Prefer "allow list" structure to check a type

rust-lang · Jun 24, 2021 · 9323a28 · 9323a28
1 parent 462c740
commit 9323a28
Showing 1 changed file with 8 additions and 18 deletions.
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
@@ -43,8 +43,8 @@ use rustc_hir::definitions::Definitions;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
 use rustc_hir::{
- Constness, HirId, ItemKind, ItemLocalId, ItemLocalMap, ItemLocalSet, Node, TraitCandidate,
- TraitItemKind,
+ Constness, ExprKind, HirId, ImplItemKind, ItemKind, ItemLocalId, ItemLocalMap, ItemLocalSet,
+ Node, TraitCandidate, TraitItemKind,
 };
 use rustc_index::vec::{Idx, IndexVec};
 use rustc_macros::HashStable;
@@ -1499,24 +1499,14 @@ impl<'tcx> TyCtxt<'tcx> {
  }
 
  pub fn return_type_impl_trait(self, scope_def_id: LocalDefId) -> Option<(Ty<'tcx>, Span)> {
- // HACK: `type_of()` will fail on these (#55796), so return `None`.
+ // `type_of()` will fail on these (#55796, #86483), so only allow `fn`s or closures.
  let hir_id = self.hir().local_def_id_to_hir_id(scope_def_id);
  match self.hir().get(hir_id) {
- Node::Item(item) => {
- match item.kind {
- ItemKind::Fn(..) => { /* `type_of()` will work */ }
- _ => {
- return None;
- }
- }
- }
- Node::TraitItem(item) => {
- // #86483: Return early if it doesn't have a concrete type.
- if let TraitItemKind::Type(_, None) = item.kind {
- return None;
- }
- }
- _ => { /* `type_of()` will work or panic */ }
+ Node::Item(&hir::Item { kind: ItemKind::Fn(..), .. }) => {}
+ Node::TraitItem(&hir::TraitItem { kind: TraitItemKind::Fn(..), .. }) => {}
+ Node::ImplItem(&hir::ImplItem { kind: ImplItemKind::Fn(..), .. }) => {}
+ Node::Expr(&hir::Expr { kind: ExprKind::Closure(..), .. }) => {}
+ _ => return None,
  }
 
  let ret_ty = self.type_of(scope_def_id);