Store a SrcSpan instead of a SrcLoc inside a Name

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

diff --git a/compiler/typecheck/TcSimplify.lhs b/compiler/typecheck/TcSimplify.lhs
index 7311ae0..b9ff789 100644 (file)
--- a/compiler/typecheck/TcSimplify.lhs
+++ b/compiler/typecheck/TcSimplify.lhs
@@ -889,7 +889,7 @@ makeImplicationBind loc all_tvs reft
  | otherwise                   -- Otherwise we must generate a binding
  = do  { uniq <- newUnique 
        ; span <- getSrcSpanM
-       ; let name = mkInternalName uniq (mkVarOcc "ic") (srcSpanStart span)
+       ; let name = mkInternalName uniq (mkVarOcc "ic") span
              implic_inst = ImplicInst { tci_name = name, tci_reft = reft,
                                         tci_tyvars = all_tvs, 
                                         tci_given = givens,
@@ -1202,9 +1202,22 @@ tcSimplifyRestricted doc top_lvl bndrs tau_tvs wanteds
        ; gbl_tvs' <- tcGetGlobalTyVars
        ; constrained_dicts' <- mappM zonkInst constrained_dicts
 
-       ; let constrained_tvs' = tyVarsOfInsts constrained_dicts'
-             qtvs = (tau_tvs' `minusVarSet` oclose (fdPredsOfInsts constrained_dicts) gbl_tvs')
-                        `minusVarSet` constrained_tvs'
+       ; let qtvs1 = tau_tvs' `minusVarSet` oclose (fdPredsOfInsts constrained_dicts) gbl_tvs'
+                               -- As in tcSimplifyInfer
+
+               -- Do not quantify over constrained type variables:
+               -- this is the monomorphism restriction
+             constrained_tvs' = tyVarsOfInsts constrained_dicts'
+             qtvs = qtvs1 `minusVarSet` constrained_tvs'
+             pp_bndrs = pprWithCommas (quotes . ppr) bndrs
+
+       -- Warn in the mono
+       ; warn_mono <- doptM Opt_WarnMonomorphism
+       ; warnTc (warn_mono && (constrained_tvs' `intersectsVarSet` qtvs1))
+                (vcat[ ptext SLIT("the Monomorphism Restriction applies to the binding")
+                               <> plural bndrs <+> ptext SLIT("for") <+> pp_bndrs,
+                       ptext SLIT("Consider giving a type signature for") <+> pp_bndrs])
+
        ; traceTc (text "tcSimplifyRestricted" <+> vcat [
                pprInsts wanteds, pprInsts constrained_dicts',
                ppr _binds,
@@ -2320,8 +2333,8 @@ disambigGroup default_tys dicts
 getDefaultTys :: Bool -> Bool -> TcM [Type]
 getDefaultTys extended_deflts ovl_strings
   = do { mb_defaults <- getDeclaredDefaultTys
-       ; case mb_defaults of
-          Just tys -> return tys       -- User-supplied defaults
+       ; case mb_defaults of {
+          Just tys -> return tys ;     -- User-supplied defaults
           Nothing  -> do
 
        -- No use-supplied default
@@ -2334,7 +2347,7 @@ getDefaultTys extended_deflts ovl_strings
                        ++
                  [integer_ty,doubleTy]
                        ++
-                 opt_deflt ovl_strings string_ty) }}
+                 opt_deflt ovl_strings string_ty) } } }
   where
     opt_deflt True  ty = [ty]
     opt_deflt False ty = []
@@ -2564,7 +2577,7 @@ report_no_instances tidy_env mb_what insts
                                 quotes (pprWithCommas ppr (varSetElems (tyVarsOfInst dict))),
                              ptext SLIT("Use -fallow-incoherent-instances to use the first choice above")])]
       where
-       ispecs = [ispec | (_, ispec) <- matches]
+       ispecs = [ispec | (ispec, _) <- matches]
 
     mk_no_inst_err insts
       | null insts = empty
@@ -2637,6 +2650,10 @@ mkMonomorphismMsg tidy_env inst_tvs
   = findGlobals (mkVarSet inst_tvs) tidy_env   `thenM` \ (tidy_env, docs) ->
     returnM (tidy_env, mk_msg docs)
   where
+    mk_msg _ | any isRuntimeUnk inst_tvs
+        =  vcat [ptext SLIT("Cannot resolve unknown runtime types:") <+>
+                   (pprWithCommas ppr inst_tvs),
+                ptext SLIT("Use :print or :force to determine these types")]
     mk_msg []   = ptext SLIT("Probable fix: add a type signature that fixes these type variable(s)")
                        -- This happens in things like
                        --      f x = show (read "foo")
@@ -2645,6 +2662,11 @@ mkMonomorphismMsg tidy_env inst_tvs
                        nest 2 (vcat docs),
                        monomorphism_fix
                       ]
+
+isRuntimeUnk :: TcTyVar -> Bool
+isRuntimeUnk x | SkolemTv RuntimeUnkSkol <- tcTyVarDetails x = True
+               | otherwise = False
+
 monomorphism_fix :: SDoc
 monomorphism_fix = ptext SLIT("Probable fix:") <+> 
                   (ptext SLIT("give these definition(s) an explicit type signature")