Fixed some more or less valid clang and clang-tidy errors.

source/mijin/util/scope_guard.hpp

@@ -7,7 +7,7 @@
 #include "./common_macros.hpp"
 
 #define MIJIN_SCOPE_EXIT_NAMED(name) \
-mijin::ScopeExitGuard name = [&]()
+const mijin::ScopeExitGuard name = [&]()
 
 #define MIJIN_SCOPE_EXIT MIJIN_SCOPE_EXIT_NAMED(MIJIN_CONCAT(MIJIN_CONCAT(scope_guard_, __LINE__), __))
 
@@ -16,7 +16,7 @@ namespace mijin
 class ScopeExitGuard
 {
 private:
-    std::function<void(void)> func;
+    mutable std::function<void(void)> func; // variable is declared const to make clang-tidy happy, but we still want to be able to reset()
 public:
     template<typename TFunc>
     inline ScopeExitGuard(TFunc&& func_) noexcept : func(std::forward<TFunc>(func_)) {}
@@ -32,7 +32,7 @@ public:
     ScopeExitGuard& operator=(const ScopeExitGuard&) noexcept = delete;
     ScopeExitGuard& operator=(ScopeExitGuard&&) noexcept = delete;
 
-    inline void reset() noexcept
+    inline void reset() const noexcept
     {
         func = {};
     }