-
Notifications
You must be signed in to change notification settings - Fork 15.6k
[libc++][ranges] Applied [[nodiscard]] to single_view
#173709
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Open
H-G-Hristov
wants to merge
2
commits into
llvm:main
Choose a base branch
from
H-G-Hristov:hgh/libcxx/nodiscard-to-single_view
base: main
Could not load branches
Branch not found: {{ refName }}
Loading
Could not load tags
Nothing to show
Loading
Are you sure you want to change the base?
Some commits from the old base branch may be removed from the timeline,
and old review comments may become outdated.
Open
[libc++][ranges] Applied [[nodiscard]] to single_view
#173709
H-G-Hristov
wants to merge
2
commits into
llvm:main
from
H-G-Hristov:hgh/libcxx/nodiscard-to-single_view
+56
−8
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
`[[nodiscard]]` should be applied to functions where discarding the return value is most likely a correctness issue. - https://libcxx.llvm.org/CodingGuidelines.html - https://wg21.link/range.single Towards llvm#172124
Member
|
@llvm/pr-subscribers-libcxx Author: Hristo Hristov (H-G-Hristov) Changes
Towards #172124 Full diff: https://github.com/llvm/llvm-project/pull/173709.diff 2 Files Affected:
diff --git a/libcxx/include/__ranges/single_view.h b/libcxx/include/__ranges/single_view.h
index 955578b99cf58..213c507138e68 100644
--- a/libcxx/include/__ranges/single_view.h
+++ b/libcxx/include/__ranges/single_view.h
@@ -63,21 +63,21 @@ class _LIBCPP_ABI_LLVM18_NO_UNIQUE_ADDRESS single_view : public view_interface<s
_LIBCPP_HIDE_FROM_ABI constexpr explicit single_view(in_place_t, _Args&&... __args)
: __value_{in_place, std::forward<_Args>(__args)...} {}
- _LIBCPP_HIDE_FROM_ABI constexpr _Tp* begin() noexcept { return data(); }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp* begin() noexcept { return data(); }
- _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* begin() const noexcept { return data(); }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* begin() const noexcept { return data(); }
- _LIBCPP_HIDE_FROM_ABI constexpr _Tp* end() noexcept { return data() + 1; }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp* end() noexcept { return data() + 1; }
- _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* end() const noexcept { return data() + 1; }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* end() const noexcept { return data() + 1; }
- _LIBCPP_HIDE_FROM_ABI static constexpr bool empty() noexcept { return false; }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr bool empty() noexcept { return false; }
- _LIBCPP_HIDE_FROM_ABI static constexpr size_t size() noexcept { return 1; }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr size_t size() noexcept { return 1; }
- _LIBCPP_HIDE_FROM_ABI constexpr _Tp* data() noexcept { return __value_.operator->(); }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _Tp* data() noexcept { return __value_.operator->(); }
- _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* data() const noexcept { return __value_.operator->(); }
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _Tp* data() const noexcept { return __value_.operator->(); }
};
template <class _Tp>
diff --git a/libcxx/test/libcxx/ranges/range.factories/range.single.view/nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.factories/range.single.view/nodiscard.verify.cpp
new file mode 100644
index 0000000000000..6f4be85ee27a6
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.factories/range.single.view/nodiscard.verify.cpp
@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++20
+
+// <ranges>
+
+// Check that functions are marked [[nodiscard]]
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ auto v = std::views::single(94);
+
+ // [range.single.view]
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ v.begin();
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(v).begin();
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ v.end();
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(v).end();
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ v.size();
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ v.empty();
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ v.data();
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(v).data();
+
+ // [range.single.overview]
+
+ // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::views::single(82);
+}
|
frederick-vs-ja
approved these changes
Dec 27, 2025
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
[[nodiscard]]should be applied to functions where discarding the return value is most likely a correctness issue.Towards #172124