Replace lazy_static with once_cell

Cargo.toml

@@ -42,7 +42,7 @@ serialize = ["serde", "erased-serde"]
 [dependencies]
 mlua_derive = { version = "0.5", optional = true, path = "mlua_derive" }
 bstr = { version = "0.2", features = ["std"], default_features = false }
-lazy_static = { version = "1.4" }
+once_cell = { version = "1.7" }
 num-traits = { version = "0.2.14" }
 futures-core = { version = "0.3.5", optional = true }
 futures-task = { version = "0.3.5", optional = true }

src/util.rs

@@ -6,13 +6,15 @@ use std::panic::{catch_unwind, resume_unwind, AssertUnwindSafe};
 use std::sync::{Arc, Mutex};
 use std::{mem, ptr, slice};
 
+use once_cell::sync::Lazy;
+
 use crate::error::{Error, Result};
 use crate::ffi;
 
-lazy_static::lazy_static! {
+static METATABLE_CACHE: Lazy<Mutex<HashMap<TypeId, u8>>> = Lazy::new(|| {
     // The capacity must(!) be greater than number of stored keys
-    static ref METATABLE_CACHE: Mutex<HashMap<TypeId, u8>> = Mutex::new(HashMap::with_capacity(32));
-}
+    Mutex::new(HashMap::with_capacity(32))
+});
 
 // Checks that Lua has enough free stack space for future stack operations.  On failure, this will
 // panic with an internal error message.