refactor: fix clippy/rustc warnings

Author: ALVAROPING1

src/parser.rs

@@ -202,6 +202,7 @@ macro_rules! parse_with {
         }()
     }};
 }
+#[allow(unused_imports)] // This is used below, but clippy doesn't seem to detect it
 use parse_with;
 
 /// Parses the input creating an abstract syntax tree

src/parser/expression.rs

@@ -107,16 +107,16 @@ pub enum Expr {
         /// Operation to perform
         op: Spanned<UnaryOp>,
         /// Operand to perform the operation on
-        operand: Box<Spanned<Expr>>,
+        operand: Box<Spanned<Self>>,
     },
     /// Binary operation on other expressions
     BinaryOp {
         /// Operation to perform
         op: Spanned<BinaryOp>,
         /// Left operand of the operation
-        lhs: Box<Spanned<Expr>>,
+        lhs: Box<Spanned<Self>>,
         /// Right operand of the operation
-        rhs: Box<Spanned<Expr>>,
+        rhs: Box<Spanned<Self>>,
     },
 }