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llvm-project/libcxx/test/std/algorithms/alg.modifying.operations/alg.copy/copy.pass.cpp
Peng Liu a5b3d3a03f
[libc++] Fix {std, ranges}::copy for vector<bool> with small storage types (#131545) 
The current implementation of `{std, ranges}::copy` fails to copy
`vector<bool>` correctly when the underlying storage type
(`__storage_type`) is smaller than `int`, such as `unsigned char`,
`unsigned short`, `uint8_t` and `uint16_t`. The root cause is that the
unsigned small storage type undergoes integer promotion to (signed)
`int`, which is then left and right shifted, leading to UB (before
C++20) and sign-bit extension (since C++20) respectively. As a result,
the underlying bit mask evaluations become incorrect, causing erroneous
copying behavior.

This patch resolves the issue by correcting the internal bitwise
operations, ensuring that `{std, ranges}::copy` operates correctly for
`vector<bool>` with any custom (unsigned) storage types.

Fixes #131692.
2025-03-19 11:55:51 -04:00

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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <algorithm>
// template<InputIterator InIter, OutputIterator<auto, InIter::reference> OutIter>
// constexpr OutIter // constexpr after C++17
// copy(InIter first, InIter last, OutIter result);
// XFAIL: FROZEN-CXX03-HEADERS-FIXME
#include <algorithm>
#include <cassert>
#include <vector>
#include "sized_allocator.h"
#include "test_macros.h"
#include "test_iterators.h"
#include "type_algorithms.h"
class PaddedBase {
public:
TEST_CONSTEXPR PaddedBase(std::int16_t a, std::int8_t b) : a_(a), b_(b) {}
std::int16_t a_;
std::int8_t b_;
};
class Derived : public PaddedBase {
public:
TEST_CONSTEXPR Derived(std::int16_t a, std::int8_t b, std::int8_t c) : PaddedBase(a, b), c_(c) {}
std::int8_t c_;
};
template <class InIter>
struct Test {
template <class OutIter>
TEST_CONSTEXPR_CXX20 void operator()() {
const unsigned N = 1000;
int ia[N] = {};
for (unsigned i = 0; i < N; ++i)
ia[i] = i;
int ib[N] = {0};
OutIter r = std::copy(InIter(ia), InIter(ia + N), OutIter(ib));
assert(base(r) == ib + N);
for (unsigned i = 0; i < N; ++i)
assert(ia[i] == ib[i]);
}
};
struct TestInIters {
template <class InIter>
TEST_CONSTEXPR_CXX20 void operator()() {
types::for_each(
types::concatenate_t<types::cpp17_input_iterator_list<int*>, types::type_list<cpp17_output_iterator<int*> > >(),
Test<InIter>());
}
};
TEST_CONSTEXPR_CXX20 bool test_vector_bool(std::size_t N) {
std::vector<bool> in(N, false);
for (std::size_t i = 0; i < N; i += 2)
in[i] = true;
{ // Test copy with aligned bytes
std::vector<bool> out(N);
std::copy(in.begin(), in.end(), out.begin());
assert(in == out);
}
{ // Test copy with unaligned bytes
std::vector<bool> out(N + 8);
std::copy(in.begin(), in.end(), out.begin() + 4);
for (std::size_t i = 0; i < N; ++i)
assert(out[i + 4] == in[i]);
}
return true;
}
TEST_CONSTEXPR_CXX20 bool test() {
types::for_each(types::cpp17_input_iterator_list<const int*>(), TestInIters());
{ // Make sure that padding bits aren't copied
Derived src(1, 2, 3);
Derived dst(4, 5, 6);
std::copy(static_cast<PaddedBase*>(&src), static_cast<PaddedBase*>(&src) + 1, static_cast<PaddedBase*>(&dst));
assert(dst.a_ == 1);
assert(dst.b_ == 2);
assert(dst.c_ == 6);
}
{ // Make sure that overlapping ranges can be copied
int a[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
std::copy(a + 3, a + 10, a);
int expected[] = {4, 5, 6, 7, 8, 9, 10, 8, 9, 10};
assert(std::equal(a, a + 10, expected));
}
{ // Test vector<bool>::iterator optimization
assert(test_vector_bool(8));
assert(test_vector_bool(19));
assert(test_vector_bool(32));
assert(test_vector_bool(49));
assert(test_vector_bool(64));
assert(test_vector_bool(199));
assert(test_vector_bool(256));
}
// Validate std::copy with std::vector<bool> iterators and custom storage types.
// Ensure that assigned bits hold the intended values, while unassigned bits stay unchanged.
// Related issue: https://github.com/llvm/llvm-project/issues/131692.
{
//// Tests for std::copy 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(8, false, Alloc(1));
std::vector<bool, Alloc> out(8, true, Alloc(1));
std::copy(in.begin() + 1, in.begin() + 2, out.begin() + 1); // out[1] = false
assert(out[1] == false);
for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
if (i != 1)
assert(out[i] == true);
}
{ // Test the last (partial) word for uint8_t
using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
std::vector<bool, Alloc> in(8, false, Alloc(1));
std::vector<bool, Alloc> out(8, true, Alloc(1));
std::copy(in.begin(), in.begin() + 1, out.begin()); // out[0] = false
assert(out[0] == false);
