fix: structural recursion: do not check for brecOn too early #4831
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Due to nested recursion, we do two passes of `getRecArgInfo`: One on each argument in isolation, to see which inductive types are around (e.g. `Tree` and `List`), and then we later refine/replace this result with the data for the nested type former (the implicit `ListTree`). If we have nested recursion through a non-recursive data type like `Array` or `Prod` then arguemnts of these types should survive the first phase, so that we can still use them when looking for, say, `Array Tree`. This was helpfully reported by @arthur-adjedj.
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Due to nested recursion, we do two passes of
getRecArgInfo: One oneach argument in isolation, to see which inductive types are around
(e.g.
TreeandList), andthen we later refine/replace this result with the data for the nested
type former (the implicit
ListTree).If we have nested recursion through a non-recursive data type like
ArrayorProdthen arguemnts of these types should survive the firstphase, so that we can still use them when looking for, say,
Array Tree.This was helpfully reported by @arthur-adjedj.