improving proof procedure for transforming cases rule in the predicate compiler to handle free variables of function type

--- a/src/HOL/Tools/Predicate_Compile/predicate_compile_core.ML	Wed Apr 28 15:42:10 2010 +0200
+++ b/src/HOL/Tools/Predicate_Compile/predicate_compile_core.ML	Wed Apr 28 16:45:48 2010 +0200
@@ -531,14 +531,17 @@
       let
         val (cases, (eqs, prems)) = apsnd (chop (nargs - nparams)) (chop n prems)
         val case_th = MetaSimplifier.simplify true
-        (@{thm Predicate.eq_is_eq} :: map meta_eq_of eqs)
-          (nth cases (i - 1))
+          (@{thm Predicate.eq_is_eq} :: map meta_eq_of eqs) (nth cases (i - 1))
         val prems' = maps (dest_conjunct_prem o MetaSimplifier.simplify true tuple_rew_rules) prems
         val pats = map (swap o HOLogic.dest_eq o HOLogic.dest_Trueprop) (take nargs (prems_of case_th))
         val (_, tenv) = fold (Pattern.match thy) pats (Vartab.empty, Vartab.empty)
         fun term_pair_of (ix, (ty,t)) = (Var (ix,ty), t)
         val inst = map (pairself (cterm_of thy) o term_pair_of) (Vartab.dest tenv)
-        val thesis = Thm.instantiate ([], inst) case_th OF (replicate nargs @{thm refl}) OF prems'
+        val case_th' = Thm.instantiate ([], inst) case_th OF (replicate nargs @{thm refl})
+        val (_, tenv) = fold (Pattern.match thy) (prems_of case_th' ~~ map prop_of prems') (Vartab.empty, Vartab.empty)
+        val inst' = map (pairself (cterm_of thy) o term_pair_of) (Vartab.dest tenv)
+        val case_th'' = Thm.instantiate ([], inst') case_th'
+        val thesis = case_th'' OF prems'
       in
         (rtac thesis 1)
       end