Segmentation fault on "DynFlags" "rawSettings" field

[bitc]

When I run anythingToString on DynFlags (from GHC api) I get a crash.

Specifically, the problem is with the "rawSettings" field. This is interesting because the type of "rawSettings" is [(String, String)]

Doing a regular print works fine, but anythingToString causes a segfault. I tried running through GDB but did not get any useful backtrace or extra helpful information.

All the other fields of DynFlags work great with anythingToString

test :: DynFlags -> IO ()
test df = do
  print (rawSettings df)                          -- This successfully prints the value
  putStrLn (anythingToString (rawSettings df))    -- This  crashes

Thank you

[edsko]

Hmm, this is really strange! Could you do me a favour? I've just pushed a tiny commit to master that exposes Debug.RecoverRTTI.ClosureTree. Could you use showClosureTree (with some suitable depth) to print the full closure tree? That might give a clue about what is going on.

Thanks for the report, again! :)