# Unable to compile

**URL:** <https://discourse.julialang.org/t/unable-to-compile/53617>\
**Category:** New to Julia\
**Tags:** package-compiler\
**Created:** [January 19, 2021, 3:42pm UTC](https://discourse.julialang.org/t/unable-to-compile/53617 "2021-01-19T15:42:29Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ribeiro](https://avatars.discourse-cdn.com/v4/letter/r/d9b06d/32.png) [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)\
**Post date:** [January 19, 2021, 3:42pm UTC](https://discourse.julialang.org/t/unable-to-compile/53617/1 "2021-01-19T15:42:29Z")

</div>

Hello,  
Total noob here. I’m writing some Julia code and I wanted to make sure I can compile it (I’ll need to ship it in the future and can’t guarantee a local install).  
I can’t get the compiler to work. The latest error I managed to get was:  
/tmp/ccxwbUfj.o: In function `main': CPU.c:(.text.startup+0xd7): undefined reference to `julia\_main’  
collect2: error: ld returned 1 exit status

Even though I am declaring julia\_main.  
Code (mostly copied from the manual):

CPU.jl:

```julia
module CPU
using LinearAlgebra
Base.@ccallable function julia_main()::Cint
    try
        real_main()
    catch
        Base.invokelatest(Base.display_error, Base.catch_stack())
        return 1
    end
    return 0
end

function real_main()
    A=rand(3,3);
    B=rand(3);
    C=A\B;
end

if abspath(PROGRAM_FILE) == @ __FILE__
    real_main()
end
end

```

CPU.c:

```julia
#include <string.h>
#include <stdint.h>
#include "uv.h"
#include "julia.h"
JULIA_DEFINE_FAST_TLS()
int julia_main();
int main(int argc, char *argv[])
{
        uv_setup_args(argc, argv);
        libsupport_init();
        jl_options.image_file = JULIAC_PROGRAM_LIBNAME;
        julia_init(JL_IMAGE_JULIA_HOME);
        jl_set_ARGS(argc, argv);
        jl_set_global(jl_base_module, jl_symbol("PROGRAM_FILE"), (jl_value_t*)jl_cstr_to_string(argv[0]));
        jl_array_t *ARGS = (jl_array_t*)jl_get_global(jl_base_module, jl_symbol("ARGS"));
        jl_array_grow_end(ARGS, argc - 1);
        for (int i = 1; i < argc; i++) {
                jl_value_t *s = (jl_value_t*)jl_cstr_to_string(argv[i]);
                jl_arrayset(ARGS, s, i - 1);
        }
        int ret = julia_main();
        jl_atexit_hook(ret);
        return ret;
}

```

custom\_sysimage.jl:

```julia
Base.reinit_stdio()
Base.init_depot_path()
Base.init_load_path()
using LinearAlgebra
@eval Module() begin
    Base.include(@ __MODULE__ , "CPU.jl")
    for (pkgid, mod) in Base.loaded_modules
        if !(pkgid.name in ("Main", "Core", "Base"))
            eval(@ __MODULE__ , :(const $(Symbol(mod)) = $mod))
        end
    end
    for statement in readlines("app_precompile.jl")
        try
            Base.include_string(@ __MODULE__ , statement)
        catch
            # See julia issue #28808
            Core.println("failed to compile statement: $statement")
        end
    end
end # module
empty!(LOAD_PATH)
empty!(DEPOT_PATH)

```

What I run:  
`julia --startup-file=no --trace-compile=app_precompile.jl CPU.jl`  
 → app\_precompile.jl gets written  
`julia --startup-file=no -J"/path/julia-1.5.3/lib/julia/sys.so" --output-o sys.o custom_sysimage.jl`  
 → sys.o gets written  
`gcc -shared -o sys.so -fPIC -Wl,--whole-archive sys.o -Wl,--no-whole-archive -L"/path/julia-1.5.3/lib" -ljulia`  
 → sys.so gets written

```julia
gcc -DJULIAC_PROGRAM_LIBNAME=\"sys.so\" -o CPU CPU.c sys.so -O2 -fPIE \
    -I'/path/julia-1.5.3/include/julia' \
    -L'/path/julia-1.5.3/lib' \
    -ljulia \
    -Wl,-rpath,'/path/julia-1.5.3/lib:$ORIGIN'

```

→ /tmp/ccxwbUfj.o: In function `main': CPU.c:(.text.startup+0xd7): undefined reference to `julia\_main’  
collect2: error: ld returned 1 exit status

I’d really appreciate some help! Thanks a lot!

---

<div class="post-metadata">

**Author:** ![Skoffer](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/skoffer/32/378_2.png) [@Skoffer](https://discourse.julialang.org/u/Skoffer)\
**Post date:** [January 19, 2021, 3:53pm UTC](https://discourse.julialang.org/t/unable-to-compile/53617/2 "2021-01-19T15:53:13Z")

</div>

Hello Ribeiro and welcome to the Julia community!

It’s hard to help, since code that you show has nothing in common with typical julia code. What are you trying to achieve and what manual you referring to?

Also it is easier to read code if it is properly formatted and wrapped with ```

For example

```julia
println("Hello world")

```

---

<div class="post-metadata">

**Author:** ![Ribeiro](https://avatars.discourse-cdn.com/v4/letter/r/d9b06d/32.png) [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)\
**Post date:** [January 19, 2021, 3:56pm UTC](https://discourse.julialang.org/t/unable-to-compile/53617/3 "2021-01-19T15:56:03Z")

</div>

> [@Skoffer](#):
>
> nd welcome to the Julia community!
> 
> It’s hard to help, since code that you show has nothing in com

Thanks, Skoffer.  
The manual I mentioned is the PackageCompiler one ([https://julialang.github.io/PackageCompiler.jl/dev/devdocs/binaries\_part\_2/](https://julialang.github.io/PackageCompiler.jl/dev/devdocs/binaries_part_2/))  
The Julia part of the code is super simple:

```julia
using LinearAlgebra
A=rand(3,3);
B=rand(3);
C=A\B;

```

Everything else I posted was done to get it to compile. Am I doing it wrong?  
Thanks a lot!

EDIT: thanks for teaching me how to quote code… couldn’t figure it out on my own.

---

<div class="post-metadata">

**Author:** ![Ribeiro](https://avatars.discourse-cdn.com/v4/letter/r/d9b06d/32.png) [@Ribeiro](https://discourse.julialang.org/u/Ribeiro)\
**Post date:** [January 21, 2021, 9:58am UTC](https://discourse.julialang.org/t/unable-to-compile/53617/4 "2021-01-21T09:58:26Z")

</div>

@ianshmean any chance you can chime in?  
I’m thinking I’m missing something on the gcc flags. I’m on CentOS8, gcc (GCC) 9.2.1 20191120 (Red Hat 9.2.1-2)  
Thanks a lot!