patch applied (ghc): Allow class and instance decls in hs-boot files

[Simon Peyton Jones]

Tue Aug 15 05:34:02 PDT 2006  simonpj at microsoft.com
  * Allow class and instance decls in hs-boot files
  
  For some reason, in 6.5 the manual said you could put a class decl in
  an interface file, but not an instance decl; whereas the implementation
  was exactly the othe way round.
  
  This patch makes it possible to put *both* class and instance decls
  in an interface file. 
  
  I also did a bit of re-factoring; comparing the declarations in the
  hs-boot and hs file is now done by converting to IfaceSyn, because we
  have good comparison operations for IfaceSyn already implemented.
  This fixed a bug that previously let through an inconsistent declaration 
  of a data type.
  
  The remaining infelicity concerns "abstract" TyCons.  They are a bit
  of a hack anyway; and Classes are not handled in the same way.  Need
  to think about this, but I think it's probably ok as it stands.
  
  

    M ./compiler/iface/IfaceSyn.lhs -1 +43
    M ./compiler/iface/TcIface.lhs +2
    M ./compiler/typecheck/TcRnDriver.lhs -38 +23
    M ./compiler/typecheck/TcTyClsDecls.lhs -3
    M ./docs/users_guide/separate_compilation.xml -3 +5