Exported pattern synonyms does not mark top-level bindings in RHS as used (#12548) · Issues · Glasgow Haskell Compiler / GHC

Exported pattern synonyms does not mark top-level bindings in RHS as used

{-# LANGUAGE PatternSynonyms #-}

module Foo (pattern P) where

x :: Int
x = 0

pattern P :: Int
pattern P <- _ where
        P = x

gives:

Foo.hs:6:1: warning: [-Wunused-top-binds]
    Defined but not used: ‘x’

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