GHC panic (nameModule) on malformed deriving clause

Trying to derive a classname starting with a lower case letter and wrapped in parenthesis will lead to a ghc panic instead of generating an error

minimal testcase:

module Foo where
data Foo = Foo deriving (abc)

output:

[1 of 1] Compiling Foo              ( scratch3.hs, scratch3.o )
ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for x86_64-unknown-linux):
        nameModule abc{tv a9I}

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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