Closed
Description
TypeScript Version: 2.9.0-dev
Code
type Wat<T extends string> = { [x: T]: string }; // Error: An index signature cannot be a union type ?!?
Expected behavior:
Meaningful error message.
Actual behavior:
Error message complains about a union type, but there is no union type.
Related Issues:
The error message is caused by #20726. There is no verification that the type is actually a union type.