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  • #14547

Closed
Open
Opened Dec 01, 2017 by YoshikuniJujo@trac-YoshikuniJujo

Wrong warning by -Wincomplete-patterns

Wrong warning occur where I use -Wincomplete-patterns with OverloadedLists and TypeFamilies.

{-# LANGUAGE OverloadedLists #-}
{-# LANGUAGE TypeFamilies #-}
{-# OPTIONS_GHC -Wall -fno-warn-tabs #-}

class Foo f where
	type It f
	foo :: [It f] -> f

data List a = Empty | a :! List a deriving Show

instance Foo (List a) where
	type It (List a) = a
	foo [] = Empty
	foo (x : xs) = x :! foo xs

Pattern match(es) are non-exhaustive In an equation for `foo': Patterns not matched: []

Trac metadata
Trac field Value
Version 8.2.1
Type Bug
TypeOfFailure OtherFailure
Priority low
Resolution Unresolved
Component Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture
Assignee
Assign to
8.6.1
Milestone
8.6.1 (Past due)
Assign milestone
Time tracking
None
Due date
None
Reference: ghc/ghc#14547