Support Dynamic as function default return value.

src/fn_call.rs

@@ -211,7 +211,7 @@ impl Engine {
         args: &mut FnCallArgs,
         is_ref: bool,
         pub_only: bool,
-        def_val: Option<bool>,
+        def_val: &Option<Dynamic>,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
         self.inc_operations(state)?;
 
@@ -281,7 +281,7 @@ impl Engine {
 
         // Return default value (if any)
         if let Some(val) = def_val {
-            return Ok((val.into(), false));
+            return Ok((val.clone(), false));
         }
 
         // Getter function not found?
@@ -469,7 +469,7 @@ impl Engine {
         _is_method: bool,
         pub_only: bool,
         _capture: Option<Scope>,
-        def_val: Option<bool>,
+        def_val: &Option<Dynamic>,
         _level: usize,
     ) -> Result<(Dynamic, bool), Box<EvalAltResult>> {
         // Check for data race.
@@ -669,7 +669,7 @@ impl Engine {
         hash_script: u64,
         target: &mut Target,
         idx_val: Dynamic,
-        def_val: Option<bool>,
+        def_val: &Option<Dynamic>,
         native: bool,
         pub_only: bool,
         level: usize,
@@ -815,7 +815,7 @@ impl Engine {
         this_ptr: &mut Option<&mut Dynamic>,
         name: &str,
         args_expr: &[Expr],
-        def_val: Option<bool>,
+        def_val: &Option<Dynamic>,
         mut hash_script: u64,
         native: bool,
         pub_only: bool,