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[libc++] Apply [[nodiscard]] to in/out_ptr #167097

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Merged
merged 9 commits into from
Nov 15, 2025
Merged

[libc++] Apply [[nodiscard]] to in/out_ptr #167097

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ea08a3c
[libc++] Added `[[nodiscard]]` to `fstream.native_handle`, `span.at` …
H-G-Hristov Nov 8, 2025
5b4edbd
Merge branch 'main' into hgh/libcxx/nodiscard-native_handle
H-G-Hristov Nov 8, 2025
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Addressed comments
H-G-Hristov Nov 14, 2025
1a68cb6
Merge branch 'main' into hgh/libcxx/nodiscard-native_handle
H-G-Hristov Nov 14, 2025
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Address comment
H-G-Hristov Nov 14, 2025
f438302
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H-G-Hristov Nov 14, 2025
a713448
Apply suggestion from @Zingam
Zingam Nov 14, 2025
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Apply suggestion from @Zingam
Zingam Nov 14, 2025
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Fix
H-G-Hristov Nov 14, 2025
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2 changes: 1 addition & 1 deletion libcxx/include/__memory/inout_ptr.h
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Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ class inout_ptr_t {
};

template <class _Pointer = void, class _Smart, class... _Args>
_LIBCPP_HIDE_FROM_ABI auto inout_ptr(_Smart& __s, _Args&&... __args) {
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI auto inout_ptr(_Smart& __s, _Args&&... __args) {
using _Ptr = conditional_t<is_void_v<_Pointer>, __pointer_of_t<_Smart>, _Pointer>;
return std::inout_ptr_t<_Smart, _Ptr, _Args&&...>(__s, std::forward<_Args>(__args)...);
}
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2 changes: 1 addition & 1 deletion libcxx/include/__memory/out_ptr.h
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Expand Up @@ -88,7 +88,7 @@ class out_ptr_t {
};

template <class _Pointer = void, class _Smart, class... _Args>
_LIBCPP_HIDE_FROM_ABI auto out_ptr(_Smart& __s, _Args&&... __args) {
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI auto out_ptr(_Smart& __s, _Args&&... __args) {
using _Ptr = conditional_t<is_void_v<_Pointer>, __pointer_of_t<_Smart>, _Pointer>;
return std::out_ptr_t<_Smart, _Ptr, _Args&&...>(__s, std::forward<_Args>(__args)...);
}
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29 changes: 29 additions & 0 deletions libcxx/test/libcxx/utilities/smartptr/nodiscard.verify.cpp
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@philnik777 philnik777 Nov 14, 2025

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I think I'd just put this at the smartptr level. That seems fine-grained enough to not get too big, but also not so fine-grained that you have two lines you actually test in a file.

Original file line number Diff line number Diff line change
@@ -0,0 +1,29 @@
//===----------------------------------------------------------------------===//
//
// 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++23

// <memory>

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

#include <memory>

#include "test_macros.h"

void test() {
#if TEST_STD_VER >= 23
{
std::unique_ptr<int> uPtr;
// [inout.ptr]
std::inout_ptr(uPtr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
// [out.ptr]
std::out_ptr(uPtr); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
}
#endif
}
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