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ucsd-progsys / liquidhaskell

Liquid Types For Haskell
BSD 3-Clause "New" or "Revised" License
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"Incomplete patterns" error with GHC <9.0.1 #1918

Open curiousleo opened 2 years ago

curiousleo commented 2 years ago

GHC 8.10.7 but not GHC 9.0.1 reports "Pattern match(es) are non-exhaustive" in a few places.

https://github.com/ucsd-progsys/liquidhaskell/pull/1915 added {-# OPTIONS_GHC -Wno-incomplete-patterns #-} to files where this erroneous warning was reported since they are all false positives.

This ticket should be resolved by either investigating the root cause of the erroneous warning under GHC 8.10.7 and fixing it, or by waiting until we're happy to drop support for GHC <9.0.1. Either way, this ticket should not be marked as resolved before all -Wno-incomplete-patterns are removed from the code base: the pattern exhaustiveness check is generally a Good Thing and should not stay disabled longer than absolutely necessary!

facundominguez commented 4 months ago

We can drop support for GHC<9 now.