Optimize bundle-size impact of fix to closed enum parsing

packages/bundle-size/README.md

@@ -16,11 +16,11 @@ usually do. We repeat this for an increasing number of files.
 
 | code generator      | files | bundle size |  minified | compressed |
 | ------------------- | ----: | ----------: | --------: | ---------: |
-| Protobuf-ES         |     1 |   132,088 b |  68,483 b |   15,718 b |
-| Protobuf-ES         |     4 |   134,277 b |  69,993 b |   16,450 b |
-| Protobuf-ES         |     8 |   137,039 b |  71,764 b |   16,974 b |
-| Protobuf-ES         |    16 |   147,489 b |  79,745 b |   19,317 b |
-| Protobuf-ES         |    32 |   175,280 b | 101,763 b |   24,760 b |
+| Protobuf-ES         |     1 |   132,159 b |  68,489 b |   15,756 b |
+| Protobuf-ES         |     4 |   134,348 b |  69,996 b |   16,428 b |
+| Protobuf-ES         |     8 |   137,110 b |  71,767 b |   16,932 b |
+| Protobuf-ES         |    16 |   147,560 b |  79,748 b |   19,320 b |
+| Protobuf-ES         |    32 |   175,351 b | 101,766 b |   24,771 b |
 | protobuf-javascript |     1 |   104,048 b |  70,320 b |   15,540 b |
 | protobuf-javascript |     4 |   130,537 b |  85,672 b |   16,956 b |
 | protobuf-javascript |     8 |   152,429 b |  98,044 b |   18,138 b |

packages/protobuf/src/from-binary.ts

@@ -22,11 +22,8 @@ import type {
 import { scalarZeroValue } from "./reflect/scalar.js";
 import type { ScalarValue } from "./reflect/scalar.js";
 import { reflect } from "./reflect/reflect.js";
-import {
-  BinaryReader,
-  BinaryWriter,
-  WireType,
-} from "./wire/binary-encoding.js";
+import { BinaryReader, WireType } from "./wire/binary-encoding.js";
+import { varint32write } from "./wire/varint.js";
 
 /**
  * Options for parsing binary data.
@@ -163,9 +160,14 @@ export function readField(
         if (ok) {
           message.set(field, val);
         } else if (options.readUnknownFields) {
-          const data = new BinaryWriter().int32(val as number).finish();
+          const bytes: number[] = [];
+          varint32write(val as number, bytes);
           const unknownFields = message.getUnknown() ?? [];
-          unknownFields.push({ no: field.number, wireType, data });
+          unknownFields.push({
+            no: field.number,
+            wireType,
+            data: new Uint8Array(bytes),
+          });
           message.setUnknown(unknownFields);
         }
       }