Allow ast validation to mutate the ast (inserting error nodes in case…

… of validation failures)

Cargo.lock

@@ -3632,6 +3632,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
+ "smallvec",
  "thin-vec",
 ]
 

compiler/rustc_ast/src/mut_visit.rs

@@ -682,7 +682,7 @@ fn walk_meta_list_item<T: MutVisitor>(vis: &mut T, li: &mut NestedMetaItem) {
     }
 }
 
-fn walk_meta_item<T: MutVisitor>(vis: &mut T, mi: &mut MetaItem) {
+pub fn walk_meta_item<T: MutVisitor>(vis: &mut T, mi: &mut MetaItem) {
     let MetaItem { unsafety: _, path: _, kind, span } = mi;
     match kind {
         MetaItemKind::Word => {}
@@ -898,7 +898,7 @@ fn walk_coroutine_kind<T: MutVisitor>(vis: &mut T, coroutine_kind: &mut Coroutin
     }
 }
 
-fn walk_fn<T: MutVisitor>(vis: &mut T, kind: FnKind<'_>) {
+pub fn walk_fn<T: MutVisitor>(vis: &mut T, kind: FnKind<'_>) {
     match kind {
         FnKind::Fn(_ctxt, _ident, FnSig { header, decl, span }, generics, body) => {
             // Identifier and visibility are visited as a part of the item.
@@ -931,7 +931,7 @@ fn walk_fn_ret_ty<T: MutVisitor>(vis: &mut T, fn_ret_ty: &mut FnRetTy) {
     }
 }
 
-fn walk_param_bound<T: MutVisitor>(vis: &mut T, pb: &mut GenericBound) {
+pub fn walk_param_bound<T: MutVisitor>(vis: &mut T, pb: &mut GenericBound) {
     match pb {
         GenericBound::Trait(ty, _modifier) => vis.visit_poly_trait_ref(ty),
         GenericBound::Outlives(lifetime) => walk_lifetime(vis, lifetime),
@@ -981,11 +981,11 @@ pub fn walk_generic_param<T: MutVisitor>(
     smallvec![param]
 }
 
-fn walk_label<T: MutVisitor>(vis: &mut T, Label { ident }: &mut Label) {
+pub fn walk_label<T: MutVisitor>(vis: &mut T, Label { ident }: &mut Label) {
     vis.visit_ident(ident);
 }
 
-fn walk_lifetime<T: MutVisitor>(vis: &mut T, Lifetime { id, ident }: &mut Lifetime) {
+pub fn walk_lifetime<T: MutVisitor>(vis: &mut T, Lifetime { id, ident }: &mut Lifetime) {
     vis.visit_id(id);
     vis.visit_ident(ident);
 }
@@ -1323,6 +1323,14 @@ pub fn walk_crate<T: MutVisitor>(vis: &mut T, krate: &mut Crate) {
     vis.visit_span(inject_use_span);
 }
 
+pub fn walk_assoc_item(
+    visitor: &mut impl MutVisitor,
+    item: P<Item<AssocItemKind>>,
+    ctxt: AssocCtxt,
+) -> SmallVec<[P<Item<AssocItemKind>>; 1]> {
+    walk_item(visitor, item, Some(ctxt))
+}
+
 /// Mutates one item, returning the item again.
 pub fn walk_item<K: NoopVisitItemKind>(
     visitor: &mut impl MutVisitor,
@@ -1831,3 +1839,26 @@ pub enum FnKind<'a> {
     /// E.g., `|x, y| body`.
     Closure(&'a mut ClosureBinder, &'a mut P<FnDecl>, &'a mut P<Expr>),
 }
+
+impl FnKind<'_> {
+    pub fn header(&self) -> Option<&FnHeader> {
+        match self {
+            FnKind::Fn(_, _, sig, _, _) => Some(&sig.header),
+            FnKind::Closure(_, _, _) => None,
+        }
+    }
+
+    pub fn ctxt(&self) -> Option<FnCtxt> {
+        match *self {
+            FnKind::Fn(ctxt, ..) => Some(ctxt),
+            FnKind::Closure(..) => None,
+        }
+    }
+
+    pub fn decl(&self) -> &FnDecl {
+        match self {
+            FnKind::Fn(_, _, sig, _, _) => &sig.decl,
+            FnKind::Closure(_, decl, _) => decl,
+        }
+    }
+}

compiler/rustc_ast_passes/Cargo.toml

@@ -18,5 +18,6 @@ rustc_parse = { path = "../rustc_parse" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
 rustc_target = { path = "../rustc_target" }
+smallvec = { version = "1.8.1", features = ["union", "may_dangle"] }
 thin-vec = "0.2.12"
 # tidy-alphabetical-end