Fix Trac #4401: meta-tyvars allocated by the constraint solver are always touchable

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

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 950d733..65330ac 100644 (file)
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -35,7 +35,7 @@ module TcMType (
   --------------------------------
   -- Instantiation
   tcInstTyVar, tcInstTyVars, tcInstSigTyVars,
-  tcInstType, tcInstSigType,
+  tcInstType, tcInstSigType, instMetaTyVar,
   tcInstSkolTyVars, tcInstSkolTyVar, tcInstSkolType, 
   tcSkolSigType, tcSkolSigTyVars, 
 
@@ -305,6 +305,7 @@ newMetaTyVar meta_info kind
        ; let name = mkSysTvName uniq fs 
              fs = case meta_info of
                        TauTv   -> fsLit "t"
+                       TcsTv   -> fsLit "u"
                        SigTv _ -> fsLit "a"
        ; return (mkTcTyVar name kind (MetaTv meta_info ref)) }