InputCommon: Mark GetStateLock with [[nodiscard]] and fix discarding calls.

Source/Core/DolphinQt/Config/Mapping/MappingWindow.cpp

@@ -71,7 +71,7 @@ MappingWindow::MappingWindow(QWidget* parent, Type type, int port_num)
 
   timer->start(1000 / INDICATOR_UPDATE_FREQ);
 
-  GetController()->GetStateLock();
+  const auto lock = GetController()->GetStateLock();
   emit ConfigChanged();
 }
 
@@ -245,7 +245,7 @@ void MappingWindow::OnLoadProfilePressed()
   m_controller->LoadConfig(ini.GetOrCreateSection("Profile"));
   m_controller->UpdateReferences(g_controller_interface);
 
-  GetController()->GetStateLock();
+  const auto lock = GetController()->GetStateLock();
   emit ConfigChanged();
 }
 
@@ -438,7 +438,7 @@ void MappingWindow::OnDefaultFieldsPressed()
   m_controller->LoadDefaults(g_controller_interface);
   m_controller->UpdateReferences(g_controller_interface);
 
-  GetController()->GetStateLock();
+  const auto lock = GetController()->GetStateLock();
   emit ConfigChanged();
   emit Save();
 }
@@ -455,7 +455,7 @@ void MappingWindow::OnClearFieldsPressed()
 
   m_controller->UpdateReferences(g_controller_interface);
 
-  GetController()->GetStateLock();
+  const auto lock = GetController()->GetStateLock();
   emit ConfigChanged();
   emit Save();
 }

Source/Core/InputCommon/ControllerEmu/ControllerEmu.h

@@ -153,7 +153,7 @@ public:
   // references and GetState(), by extension. This prevents a race condition
   // which happens while handling a hotplug event because a control reference's State()
   // could be called before we have finished updating the reference.
-  static std::unique_lock<std::recursive_mutex> GetStateLock();
+  [[nodiscard]] static std::unique_lock<std::recursive_mutex> GetStateLock();
 
   std::vector<std::unique_ptr<ControlGroup>> groups;