Print unticked promoted data constructors (#20531)
Before this patch, GHC unconditionally printed ticks before promoted data constructors:
ghci> type T = True -- unticked (user-written)
ghci> :kind! T
T :: Bool
= 'True -- ticked (compiler output)
After this patch, GHC prints ticks only when necessary:
ghci> type F = False -- unticked (user-written)
ghci> :kind! F
F :: Bool
= False -- unticked (compiler output)
ghci> data False -- introduce ambiguity
ghci> :kind! F
F :: Bool
= 'False -- ticked by necessity (compiler output)
The old behavior can be enabled by -fprint-redundant-promotion-ticks
.