#12785: GHC panic, `tcTyVarDetails` is missing a case -------------------------------------+------------------------------------- Reporter: heisenbug | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: yes Blocked By: | Blocking: Related Tickets: #12590 | Differential Rev(s): Phab:D2931 Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * differential: => Phab:D2931 Comment: I tried poking around the code from a0899b2f66a4102a7cf21569889381446ce63833. Interestingly, adding back the explicit `isTyVar` check to `isFloatedTouchableMetaTyVar` fixes the program in comment:7, but //not// heisenbug's program. I could try to hunt for the other function that trips up heisenbug's program, but chances are there other undiscovered programs that would trip up this panic through other means. Therefore, to minimize the chances of that happening, I've opted to open Phab:D2931, which simply reverts a0899b2f66a4102a7cf21569889381446ce63833. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12785#comment:9 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler