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[libc++][bitset] Applied [[nodiscard]] #170623

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Merged
Zingam merged 3 commits into from
Dec 6, 2025
Merged

[libc++][bitset] Applied [[nodiscard]] #170623

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c47f4d5
[libc++][bitset] Applied `[[nodiscard]]`
H-G-Hristov Dec 4, 2025
2980120
Fix
H-G-Hristov Dec 6, 2025
0d01d5f
Fix
H-G-Hristov Dec 6, 2025
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2 changes: 1 addition & 1 deletion libcxx/include/__bit_reference
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Original file line number Diff line number Diff line change
Expand Up @@ -139,7 +139,7 @@ public:
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 operator bool() const _NOEXCEPT {
return static_cast<bool>(*__seg_ & __mask_);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator~() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool operator~() const _NOEXCEPT {
return !static_cast<bool>(*this);
}

Expand Down
55 changes: 33 additions & 22 deletions libcxx/include/bitset
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Expand Up @@ -675,53 +675,62 @@ public:
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& set(size_t __pos, bool __val = true);
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& reset() _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& reset(size_t __pos);
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator~() const _NOEXCEPT;
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator~() const _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& flip() _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset& flip(size_t __pos);

// element access:
# ifdef _LIBCPP_ABI_BITSET_VECTOR_BOOL_CONST_SUBSCRIPT_RETURN_BOOL
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool operator[](size_t __p) const {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool operator[](size_t __p) const {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
return __base::__make_ref(__p);
}
# else
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __const_reference operator[](size_t __p) const {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __const_reference operator[](size_t __p) const {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
return __base::__make_ref(__p);
}
# endif
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 reference operator[](size_t __p) {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 reference operator[](size_t __p) {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__p < _Size, "bitset::operator[] index out of bounds");
return __base::__make_ref(__p);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const { return __base::to_ulong(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong() const {
return __base::to_ulong();
}
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong() const {
return __base::to_ullong();
}
template <class _CharT, class _Traits, class _Allocator>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, _Allocator>
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, _Allocator>
to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
template <class _CharT, class _Traits>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, allocator<_CharT> >
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, _Traits, allocator<_CharT> >
to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, char_traits<_CharT>, allocator<_CharT> >
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<_CharT, char_traits<_CharT>, allocator<_CharT> >
to_string(_CharT __zero = _CharT('0'), _CharT __one = _CharT('1')) const;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<char, char_traits<char>, allocator<char> >
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI
_LIBCPP_CONSTEXPR_SINCE_CXX23 basic_string<char, char_traits<char>, allocator<char> >
to_string(char __zero = '0', char __one = '1') const;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 size_t count() const _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_t size() const _NOEXCEPT { return _Size; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 size_t count() const _NOEXCEPT;
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR size_t size() const _NOEXCEPT { return _Size; }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool operator==(const bitset& __rhs) const _NOEXCEPT;
# if _LIBCPP_STD_VER <= 17
_LIBCPP_HIDE_FROM_ABI bool operator!=(const bitset& __rhs) const _NOEXCEPT;
# endif
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool test(size_t __pos) const;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool all() const _NOEXCEPT { return __base::all(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool any() const _NOEXCEPT { return __base::any(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool none() const _NOEXCEPT { return !any(); }
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator<<(size_t __pos) const _NOEXCEPT;
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator>>(size_t __pos) const _NOEXCEPT;
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool test(size_t __pos) const;
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool all() const _NOEXCEPT {
return __base::all();
}
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool any() const _NOEXCEPT {
return __base::any();
}
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bool none() const _NOEXCEPT { return !any(); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator<<(size_t __pos) const _NOEXCEPT;
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset operator>>(size_t __pos) const _NOEXCEPT;

private:
template <class _CharT, class _Traits>
Expand Down Expand Up @@ -919,23 +928,23 @@ bitset<_Size>::operator>>(size_t __pos) const _NOEXCEPT {
}

template <size_t _Size>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
operator&(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
bitset<_Size> __r = __x;
__r &= __y;
return __r;
}

template <size_t _Size>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
operator|(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
bitset<_Size> __r = __x;
__r |= __y;
return __r;
}

template <size_t _Size>
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 bitset<_Size>
operator^(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {
bitset<_Size> __r = __x;
__r ^= __y;
Expand All @@ -944,7 +953,9 @@ operator^(const bitset<_Size>& __x, const bitset<_Size>& __y) _NOEXCEPT {

template <size_t _Size>
struct hash<bitset<_Size> > : public __unary_function<bitset<_Size>, size_t> {
_LIBCPP_HIDE_FROM_ABI size_t operator()(const bitset<_Size>& __bs) const _NOEXCEPT { return __bs.__hash_code(); }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t operator()(const bitset<_Size>& __bs) const _NOEXCEPT {
return __bs.__hash_code();
}
};

template <class _CharT, class _Traits, size_t _Size>
Expand Down
61 changes: 61 additions & 0 deletions libcxx/test/libcxx/utilities/template.bitset/nodiscard.verify.cpp
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@@ -0,0 +1,61 @@
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// <bitset>

// Check that functions are marked [[nodiscard]]

#include <bitset>

#include "test_macros.h"
#include "test_allocator.h"

void test() {
std::bitset<11> bs;
const std::bitset<11> cbs;

// std::bitset<>::reference operator~() const noexcept;
~bs[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

~bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

bs[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
cbs[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_ulong(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_ullong(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

struct CharTraits : public std::char_traits<char> {};

// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_string<char, CharTraits, test_allocator<char> >();
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_string<char, CharTraits>();
#if !defined(TEST_HAS_NO_WIDE_CHARACTERS)
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_string<wchar_t>();
#endif
// expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.to_string();

bs.count(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.test(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.all(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.any(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs.none(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs << 1; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs >> 1; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

bs & bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs | bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
bs ^ bs; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}

std::hash<std::bitset<11> > hash;

hash(bs); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
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