Lower fastpath table creation limit to 1 << 26

When Lua is configured without memory restrictions, we use fastpath for table creation (unprotected mode).
In generally it's safe as long as we `abort()` on allocation failure.
However some Lua versions have additional restrictions on table size that we need to adhere in mlua too.
Probably Luau has the lowest limits.
Fixes #627

Author: khvzak

src/util/mod.rs

@@ -122,7 +122,7 @@ pub(crate) unsafe fn push_table(
 ) -> Result<()> {
     let narr: c_int = narr.try_into().unwrap_or(c_int::MAX);
     let nrec: c_int = nrec.try_into().unwrap_or(c_int::MAX);
-    if protect || narr >= const { 1 << 30 } || nrec >= const { 1 << 27 } {
+    if protect || narr >= const { 1 << 26 } || nrec >= const { 1 << 26 } {
         protect_lua!(state, 0, 1, |state| ffi::lua_createtable(state, narr, nrec))
     } else {
         ffi::lua_createtable(state, narr, nrec);

tests/table.rs

@@ -61,6 +61,15 @@ fn test_table() -> Result<()> {
     Ok(())
 }
 
+#[test]
+#[cfg(target_os = "linux")] // Linux allow overcommiting the memory (relevant for CI)
+fn test_table_with_large_capacity() {
+    let lua = Lua::new();
+
+    let t = lua.create_table_with_capacity(1 << 26, 1 << 26);
+    assert!(t.is_ok());
+}
+
 #[test]
 fn test_table_push_pop() -> Result<()> {
     let lua = Lua::new();