Add an extra print to -ddump-tc-trace

diff --git a/compiler/typecheck/TcTyClsDecls.lhs b/compiler/typecheck/TcTyClsDecls.lhs
index 575c20b..eccd498 100644 (file)
--- a/compiler/typecheck/TcTyClsDecls.lhs
+++ b/compiler/typecheck/TcTyClsDecls.lhs
@@ -1095,7 +1095,8 @@ checkValidDataCon :: TyCon -> DataCon -> TcM ()
 checkValidDataCon tc con
   = setSrcSpan (srcLocSpan (getSrcLoc con))    $
     addErrCtxt (dataConCtxt con)               $ 
-    do { let tc_tvs = tyConTyVars tc
+    do { traceTc (ptext (sLit "Validity of data con") <+> ppr con)
+        ; let tc_tvs = tyConTyVars tc
              res_ty_tmpl = mkFamilyTyConApp tc (mkTyVarTys tc_tvs)
              actual_res_ty = dataConOrigResTy con
        ; checkTc (isJust (tcMatchTy (mkVarSet tc_tvs)