#12788: While using Data.Aeson.TH, "Irrefutable pattern failed for pattern sel_id : _" -------------------------------------+------------------------------------- Reporter: jchia | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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): Well that's odd. I get {{{ T12788.hs:11:14: error: Empty record update }}} which comes from `RnPat.rnHsRecUpdFields`. And is quite correct. If I change the program to {{{ $(deriveJSON defaultOptions{unwrapUnaryRecords = True} ''Bad) }}} then I get {{{ T12788.hs:11:14: error: Variable not in scope: defaultOptions :: Options }}} which is also correct; `defaultOptions` is not in scope. All this happens with the 8.0.2 release candidate and HEAD. I can't easily try 8.0 itself. Can you try with the 8.0 branch and HEAD? It really would be better if the "empty record update" didn't mask the other error, namely that `defaultOptions` isn't in scope. Reason is the latter is reported by the type checker so that we can give the type of the out-of-scope variable, whereas the former comes from the renamer. Regardless, I can't make it crash. Maybe it got fixed, somehow? Can you double-check the repro case. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12788#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler