConst1> __first1,
unsigned __clz = __bits_per_word - __first1.__ctz_;
difference_type __dn = std::min(static_cast<difference_type>(__clz), __n);
__n -= __dn;
- __storage_type __m = (~__storage_type(0) << __first1.__ctz_) & (~__storage_type(0) >> (__clz - __dn));
+ __storage_type __m = std::__middle_mask<__storage_type>(__clz - __dn, __first1.__ctz_);
if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
return false;
++__first2.__seg_;
@@ -144,7 +148,7 @@ __equal_aligned(__bit_iterator<_Cp, _IsConst1> __first1,
return false;
// do last word
if (__n > 0) {
- __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
+ __storage_type __m = std::__trailing_mask<__storage_type>(__bits_per_word - __n);
if ((*__first2.__seg_ & __m) != (*__first1.__seg_ & __m))
return false;
}
diff --git a/libcxx/include/__bit_reference b/libcxx/include/__bit_reference
index f91250c4a440d..8b3b890372f11 100644
--- a/libcxx/include/__bit_reference
+++ b/libcxx/include/__bit_reference
@@ -68,6 +68,30 @@ struct __size_difference_type_traits<_Cp, __void_t<typename _Cp::difference_type
using size_type = typename _Cp::size_type;
};
+// Creates a mask of type `_StorageType` with a specified number of leading zeros (__clz) and sets all remaining
+// bits to one.
+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>(0)) >> __clz;
+}
+
+// Creates a mask of type `_StorageType` with a specified number of trailing zeros (__ctz) and sets all remaining
+// bits to one.
+template <class _StorageType>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _StorageType __leading_mask(unsigned __ctz) {
+ static_assert(is_unsigned<_StorageType>::value, "__leading_mask only works with unsigned types");
+ return static_cast<_StorageType>(~static_cast<_StorageType>(0)) << __ctz;
+}
+
+// Creates a mask of type `_StorageType` with a specified number of leading zeros (__clz), a specified number of
+// trailing zeros (__ctz), and sets all bits in between to one.
+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 std::__leading_mask<_StorageType>(__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.
@@ -80,8 +104,7 @@ __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
diff --git a/libcxx/include/__fwd/bit_reference.h b/libcxx/include/__fwd/bit_reference.h
index d65f043e89ad6..59dab4f9e4235 100644
--- a/libcxx/include/__fwd/bit_reference.h
+++ b/libcxx/include/__fwd/bit_reference.h
@@ -30,6 +30,15 @@ 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 __leading_mask(unsigned __ctz);
+
+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
diff --git a/libcxx/include/__vector/comparison.h b/libcxx/include/__vector/comparison.h
index 960663e6ab62a..27178e41ec513 100644
--- a/libcxx/include/__vector/comparison.h
+++ b/libcxx/include/__vector/comparison.h
@@ -29,20 +29,6 @@ operator==(const vector<_Tp, _Allocator>& __x, const vector<_Tp, _Allocator>& __
return __sz == __y.size() && std::equal(__x.begin(), __x.end(), __y.begin());
}
-// FIXME: Remove this `vector<bool>` overload once #126369 is resolved, reverting to the generic `operator==`
-// with `std::equal` for better performance.
-template <class _Allocator>
-_LIBCPP_CONSTEXPR_SINCE_CXX20 inline _LIBCPP_HIDE_FROM_ABI bool
-operator==(const vector<bool, _Allocator>& __x, const vector<bool, _Allocator>& __y) {
- const typename vector<bool, _Allocator>::size_type __sz = __x.size();
- if (__sz != __y.size())
- return false;
- for (typename vector<bool, _Allocator>::size_type __i = 0; __i < __sz; ++__i)
- if (__x[__i] != __y[__i])
- return false;
- return true;
-}
-
#if _LIBCPP_STD_VER <= 17
template <class _Tp, class _Allocator>
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
index b37d788c80d3a..02cc84c288828 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp
@@ -24,12 +24,14 @@
// MSVC warning C4244: 'argument': conversion from 'wchar_t' to 'const _Ty', possible loss of data
// MSVC warning C4389: '==': signed/unsigned mismatch
// ADDITIONAL_COMPILE_FLAGS(cl-style-warnings): /wd4242 /wd4244 /wd4389
+// XFAIL: FROZEN-CXX03-HEADERS-FIXME
#include <algorithm>
#include <cassert>
#include <functional>
#include <vector>
+#include "sized_allocator.h"
#include "test_iterators.h"
#include "test_macros.h"
#include "type_algorithms.h"
@@ -173,6 +175,90 @@ TEST_CONSTEXPR_CXX20 bool test() {
test_vector_bool<256>();
}
+ // Make sure std::equal behaves properly with std::vector<bool> iterators with custom size types.
+ // See issue: https://github.com/llvm/llvm-project/issues/126369.
