[HIGHLIGHT]Support TypeScript 4.1 (#9473, #9636 by @sosukesuzuki) Key Remapping In Mapped Types // Input type MappedTypeWithNewKeys<T> = { [K in keyof T as NewKeyType]: T[K] }; // Prettier master SyntaxError: Unexpected token, expected "]" (2:17) 1 | type MappedTypeWithNewKeys<T> = { > 2 | [K in keyof T as NewKeyType]: T[K] | ^ 3 | }; // Prettier stable type MappedTypeWithNewKeys<T> = { [K in keyof T as NewKeyType]: T[K] }; Template Literal Types // Input type HelloWorld = `Hello, ${keyof World}` // Prettier master SyntaxError: Unexpected token, expected "}" (1:35) > 1 | type HelloWorld = `Hello, ${keyof World}` | ^ // Prettier stable type HelloWorld = `Hello, ${keyof World}`;