Unnecessary, misleading expansion lines for a keyof generic used in a template literal #47668
Description
Bug Report
🔎 Search Terms
keyof generic template literal type symbol
🕗 Version & Regression Information
- This is the behavior in every version I tried, and I reviewed the FAQ for entries about generics and assignability
⏯ Playground Link
Playground link with relevant code
💻 Code
type KeyGet<T> = `get${keyof T}`;🙁 Actual behavior
Notice the fourth Type 'keyof T' line onward. Seems unnecesary?
Type 'keyof T' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'string | number | symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'keyof T' is not assignable to type 'number'.
Type 'string | number | symbol' is not assignable to type 'number'.
Type 'string' is not assignable to type 'number'.🙂 Expected behavior
Type 'keyof T' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'string | number | symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.Note that if you replace keyof T with string | number | symbol, the error message is the expected behavior. [playground link with replacement]
type KeyGet<T> = `get${string | number | symbol}`;Type 'string | number | symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.
Type 'symbol' is not assignable to type 'string | number | bigint | boolean | null | undefined'.