for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
assert(out[i] == true);
}
{ // Test middle (whole) words for uint8_t
using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
std::vector<bool, Alloc> in(32, true, Alloc(1));
for (std::size_t i = 0; i < in.size(); i += 2)
in[i] = false;
std::vector<bool, Alloc> out(32, false, Alloc(1));
std::copy(in.begin() + 4, in.end() - 4, out.begin() + 4);
for (std::size_t i = 4; i < static_cast<std::size_t>(in.size() - 4); ++i)
assert(in[i] == out[i]);
for (std::size_t i = 0; i < 4; ++i)
assert(out[i] == false);
for (std::size_t i = 28; i < out.size(); ++i)
assert(out[i] == false);
}
{ // Test the first (partial) word for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(16, false, Alloc(1));
std::vector<bool, Alloc> out(16, true, Alloc(1));
std::copy(in.begin() + 1, in.begin() + 3, out.begin() + 1); // out[1..2] = false
assert(out[1] == false);
assert(out[2] == false);
for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
if (i != 1 && i != 2)
assert(out[i] == true);
}
{ // Test the last (partial) word for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(16, false, Alloc(1));
std::vector<bool, Alloc> out(16, true, Alloc(1));
std::copy(in.begin(), in.begin() + 2, out.begin()); // out[0..1] = false
assert(out[0] == false);
assert(out[1] == false);
for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
assert(out[i] == true);
}
{ // Test middle (whole) words for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(64, true, Alloc(1));
for (std::size_t i = 0; i < in.size(); i += 2)
in[i] = false;
std::vector<bool, Alloc> out(64, false, Alloc(1));
std::copy(in.begin() + 8, in.end() - 8, out.begin() + 8);
for (std::size_t i = 8; i < static_cast<std::size_t>(in.size() - 8); ++i)
assert(in[i] == out[i]);
for (std::size_t i = 0; i < 8; ++i)
assert(out[i] == false);
for (std::size_t i = static_cast<std::size_t>(out.size() - 8); i < out.size(); ++i)
assert(out[i] == false);
}
//// Tests for std::copy 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(8, false, Alloc(1));
std::vector<bool, Alloc> out(8, true, Alloc(1));
std::copy(in.begin() + 7, in.end(), out.begin()); // out[0] = false
assert(out[0] == false);
for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
assert(out[i] == true);
}
{ // Test the last (partial) word for uint8_t
using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
std::vector<bool, Alloc> in(8, false, Alloc(1));
std::vector<bool, Alloc> out(8, true, Alloc(1));
std::copy(in.begin(), in.begin() + 1, out.begin() + 2); // out[2] = false
assert(out[2] == false);
for (std::size_t i = 1; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
if (i != 2)
assert(out[i] == true);
}
{ // Test middle (whole) words for uint8_t
using Alloc = sized_allocator<bool, std::uint8_t, std::int8_t>;
std::vector<bool, Alloc> in(36, true, Alloc(1));
for (std::size_t i = 0; i < in.size(); i += 2)
in[i] = false;
std::vector<bool, Alloc> out(40, false, Alloc(1));
std::copy(in.begin(), in.end(), out.begin() + 4);
for (std::size_t i = 0; i < in.size(); ++i)
assert(in[i] == out[i + 4]);
for (std::size_t i = 0; i < 4; ++i)
assert(out[i] == false);
}
{ // Test the first (partial) word for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(16, false, Alloc(1));
std::vector<bool, Alloc> out(16, true, Alloc(1));
std::copy(in.begin() + 14, in.end(), out.begin()); // out[0..1] = false
assert(out[0] == false);
assert(out[1] == false);
for (std::size_t i = 2; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
assert(out[i] == true);
}
{ // Test the last (partial) word for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(16, false, Alloc(1));
std::vector<bool, Alloc> out(16, true, Alloc(1));
std::copy(in.begin(), in.begin() + 2, out.begin() + 1); // out[1..2] = false
assert(out[1] == false);
assert(out[2] == false);
for (std::size_t i = 0; i < out.size(); ++i) // Ensure that unassigned bits remain unchanged
if (i != 1 && i != 2)
assert(out[i] == true);
}
{ // Test middle (whole) words for uint16_t
using Alloc = sized_allocator<bool, std::uint16_t, std::int16_t>;
std::vector<bool, Alloc> in(72, true, Alloc(1));
for (std::size_t i = 0; i < in.size(); i += 2)
in[i] = false;
std::vector<bool, Alloc> out(80, false, Alloc(1));
std::copy(in.begin(), in.end(), out.begin() + 4);
for (std::size_t i = 0; i < in.size(); ++i)
assert(in[i] == out[i + 4]);
for (std::size_t i = 0; i < 4; ++i)
assert(out[i] == false);
for (std::size_t i = in.size() + 4; i < out.size(); ++i)
assert(out[i] == false);
}
}
return true;
}
int main(int, char**) {
test();
#if TEST_STD_VER >= 20
static_assert(test());
#endif
return 0;
}
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