[libcxx-commits] [libcxx] [libc++][string_view] Applied `[[nodiscard]]` (PR #169010)
Hristo Hristov via libcxx-commits
libcxx-commits at lists.llvm.org
Fri Nov 21 09:27:47 PST 2025
https://github.com/H-G-Hristov updated https://github.com/llvm/llvm-project/pull/169010
>From f3a77eada23b23dee92d8e78c8d14ddbd8f72fd4 Mon Sep 17 00:00:00 2001
From: Hristo Hristov <hghristov.rmm at gmail.com>
Date: Fri, 21 Nov 2025 09:13:28 +0200
Subject: [PATCH] [libc++][string_view] Applied `[[nodiscard]]`
`[[nodiscard]]` should be applied to functions where discarding the return value is most likely a correctness issue.
- https://libcxx.llvm.org/CodingGuidelines.html#apply-nodiscard-where-relevant
---
libcxx/include/string_view | 137 ++++++++++--------
.../string_view.nodiscard.verify.cpp | 131 ++++++++++++++++-
.../strings/string.view/nonnull.verify.cpp | 6 +-
3 files changed, 207 insertions(+), 67 deletions(-)
diff --git a/libcxx/include/string_view b/libcxx/include/string_view
index 5ecaa3de7deba..5dd04a9ba8479 100644
--- a/libcxx/include/string_view
+++ b/libcxx/include/string_view
@@ -362,11 +362,11 @@ public:
# endif
// [string.view.iterators], iterators
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return cbegin(); }
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator begin() const _NOEXCEPT { return cbegin(); }
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return cend(); }
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator end() const _NOEXCEPT { return cend(); }
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cbegin() const _NOEXCEPT {
# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS
return std::__make_bounded_iter(data(), data(), data() + size());
# else
@@ -374,7 +374,7 @@ public:
# endif
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_iterator cend() const _NOEXCEPT {
# ifdef _LIBCPP_ABI_BOUNDED_ITERATORS
return std::__make_bounded_iter(data() + size(), data(), data() + size());
# else
@@ -382,51 +382,54 @@ public:
# endif
}
- _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator
+ rbegin() const _NOEXCEPT {
return const_reverse_iterator(cend());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator rend() const _NOEXCEPT {
return const_reverse_iterator(cbegin());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crbegin() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator
+ crbegin() const _NOEXCEPT {
return const_reverse_iterator(cend());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX17 _LIBCPP_HIDE_FROM_ABI const_reverse_iterator crend() const _NOEXCEPT {
return const_reverse_iterator(cbegin());
}
// [string.view.capacity], capacity
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size_; }
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type size() const _NOEXCEPT { return __size_; }
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type length() const _NOEXCEPT { return __size_; }
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type length() const _NOEXCEPT { return __size_; }
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT {
return numeric_limits<size_type>::max() / sizeof(value_type);
}
[[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT { return __size_ == 0; }
// [string.view.access], element access
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference operator[](size_type __pos) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference
+ operator[](size_type __pos) const _NOEXCEPT {
return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__pos < size(), "string_view[] index out of bounds"), __data_[__pos];
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference at(size_type __pos) const {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference at(size_type __pos) const {
return __pos >= size() ? (__throw_out_of_range("string_view::at"), __data_[0]) : __data_[__pos];
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference front() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference front() const _NOEXCEPT {
return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string_view::front(): string is empty"), __data_[0];
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference back() const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_reference back() const _NOEXCEPT {
return _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(!empty(), "string_view::back(): string is empty"), __data_[__size_ - 1];
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_pointer data() const _NOEXCEPT { return __data_; }
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI const_pointer data() const _NOEXCEPT { return __data_; }
// [string.view.modifiers], modifiers:
_LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI void remove_prefix(size_type __n) _NOEXCEPT {
@@ -459,7 +462,8 @@ public:
return __rlen;
}
- _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view substr(size_type __pos = 0, size_type __n = npos) const {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR _LIBCPP_HIDE_FROM_ABI basic_string_view
+ substr(size_type __pos = 0, size_type __n = npos) const {
// Use the `__assume_valid` form of the constructor to avoid an unnecessary check. Any substring of a view is a
// valid view. In particular, `size()` is known to be smaller than `numeric_limits<difference_type>::max()`, so the
// new size is also smaller. See also https://llvm.org/PR91634.
@@ -474,7 +478,7 @@ public:
}
# endif
- _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 int compare(basic_string_view __sv) const _NOEXCEPT {
size_type __rlen = std::min(size(), __sv.size());
int __retval = _Traits::compare(data(), __sv.data(), __rlen);
if (__retval == 0) // first __rlen chars matched
@@ -482,50 +486,51 @@ public:
return __retval;
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
compare(size_type __pos1, size_type __n1, basic_string_view __sv) const {
return substr(__pos1, __n1).compare(__sv);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
compare(size_type __pos1, size_type __n1, basic_string_view __sv, size_type __pos2, size_type __n2) const {
return substr(__pos1, __n1).compare(__sv.substr(__pos2, __n2));
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
compare(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s) const _NOEXCEPT {
return compare(basic_string_view(__s));
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
compare(size_type __pos1, size_type __n1, const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
return substr(__pos1, __n1).compare(basic_string_view(__s));
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI int
compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n2 != 0 && __s == nullptr, " if n2 is not zero") {
return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
}
// find
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ find(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find(): received nullptr");
return std::__str_find<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find(): received nullptr");
return std::__str_find<value_type, size_type, traits_type, npos>(
@@ -533,24 +538,24 @@ public:
}
// rfind
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
rfind(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::rfind(): received nullptr");
return std::__str_rfind<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
rfind(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::rfind(): received nullptr");
return std::__str_rfind<value_type, size_type, traits_type, npos>(
@@ -558,25 +563,25 @@ public:
}
// find_first_of
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
return find(__c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_of(): received nullptr");
return std::__str_find_first_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_of(): received nullptr");
return std::__str_find_first_of<value_type, size_type, traits_type, npos>(
@@ -584,25 +589,25 @@ public:
}
// find_last_of
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
return rfind(__c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_of(): received nullptr");
return std::__str_find_last_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_of(): received nullptr");
return std::__str_find_last_of<value_type, size_type, traits_type, npos>(
@@ -610,25 +615,25 @@ public:
}
// find_first_not_of
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_not_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT {
return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_not_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT {
return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): received nullptr");
return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_first_not_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = 0) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_first_not_of(): received nullptr");
return std::__str_find_first_not_of<value_type, size_type, traits_type, npos>(
@@ -636,25 +641,25 @@ public:
}
// find_last_not_of
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_not_of(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT {
return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
data(), size(), __s.data(), __pos, __s.size());
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_not_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT {
return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __c, __pos);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const _NOEXCEPT
_LIBCPP_DIAGNOSE_NULLPTR_IF(__n != 0 && __s == nullptr, " if n is not zero") {
_LIBCPP_ASSERT_NON_NULL(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): received nullptr");
return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(data(), size(), __s, __pos, __n);
}
- _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
+ [[__nodiscard__]] _LIBCPP_CONSTEXPR_SINCE_CXX14 _LIBCPP_HIDE_FROM_ABI size_type
find_last_not_of(const _CharT* _LIBCPP_DIAGNOSE_NULLPTR __s, size_type __pos = npos) const _NOEXCEPT {
_LIBCPP_ASSERT_NON_NULL(__s != nullptr, "string_view::find_last_not_of(): received nullptr");
return std::__str_find_last_not_of<value_type, size_type, traits_type, npos>(
@@ -662,37 +667,43 @@ public:
}
# if _LIBCPP_STD_VER >= 20
- constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(basic_string_view __s) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(basic_string_view __s) const noexcept {
return size() >= __s.size() && compare(0, __s.size(), __s) == 0;
}
- constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(value_type __c) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(value_type __c) const noexcept {
return !empty() && _Traits::eq(front(), __c);
}
- constexpr _LIBCPP_HIDE_FROM_ABI bool starts_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool
+ starts_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
return starts_with(basic_string_view(__s));
}
- constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(basic_string_view __s) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(basic_string_view __s) const noexcept {
return size() >= __s.size() && compare(size() - __s.size(), npos, __s) == 0;
}
- constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(value_type __c) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(value_type __c) const noexcept {
return !empty() && _Traits::eq(back(), __c);
}
- constexpr _LIBCPP_HIDE_FROM_ABI bool ends_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool
+ ends_with(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const noexcept {
return ends_with(basic_string_view(__s));
}
# endif
# if _LIBCPP_STD_VER >= 23
- constexpr _LIBCPP_HIDE_FROM_ABI bool contains(basic_string_view __sv) const noexcept { return find(__sv) != npos; }
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(basic_string_view __sv) const noexcept {
+ return find(__sv) != npos;
+ }
- constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept { return find(__c) != npos; }
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(value_type __c) const noexcept {
+ return find(__c) != npos;
+ }
- constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
+ [[nodiscard]] constexpr _LIBCPP_HIDE_FROM_ABI bool contains(const value_type* _LIBCPP_DIAGNOSE_NULLPTR __s) const {
return find(__s) != npos;
}
# endif
@@ -897,7 +908,8 @@ operator<<(basic_ostream<_CharT, _Traits>& __os, basic_string_view<_CharT, _Trai
// [string.view.hash]
template <class _CharT>
struct __string_view_hash : public __unary_function<basic_string_view<_CharT, char_traits<_CharT> >, size_t> {
- _LIBCPP_HIDE_FROM_ABI size_t operator()(const basic_string_view<_CharT, char_traits<_CharT> > __val) const _NOEXCEPT {
+ [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI size_t
+ operator()(const basic_string_view<_CharT, char_traits<_CharT> > __val) const _NOEXCEPT {
return std::__do_string_hash(__val.data(), __val.data() + __val.size());
