Polyfill Symbol.metadata, DecoratorContext.metadata

.github/workflows/release.yaml

@@ -14,6 +14,8 @@ jobs:
     release:
         runs-on: ubuntu-latest
         needs: ci
+        permissions:
+            id-token: write
         steps:
             - name: Checkout
               uses: actions/checkout@v3
@@ -30,6 +32,6 @@ jobs:
               run: npm run build
 
             - name: Publish
-              run: npm publish --access=public
+              run: npm publish --access=public --provenance
               env:
                   NODE_AUTH_TOKEN: ${{secrets.npm_token}}

src/internal/struct.ts

@@ -62,11 +62,34 @@ export function isValidMetadata<T extends Metadata = Metadata>(
 	return arg != null && typeof arg == 'object' && metadata in arg;
 }
 
+/**
+ * Polyfill Symbol.metadata
+ * @see https://github.com/microsoft/TypeScript/issues/53461
+ */
+(Symbol as { metadata: symbol }).metadata ??= Symbol.for('Symbol.metadata');
+
+/**
+ * Polyfill context.metadata
+ * @see https://github.com/microsoft/TypeScript/issues/53461
+ */
+export function _polyfill_contextMetadata(target: object): void {
+	if (!Symbol?.metadata) {
+		return;
+	}
+	Object.defineProperty(target, Symbol.metadata, {
+		enumerable: true,
+		configurable: true,
+		writable: true,
+		value: Object.create(null),
+	});
+}
+
 /**
  * Gets a reference to Symbol.metadata, even on platforms that do not expose it globally (like Node)
  */
 export function symbol_metadata(arg: ClassLike): typeof Symbol.metadata {
 	const symbol_metadata = Symbol.metadata || Object.getOwnPropertySymbols(arg).find(s => s.description == 'Symbol.metadata');
+	_polyfill_contextMetadata(arg);
 	if (!symbol_metadata) {
 		throw new ReferenceError('Could not get a reference to Symbol.metadata');
 	}