Fix setting Luau version number in `_VERSION` env var

mlua-sys/src/luau/lua.rs

@@ -84,6 +84,11 @@ pub type lua_Alloc = unsafe extern "C" fn(
     nsize: usize,
 ) -> *mut c_void;
 
+/// Returns Luau release version (eg. `0.xxx`).
+pub const fn luau_version() -> Option<&'static str> {
+    option_env!("LUAU_VERSION")
+}
+
 extern "C" {
     //
     // State manipulation

src/luau.rs

@@ -24,7 +24,7 @@ impl Lua {
 
         // Set `_VERSION` global to include version number
         // The environment variable `LUAU_VERSION` set by the build script
-        if let Some(version) = option_env!("LUAU_VERSION") {
+        if let Some(version) = ffi::luau_version() {
             globals.raw_set("_VERSION", format!("Luau {version}"))?;
         }
 

tests/luau.rs

@@ -9,6 +9,16 @@ use std::sync::Arc;
 
 use mlua::{Compiler, CoverageInfo, Error, Lua, Result, Table, ThreadStatus, Value, VmState};
 
+#[test]
+fn test_version() -> Result<()> {
+    let lua = Lua::new();
+    assert!(lua
+        .globals()
+        .get::<_, String>("_VERSION")?
+        .starts_with("Luau 0."));
+    Ok(())
+}
+
 #[test]
 fn test_require() -> Result<()> {
     let lua = Lua::new();