Support flow function type annotation with no parent (#14014)

babel · Dec 3, 2021 · 4079ee5 · 4079ee5
1 parent f4236f4
commit 4079ee5
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Showing 2 changed files with 16 additions and 4 deletions.
diff --git a/packages/babel-generator/src/generators/flow.ts b/packages/babel-generator/src/generators/flow.ts
@@ -290,7 +290,7 @@ export function ExistsTypeAnnotation(this: Printer) {
 export function FunctionTypeAnnotation(
   this: Printer,
   node: t.FunctionTypeAnnotation,
-  parent: any,
+  parent: t.Node | void,
 ) {
   this.print(node.typeParameters, node);
   this.token("(");
@@ -321,9 +321,10 @@ export function FunctionTypeAnnotation(
 
   // this node type is overloaded, not sure why but it makes it EXTREMELY annoying
   if (
-    parent.type === "ObjectTypeCallProperty" ||
-    parent.type === "DeclareFunction" ||
-    (parent.type === "ObjectTypeProperty" && parent.method)
+    parent &&
+    (parent.type === "ObjectTypeCallProperty" ||
+      parent.type === "DeclareFunction" ||
+      (parent.type === "ObjectTypeProperty" && parent.method))
   ) {
     this.token(":");
   } else {

diff --git a/packages/babel-generator/test/index.js b/packages/babel-generator/test/index.js
@@ -497,6 +497,17 @@ describe("programmatic generation", function () {
     expect(output).toBe("interface A {}");
   });
 
+  it("flow function type annotation with no parent", () => {
+    const functionTypeAnnotation = t.functionTypeAnnotation(
+      null,
+      [],
+      null,
+      t.voidTypeAnnotation(),
+    );
+    const output = generate(functionTypeAnnotation).code;
+    expect(output).toBe("() => void");
+  });
+
   describe("directives", function () {
     it("preserves escapes", function () {
       const directive = t.directive(