diff --git a/libcxx/include/__condition_variable/condition_variable.h b/libcxx/include/__condition_variable/condition_variable.h index 1e8edd5dcb009..b7151930e9226 100644 --- a/libcxx/include/__condition_variable/condition_variable.h +++ b/libcxx/include/__condition_variable/condition_variable.h @@ -170,7 +170,7 @@ class _LIBCPP_EXPORTED_FROM_ABI condition_variable { wait_for(unique_lock& __lk, const chrono::duration<_Rep, _Period>& __d, _Predicate __pred); typedef __libcpp_condvar_t* native_handle_type; - _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__cv_; } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__cv_; } private: void diff --git a/libcxx/include/__mutex/mutex.h b/libcxx/include/__mutex/mutex.h index 68c8842b35eda..e9cedf8db1cca 100644 --- a/libcxx/include/__mutex/mutex.h +++ b/libcxx/include/__mutex/mutex.h @@ -37,11 +37,11 @@ class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_CAPABILITY("mutex") mutex { # endif _LIBCPP_ACQUIRE_CAPABILITY() void lock(); - _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) bool try_lock() _NOEXCEPT; + [[__nodiscard__]] _LIBCPP_TRY_ACQUIRE_CAPABILITY(true) bool try_lock() _NOEXCEPT; _LIBCPP_RELEASE_CAPABILITY void unlock() _NOEXCEPT; typedef __libcpp_mutex_t* native_handle_type; - _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__m_; } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__m_; } }; static_assert(is_nothrow_default_constructible::value, "the default constructor for std::mutex must be nothrow"); diff --git a/libcxx/include/__thread/thread.h b/libcxx/include/__thread/thread.h index a3b672bc0f0e7..561f092ddb7c0 100644 --- a/libcxx/include/__thread/thread.h +++ b/libcxx/include/__thread/thread.h @@ -242,13 +242,13 @@ class _LIBCPP_EXPORTED_FROM_ABI thread { _LIBCPP_HIDE_FROM_ABI void swap(thread& __t) _NOEXCEPT { std::swap(__t_, __t.__t_); } - _LIBCPP_HIDE_FROM_ABI bool joinable() const _NOEXCEPT { return !__libcpp_thread_isnull(&__t_); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool joinable() const _NOEXCEPT { return !__libcpp_thread_isnull(&__t_); } void join(); void detach(); - _LIBCPP_HIDE_FROM_ABI id get_id() const _NOEXCEPT { return __libcpp_thread_get_id(&__t_); } - _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() _NOEXCEPT { return __t_; } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI id get_id() const _NOEXCEPT { return __libcpp_thread_get_id(&__t_); } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() _NOEXCEPT { return __t_; } - static unsigned hardware_concurrency() _NOEXCEPT; + [[__nodiscard__]] static unsigned hardware_concurrency() _NOEXCEPT; }; inline _LIBCPP_HIDE_FROM_ABI void swap(thread& __x, thread& __y) _NOEXCEPT { __x.swap(__y); } diff --git a/libcxx/include/barrier b/libcxx/include/barrier index 41fbfb3e8fb7b..5f9b471f01741 100644 --- a/libcxx/include/barrier +++ b/libcxx/include/barrier @@ -158,7 +158,9 @@ class barrier { public: using arrival_token = typename __barrier_base<_CompletionF>::arrival_token; - static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { return __barrier_base<_CompletionF>::max(); } + [[nodiscard]] static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { + return __barrier_base<_CompletionF>::max(); + } _LIBCPP_HIDE_FROM_ABI explicit barrier(ptrdiff_t __count, _CompletionF __completion = _CompletionF()) : __b_(__count, std::move(__completion)) { diff --git a/libcxx/include/latch b/libcxx/include/latch index c3b8f62e9b50e..33268d9655f25 100644 --- a/libcxx/include/latch +++ b/libcxx/include/latch @@ -70,7 +70,9 @@ class latch { atomic __a_; public: - static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { return numeric_limits::max(); } + [[nodiscard]] static _LIBCPP_HIDE_FROM_ABI constexpr ptrdiff_t max() noexcept { + return numeric_limits::max(); + } inline _LIBCPP_HIDE_FROM_ABI constexpr explicit latch(ptrdiff_t __expected) : __a_(__expected) { _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN( @@ -97,7 +99,7 @@ public: if (__old == __update) __a_.notify_all(); } - inline _LIBCPP_HIDE_FROM_ABI bool try_wait() const noexcept { + [[nodiscard]] inline _LIBCPP_HIDE_FROM_ABI bool try_wait() const noexcept { auto __value = __a_.load(memory_order_acquire); return try_wait_impl(__value); } diff --git a/libcxx/include/mutex b/libcxx/include/mutex index 0b81f1bb1c8a6..bec0185ede21a 100644 --- a/libcxx/include/mutex +++ b/libcxx/include/mutex @@ -229,12 +229,12 @@ public: recursive_mutex& operator=(const recursive_mutex&) = delete; void lock(); - bool try_lock() _NOEXCEPT; + [[__nodiscard__]] bool try_lock() _NOEXCEPT; void unlock() _NOEXCEPT; typedef __libcpp_recursive_mutex_t* native_handle_type; - _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__m_; } + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI native_handle_type native_handle() { return &__m_; } }; class _LIBCPP_EXPORTED_FROM_ABI timed_mutex { @@ -251,14 +251,14 @@ public: public: void lock(); - bool try_lock() _NOEXCEPT; + [[__nodiscard__]] bool try_lock() _NOEXCEPT; template - _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __d) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __d) { return try_lock_until(chrono::steady_clock::now() + __d); } template - _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) { using namespace chrono; unique_lock __lk(__m_); bool __no_timeout = _Clock::now() < __t; @@ -288,14 +288,14 @@ public: recursive_timed_mutex& operator=(const recursive_timed_mutex&) = delete; void lock(); - bool try_lock() _NOEXCEPT; + [[__nodiscard__]] bool try_lock() _NOEXCEPT; template - _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __d) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool try_lock_for(const chrono::duration<_Rep, _Period>& __d) { return try_lock_until(chrono::steady_clock::now() + __d); } template - _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) { + [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI bool try_lock_until(const chrono::time_point<_Clock, _Duration>& __t) { using namespace chrono; __thread_id __id = this_thread::get_id(); unique_lock __lk(__m_); @@ -320,7 +320,7 @@ public: }; template -_LIBCPP_NO_THREAD_SAFETY_ANALYSIS _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, _L1& __l1) { +[[__nodiscard__]] _LIBCPP_NO_THREAD_SAFETY_ANALYSIS _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, _L1& __l1) { unique_lock<_L0> __u0(__l0, try_to_lock_t()); if (__u0.owns_lock()) { if (__l1.try_lock()) { @@ -335,7 +335,8 @@ _LIBCPP_NO_THREAD_SAFETY_ANALYSIS _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, # ifndef _LIBCPP_CXX03_LANG template -_LIBCPP_NO_THREAD_SAFETY_ANALYSIS _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3) { +[[__nodiscard__]] _LIBCPP_NO_THREAD_SAFETY_ANALYSIS + _LIBCPP_HIDE_FROM_ABI int try_lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3&... __l3) { int __r = 0; unique_lock<_L0> __u0(__l0, try_to_lock); if (__u0.owns_lock()) { diff --git a/libcxx/include/semaphore b/libcxx/include/semaphore index 99c4ad24b35ec..1f19d50e32af7 100644 --- a/libcxx/include/semaphore +++ b/libcxx/include/semaphore @@ -133,7 +133,7 @@ class counting_semaphore { public: static_assert(__least_max_value >= 0, "The least maximum value must be a positive number"); - static constexpr ptrdiff_t max() noexcept { return __least_max_value; } + [[nodiscard]] static constexpr ptrdiff_t max() noexcept { return __least_max_value; } _LIBCPP_HIDE_FROM_ABI constexpr explicit counting_semaphore(ptrdiff_t __count) : __semaphore_(__count) { _LIBCPP_ASSERT_ARGUMENT_WITHIN_DOMAIN( @@ -156,12 +156,12 @@ public: } _LIBCPP_HIDE_FROM_ABI void acquire() { __semaphore_.acquire(); } template - _LIBCPP_HIDE_FROM_ABI bool try_acquire_for(chrono::duration<_Rep, _Period> const& __rel_time) { + [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool try_acquire_for(chrono::duration<_Rep, _Period> const& __rel_time) { return __semaphore_.try_acquire_for(chrono::duration_cast(__rel_time)); } - _LIBCPP_HIDE_FROM_ABI bool try_acquire() { return __semaphore_.try_acquire(); } + [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool try_acquire() { return __semaphore_.try_acquire(); } template - _LIBCPP_HIDE_FROM_ABI bool try_acquire_until(chrono::time_point<_Clock, _Duration> const& __abs_time) { + [[nodiscard]] _LIBCPP_HIDE_FROM_ABI bool try_acquire_until(chrono::time_point<_Clock, _Duration> const& __abs_time) { auto const __current = _Clock::now(); if (__current >= __abs_time) return try_acquire(); diff --git a/libcxx/test/libcxx/thread/nodiscard.verify.cpp b/libcxx/test/libcxx/thread/nodiscard.verify.cpp new file mode 100644 index 0000000000000..19e43f88db700 --- /dev/null +++ b/libcxx/test/libcxx/thread/nodiscard.verify.cpp @@ -0,0 +1,144 @@ +//===----------------------------------------------------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// + +// UNSUPPORTED: c++03 +// UNSUPPORTED: no-threads + +// Check that functions are marked [[nodiscard]] + +#include +#include +#include +#include +#include +#include + +#include "test_macros.h" + +const auto timePoint = std::chrono::steady_clock::now(); + +void test() { + // Threads + { + std::thread th; + + th.joinable(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + th.get_id(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + th.native_handle(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + th.hardware_concurrency(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } +#if TEST_STD_VER >= 20 + { + std::jthread jt; + + jt.joinable(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + jt.get_id(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + jt.native_handle(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + jt.get_stop_source(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + jt.get_stop_token(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + jt.hardware_concurrency(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } +#endif + + // Mutual exclusion + + { // + std::mutex m; + + m.try_lock(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + m.native_handle(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } + { + std::recursive_mutex m; + + m.try_lock(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + m.native_handle(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } + { + std::timed_mutex m; + + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock(); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock_for(std::chrono::nanoseconds{82}); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock_until(timePoint); + } + { + std::recursive_timed_mutex m; + + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock(); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock_for(std::chrono::nanoseconds{82}); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + m.try_lock_until(timePoint); + } + { + std::mutex m1; + std::mutex m2; + std::mutex m3; + + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + std::try_lock(m1, m2); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + std::try_lock(m1, m2, m3); + } + + // Condition variables + + { // + std::condition_variable cv; + + cv.native_handle(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } + +#if TEST_STD_VER >= 20 + + // Semaphores + + { // + std::counting_semaphore<> cs{0}; + + cs.max(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.try_acquire_for(std::chrono::nanoseconds{82}); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.try_acquire(); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + cs.try_acquire_until(timePoint); + + std::binary_semaphore bs{0}; + + bs.max(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + bs.try_acquire_for(std::chrono::nanoseconds{82}); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + bs.try_acquire(); + // expected-warning@+1 {{ignoring return value of function declared with 'nodiscard' attribute}} + bs.try_acquire_until(timePoint); + } + + // Latches and barriers + + { // + std::barrier<> b{94}; + + b.max(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } + { // + std::latch l{94}; + + l.max(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + l.try_wait(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}} + } + +#endif +} diff --git a/libcxx/test/std/thread/thread.jthread/nodiscard.verify.cpp b/libcxx/test/std/thread/thread.jthread/nodiscard.verify.cpp deleted file mode 100644 index 2ef5cf874da90..0000000000000 --- a/libcxx/test/std/thread/thread.jthread/nodiscard.verify.cpp +++ /dev/null @@ -1,29 +0,0 @@ -//===----------------------------------------------------------------------===// -// -// 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 -// -//===----------------------------------------------------------------------===// -// -// UNSUPPORTED: no-threads -// UNSUPPORTED: c++03, c++11, c++14, c++17 - -// [[nodiscard]] bool joinable() const noexcept; -// [[nodiscard]] id get_id() const noexcept; -// [[nodiscard]] native_handle_type native_handle(); -// [[nodiscard]] stop_source get_stop_source() noexcept; -// [[nodiscard]] stop_token get_stop_token() const noexcept; -// [[nodiscard]] static unsigned int hardware_concurrency() noexcept; - -#include - -void test() { - std::jthread jt; - jt.joinable(); // expected-warning {{ignoring return value of function}} - jt.get_id(); // expected-warning {{ignoring return value of function}} - jt.native_handle(); // expected-warning {{ignoring return value of function}} - jt.get_stop_source(); // expected-warning {{ignoring return value of function}} - jt.get_stop_token(); // expected-warning {{ignoring return value of function}} - jt.hardware_concurrency(); // expected-warning {{ignoring return value of function}} -}