Recover after an error in an implication constraint

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

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index ee4be27..bb76c1d 100644 (file)
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -210,8 +210,12 @@ simplifyInfer apply_mr tau_tvs wanted
                           zonked_tau_tvs `minusVarSet` gbl_tvs
              (perhaps_bound, surely_free) 
                   = partitionBag (quantifyMeWC proto_qtvs) zonked_wanted
+      
        ; emitConstraints surely_free
-       ; traceTc "sinf" (ppr proto_qtvs $$ ppr perhaps_bound $$ ppr surely_free)
+       ; traceTc "sinf"  $ vcat
+             [ ptext (sLit "perhaps_bound =") <+> ppr perhaps_bound
+             , ptext (sLit "surely_free   =") <+> ppr surely_free
+             ]
 
                      -- Now simplify the possibly-bound constraints
        ; (simplified_perhaps_bound, tc_binds) 
@@ -702,6 +706,10 @@ solveImplication inert
                  , ic_wanted = wanteds
                  , ic_loc    = loc })
   = nestImplicTcS ev_binds untch $
+    recoverTcS (return (emptyBag, emptyBag)) $
+       -- Recover from nested failures.  Even the top level is
+       -- just a bunch of implications, so failing at the first
+       -- one is bad
     do { traceTcS "solveImplication {" (ppr imp) 
 
          -- Solve flat givens
@@ -808,7 +816,7 @@ applyDefaultingRules inert wanteds
   | otherwise
   = do { untch <- getUntouchables
        ; tv_cts <- mapM (defaultTyVar untch) $
-                   varSetElems (tyVarsOfCanonicals wanteds)
+                   varSetElems (tyVarsOfCDicts wanteds) 
 
        ; info@(_, default_tys, _) <- getDefaultInfo
        ; let groups = findDefaultableGroups info untch wanteds
@@ -836,10 +844,9 @@ defaultTyVar :: Untouchables -> TcTyVar -> TcS CanonicalCts
 -- whatever, because the type-class defaulting rules have yet to run.
 
 defaultTyVar untch the_tv 
-  | isMetaTyVar the_tv
-  , inTouchableRange untch the_tv
+  | isTouchableMetaTyVar_InRange untch the_tv
   , not (k `eqKind` default_k)
-  = do { (ev, better_ty) <- TcSMonad.newKindConstraint (mkTyVarTy the_tv) default_k
+  = do { (ev, better_ty) <- TcSMonad.newKindConstraint the_tv default_k
        ; let loc = CtLoc DefaultOrigin (getSrcSpan the_tv) [] -- Yuk
                           -- 'DefaultOrigin' is strictly the declaration, but it's convenient
              wanted_eq  = CTyEqCan { cc_id     = ev
@@ -887,7 +894,7 @@ findDefaultableGroups (ctxt, default_tys, (ovl_strings, extended_defaults))
     is_defaultable_group ds@((_,tv):_)
         = isTyConableTyVar tv  -- Note [Avoiding spurious errors]
         && not (tv `elemVarSet` bad_tvs)
-        && inTouchableRange untch tv
+        && isTouchableMetaTyVar_InRange untch tv 
         && defaultable_classes [cc_class cc | (cc,_) <- ds]
     is_defaultable_group [] = panic "defaultable_group"