Use == to compare OpaqueTyOrigin values

Author: spastorino

compiler/rustc_hir/src/hir.rs

@@ -2264,7 +2264,7 @@ pub struct OpaqueTy<'hir> {
 }
 
 /// From whence the opaque type came.
-#[derive(Copy, Clone, Encodable, Decodable, Debug, HashStable_Generic)]
+#[derive(Copy, Clone, PartialEq, Eq, Encodable, Decodable, Debug, HashStable_Generic)]
 pub enum OpaqueTyOrigin {
     /// `-> impl Trait`
     FnReturn,

compiler/rustc_typeck/src/check/writeback.rs

@@ -521,7 +521,7 @@ impl<'cx, 'tcx> WritebackCx<'cx, 'tcx> {
             let mut skip_add = false;
 
             if let ty::Opaque(definition_ty_def_id, _substs) = *definition_ty.kind() {
-                if let hir::OpaqueTyOrigin::TyAlias = opaque_defn.origin {
+                if opaque_defn.origin == hir::OpaqueTyOrigin::TyAlias {
                     if opaque_type_key.def_id == definition_ty_def_id {
                         debug!(
                             "skipping adding concrete definition for opaque type {:?} {:?}",