GHC.Types.Any leaks in -Wincomplete-patterns warning
Summary
{-# OPTIONS_GHC -Wincomplete-patterns #-}
module Bug where
foo :: Either a Char
foo = Right 'x'
bar :: String
bar = case foo of
Right c -> [c]
we get a warning message:
Bug.hs:9:7: warning: [-Wincomplete-patterns]
Pattern match(es) are non-exhaustive
In a case alternative:
Patterns of type ‘Either GHC.Types.Any Char’ not matched: Left _
|
9 | bar = case foo of
| ^^^^^^^^^^^...
which leaks details about GHC.Types.Any
.
Environment
-
GHC version used: 9.2.4, 9.4.2
The bug does not occur in GHC 8.10.7 or GHC 9.0.2. Those versions do not have a
Patterns of type
clause in the warning.