Functional dependencies error message has no position information

When compiling the attached file (sorry its really long, it could easily be reduced to a minimal test case - although I don't think its necessary to fix the bug), I get the error message:

E:\Neil\thesis\obj\haskell2/Proof_default.hs:1:0:
    Couldn't match expected type `Expr' against inferred type `VarName'
      Expected type: ([Expr], [Expr])
      Inferred type: ([VarName], a)
    When using functional dependencies to combine
      Subst (Prop (Sat VarName)) ([VarName], a) (Prop (Sat Expr)),
        arising from a use of `/'
                     at E:\Neil\thesis\obj\haskell2/Proof_default.hs:391:17-54
      Subst (Prop (Sat Expr)) ([Expr], [Expr]) (Prop (Sat Expr)),
        arising from a use of `/'
                     at E:\Neil\thesis\obj\haskell2/Proof_default.hs:399:17-44

The error message lists two positions further down, but gives no position (or 1:0) at the top of the message. One of the positions from further down should be given - either one would do - otherwise the user may miss that there is position information available (I did at first).

Trac metadata

Trac field	Value
Version	6.8.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
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Blocking
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Operating system	Unknown
Architecture	Unknown