Improve error message (push to 6.6 branch)

diff --git a/compiler/typecheck/TcMType.lhs b/compiler/typecheck/TcMType.lhs
index 4aef899..dd7b627 100644 (file)
--- a/compiler/typecheck/TcMType.lhs
+++ b/compiler/typecheck/TcMType.lhs
@@ -1111,7 +1111,8 @@ checkValidInstance tyvars theta clas inst_tys
                  (instTypeErr (pprClassPred clas inst_tys) msg)
        }
   where
-    msg  = parens (ptext SLIT("the Coverage Condition fails for one of the functional dependencies"))
+    msg  = parens (vcat [ptext SLIT("the Coverage Condition fails for one of the functional dependencies;"),
+                        undecidableMsg])
 \end{code}
 
 Termination test: each assertion in the context satisfies