From 9f9dbc8e09cf48406aa24b6c78735f1a7912cc4e Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Thu, 17 Dec 2020 13:16:02 +0000 Subject: [PATCH] libstdc++: Fix -Wunused warning As noted in PR 66146 comment 35, there is a new warning in the new std::call_once implementation. libstdc++-v3/ChangeLog: * src/c++11/mutex.cc (std::once_flag::_M_finish): Add maybe_unused attribute to variable used in assertion. --- libstdc++-v3/src/c++11/mutex.cc | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/src/c++11/mutex.cc b/libstdc++-v3/src/c++11/mutex.cc index 4d42bed8ecc..93a5eae391d 100644 --- a/libstdc++-v3/src/c++11/mutex.cc +++ b/libstdc++-v3/src/c++11/mutex.cc @@ -74,7 +74,8 @@ std::once_flag::_M_finish(bool returning) noexcept } else { - int prev = __atomic_exchange_n(&_M_once, newval, __ATOMIC_RELEASE); + int prev [[maybe_unused]] + = __atomic_exchange_n(&_M_once, newval, __ATOMIC_RELEASE); __glibcxx_assert(prev & _Bits::_Active); // Wake any other threads waiting for this execution to finish. constexpr int futex_wake = 129; // FUTEX_WAKE_PRIVATE -- 2.30.2