[project @ 2003-11-05 14:51:53 by simonpj]

[ghc-hetmet.git] / ghc / compiler / typecheck / TcDeriv.lhs

diff --git a/ghc/compiler/typecheck/TcDeriv.lhs b/ghc/compiler/typecheck/TcDeriv.lhs
index a9e1a83..1d23c7b 100644 (file)
--- a/ghc/compiler/typecheck/TcDeriv.lhs
+++ b/ghc/compiler/typecheck/TcDeriv.lhs
@@ -19,7 +19,7 @@ import CmdLineOpts    ( DynFlag(..) )
 import Generics                ( mkTyConGenericBinds )
 import TcRnMonad
 import TcEnv           ( newDFunName, 
-                         InstInfo(..), pprInstInfo, InstBindings(..),
+                         InstInfo(..), InstBindings(..),
                          pprInstInfoDetails, tcLookupTyCon, tcExtendTyVarEnv
                        )
 import TcGenDeriv      -- Deriv stuff
@@ -215,8 +215,10 @@ tcDeriving tycl_decls
        ; let inst_info  = newtype_inst_info ++ ordinary_inst_info
 
        -- Rename these extra bindings, discarding warnings about unused bindings etc
+       -- Set -fglasgow exts so that we can have type signatures in patterns,
+       -- which is used in the generic binds
        ; (rn_binds, gen_bndrs) 
-               <- discardWarnings $ do
+               <- discardWarnings $ setOptM Opt_GlasgowExts $ do
                        { (rn_deriv, _dus1) <- rnTopMonoBinds deriv_binds []
                        ; (rn_gen, dus_gen) <- rnTopMonoBinds gen_binds   []
                        ; return (rn_deriv `ThenBinds` rn_gen, duDefs dus_gen) }