Make Luau registered aliases case-insensitive

Executing `require("@my_module")` or `require("@My_Module")` should give the same result and use case-insensitive name.
See #620 for details

Author: khvzak

src/luau/require.rs

@@ -567,10 +567,20 @@ pub(super) fn create_require_function<R: Require + MaybeSend + 'static>(
         1
     }
 
-    let (error, r#type) = unsafe {
-        lua.exec_raw::<(Function, Function)>((), move |state| {
+    unsafe extern "C-unwind" fn to_lowercase(state: *mut ffi::lua_State) -> c_int {
+        let s = ffi::luaL_checkstring(state, 1);
+        let s = CStr::from_ptr(s);
+        callback_error_ext(state, ptr::null_mut(), true, |extra, _| {
+            let s = s.to_string_lossy().to_lowercase();
+            (*extra).raw_lua().push(s).map(|_| 1)
+        })
+    }
+
+    let (error, r#type, to_lowercase) = unsafe {
+        lua.exec_raw::<(Function, Function, Function)>((), move |state| {
             ffi::lua_pushcfunctiond(state, error, cstr!("error"));
             ffi::lua_pushcfunctiond(state, r#type, cstr!("type"));
+            ffi::lua_pushcfunctiond(state, to_lowercase, cstr!("to_lowercase"));
         })
     }?;
 
@@ -583,6 +593,7 @@ pub(super) fn create_require_function<R: Require + MaybeSend + 'static>(
     env.raw_set("LOADER_CACHE", loader_cache)?;
     env.raw_set("error", error)?;
     env.raw_set("type", r#type)?;
+    env.raw_set("to_lowercase", to_lowercase)?;
 
     lua.load(
         r#"
@@ -592,7 +603,7 @@ pub(super) fn create_require_function<R: Require + MaybeSend + 'static>(
         end
 
         -- Check if the module (path) is explicitly registered
-        local maybe_result = REGISTERED_MODULES[path]
+        local maybe_result = REGISTERED_MODULES[to_lowercase(path)]
         if maybe_result ~= nil then
             return maybe_result
         end

src/state.rs

@@ -358,6 +358,8 @@ impl Lua {
         if cfg!(feature = "luau") && !modname.starts_with('@') {
             return Err(Error::runtime("module name must begin with '@'"));
         }
+        #[cfg(feature = "luau")]
+        let modname = modname.to_lowercase();
         unsafe {
             self.exec_raw::<()>(value, |state| {
                 ffi::luaL_getsubtable(state, ffi::LUA_REGISTRYINDEX, LOADED_MODULES_KEY);

tests/luau/require.rs

@@ -179,6 +179,11 @@ fn test_require_with_config() {
     let res = run_require(&lua, "./tests/luau/require/with_config/src/alias_requirer").unwrap();
     assert_eq!("result from dependency", get_str(&res, 1));
 
+    // RequirePathWithAlias (case-insensitive)
+    let res2 = run_require(&lua, "./tests/luau/require/with_config/src/alias_requirer_uc").unwrap();
+    assert_eq!("result from dependency", get_str(&res2, 1));
+    assert_eq!(res.to_pointer(), res2.to_pointer());
+
     // RequirePathWithParentAlias
     let res = run_require(&lua, "./tests/luau/require/with_config/src/parent_alias_requirer").unwrap();
     assert_eq!("result from other_dependency", get_str(&res, 1));

tests/luau/require/with_config/src/alias_requirer_uc.luau

@@ -0,0 +1 @@
+return require("@DeP")

tests/tests.rs

@@ -1242,6 +1242,17 @@ fn test_register_module() -> Result<()> {
             res.unwrap_err().to_string(),
             "runtime error: module name must begin with '@'"
         );
+
+        // Luau registered modules (aliases) are case-insensitive
+        let res = lua.register_module("@My_Module", &t);
+        assert!(res.is_ok());
+        lua.load(
+            r#"
+            local my_module = require("@MY_MODule")
+            assert(my_module.name == "my_module")
+        "#,
+        )
+        .exec()?;
     }
 
     Ok(())