Relax validation now

compiler/rustc_middle/src/ty/sty.rs

@@ -694,8 +694,6 @@ impl<'tcx> CoroutineArgs<'tcx> {
     #[inline]
     pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
         // FIXME requires optimized MIR
-        // FIXME(async_closures): We should assert all coroutine layouts have
-        // the same number of variants.
         FIRST_VARIANT
             ..tcx.coroutine_layout(def_id, tcx.types.unit).unwrap().variant_fields.next_index()
     }