merge DefKind::Coroutine into DefKind::Closure

compiler/rustc_mir_transform/src/lib.rs

@@ -395,7 +395,7 @@ fn inner_mir_for_ctfe(tcx: TyCtxt<'_>, def: LocalDefId) -> Body<'_> {
 /// mir borrowck *before* doing so in order to ensure that borrowck can be run and doesn't
 /// end up missing the source MIR due to stealing happening.
 fn mir_drops_elaborated_and_const_checked(tcx: TyCtxt<'_>, def: LocalDefId) -> &Steal<Body<'_>> {
-    if let DefKind::Coroutine = tcx.def_kind(def) {
+    if tcx.is_coroutine(def.to_def_id()) {
         tcx.ensure_with_value().mir_coroutine_witnesses(def);
     }
     let mir_borrowck = tcx.mir_borrowck(def);