Remove unused imports in parser.rs

Box return values in LoxError

- Box Return.value in LoxError
- Deref boxed value when assigning to ret
- Box value when constructing Return variants
- Update Cargo.toml edition to 2024 and add nightly toolchain

src/backend/interpreter.rs

@@ -112,7 +112,7 @@ impl Interpreter {
                     match self.eval_expr(body) {
                         Ok(val) => ret = val,
                         Err(LoxError::Return { value, .. }) => {
-                            ret = value;
+                            ret = *value;
                             break;
                         }
                         Err(err) => return Err(err),
@@ -136,7 +136,7 @@ impl Interpreter {
                     match self.eval_expr(body) {
                         Ok(val) => ret = val,
                         Err(LoxError::Return { value, .. }) => {
-                            ret = value;
+                            ret = *value;
                             break;
                         }
                         Err(err) => return Err(err),
@@ -217,7 +217,7 @@ impl Interpreter {
                 // Execute the function body
                 let result = match self.eval_expr(&func.body) {
                     Ok(value) => Ok(value),
-                    Err(LoxError::Return { value, .. }) => Ok(value),
+                    Err(LoxError::Return { value, .. }) => Ok(*value),
                     Err(err) => Err(err),
                 };
 
@@ -328,7 +328,7 @@ impl Interpreter {
 
                     result = Err(LoxError::Return {
                         source_slice: statement.source_slice.clone(),
-                        value,
+                        value: Box::new(value),
                         return_label: "Hi".to_string(),
                     });
                     break;

src/common/lox_result.rs

@@ -28,7 +28,7 @@ pub enum LoxError {
     },
     Return {
         source_slice: SourceSlice,
-        value: BaseValue,
+        value: Box<BaseValue>,
         return_label: String,
     },
 }