fix(declarations): add workaround for TypeScript issue 40361 for olde…

…r TypeScript versions. Closes #108
wessberg · Sep 2, 2020 · 659775f · 659775f
1 parent 874777c
commit 659775f
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Showing 2 changed files with 33 additions and 1 deletion.
diff --git a/...claration-bundler/transformers/deconflicter/visitor/deconflict-constructor-declaration.ts b/...claration-bundler/transformers/deconflicter/visitor/deconflict-constructor-declaration.ts
@@ -15,7 +15,7 @@ export function deconflictConstructorDeclaration(options: DeconflicterVisitorOpt
 	// The body and parameters share the same lexical environment
 	const nextContinuationOptions: ContinuationOptions = {lexicalEnvironment: cloneLexicalEnvironment(lexicalEnvironment)};
 
-	const parametersContResult = node.parameters.map(parameter => continuation(parameter, nextContinuationOptions));
+	const parametersContResult = node.parameters?.map(parameter => continuation(parameter, nextContinuationOptions)) ?? [];
 	const bodyContResult = node.body == null ? undefined : continuation(node.body, nextContinuationOptions);
 
 	const isIdentical = nodeArraysAreEqual(parametersContResult, node.parameters) && bodyContResult === node.body;

diff --git a/test/declaration.test.ts b/test/declaration.test.ts
@@ -746,3 +746,35 @@ test("Flattens declarations. #16", async (t, {typescript}) => {
 		`)
 	);
 });
+
+test("Flattens declarations. #17", async (t, {typescript}) => {
+	const bundle = await generateRollupBundle(
+		[
+			{
+				entry: true,
+				fileName: "index.ts",
+				text: `\
+					export class Singleton {
+						private constructor() {}
+					}
+					`
+			}
+		],
+		{
+			typescript,
+			debug: false
+		}
+	);
+	const {
+		declarations: [file]
+	} = bundle;
+	t.deepEqual(
+		formatCode(file.code),
+		formatCode(`\
+		declare class Singleton {
+			private constructor();
+		}
+		export {Singleton};
+		`)
+	);
+});