Add TyKind::TyAlias support in rustc_ty_utils

Author: GuillaumeGomez

compiler/rustc_ty_utils/src/layout.rs

@@ -1345,6 +1345,12 @@ fn layout_of_uncached<'tcx>(
             bug!("Layout::compute: unexpected type `{}`", ty)
         }
 
+        ty::TyAlias(def_id, substs) => {
+            let binder_ty = tcx.bound_type_of(def_id);
+            let ty = binder_ty.subst(tcx, substs);
+            return layout_of_uncached(cx, ty);
+        }
+
         ty::Bound(..) | ty::Param(_) | ty::Error(_) => {
             return Err(LayoutError::Unknown(ty));
         }

compiler/rustc_ty_utils/src/representability.rs

@@ -47,6 +47,16 @@ fn representability_ty<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Representabilit
             }
             Representability::Representable
         }
+        ty::TyAlias(def_id, substs) => {
+            let binder_ty = tcx.bound_type_of(def_id);
+            let ty = binder_ty.subst(tcx, substs);
+            representability_ty(tcx, ty)
+        }
+        ty::Closure(..) => {
+            // this check is run on type definitions, so we don't expect
+            // to see closure types
+            bug!("requires check invoked on inapplicable type: {:?}", ty)
+        }
         _ => Representability::Representable,
     }
 }

compiler/rustc_ty_utils/src/ty.rs

@@ -37,7 +37,7 @@ fn sized_constraint_for_ty<'tcx>(
                 .collect()
         }
 
-        Projection(..) | Opaque(..) => {
+        Projection(..) | Opaque(..) | TyAlias(..) => {
             // must calculate explicitly.
             // FIXME: consider special-casing always-Sized projections
             vec![ty]