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[libc++] Applied [[nodiscard]] to array::iterator (#198492)

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Towards #172124
This commit is contained in:
Hristo Hristov 2026-05-28 21:59:59 +03:00 committed by GitHub
parent 09ad100529
commit 184a8f9475
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GPG key ID: B5690EEEBB952194
3 changed files with 58 additions and 13 deletions
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13
libcxx/include/__iterator/static_bounded_iter.h
View file

@ -128,7 +128,7 @@ private:
public:
// Dereference and indexing operations.
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator*() const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator*() const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__current() != __end(), "__static_bounded_iter::operator*: Attempt to dereference an iterator at the end");
return *__current();
@ -140,7 +140,8 @@ public:
return std::__to_address(__current());
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator[](difference_type __n) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference
operator[](difference_type __n) const _NOEXCEPT {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__n >= __begin() - __current(),
"__static_bounded_iter::operator[]: Attempt to index an iterator past the start");
@ -186,13 +187,13 @@ public:
__current() += __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
operator+(__static_bounded_iter const& __self, difference_type __n) _NOEXCEPT {
__static_bounded_iter __tmp(__self);
__tmp += __n;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
operator+(difference_type __n, __static_bounded_iter const& __self) _NOEXCEPT {
__static_bounded_iter __tmp(__self);
__tmp += __n;
@ -208,13 +209,13 @@ public:
__current() -= __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend __static_bounded_iter
operator-(__static_bounded_iter const& __self, difference_type __n) _NOEXCEPT {
__static_bounded_iter __tmp(__self);
__tmp -= __n;
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend difference_type
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 friend difference_type
operator-(__static_bounded_iter const& __x, __static_bounded_iter const& __y) _NOEXCEPT {
return __x.__current() - __y.__current();
}

19
libcxx/include/__iterator/wrap_iter.h
View file

@ -55,7 +55,9 @@ public:
int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter(const __wrap_iter<_OtherIter>& __u) _NOEXCEPT
: __i_(__u.__i_) {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator*() const _NOEXCEPT { return *__i_; }
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator*() const _NOEXCEPT {
return *__i_;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 pointer operator->() const _NOEXCEPT {
return std::__to_address(__i_);
}
@ -78,7 +80,8 @@ public:
--(*this);
return __tmp;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter operator+(difference_type __n) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter
operator+(difference_type __n) const _NOEXCEPT {
__wrap_iter __w(*this);
__w += __n;
return __w;
@ -87,14 +90,16 @@ public:
__i_ += __n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter operator-(difference_type __n) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter
operator-(difference_type __n) const _NOEXCEPT {
return *this + (-__n);
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter& operator-=(difference_type __n) _NOEXCEPT {
*this += -__n;
return *this;
}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference operator[](difference_type __n) const _NOEXCEPT {
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 reference
operator[](difference_type __n) const _NOEXCEPT {
return __i_[__n];
}
@ -201,18 +206,18 @@ private:
#ifndef _LIBCPP_CXX03_LANG
template <class _Iter2>
_LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14 auto
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14 auto
operator-(const __wrap_iter& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT->decltype(__x.__i_ - __y.__i_)
#else
template <class _Iter2>
_LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14
typename __wrap_iter::difference_type operator-(const __wrap_iter& __x, const __wrap_iter<_Iter2>& __y) _NOEXCEPT
#endif // C++03
{
return __x.__i_ - __y.__i_;
}
_LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI friend _LIBCPP_CONSTEXPR_SINCE_CXX14 __wrap_iter
operator+(typename __wrap_iter::difference_type __n, __wrap_iter __x) _NOEXCEPT {
__x += __n;
return __x;

39
libcxx/test/libcxx/containers/sequences/array/nodiscard.iterator.verify.cpp Normal file
View file

@ -0,0 +1,39 @@
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// <array>
// Check that functions are marked [[nodiscard]]
#include <array>
#include "test_macros.h"
void test() {
typedef std::array<int, 94> Container;
Container c;
Container::iterator it = c.begin();
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
*it;
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
it[0];
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
it + 1;
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
1 + it;
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
it - 1;
// expected-warning-re@+1 {{{{(ignoring return value of function declared with 'nodiscard' attribute|expression result unused)}}}}
it - it;
}