Weird bug on Mac OS X

[Markus Mottl]

Should have mentioned that, too: I'm running Mac OS X 10.8.2 with the
latest XCode version (4.5.2).

On Thu, Nov 8, 2012 at 12:11 PM, Ashish Agarwal <agarwal1975 at gmail.com> wrote:
> I correctly get an exception with OCaml 3.12.1, Core 108.00.02, on Mac OS X
> 10.7.5.
>
> On Thu, Nov 8, 2012 at 12:04 PM, Markus Mottl <markus.mottl at gmail.com>
> wrote:
>>
>> Hi,
>>
>> I've run into a segfault on Mac OS X with a very trivial program that
>> basically just links with Jane Street Core.  Here is the file test.ml:
>>
>> ----------
>> module X = Core
>>
>> let () = [||].(0) <- 42
>> ----------
>>
>> You can build it as follows:
>>
>>   ocamlbuild -use-ocamlfind -cflag -thread -lflag -thread -pkgs core
>> test.native
>>
>> Running test.native will give you a segfault.  Here is the stack
>> backtrace:
>>
>> ----------
>> #0  0x00007fff90fa78a5 in misaligned_stack_error_entering_dyld_stub_binder
>> ()
>> #1  0x0000000000000103 in ?? ()
>> #2  0x0000000101c0a088 in pvars ()
>> #3  0x0000000101bddedd in caml_raise ()
>> #4  0x0000000101bddf99 in caml_array_bound_error ()
>> #5  0x00000001019b6aca in .L101 ()
>> ----------
>>
>> The program should just raise an exception due to the illegal array
>> access.  Merely raising an exception directly doesn't trigger the
>> problem.  The program won't segfault either if the "module X = Core"
>> line is commented out, i.e. Core has to be linked in.  Other libraries
>> apparently also don't cause this issue.
>>
>> Could another Mac OS X user here please verify the problem?  I'm using
>> OCaml 4.00.1 with Opam and the latest release of Core in there.
>>
>> Maybe somebody more knowledgeable about stack alignment and linking
>> issues on Mac OS X has an idea what's going wrong here.  I suspect
>> it's a code generation, linking or even runtime issue that may need to
>> be fixed in the compiler.  Or there could be a bug in some module
>> initialization in Core that is using C-bindings (less likely, I'm not
>> aware of anything that could cause this).
>>
>> Regards,
>> Markus
>>
>> --
>> Markus Mottl        http://www.ocaml.info        markus.mottl at gmail.com
>
>



-- 
Markus Mottl        http://www.ocaml.info        markus.mottl at gmail.com