Handle aligned vector<bool> in constexpr copy() properly

stl/inc/vector

@@ -3816,7 +3816,7 @@ _CONSTEXPR20 _OutIt _Copy_vbool(_VbIt _First, _VbIt _Last, _OutIt _Dest) {
 
     const auto _FirstSourceMask = static_cast<_Vbase>(-1) << _First._Myoff;
     const auto _FirstDestMask   = _Dest._Myoff == 0 ? 0 : (static_cast<_Vbase>(-1) >> (_VBITS - _Dest._Myoff));
-    const auto _LastSourceMask  = static_cast<_Vbase>(-1) >> (_VBITS - _Last._Myoff);
+    const auto _LastSourceMask  = _Last._Myoff == 0 ? 0 : (static_cast<_Vbase>(-1) >> (_VBITS - _Last._Myoff));
     const auto _LastDestMask    = static_cast<_Vbase>(-1) << _DestEnd._Myoff;
 
     const bool _IsSingleBlockSource = _VbFirst == _VbLast;
@@ -3859,8 +3859,26 @@ _CONSTEXPR20 _OutIt _Copy_vbool(_VbIt _First, _VbIt _Last, _OutIt _Dest) {
     }
 
 #if _HAS_CXX20
-    if (!_STD is_constant_evaluated())
-#endif
+    if (_STD is_constant_evaluated()) {
+        if (_Dest._Myoff == _First._Myoff) {
+            const auto _FirstSourceVal = *_VbFirst & _FirstSourceMask;
+            *_VbDest                   = (*_VbDest & _FirstDestMask) | _FirstSourceVal;
+
+            ++_VbFirst;
+            ++_VbDest;
+            for (; _VbFirst != _VbLast; ++_VbFirst, ++_VbDest) {
+                *_VbDest = *_VbFirst;
+            }
+
+            if (_Last._Myoff != 0) {
+                const auto _LastSourceVal = *_VbFirst & _LastSourceMask;
+                *_VbDest                  = (*_VbDest & _LastDestMask) | _LastSourceVal;
+            }
+
+            return _DestEnd;
+        }
+    } else
+#endif // _HAS_CXX20
     {
         // If _First and _Dest have matching char alignment, use memmove
         const auto _UnalignedFirstBits = _First._Myoff & _Vbase{7};

tests/libcxx/expected_results.txt

@@ -656,13 +656,6 @@ std/input.output/string.streams/stringbuf/stringbuf.members/view.pass.cpp FAIL
 std/input.output/syncstream/syncbuf/syncstream.syncbuf.cons/dtor.pass.cpp FAIL
 std/input.output/syncstream/syncbuf/syncstream.syncbuf.members/emit.pass.cpp FAIL
 
-# GH-5345: <vector>: _Copy_vbool() mishandles vector<bool>s of size 32 and 64, revealed by constexpr Clang
-std/algorithms/alg.modifying.operations/alg.copy/copy_n.pass.cpp:2 FAIL
-std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp:2 FAIL
-std/algorithms/alg.modifying.operations/alg.move/move.pass.cpp:2 FAIL
-std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp FAIL
-std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp FAIL
-
 
 # *** VCRUNTIME BUGS ***
 
@@ -1067,6 +1060,7 @@ std/utilities/utility/mem.res/mem.poly.allocator.class/mem.poly.allocator.mem/co
 
 # Not analyzed, failing due to constexpr step limits.
 std/algorithms/alg.modifying.operations/alg.copy/ranges.copy_backward.pass.cpp:2 FAIL
+std/algorithms/alg.modifying.operations/alg.move/move.pass.cpp:2 FAIL
 std/algorithms/alg.modifying.operations/alg.rotate/rotate.pass.cpp FAIL
 std/algorithms/alg.nonmodifying/alg.contains/ranges.contains_subrange.pass.cpp:2 FAIL
 std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp FAIL
@@ -1198,6 +1192,15 @@ std/containers/views/mdspan/mdspan/index_operator.pass.cpp:1 FAIL
 std/utilities/utility/utility.swap/swap_array.pass.cpp:0 FAIL
 std/utilities/utility/utility.swap/swap_array.pass.cpp:1 FAIL
 
+# Not analyzed. MSVC constexpr ICE.
+std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp:0 FAIL
+std/algorithms/alg.nonmodifying/alg.equal/equal.pass.cpp:1 FAIL
+std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp:0 FAIL
+std/algorithms/alg.nonmodifying/alg.equal/ranges.equal.pass.cpp:1 FAIL
+
+# Not analyzed. Possible Clang constexpr bug involving the test's sized_allocator and our check for transposed ranges.
+std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp:2 FAIL
+
 # Not analyzed. SKIPPED because this is x86-specific, fatal error C1060: compiler is out of heap space
 std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.binary.iterator.pass.cpp:0 SKIPPED
 std/algorithms/alg.modifying.operations/alg.transform/ranges.transform.binary.iterator.pass.cpp:1 SKIPPED

tests/std/tests/GH_000625_vector_bool_optimization/test.cpp

@@ -1304,6 +1304,35 @@ void randomized_test_copy(mt19937_64& gen) {
     }
 }
 
+#if _HAS_CXX20
+template <size_t N, size_t Offset = 0>
+constexpr bool test_gh_5345() {
+    // GH-5345 <vector>: _Copy_vbool() mishandles vector<bool>s of size 32 and 64, revealed by constexpr Clang
+    vector<bool> src(N, true);
+
+    for (size_t i = 2; i != N; ++i) {
+        for (size_t j = i * 2; j < N; j += i) {
+            src[j] = false;
+        }
+    }
+
+    vector<bool> dst(N, false);
+    copy(src.begin() + Offset, src.end(), dst.begin() + Offset);
+    return equal(src.begin() + Offset, src.end(), dst.begin() + Offset, dst.end());
+}
+
+static_assert(test_gh_5345<17>());
+static_assert(test_gh_5345<17, 1>());
+static_assert(test_gh_5345<32>());
+static_assert(test_gh_5345<32, 5>());
+static_assert(test_gh_5345<43>());
+static_assert(test_gh_5345<43, 10>());
+static_assert(test_gh_5345<64>());
+static_assert(test_gh_5345<64, 16>());
+static_assert(test_gh_5345<120>());
+static_assert(test_gh_5345<120, 31>());
+#endif // _HAS_CXX20
+
 int main() {
     test_fill();
     test_find();