}
};
@@ -924,30 +936,31 @@ struct hash<basic_string_view<wchar_t, char_traits<wchar_t> > > : __string_view_
# if _LIBCPP_STD_VER >= 14
inline namespace literals {
inline namespace string_view_literals {
-inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char> operator""sv(const char* __str, size_t __len) noexcept {
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char>
+operator""sv(const char* __str, size_t __len) noexcept {
return basic_string_view<char>(__str, __len);
}
# if _LIBCPP_HAS_WIDE_CHARACTERS
-inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<wchar_t>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<wchar_t>
operator""sv(const wchar_t* __str, size_t __len) noexcept {
return basic_string_view<wchar_t>(__str, __len);
}
# endif
# if _LIBCPP_HAS_CHAR8_T
-inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char8_t>
+[[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char8_t>
operator""sv(const char8_t* __str, size_t __len) noexcept {
return basic_string_view<char8_t>(__str, __len);
}
# endif
-inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char16_t>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char16_t>
operator""sv(const char16_t* __str, size_t __len) noexcept {
return basic_string_view<char16_t>(__str, __len);
}
-inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char32_t>
+[[__nodiscard__]] inline _LIBCPP_HIDE_FROM_ABI constexpr basic_string_view<char32_t>
operator""sv(const char32_t* __str, size_t __len) noexcept {
return basic_string_view<char32_t>(__str, __len);
}
diff --git a/libcxx/test/libcxx/diagnostics/string_view.nodiscard.verify.cpp b/libcxx/test/libcxx/diagnostics/string_view.nodiscard.verify.cpp
index e5b2258315fe4..f391238c299d2 100644
--- a/libcxx/test/libcxx/diagnostics/string_view.nodiscard.verify.cpp
+++ b/libcxx/test/libcxx/diagnostics/string_view.nodiscard.verify.cpp
@@ -12,12 +12,137 @@
#include <string_view>
+#include "type_algorithms.h"
#include "test_macros.h"
void test() {
- std::string_view string_view;
- string_view.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::string_view sv;
+
+ sv.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.cbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.cend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.rbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.rend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.crbegin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.crend(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.length(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.max_size(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.empty(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv[0]; // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.at(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.front(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.back(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.data(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.substr(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
#if TEST_STD_VER >= 26
- string_view.subview(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.subview(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+#endif
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare(sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare(0, 0, sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare(0, 0, sv, 0, 0);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare("");
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare(0, 0, "");
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.compare(0, 0, "", 0);
+
+ sv.find(sv); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find(' '); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find("", 0, 0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find("", 0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.rfind(sv); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.rfind(' '); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.rfind("", 0, 0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.rfind("", 0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_of(sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_of(' ');
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_of("", 0, 0);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_of("", 0);
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_of(sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_of(' ');
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_of("", 0, 0);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_of("", 0);
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_not_of(sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_not_of(' ');
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_not_of("", 0, 0);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_first_not_of("", 0);
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_not_of(sv);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_not_of(' ');
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_not_of("", 0, 0);
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.find_last_not_of("", 0);
+
+#if TEST_STD_VER >= 20
+ sv.starts_with(sv); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.starts_with(' '); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.starts_with(""); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ sv.ends_with(sv); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.ends_with(' '); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.ends_with(""); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+#endif
+
+#if TEST_STD_VER >= 23
+ sv.contains(sv); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.contains(' '); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ sv.contains(""); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+#endif
+
+ // std::hash<>
+ types::for_each(types::character_types(), []<typename CharT>() {
+ using StringViewT = std::basic_string_view<CharT>;
+ std::hash<StringViewT> hash;
+ // expected-warning at +1 4-5 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ hash(StringViewT{});
+ });
+
+#if TEST_STD_VER >= 14
+ // string_view literals
+ using namespace std::string_view_literals;
+
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ ""sv; // const char*
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ L""sv; // const wchar_t*
+# if !defined(TEST_HAS_NO_CHAR8_T)
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ u8""sv; // const char8_t*
+# endif
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ u""sv; // const char16_t*
+ // expected-warning at +1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ U""sv; // const char32_t*
#endif
}
diff --git a/libcxx/test/libcxx/strings/string.view/nonnull.verify.cpp b/libcxx/test/libcxx/strings/string.view/nonnull.verify.cpp
index 316c9828e0de5..ffe048730e687 100644
--- a/libcxx/test/libcxx/strings/string.view/nonnull.verify.cpp
+++ b/libcxx/test/libcxx/strings/string.view/nonnull.verify.cpp
@@ -10,8 +10,10 @@
// Ensure that APIs which take a CharT* are diagnosing passing a nullptr to them
-// Clang 19 and AppleClang don't have diagnose_if with diagnostic flags
-// UNSUPPORTED: clang-19, apple-clang-17
+// AppleClang doesn't have diagnose_if with diagnostic flags
+// UNSUPPORTED: apple-clang-17
+
+// ADDITIONAL_COMPILE_FLAGS: -Wno-unused-result
#include <string_view>
More information about the libcxx-commits
mailing list