Rollup merge of #75485 - RalfJung:pin, r=nagisa

[rust.git] / src / librustc_middle / traits / specialization_graph.rs

diff --git a/src/librustc_middle/traits/specialization_graph.rs b/src/librustc_middle/traits/specialization_graph.rs
index f4961617b81c6e8365a4ee6ec6be635b19c5ba7b..969404c68cab7084513835d141ce4e4c9a5231ab 100644 (file)
--- a/src/librustc_middle/traits/specialization_graph.rs
+++ b/src/librustc_middle/traits/specialization_graph.rs
@@ -1,5 +1,6 @@
 use crate::ich::{self, StableHashingContext};
 use crate::ty::fast_reject::SimplifiedType;
+use crate::ty::fold::TypeFoldable;
 use crate::ty::{self, TyCtxt};
 use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -22,7 +23,7 @@
 ///   parents of a given specializing impl, which is needed for extracting
 ///   default items amongst other things. In the simple "chain" rule, every impl
 ///   has at most one parent.
-#[derive(RustcEncodable, RustcDecodable, HashStable)]
+#[derive(TyEncodable, TyDecodable, HashStable)]
 pub struct Graph {
     /// All impls have a parent; the "root" impls have as their parent the `def_id`
     /// of the trait.
@@ -49,7 +50,7 @@ pub fn parent(&self, child: DefId) -> DefId {
 
 /// Children of a given impl, grouped into blanket/non-blanket varieties as is
 /// done in `TraitDef`.
-#[derive(Default, RustcEncodable, RustcDecodable)]
+#[derive(Default, TyEncodable, TyDecodable)]
 pub struct Children {
     // Impls of a trait (or specializations of a given impl). To allow for
     // quicker lookup, the impls are indexed by a simplified version of their
@@ -226,7 +227,8 @@ pub fn ancestors(
     start_from_impl: DefId,
 ) -> Result<Ancestors<'tcx>, ErrorReported> {
     let specialization_graph = tcx.specialization_graph_of(trait_def_id);
-    if specialization_graph.has_errored {
+
+    if specialization_graph.has_errored || tcx.type_of(start_from_impl).references_error() {
         Err(ErrorReported)
     } else {
         Ok(Ancestors {