id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
2612,deriving Data.Typeable on phantom newtypes does not report that DeriveDataTypeable is needed,guest,,"newtype Foo x = Foo deriving (Typeable)

reports the rather cryptic error message:
    Can't make a derived instance of `Typeable (Foo x)'
      (even with cunning newtype deriving:)
    In the newtype declaration for `Foo'

When newtype is replaced with data, this much more useful error message is given:
    Can't make a derived instance of `Typeable (Foo x)'
      (You need -XDeriveDataTypeable to derive an instance for this class)
    In the data type declaration for `Foo'
",bug,closed,normal,,Compiler,6.9,duplicate,,tom.davie@…,MacOS X,x86,,Unknown,,,,