engine: Use C++17 standard for compilation

Author: cassava

engine/CMakeLists.txt

@@ -28,7 +28,7 @@ add_library(${libstack}
     src/plugin.cpp
 )
 set_target_properties(${libstack} PROPERTIES
-    CXX_STANDARD 14
+    CXX_STANDARD 17
     CXX_STANDARD_REQUIRED ON
 )
 target_include_directories(${libstack}
@@ -53,7 +53,7 @@ if(BUILD_TESTING)
         src/stack_test.cpp
     )
     set_target_properties(${test-libstack} PROPERTIES
-        CXX_STANDARD 14
+        CXX_STANDARD 17
         CXX_STANDARD_REQUIRED ON
     )
     target_link_libraries(${test-libstack}
@@ -78,7 +78,7 @@ add_executable(${target}
     src/utility/command.cpp
 )
 set_target_properties(${target} PROPERTIES
-    CXX_STANDARD 14
+    CXX_STANDARD 17
     CXX_STANDARD_REQUIRED ON
     OUTPUT_NAME ${output}
 )

engine/src/coordinator.cpp

@@ -117,7 +117,7 @@ void Coordinator::enroll(Registrar& r) {
       switch (q.method()) {
       case RequestMethod::GET:
         {
-          std::unique_lock<std::mutex> guard(input_mutex_);
+          std::unique_lock guard(input_mutex_);
           r.write(input_queue_);
           break;
         }
@@ -181,7 +181,7 @@ Duration Coordinator::process(const Sync& sync) {
   // input queue into their respective storage locations. We are responsible
   // for thread safety here!
   auto now = sync.time();
-  std::unique_lock<std::mutex> guard(input_mutex_);
+  std::unique_lock guard(input_mutex_);
   while (!input_queue_.empty()) {
     auto tp = std::move(input_queue_.front());
     input_queue_.pop_front();
@@ -287,7 +287,7 @@ void Coordinator::queue_trigger(TriggerPtr&& t) {
     // This only really happens if a trigger is an optional trigger.
     return;
   }
-  std::unique_lock<std::mutex> guard(input_mutex_);
+  std::unique_lock guard(input_mutex_);
   input_queue_.emplace_back(std::move(t));
 }