Add let-else to AST

[rust.git] / compiler / rustc_ast / src / ast.rs

diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs
index 2b86128b3f793b4545426a0257eb8cd39b012b9b..0632d937c4c17e2d154fe856e0f4343e3b746608 100644 (file)
--- a/compiler/rustc_ast/src/ast.rs
+++ b/compiler/rustc_ast/src/ast.rs
@@ -332,8 +332,8 @@ pub fn span(&self) -> Span {
 pub enum ParamKindOrd {
     Lifetime,
     Type,
-    // `unordered` is only `true` if `sess.has_features().const_generics`
-    // is active. Specifically, if it's only `min_const_generics`, it will still require
+    // `unordered` is only `true` if `sess.unordered_const_ty_params()`
+    // returns true. Specifically, if it's only `min_const_generics`, it will still require
     // ordering consts after types.
     Const { unordered: bool },
     // `Infer` is not actually constructed directly from the AST, but is implicitly constructed
@@ -1005,13 +1005,42 @@ pub struct Local {
     pub id: NodeId,
     pub pat: P<Pat>,
     pub ty: Option<P<Ty>>,
-    /// Initializer expression to set the value, if any.
-    pub init: Option<P<Expr>>,
+    pub kind: LocalKind,
     pub span: Span,
     pub attrs: AttrVec,
     pub tokens: Option<LazyTokenStream>,
 }
 
+#[derive(Clone, Encodable, Decodable, Debug)]
+pub enum LocalKind {
+    /// Local declaration.
+    /// Example: `let x;`
+    Decl,
+    /// Local declaration with an initializer.
+    /// Example: `let x = y;`
+    Init(P<Expr>),
+    /// Local declaration with an initializer and an `else` clause.
+    /// Example: `let Some(x) = y else { return };`
+    InitElse(P<Expr>, P<Block>),
+}
+
+impl LocalKind {
+    pub fn init(&self) -> Option<&Expr> {
+        match self {
+            Self::Decl => None,
+            Self::Init(i) | Self::InitElse(i, _) => Some(i),
+        }
+    }
+
+    pub fn init_else_opt(&self) -> Option<(&Expr, Option<&Block>)> {
+        match self {
+            Self::Decl => None,
+            Self::Init(init) => Some((init, None)),
+            Self::InitElse(init, els) => Some((init, Some(els))),
+        }
+    }
+}
+
 /// An arm of a 'match'.
 ///
 /// E.g., `0..=10 => { println!("match!") }` as in