Remove old `-Wcompat` flags
There seem to be many flags in -Wcompat
that are out of date.
This ticket is for the task of going through them, deciding if they are out of date, and removing them from -Wcompat
. The current set is:
-Wsemigroup
-Wnoncanonical-monoid-instances
-Wnoncanonical-monad-instances
-Wcompat-unqualified-imports
-Wtype-equality-out-of-scope
-Wimplicit-rhs-quantification
-Wdeprecated-type-abstractions
There is a real question about whether -Wcompat
is useful at all; see the discussion starting here. If we end up with no flags in -Wcompat
, that would add evidence to that case.
In general -Wcompat
should be used only for warnings where the user cannot adapt their code with the current GHC. If the user can adapt their code, the warning should be in -Wdefault
.