v1.12-rc1, embedding: A new constant only becomes visible if it has never been looked up

[Taaitaaiger]

The following code succeeds, unless the commented lines are uncommented:

#include <julia.h>

JULIA_DEFINE_FAST_TLS

int main(int argc, char *argv[])
{
    jl_init();

    jl_sym_t *var_name = jl_symbol("FOO");
    jl_value_t *global;

    // global = jl_get_global(jl_main_module, var_name);
    // assert(global == NULL);

    jl_set_const(jl_main_module, var_name, jl_true);

    global = jl_get_global(jl_main_module, var_name);
    assert(global == jl_true);

    jl_atexit_hook(0);

    return 0;
}

Tested on Ubuntu 24.04 with GCC 13

[Keno]

JL_DLLEXPORT void jl_set_const(jl_module_t *m JL_ROOTING_ARGUMENT, jl_sym_t *var, jl_value_t *val JL_ROOTED_ARGUMENT)
{
    // this function is dangerous and unsound. do not use.

Emphasis on the comment

[Keno]

Honestly, we should probably delete this function - I've already excised it from the bootstrap path. There's no good reason to keep it.

[Keno]

(You're probably looking for jl_declare_constant_val).

[Taaitaaiger]

Fair enough. If the function is left in place, I think that comment should be in julia.h instead of inside the implementation. I interpreted it as a fixme due to its location.

You're probably looking for jl_declare_constant_val

It's currently not exported, but I can confirm it works if it is.

[Taaitaaiger]

The gcext test is still using jl_set_const, I assume those should also be adjusted to use jl_declare_constant_val?