Outdated comment (or bug?) in `types/TyCon.hs`
The docstring for coreExpandTyCon_maybe
says it should do something different than tcExpandTyCon_maybe
, but it doesn't:
-- ^ Used to create the view the /typechecker/ has on 'TyCon's.
-- We expand (closed) synonyms only, cf. 'coreExpandTyCon_maybe'
tcExpandTyCon_maybe = ...
-- ^ Used to create the view /Core/ has on 'TyCon's. We expand
-- not only closed synonyms like 'tcExpandTyCon_maybe',
-- but also non-recursive @newtype@s
coreExpandTyCon_maybe tycon tys = tcExpandTyCon_maybe tycon tys
If the code is correct, and the comment is just outdated, than Note [Newtype eta] and the docstrings for Type.coreView
and Type.tcView
should be updated as well.
The last big change to coreExpandTyCon_maybe
was made in commit fdf86568.