[project @ 2002-09-02 16:31:34 by simonpj]

Do not specialise functions that take implicit parameters.
The specialisation mechanism doesn't work for them, because
their implicit args are not driven by their type args (unlike
the implicit dictionary parameters)

		MERGE TO STABLE

diff --git a/ghc/compiler/specialise/Specialise.lhs b/ghc/compiler/specialise/Specialise.lhs
index c9ffa0b..56aa638 100644 (file)
--- a/ghc/compiler/specialise/Specialise.lhs
+++ b/ghc/compiler/specialise/Specialise.lhs
@@ -11,7 +11,7 @@ module Specialise ( specProgram ) where
 import CmdLineOpts     ( DynFlags, DynFlag(..) )
 import Id              ( Id, idName, idType, mkUserLocal, idSpecialisation, isDataConWrapId )
 import TcType          ( Type, mkTyVarTy, tcSplitSigmaTy, 
-                         tyVarsOfTypes, tyVarsOfTheta, 
+                         tyVarsOfTypes, tyVarsOfTheta, isClassPred,
                          mkForAllTys, tcCmpType
                        )
 import Subst           ( Subst, mkSubst, substTy, mkSubst, extendSubstList, mkInScopeSet,
@@ -1003,6 +1003,10 @@ callDetailsToList calls = [ (id,tys,dicts)
 
 mkCallUDs subst f args 
   | null theta
+  || not (all isClassPred theta)       
+       -- Only specialise if all overloading is on class params. 
+       -- In ptic, with implicit params, the type args
+       -- *don't* say what the value of the implicit param is!
   || not (spec_tys `lengthIs` n_tyvars)
   || not ( dicts   `lengthIs` n_dicts)
   || maybeToBool (lookupRule (\act -> True) (substInScope subst) f args)