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[libc++] Applied [[nodiscard]] to Allocators #172131

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[libc++] Applied [[nodiscard]] to Allocators #172131

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12 changes: 7 additions & 5 deletions libcxx/include/__memory/addressof.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,32 +19,34 @@
_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp>
inline _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_NO_CFI _LIBCPP_HIDE_FROM_ABI _Tp* addressof(_Tp& __x) _NOEXCEPT {
[[__nodiscard__]] inline _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_NO_CFI _LIBCPP_HIDE_FROM_ABI _Tp*
addressof(_Tp& __x) _NOEXCEPT {
return __builtin_addressof(__x);
}

#if __has_feature(objc_arc)
// Objective-C++ Automatic Reference Counting uses qualified pointers
// that require special addressof() signatures.
template <class _Tp>
inline _LIBCPP_HIDE_FROM_ABI __strong _Tp* addressof(__strong _Tp& __x) _NOEXCEPT {
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI __strong _Tp* addressof(__strong _Tp& __x) _NOEXCEPT {
return &__x;
}

# if __has_feature(objc_arc_weak)
template <class _Tp>
inline _LIBCPP_HIDE_FROM_ABI __weak _Tp* addressof(__weak _Tp& __x) _NOEXCEPT {
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI __weak _Tp* addressof(__weak _Tp& __x) _NOEXCEPT {
return &__x;
}
# endif

template <class _Tp>
inline _LIBCPP_HIDE_FROM_ABI __autoreleasing _Tp* addressof(__autoreleasing _Tp& __x) _NOEXCEPT {
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI __autoreleasing _Tp* addressof(__autoreleasing _Tp& __x) _NOEXCEPT {
return &__x;
}

template <class _Tp>
inline _LIBCPP_HIDE_FROM_ABI __unsafe_unretained _Tp* addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT {
[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI __unsafe_unretained _Tp*
addressof(__unsafe_unretained _Tp& __x) _NOEXCEPT {
return &__x;
}
#endif
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7 changes: 4 additions & 3 deletions libcxx/include/__memory/allocator.h
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Expand Up @@ -120,18 +120,19 @@ class allocator
typedef allocator<_Up> other;
};

_LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT {
return std::addressof(__x);
}
_LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer
address(const_reference __x) const _NOEXCEPT {
return std::addressof(__x);
}

[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp* allocate(size_t __n, const void*) {
return allocate(__n);
}

_LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
return size_type(~0) / sizeof(_Tp);
}

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2 changes: 1 addition & 1 deletion libcxx/include/__memory/is_sufficiently_aligned.h
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Expand Up @@ -23,7 +23,7 @@ _LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 26

template <size_t _Alignment, class _Tp>
_LIBCPP_HIDE_FROM_ABI bool is_sufficiently_aligned(_Tp* __ptr) {
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool is_sufficiently_aligned(_Tp* __ptr) {
return reinterpret_cast<uintptr_t>(__ptr) % _Alignment == 0;
}

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2 changes: 1 addition & 1 deletion libcxx/include/__memory/raw_storage_iterator.h
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Expand Up @@ -67,7 +67,7 @@ class _LIBCPP_DEPRECATED_IN_CXX17 raw_storage_iterator
return __t;
}
# if _LIBCPP_STD_VER >= 14
_LIBCPP_HIDE_FROM_ABI _OutputIterator base() const { return __x_; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _OutputIterator base() const { return __x_; }
# endif
};

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33 changes: 28 additions & 5 deletions libcxx/test/libcxx/diagnostics/memory.nodiscard.verify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@

// check that <memory> functions are marked [[nodiscard]]

// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_RAW_STORAGE_ITERATOR
// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ENABLE_CXX20_REMOVED_TEMPORARY_BUFFER
// ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_DISABLE_DEPRECATION_WARNINGS

Expand All @@ -20,7 +21,13 @@
#include "test_macros.h"

void test() {
int i = 0;

std::addressof(i); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
std::get_temporary_buffer<int>(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#if _LIBCPP_STD_VER >= 26
std::is_sufficiently_aligned<2>(&i); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#endif
}

void test_allocator_traits() {
Expand All @@ -31,12 +38,28 @@ void test_allocator_traits() {
}

void test_allocator() {
std::allocator<int> allocator;
allocator.allocate(1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#if TEST_STD_VER <= 17
allocator.allocate(1, nullptr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#endif
[[maybe_unused]] std::allocator<int> allocator;

#if TEST_STD_VER >= 23
allocator.allocate_at_least(1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#endif

#if TEST_STD_VER <= 17
int i = 0;
const int ci = 0;

allocator.address(i); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
allocator.address(ci); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
allocator.allocate(1); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
allocator.allocate(1, nullptr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
allocator.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#endif
}

#if TEST_STD_VER >= 14
void test_raw_storage_iterator() {
std::raw_storage_iterator<int*, int> it(nullptr);

it.base(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif
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