kevin wrote:Hm, okay, though my question was about how to turn the former into a relative clause like abairt a ... So you're saying that while as a main clause the sentence is perfectly fine, putting it into a relative clause would be unnatural, so that there isn't even a way to say how it would be gramatically correct? This is surprising.
It just isn't used. I searched fourty novels by native speakers there electronically and I don't see an example of it. I don't recall hearing a native speaker using such a construction ever either.
It's quite common in Irish for a expected "variant" of a sentence not to exist and a different construction entirely to be used in the negative or relative versions of the sentence. For example when forming a perfect with:
Tá + verbal adjective + form of ag (for agent)
Tá an obair déanta agam.
It's reasonably uncommon for this to be negated with Níl, rather they will switch to the past:
Níor dheineas an obair.
Just as how "tar éis" is rarely negated with "níl", but with "gan":
Táim tar éis an obair a dhéanamh
Táim gan obair a dhéanamh (fós)
Is this really a relative clause?
No. I just mean it is being used like one, it was the closest I could think of, in the sense that it expanded on an antecedent. It's actually the original way tar éis was used historically, when it was still an alternate to "iar". It's not grammatically a relative clause in Irish.
Really though, these sentence types are not used. I asked a native speaker friend and she said you could say:An abairt a bhfuil tar éis a scríofa dhuit
but said that it would be better to use the past.