Update check_stack requirements

src/lua.rs

@@ -554,7 +554,7 @@ impl Lua {
     {
         let loaded = unsafe {
             let _sg = StackGuard::new(self.state);
-            check_stack(self.state, 3)?;
+            check_stack(self.state, 2)?;
             protect_lua!(self.state, 0, 1, state => {
                 ffi::luaL_getsubtable(state, ffi::LUA_REGISTRYINDEX, cstr!("_LOADED"));
             })?;
@@ -976,7 +976,7 @@ impl Lua {
     pub fn create_table(&self) -> Result<Table> {
         unsafe {
             let _sg = StackGuard::new(self.state);
-            check_stack(self.state, 3)?;
+            check_stack(self.state, 2)?;
             protect_lua!(self.state, 0, 1, state => ffi::lua_newtable(state))?;
             Ok(Table(self.pop_ref()))
         }

src/scope.rs

@@ -250,7 +250,7 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
         fn wrap_method<'scope, 'lua, 'callback: 'scope, T: 'scope>(
             scope: &Scope<'lua, 'scope>,
             data: Rc<RefCell<T>>,
-            data_ptr: *mut c_void,
+            data_ptr: *const c_void,
             method: NonStaticMethod<'callback, T>,
         ) -> Result<Function<'lua>> {
             // On methods that actually receive the userdata, we fake a type check on the passed in
@@ -264,9 +264,9 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
                 if let Some(Value::UserData(ud)) = value {
                     unsafe {
                         let _sg = StackGuard::new(lua.state);
-                        check_stack(lua.state, 3)?;
+                        check_stack(lua.state, 2)?;
                         lua.push_userdata_ref(&ud.0)?;
-                        if get_userdata(lua.state, -1) == data_ptr {
+                        if get_userdata(lua.state, -1) as *const _ == data_ptr {
                             return Ok(());
                         }
                     }

src/serde/mod.rs

@@ -240,9 +240,9 @@ impl<'lua> LuaSerdeExt<'lua> for Lua {
     }
 }
 
-// Uses 6 stack spaces and calls checkstack.
+// Uses 2 stack spaces and calls checkstack.
 pub(crate) unsafe fn init_metatables(state: *mut ffi::lua_State) -> Result<()> {
-    check_stack(state, 3)?;
+    check_stack(state, 2)?;
     protect_lua!(state, 0, 0, state => {
         ffi::lua_createtable(state, 0, 1);
 

src/serde/ser.rs

@@ -318,7 +318,7 @@ impl<'lua> ser::SerializeSeq for SerializeVec<'lua> {
         let value = lua.to_value_with(value, self.options)?;
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 5)?;
+            check_stack(lua.state, 4)?;
 
             lua.push_ref(&self.table.0);
             lua.push_value(value)?;

src/table.rs

@@ -62,7 +62,7 @@ impl<'lua> Table<'lua> {
 
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 6)?;
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
@@ -101,7 +101,7 @@ impl<'lua> Table<'lua> {
 
         let value = unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 5)?;
+            check_stack(lua.state, 4)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
@@ -119,7 +119,7 @@ impl<'lua> Table<'lua> {
 
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 5)?;
+            check_stack(lua.state, 4)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;
@@ -192,7 +192,7 @@ impl<'lua> Table<'lua> {
 
         unsafe {
             let _sg = StackGuard::new(lua.state);
-            check_stack(lua.state, 6)?;
+            check_stack(lua.state, 5)?;
 
             lua.push_ref(&self.0);
             lua.push_value(key)?;

src/util.rs

@@ -246,7 +246,7 @@ pub unsafe fn pop_error(state: *mut ffi::lua_State, err_code: c_int) -> Error {
     }
 }
 
-// Uses 3 stack spaces
+// Uses 3 stack spaces, does not call checkstack.
 #[inline]
 pub unsafe fn push_string<S: AsRef<[u8]> + ?Sized>(
     state: *mut ffi::lua_State,
@@ -258,13 +258,13 @@ pub unsafe fn push_string<S: AsRef<[u8]> + ?Sized>(
     })
 }
 
-// Uses 3 stack spaces
+// Uses 3 stack spaces, does not call checkstack.
 #[inline]
 pub unsafe fn push_table(state: *mut ffi::lua_State, narr: c_int, nrec: c_int) -> Result<()> {
     protect_lua!(state, 0, 1, |state| ffi::lua_createtable(state, narr, nrec))
 }
 
-// Uses 4 stack spaces
+// Uses 4 stack spaces, does not call checkstack.
 pub unsafe fn rawset_field<S>(state: *mut ffi::lua_State, table: c_int, field: &S) -> Result<()>
 where
     S: AsRef<[u8]> + ?Sized,