failure implementing :next command in ghci

[Peter Hercek]

Hi,

Maybe the code adding one Int argument to rts_breakpoint_io_action is 
correct in general since when Pepe Iborra applied the patch to his ghc 
trunk the test did not crash on his machine. Regardless on my machine 
the test does not work even with the stock ghc 6.10.2 sources (so even 
when I do not have the patch applied). Here is how I did the test on my 
32 bit archlinux:
* downloaded ghc-6.10.2-src.tar.bz2 from 
http://haskell.org/ghc/download_ghc_6_10_2.html#sources
  (I did not download the extralibs tarball)
* unpacked ghc-6.10.2-src.tar.bz2 and did this in the ghc-6.10.2 directory:
  ./boot
  ./configure
  make
* then I did this test:
status:0 peter at metod [892] ~/haskell/ghc-6.10.2
% cat a.hs
f :: Int -> Int
f x = x + 1
a = f 1
status:0 peter at metod [893] ~/haskell/ghc-6.10.2
% ghc/stage2-inplace/ghc --interactive a.hs
GHCi, version 6.10.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( a.hs, interpreted )
Ok, modules loaded: Main.
*Main> :break f
Breakpoint 0 activated at a.hs:2:0-10
*Main> :force a
zsh: segmentation fault  ghc/stage2-inplace/ghc --interactive a.hs
status:139 peter at metod [894] ~/haskell/ghc-6.10.2
%

The test works ok when I do it with the ghc-custom I have installed 
(6.10.1 with few of my patches).
The same behavior is on my laptop which has only stock uptodate 
archlinux, and stock ghc 6.10.1 installed (so I think it cannot be 
because of my few patches in ghc 6.10.1). I did the clean build and the 
test there too. Well to be precise, it works worse on my laptop  since 
when I try to run ghci 6.10.1 (as distributed by archlinux) I'll get a 
crash too:
status:0 peter at dwarf [852] ~/haskell/ghc-6.10.2
% ghci a.hs
GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( a.hs, interpreted )
Ok, modules loaded: Main.
*Main> :break f
Breakpoint 0 activated at a.hs:2:0-10
*Main> :force 
a%                                                                                                                                                                   

status:139 peter at dwarf [853] ~/haskell/ghc-6.10.2
%

The question is: Is the test supposed to work with ghc 6.10.2 without 
installing it?
I hope I'm doing some stupid mistake and that archlinux is not borked.
What is the platform (distribution and it's version) ghc HQ uses for ghc 
development (on which the test I presented works)?

Thanks,
Peter.