Enable compiler errors for implicit switch case fallthroughs.

Also unify warning options across Clang and GCC and fix minor issues that was surfaced by this.

PiperOrigin-RevId: 508619655
Change-Id: I59b777bf2dfea4422485670e2427c7d3f5cf6405

python/mujoco/simulate.cc

@@ -25,6 +25,11 @@
 
 namespace mujoco::python {
 namespace {
+template <typename T, int N>
+constexpr inline std::size_t sizeof_arr(const T(&arr)[N]) {
+  return sizeof(arr);
+}
+
 PYBIND11_MODULE(_simulate, pymodule) {
   namespace py = ::pybind11;
   using SimulateMutex = decltype(mujoco::Simulate::mtx);
@@ -138,8 +143,9 @@ PYBIND11_MODULE(_simulate, pymodule) {
             return simulate.loadError;
           },
           [](mujoco::Simulate& simulate, const std::string& error) {
-            std::strncpy(simulate.loadError, error.c_str(),
-                         simulate.kMaxFilenameLength);
+            const auto max_length = sizeof_arr(simulate.loadError);
+            std::strncpy(simulate.loadError, error.c_str(), max_length - 1);
+            simulate.loadError[max_length - 1] = '\0';
           });
 
   pymodule.def("setglfwdlhandle", [](std::uintptr_t dlhandle) {