#15122: GHC HEAD typechecker regression -------------------------------------+------------------------------------- Reporter: fmixing | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.5 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"a32c8f7514c8192fa064537fb93d5a5c224991a0/ghc" a32c8f75/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="a32c8f7514c8192fa064537fb93d5a5c224991a0" Use dischargeFunEq consistently Trac #15122 turned out to be interesting. * Were calling dischargeFmv in three places. * In all three cases we dealt with the Given case separately. * In two of the three cases the Given code was right, (albeit duplicated). * In the third case (in TcCanonical.canCFunEqCan), we had ; case flav of Given -> return () -- nothing more to do. which was utterly wrong. The solution is easy: move the Given-case handling into dischargeFmv (now reenamed dischargeFunEq), and delete it from the call sites. Result: less code, easier to understand (dischargeFunEq handles all three cases, not just two out of three), and Trac #15122 is fixed. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15122#comment:11> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler