Add full optimization level for aggressive optimizing.

tests/call_fn.rs

@@ -0,0 +1,27 @@
+#![cfg(not(feature = "no_function"))]
+use rhai::{Engine, EvalAltResult, INT};
+
+#[test]
+fn test_call_fn() -> Result<(), EvalAltResult> {
+    let mut engine = Engine::new();
+
+    engine.consume(
+        true,
+        r"
+            fn hello(x, y) {
+                x + y
+            }
+            fn hello(x) {
+                x * 2
+            }
+                ",
+    )?;
+
+    let r: i64 = engine.call_fn("hello", (42 as INT, 123 as INT))?;
+    assert_eq!(r, 165);
+
+    let r: i64 = engine.call_fn("hello", 123 as INT)?;
+    assert_eq!(r, 246);
+
+    Ok(())
+}