`without` statement can fail in generic code

[markspanbroek]

Context

Use the without statement on an expression that returns Result whereby you access the error inside generic code.

Failure

The error is set to nil, whereas it should have a value

Reproduce

  test "without statement works in generic code":
    proc test(_: type) =
      without a =? int.failure "error", e:
        check e.msg == "error"
        return
      fail

    test(int)

Removing the generic parameter makes the test pass.

Possible cause

Replacing infix operator =? with override=? override doesn't seem to work. It seems that the =? has already been evaluated by the compiler before it evaluates the without template.

https://github.com/status-im/questionable/blob/d7e9f0bf7fec14df13a26e699437a2fe577b26ba/questionable/withoutresult.nim#L37