Implement -XPolymorphicComponents

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

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 18e58fc..c34387b 100644 (file)
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -697,6 +697,7 @@ checkValidType ctxt ty
     doptM Opt_GlasgowExts      `thenM` \ gla_exts ->
     doptM Opt_Rank2Types       `thenM` \ rank2 ->
     doptM Opt_RankNTypes       `thenM` \ rankn ->
+    doptM Opt_PolymorphicComponents    `thenM` \ polycomp ->
     let 
        rank | rankn = Arbitrary
             | rank2 = Rank 2
@@ -710,8 +711,11 @@ checkValidType ctxt ty
                 TySynCtxt _    -> Rank 0
                 ExprSigCtxt    -> Rank 1
                 FunSigCtxt _   -> Rank 1
-                ConArgCtxt _   -> Rank 1       -- We are given the type of the entire
-                                               -- constructor, hence rank 1
+                ConArgCtxt _   -> if polycomp
+                           then Rank 2
+                                -- We are given the type of the entire
+                                -- constructor, hence rank 1
+                           else Rank 1
                 ForSigCtxt _   -> Rank 1
                 SpecInstCtxt   -> Rank 1