randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin)

randomRIO (1,100) ghc: panic! (the 'impossible' happened)

(GHC version 8.4.3 for x86_64-apple-darwin):

nameModule

system $dShow_a78p

Call stack:

CallStack (from HasCallStack):

callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable

pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug

changed weight to 5

added Tbug Trac import labels

changed the description

Can you provide more specific reproduction instructions?

I've also encountered this on macos 10.13. Here's the logs from a ghci session:

λ> :set -package random
package flags have changed, resetting and loading new packages...
λ> import System.Random (randomRIO)
λ> randomRIO (10, 100)
ghc: panic! (the 'impossible' happened)
  (GHC version 8.4.4 for x86_64-apple-darwin):
	nameModule
  system $dShow_a12oz
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable
        pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

λ> r <- randomRIO (10, 100)
λ> r
46

Maybe ghci has a problem with showing unbound values?

closed

Thanks for the bug report. This is a duplicate of #14963 (closed), so closing. It's worth noting that this issue no longer occurs in GHC 8.6.

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedDuplicate
Related	- → #14963 (closed)

added Pnormal label