Bogus warning with OverloadedLists

When I say

{-# LANGUAGE OverloadedLists #-}

lgo :: [a] -> ()
lgo [] = ()
lgo (_:_) = ()

I get

/Users/rae/temp/Bug.hs:4:1: Warning:
    Pattern match(es) are non-exhaustive
    In an equation for ‘lgo’: Patterns not matched: []

I don't know !OverloadedLists deeply, but that warning surely is confusing!

Happens on both 7.8.3 and 7.10.1.

Trac metadata

Trac field	Value
Version	7.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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