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[libc++] Fix constructing bitset from non-null-terminated arrays #143691

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Merged
merged 4 commits into from
Jun 12, 2025
Merged

[libc++] Fix constructing bitset from non-null-terminated arrays #143691

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930f956
[libc++] Fix constructing `bitset` from non-null-terminated arrays
frederick-vs-ja Jun 11, 2025
5a9c867
Restore `basic_string<_CharT>::npos` and add a proper description.
frederick-vs-ja Jun 11, 2025
8921322
Merge branch 'main' into bitset-from-data-size
frederick-vs-ja Jun 11, 2025
1ec0c23
Change `v[i] == false` to `!v[i]` as it's type is boolean-testable
frederick-vs-ja Jun 11, 2025
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13 changes: 5 additions & 8 deletions libcxx/include/bitset
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Original file line number Diff line number Diff line change
Expand Up @@ -645,16 +645,13 @@ public:
template <class _CharT, __enable_if_t<_IsCharLikeType<_CharT>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 explicit bitset(
const _CharT* __str,
# if _LIBCPP_STD_VER >= 26
typename basic_string_view<_CharT>::size_type __n = basic_string_view<_CharT>::npos,
# else
typename basic_string<_CharT>::size_type __n = basic_string<_CharT>::npos,
# endif
size_t __n = basic_string<_CharT>::npos,
_CharT __zero = _CharT('0'),
_CharT __one = _CharT('1')) {

size_t __rlen = std::min(__n, char_traits<_CharT>::length(__str));
__init_from_string_view(basic_string_view<_CharT>(__str, __rlen), __zero, __one);
if (__n == basic_string<_CharT>::npos)
__init_from_string_view(basic_string_view<_CharT>(__str), __zero, __one);
else
__init_from_string_view(basic_string_view<_CharT>(__str, __n), __zero, __one);
}
# if _LIBCPP_STD_VER >= 26
template <class _CharT, class _Traits>
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29 changes: 29 additions & 0 deletions libcxx/test/std/utilities/template.bitset/bitset.cons/char_ptr_ctor.pass.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,35 @@ TEST_CONSTEXPR_CXX23 void test_char_pointer_ctor()
for (std::size_t i = 10; i < v.size(); ++i)
assert(v[i] == false);
}
// Verify that this constructor doesn't read over the given bound.
// See https://github.com/llvm/llvm-project/issues/143684
{
const char not_null_terminated[] = {'1', '0', '1', '0', '1', '0', '1', '0', '1', '0'};
std::bitset<N> v(not_null_terminated, 10);
std::size_t M = std::min<std::size_t>(v.size(), 10);
for (std::size_t i = 0; i < M; ++i)
assert(v[i] == (not_null_terminated[M - 1 - i] == '1'));
for (std::size_t i = 10; i < v.size(); ++i)
assert(!v[i]);
}
{
const char not_null_terminated[] = {'1', 'a', '1', 'a', '1', 'a', '1', 'a', '1', 'a'};
std::bitset<N> v(not_null_terminated, 10, 'a');
std::size_t M = std::min<std::size_t>(v.size(), 10);
for (std::size_t i = 0; i < M; ++i)
assert(v[i] == (not_null_terminated[M - 1 - i] == '1'));
for (std::size_t i = 10; i < v.size(); ++i)
assert(!v[i]);
}
{
const char not_null_terminated[] = {'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a', 'b', 'a'};
std::bitset<N> v(not_null_terminated, 10, 'a', 'b');
std::size_t M = std::min<std::size_t>(v.size(), 10);
for (std::size_t i = 0; i < M; ++i)
assert(v[i] == (not_null_terminated[M - 1 - i] == 'b'));
for (std::size_t i = 10; i < v.size(); ++i)
assert(!v[i]);
}
}

TEST_CONSTEXPR_CXX23 bool test() {
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