#14777: panic when using a function defined in terms of `error` -------------------------------------+------------------------------------- Reporter: zilinc | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: Operating System: Linux | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by zilinc: Old description:
The error message I got from GHC was:
{{{ <no location info>: error: ghc: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-linux): idInfo t_XG0J Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Var.hs:526:34 in ghc:Var
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}}
How was it triggerred (in short): There's function definition, `f x = undefined`. If I change it to `f x = __impossible "Oops!"`, ghc crashes. The definition of `__impossible` is simply `__impossible s = error $ s ++ "some text"`.
The code can be found here: https://github.com/NICTA/cogent/blob/92c40530cbcbac77469865e096dab3228a2fb92... and https://github.com/NICTA/cogent/blob/92c40530cbcbac77469865e096dab3228a2fb92...
It seems that this bug is not limited to 8.2.2; it also happened in 8.2.1.
I'm happy to provide more information, if someone can advice me what is needed. I'll also try to shrink it to a small test case.
New description: The error message I got from GHC was: {{{ <no location info>: error: ghc: panic! (the 'impossible' happened) (GHC version 8.2.2 for x86_64-unknown-linux): idInfo t_XG0J Call stack: CallStack (from HasCallStack): prettyCurrentCallStack, called at compiler/utils/Outputable.hs:1133:58 in ghc:Outputable callStackDoc, called at compiler/utils/Outputable.hs:1137:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Var.hs:526:34 in ghc:Var Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} How was it triggerred (in short): There's function definition, `f x = undefined`. If I change it to `f x = __impossible "Oops!"`, ghc crashes. If I change it to `f x = error "Oops!", it's OK. `The definition of `__impossible` is simply `__impossible s = error $ s ++ "some text"`. The code can be found here: https://github.com/NICTA/cogent/blob/92c40530cbcbac77469865e096dab3228a2fb92... and https://github.com/NICTA/cogent/blob/92c40530cbcbac77469865e096dab3228a2fb92... It seems that this bug is not limited to 8.2.2; it also happened in 8.2.1. I'm happy to provide more information, if someone can advice me what is needed. I'll also try to shrink it to a small test case. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14777#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler