fix(typescript): preserve necessary parens for TSOptionalType (#5056)

src/language-js/needs-parens.js

@@ -317,7 +317,8 @@ function needsParens(path, options) {
           parent.type === "TSTypeReference") &&
         (node.typeAnnotation.type === "TSTypeAnnotation" &&
           node.typeAnnotation.typeAnnotation.type !== "TSFunctionType" &&
-          grandParent.type !== "TSTypeOperator")
+          grandParent.type !== "TSTypeOperator" &&
+          grandParent.type !== "TSOptionalType")
       ) {
         return false;
       }

tests/typescript_optional_type/__snapshots__/jsfmt.spec.js.snap

@@ -1,5 +1,12 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`complex.ts - typescript-verify 1`] = `
+type T = [("a" | "b")?];
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+type T = [("a" | "b")?];
+
+`;
+
 exports[`simple.ts - typescript-verify 1`] = `
 type X = [number, string?];
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tests/typescript_optional_type/complex.ts

@@ -0,0 +1 @@
+type T = [("a" | "b")?];