Avoiding `OtherCon []` unfoldings, restoring definitions from unfoldings

[Ben Gamari]

Simon Peyton Jones <simon.peytonjones at gmail.com> writes:

> I don't think any top-level Ids should have OtherCon [] unfoldings?  If
> they do, can you give a repro case?  OtherCon [] unfoldings usually mean "I
> know this variable is evaluated, but I don't know what its value is.  E.g
>    data T = MkT !a !a
>   f (MkT x y) = ...
>
> here x and y have OtherCon [] unfoldings. They are definitely not bottom!
>
Is there a reason why we wouldn't potentially give a static data
constructor application an OtherCon [] unfolding? I would guess that
usually these are small enough to have a CoreUnfolding, but in cases
where the expression is too large to have an unstable unfolding we might
rather want to give it an OtherCon [].

Cheers,

- Ben

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