#16104: Plugin name lookup behavior change from GHC 8.4 series -------------------------------------+------------------------------------- Reporter: lerkok | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): In GHC 8.4 we have {{{ thNameToGhcName th_name = do hsc_env <- getHscEnv liftIO $ initTcForLookup hsc_env (lookupThName_maybe th_name) }}} `lookupThName` ends up calling `lookupGlobalOccRn_maybe`; and (since I think we have an `Orig` at this point) thence `lookupExactOrOrig`, and thence `IfaceEnv.lookupOrig`. The latter * Looks up in the original-name cache * If the lookup fails, it makes a fresh external `Name`, updates the orig- name cache, and returns the `Name`. But in 8.6 we have {{{ thNameToGhcName th_name = do { names <- mapMaybeM lookup (thRdrNameGuesses th_name) -- Pick the first that works -- E.g. reify (mkName "A") will pick the class A in preference -- to the data constructor A ; return (listToMaybe names) } where lookup rdr_name | Just n <- isExact_maybe rdr_name -- This happens in derived code = return $ if isExternalName n then Just n else Nothing | Just (rdr_mod, rdr_occ) <- isOrig_maybe rdr_name = do { cache <- getOrigNameCache ; return $ lookupOrigNameCache cache rdr_mod rdr_occ } | otherwise = return Nothing }}} See: it looks up in the orig-name cache, but doesn't extend it on failure. That's what's going wrong. We just need to do what `lookupOrig` does. In HEAD some more refactoring has happened, which makes it easier. We want `thNameToGhcName` to call something very like `IfaceEnv.lookupOrigIO`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/16104#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler