TypeScript: Nested infer fails: Expected ">" but found "?"

[geirsagberg]

I have the following type, used as a return type for a function that recursively turns arrays into objects:

type Normalized<T> = T extends Array<infer A extends object ? infer A : never>
  ? Dictionary<Normalized<A>>
  : {
      [P in keyof T]: T[P] extends Array<infer A extends object ? infer A : never>
        ? Dictionary<Normalized<A>>
        : Normalized<T[P]>
    }

When I compile with esbuild, I get an error: ERROR: Expected ">" but found "?"

I have also made a test that fails: 2aac25c

Failure:

node scripts/plugin-tests.js
--- FAIL: TestTSTypes (0.01s)
    --- FAIL: TestTSTypes/type_Normalized<T>_=_T_extends_Array<infer_A_extends_object_?_infer_A_:_never>___?_Dictionary<Normalized<A>>___:_{_______[P_in_keyof_T]:_T[P]_extends_Array<infer_A_extends_object_?_infer_A_:_never>_________?_Dictionary<Normalized<A>>_________:_Normalized<T[P]>_____} (0.00s)
        ts_parser_test.go:183:
            +<stdin>: ERROR: Expected ">" but found "?"

FAIL

[evanw]

Thanks for the report. I'll fix this. In the meantime, you can use parentheses to work around this problem: infer A extends object => (infer A) extends object.