@@ -218,8 +218,6 @@ common compile-options
218218common default-extensions
219219 default-extensions:
220220 BangPatterns
221− CApiFFI
222− CPP
223221 ConstraintKinds
224222 DeriveDataTypeable
225223 DeriveGeneric
@@ -230,24 +228,29 @@ common default-extensions
230228 GeneralizedNewtypeDeriving
231229 InstanceSigs
232230 KindSignatures
233− LambdaCase
234− MagicHash
235231 MultiParamTypeClasses
236− PatternSynonyms
237232 RankNTypes
238− RecordWildCards
239233 ScopedTypeVariables
240234 StandaloneDeriving
241235 TupleSections
242236 TypeApplications
243− TypeFamilies
244237 TypeOperators
245− ViewPatterns
246238
239+ -- Not GHC2021
240+ CApiFFI
241+ CPP
242+ DefaultSignatures
243+ LambdaCase
244+ MagicHash
245+ RecordWildCards
246+
247+ -- TypeFamilies is required by IsList, IsMap type classes and
248+ -- Unbox generic deriving code.
249+ -- TypeFamilies
247250 -- MonoLocalBinds, enabled by TypeFamilies, causes performance
248251 -- regressions. Disable it. This must come after TypeFamilies,
249252 -- otherwise TypeFamilies will enable it again.
250− NoMonoLocalBinds
253+ -- NoMonoLocalBinds
251254
252255 -- UndecidableInstances -- Does not show any perf impact
253256 -- UnboxedTuples -- interferes with (#.)