Use: add alias use foo as bar form

src/ast.rs

@@ -42,7 +42,7 @@ pub enum Expr<A: Annotation = Span> {
     Lit(Literal),
     /// use Use
     Use(Use),
-    /// `(let | const | static) Pat::NoTopAlt (= expr (else expr)?)?` |
+    /// `let Pat::NoTopAlt (= expr (else expr)?)?` |
     /// `(fn | mod | impl) Pat::Fn Expr`
     Bind(Box<Bind<A>>),
     /// Expr { (Ident (: Expr)?),* }
@@ -169,6 +169,8 @@ pub enum Use {
     Glob,
     /// Identifier
     Name(String),
+    /// Identifier as Identifier
+    Alias(String, String),
     /// Identifier :: Use
     Path(String, Box<Use>),
     /// { Use, * }