Constant can be set multiple times with jl_set_const

[Taaitaaiger]

The following code succeeds on nightly:

#include <julia.h>

JULIA_DEFINE_FAST_TLS

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

    {
        jl_value_t *v1 = NULL;
        jl_value_t *v2 = NULL;
        JL_GC_PUSH2(v1, v2);
        
        jl_sym_t *s = jl_symbol("foo");
        v1 = jl_box_uint8(3);
        v2 = jl_box_uint8(4);

        jl_set_const(jl_main_module, s, v1);
        jl_set_const(jl_main_module, s, v2);

        JL_GC_POP();
    }

    jl_atexit_hook(0);
    return 0;
}

Previously this caused an error:

fatal: error thrown and no exception handler available.
ErrorException("invalid redefinition of constant foo")
ijl_errorf at /cache/build/builder-amdci4-4/julialang/julia-release-1-dot-10/src/rtutils.c:77
ijl_set_const at /cache/build/builder-amdci4-4/julialang/julia-release-1-dot-10/src/module.c:798 [inlined]
ijl_set_const at /cache/build/builder-amdci4-4/julialang/julia-release-1-dot-10/src/module.c:792
main at ./test (unknown line)
unknown function (ip: 0x7163d522a1c9)
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
_start at ./test (unknown line)

Tested on Linux with commit ff0a1be

[Taaitaaiger]

The code can be compiled as in the embedding docs: gcc -o test -fPIC -I$JULIA_DIR/include/julia -L$JULIA_DIR/lib -Wl,-rpath,$JULIA_DIR/lib test.c -ljulia

[Keno]

This part of the code is in flux and constant re-definition (via binding partition) will be allowed in 1.12. The current state of the code is mostly the new code with extra error checks to make Julia behave as it did before.

[Taaitaaiger]

Ah okay, then this isn't a bug. From what I can tell I should look at #54654 for more info