import Foo hiding (X) should not be a fatal error when X is not exported by Foo

We recently got into a situation on a team where two developers had two different versions of a module with many exports installed, and we were using a compatible subset of both versions. I then introduced a symbol (say X) with the same name as an export from one of the versions. Because GHC raises a fatal error on import Foo hiding (X) when X is not exported by Foo, we had no way to have X refer to the local definition -- since if hiding (X) was present, my GHC would error, and if it wasn't, he would get ambiguous reference errors.

The alternative would be to list all symbols except X in the import list (there were a good couple hundred). But isn't that what hiding (X) is supposed to be short for anyway?

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture