Use let instead of match to get value of enum with single variant.

Author: matthiaskrgr

src/librustc_mir/monomorphize/collector.rs

@@ -824,11 +824,8 @@ fn find_vtable_types_for_unsizing<'tcx>(
         (&ty::Adt(source_adt_def, source_substs), &ty::Adt(target_adt_def, target_substs)) => {
             assert_eq!(source_adt_def, target_adt_def);
 
-            let kind = monomorphize::custom_coerce_unsize_info(tcx, source_ty, target_ty);
-
-            let coerce_index = match kind {
-                CustomCoerceUnsized::Struct(i) => i,
-            };
+            let CustomCoerceUnsized::Struct(coerce_index) =
+                monomorphize::custom_coerce_unsize_info(tcx, source_ty, target_ty);
 
             let source_fields = &source_adt_def.non_enum_variant().fields;
             let target_fields = &target_adt_def.non_enum_variant().fields;