Hi all, I just realized that when `+RTS -xc` is used and a <<loop>> error is happened, stack trace is reported twice. This is not the case with `error` calls, in that case stack traces are reported only once. Here's a demonstration: ➜ haskell cat loop.hs myFun :: Int myFun = let g = g + 1 in g + 10 myFun2 :: Int myFun2 = error "unexpected happened" main = print myFun ➜ haskell ./loop +RTS -xc *** Exception (reporting due to +RTS -xc): (THUNK_STATIC), stack trace: Main.myFun.g, called from Main.myFun, called from Main.CAF *** Exception (reporting due to +RTS -xc): (THUNK_STATIC), stack trace: Main.myFun.g, called from Main.myFun, called from Main.CAF loop: <<loop>> Here the stack trace is reported twice. If I use `myFun2` instead of `myFun`: ➜ haskell ./loop +RTS -xc *** Exception (reporting due to +RTS -xc): (THUNK_1_0), stack trace: Main.myFun2, called from Main.CAF --> evaluated by: Main.main, called from Main.CAF loop: unexpected happened Why is this happening in the case of <<loop>> error? Is this expected or is this a bug? I'm willing to trace the code through the RTS and fix it but I just want to make sure that this really is a bug. Thanks. --- Ömer Sinan Ağacan http://osa1.net