FieldError exception messages for generics

[mratsim]

Following #10053 and #11951, field error messages has been improved.

For generics, however the generic type isn't reported:

type Result[T, E] = object
  case ok: bool
  of false:
    error: E
  of true:
    value: T

proc main()=
  var foo = Result[int, cstring]()
  echo foo.value

main()

Error

Error: unhandled exception: 'value' is not accessible using discriminant 'ok' of type 'Result' [FieldError]

[timotheecour]

can you clarify the issue by adding what you expect the compiler to output? I'm assuming it'd be:

Error: unhandled exception: 'value' is not accessible using discriminant 'ok' of type 'Result[int, cstring]' [FieldError]

?

see also #11955 which I need to update (related but different from this issue)

[mratsim]

Yes, the full instantiated type Result[int, cstring]

The better error message would be:

Error: unhandled exception: 'value' is not accessible using discriminant 'ok' of type 'bool' in variant object of type 'Result[int, cstring]' [FieldError]