Fix unused param warning with ENABLE_NDEBUG.

diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index 073110f16104ae44d3d5c150ea33431ee4387ae6..a562d253c900d22ed6c5ebfab05af5cdc4440192 100644 (file)
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -970,7 +970,7 @@ public:
 #ifndef NDEBUG
        void check(Module *mod = nullptr) const;
 #else
-       void check(Module *mod = nullptr) const { }
+       void check(Module *mod = nullptr) const { (void)mod; }
 #endif
 };