Get rid of warnings

schala-lang/language/src/ast_visitor.rs

@@ -22,15 +22,11 @@ pub trait ASTVisitor<T> {
   type EV : ExpressionVisitor<T>;
   type DV : DeclarationVisitor<T>;
 
-  fn ast(&mut self, ast: &AST) {
-  }
-  fn done(&mut self) -> T;
-
-  fn statement(&mut self, statement: &Statement) {
-  }
-
+  fn ast(&mut self, _ast: &AST) { }
+  fn statement(&mut self, _statement: &Statement) { }
   fn expression(&mut self) -> Self::EV;
   fn declaration(&mut self) -> Self::DV;
+  fn done(&mut self) -> T;
 }
 
 pub trait ExpressionVisitor<T> {
@@ -38,8 +34,7 @@ pub trait ExpressionVisitor<T> {
     visitor.expression(expr);
     visitor.done()
   }
-  fn expression(&mut self, expression: &Expression) {
-  }
+  fn expression(&mut self, _expression: &Expression) { }
   fn done(&mut self) -> T;
 }
 
@@ -58,18 +53,10 @@ pub trait DeclarationVisitor<T> {
     visitor.done()
   }
 
-  fn declaration(&mut self, decl: &Declaration) {
-  }
-
-  fn func_signature(&mut self, sig: &Signature) {
-  }
-
-  fn func_declaration(&mut self, sig: &Signature, block: &Vec<Statement>) {
-  }
-
-  fn type_declaration(&mut self, name: &TypeSingletonName, body: &TypeBody, mutable: &bool) {
-  }
-
+  fn declaration(&mut self, _decl: &Declaration) { }
+  fn func_signature(&mut self, _sig: &Signature) { }
+  fn func_declaration(&mut self, _sig: &Signature, _block: &Vec<Statement>) { }
+  fn type_declaration(&mut self, _name: &TypeSingletonName, _body: &TypeBody, _mutable: &bool) { }
   fn done(&mut self) -> T;
 }