+ {
+ //// Tests for std::equal with aligned bits
+
+ { // Test the first (partial) word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(6, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ assert(std::equal(in.begin() + 4, in.end(), expected.begin() + 4));
+ }
+ { // Test the last word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin()));
+ }
+ { // Test middle words for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(24, true, Alloc(1));
+ std::vector<bool, Alloc> expected(29, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin()));
+ }
+
+ { // Test the first (partial) word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ assert(std::equal(in.begin() + 4, in.end(), expected.begin() + 4));
+ }
+ { // Test the last word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(24, true, Alloc(1));
+ std::vector<bool, Alloc> expected(32, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin()));
+ }
+ { // Test middle words for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(48, true, Alloc(1));
+ std::vector<bool, Alloc> expected(55, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin()));
+ }
+
+ //// Tests for std::equal with unaligned bits
+
+ { // Test the first (partial) word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(6, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ assert(std::equal(in.begin() + 4, in.end(), expected.begin()));
+ }
+ { // Test the last word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(4, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin() + 3));
+ }
+ { // Test middle words for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(16, true, Alloc(1));
+ std::vector<bool, Alloc> expected(24, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin() + 4));
+ }
+
+ { // Test the first (partial) word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ assert(std::equal(in.begin() + 4, in.end(), expected.begin()));
+ }
+ { // Test the last word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin() + 3));
+ }
+ { // Test the middle words for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(32, true, Alloc(1));
+ std::vector<bool, Alloc> expected(64, true, Alloc(1));
+ assert(std::equal(in.begin(), in.end(), expected.begin() + 4));
+ }
+ }
+
return true;
}
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp
index 4c1c29c72cab0..3f3af71de6a1e 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp
@@ -31,6 +31,7 @@
#include <vector>
#include "almost_satisfies_types.h"
+#include "sized_allocator.h"
#include "test_iterators.h"
#include "test_macros.h"
@@ -432,15 +433,123 @@ constexpr bool test() {
assert(projCount == 6);
}
}
+ }
+
+ { // Test vector<bool>::iterator optimization
+ test_vector_bool<8>();
+ test_vector_bool<19>();
+ test_vector_bool<32>();
+ test_vector_bool<49>();
+ test_vector_bool<64>();
+ test_vector_bool<199>();
+ test_vector_bool<256>();
+ }
+
+ // Make sure std::equal behaves properly with std::vector<bool> iterators with custom size types.
+ // See issue: https://github.com/llvm/llvm-project/issues/126369.
+ {
+ //// Tests for std::equal with aligned bits
+
+ { // Test the first (partial) word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(6, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin() + 4, in.end());
+ auto b = std::ranges::subrange(expected.begin() + 4, expected.begin() + 4 + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test the last word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test middle words for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(24, true, Alloc(1));
+ std::vector<bool, Alloc> expected(29, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
- { // Test vector<bool>::iterator optimization
- test_vector_bool<8>();
- test_vector_bool<19>();
- test_vector_bool<32>();
- test_vector_bool<49>();
- test_vector_bool<64>();
- test_vector_bool<199>();
- test_vector_bool<256>();
+ { // Test the first (partial) word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin() + 4, in.end());
+ auto b = std::ranges::subrange(expected.begin() + 4, expected.begin() + 4 + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test the last word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(24, true, Alloc(1));
+ std::vector<bool, Alloc> expected(32, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test middle words for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(48, true, Alloc(1));
+ std::vector<bool, Alloc> expected(55, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+
+ //// Tests for std::equal with unaligned bits
+
+ { // Test the first (partial) word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(6, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin() + 4, in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test the last word for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(4, true, Alloc(1));
+ std::vector<bool, Alloc> expected(8, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin() + 3, expected.begin() + 3 + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test middle words for uint8_t
+ using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
+ std::vector<bool, Alloc> in(16, true, Alloc(1));
+ std::vector<bool, Alloc> expected(24, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin() + 4, expected.begin() + 4 + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+
+ { // Test the first (partial) word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin() + 4, in.end());
+ auto b = std::ranges::subrange(expected.begin(), expected.begin() + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test the last word for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(12, true, Alloc(1));
+ std::vector<bool, Alloc> expected(16, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin() + 3, expected.begin() + 3 + a.size());
+ assert(std::ranges::equal(a, b));
+ }
+ { // Test the middle words for uint16_t
+ using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
+ std::vector<bool, Alloc> in(32, true, Alloc(1));
+ std::vector<bool, Alloc> expected(64, true, Alloc(1));
+ auto a = std::ranges::subrange(in.begin(), in.end());
+ auto b = std::ranges::subrange(expected.begin() + 4, expected.begin() + 4 + a.size());
+ assert(std::ranges::equal(a, b));
}
}
diff --git a/libcxx/test/std/utilities/template.bitset/bitset.members/left_shift_eq.pass.cpp b/libcxx/test/std/utilities/template.bitset/bitset.members/left_shift_eq.pass.cpp
index 521a4ff13abba..902612d0697d2 100644
--- a/libcxx/test/std/utilities/template.bitset/bitset.members/left_shift_eq.pass.cpp
+++ b/libcxx/test/std/utilities/template.bitset/bitset.members/left_shift_eq.pass.cpp
@@ -6,6 +6,8 @@
//
//===----------------------------------------------------------------------===//
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=15000000
+
// bitset<N>& operator<<=(size_t pos); // constexpr since C++23
#include <bitset>
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