More performance optimizations

src/conversion.rs

@@ -364,7 +364,9 @@ macro_rules! lua_convert_int {
         impl<'lua> FromLua<'lua> for $x {
             fn from_lua(value: Value<'lua>, lua: &'lua Lua) -> Result<Self> {
                 let ty = value.type_name();
-                (if let Some(i) = lua.coerce_integer(value.clone())? {
+                (if let Value::Integer(i) = value {
+                    cast(i)
+                } else if let Some(i) = lua.coerce_integer(value.clone())? {
                     cast(i)
                 } else {
                     cast(lua.coerce_number(value)?.ok_or_else(|| {

src/lua.rs

@@ -2230,13 +2230,14 @@ impl Lua {
                     args.push_front(lua.pop_value());
                 }
 
-                let results = ((*upvalue).func)(&lua, args)?;
+                let mut results = ((*upvalue).func)(&lua, args)?;
                 let nresults = results.len() as c_int;
 
                 check_stack(state, nresults)?;
-                for r in results {
+                for r in results.drain_all() {
                     lua.push_value(r)?;
                 }
+                lua.cache_multivalue(results);
 
                 Ok(nresults)
             })

src/value.rs

@@ -53,7 +53,7 @@ pub enum Value<'lua> {
 pub use self::Value::Nil;
 
 impl<'lua> Value<'lua> {
-    pub fn type_name(&self) -> &'static str {
+    pub const fn type_name(&self) -> &'static str {
         match *self {
             Value::Nil => "nil",
             Value::Boolean(_) => "boolean",