[Caml-list] Status of callback_exn bug

["Harry Chomsky" <harry@chomsky.net>]

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I am having trouble using callback_exn -- my program crashes in bytecode
mode, but works ok if I use the native-code compiler.  I saw a message in
the archive discussing a problem like this:

http://caml.inria.fr/archives/200204/msg00065.html

The CVS shows a change to byterun/interp.c on April 12 that appears to be
related to this problem.  I've tried to apply this change to my own copy of
OCaml, but my program still crashes.  Sometimes it runs a little bit longer
than it did before, but it still crashes within the next few function calls.

Was the April 12 fix supposed to resolve the problem completely?

I'm enclosing a small program that demonstrates the problem.  When prompted
for a string, if you type "hello" the OCaml code will raise an exception,
and the program will crash shortly thereafter.  The timing of the crash
varies depending whether you use "loop" or "loop1" as the main program loop.

(I'm running OCaml 3.04, native Win32 port, on Windows 2000.)

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ocamlc -custom -o exn.exe exn.ml exn_c.c
ocamlopt -o exnopt.exe exn.ml exn_c.c

[-- Attachment #3: exn.ml --]
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external do_it : (string -> unit) -> unit = "do_it"

let f s =
    print_endline ("Caml says you entered " ^ s);
    flush stdout;
    if s = "hello" then
        failwith "Oops"

let rec loop () =
    print_endline "Spot 1"; flush stdout;
    do_it f;
    print_endline "Spot 2"; flush stdout;
    loop ()

let loop1 () =
    while true do
        print_endline "Spot 1"; flush stdout;
        do_it f;
        print_endline "Spot 2"; flush stdout
    done

let _ = loop1 ()

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#include <caml/alloc.h>
#include <caml/callback.h>
#include <caml/custom.h>
#include <caml/fail.h>
#include <caml/memory.h>
#include <caml/mlvalues.h>

CAMLprim value do_it(value func)
{
    CAMLparam1(func);
    char s[256];
    CAMLlocal2(v, result);

    printf("Enter a string: ");
    scanf("%s", s);
    printf("C says you entered %s\n", s);
    v = copy_string(s);
    result = callback_exn(func, v);
    if (Is_exception_result(result))
        printf("Caught exception\n");
    CAMLreturn(Val_unit);
}