#15814: Orphan Instance Overlap Error Message -------------------------------------+------------------------------------- Reporter: parsonsmatt | Owner: (none) Type: feature request | Status: patch Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D5377 Wiki Page: | -------------------------------------+------------------------------------- Comment (by dminuoso): `- an orphan module we can report how $df came to be in scope.` You need a transitive closure of depended upon orphan modules and finally some `[ImportedBy]` for each such module. We cannot recover that information from TcGblEnv currently. My code already takes your suggested second approach, but it can't do a full job because the record `mi_deps :: Dependencies` has no field containing the full transitive closure of depended upon modules. It only contains that information for orphan modules. I hope the changes I pushed make my code a bit clearer. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15814#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler