Calling makeStableName on the same object many times causes a segfault. The following triggers this behaviour on both OSX and Linux-x86_64, provided it is compiled (it doesn't seem to occur if the call to makeStableName is interpreted).

module Main where

import Control.Monad
import System.Mem.StableName

main :: IO ()
main = replicateM_ 100000 (makeStableName foo)

foo :: Int
foo = 1

It seems to happen largely at random. The 100000 calls to makeStableName in the above example essentially guarantee its occurrence, but I have observed it happen with far fewer.

The reason this bug was discovered is it is causing frequent failures in Accelerate on 7.8.2. See https://github.com/AccelerateHS/accelerate/issues/162. In that case it seems to be causing more strange closure type errors than segfaults, but I assume it is the same root cause.