tidy - cppcoreguidelines-no-suspend-with-lock — Extra Clang Tools 22.0.0git documentation (original) (raw)

Flags coroutines that suspend while a lock guard is in scope at the suspension point.

When a coroutine suspends, any mutexes held by the coroutine will remain locked until the coroutine resumes and eventually destructs the lock guard. This can lead to long periods with a mutex held and runs the risk of deadlock.

Instead, locks should be released before suspending a coroutine.

This check only checks suspending coroutines while a lock_guard is in scope; it does not consider manual locking or unlocking of mutexes, e.g., through calls to std::mutex::lock().

Examples:

future bad_coro() { std::lock_guard lock{mtx}; ++some_counter; co_await something(); // Suspending while holding a mutex }

future good_coro() { { std::lock_guard lock{mtx}; ++some_counter; } // Destroy the lock_guard to release the mutex before suspending the coroutine co_await something(); // Suspending while holding a mutex }

This check implements CP.52from the C++ Core Guidelines.