Invalid subtyping

[torrance]

I've seen this error elsewhere (e.g. #326) but in my case I am on Julia 1.8.

I have the following toy C++:

#include <jlcxx/jlcxx.hpp>
#include <jlcxx/stl.hpp>

class Rectangle {
    int width, height;
  public:
    Rectangle(int, int);
    int area() {
        return width * height;
    }
};

Rectangle::Rectangle(int a, int b) {
  width = a;
  height = b;
}

JLCXX_MODULE define_julia_module(jlcxx::Module &mod) {
    mod.add_type<Rectangle>("Rectangle")
        .constructor<int, int>();
}

I am building this using binary builder and installing a local dev module (casacorejl_jll). When I include this in my module as such:

module Casacore

using casacorejl_jll
using CxxWrap

@wrapmodule("libcasacorejl.so")

function __init__()
    @initcxx
end

end

I get the following error:

ERROR: LoadError: invalid subtyping in definition of Rectangle with supertype Any

I'm at a loss what I am doing wrong here. Any help?

[torrance]

I've created a full MWE here (https://github.com/torrance/cxxtest), which includes the BinaryBuilder build_tarballs.jl script and CMake files, in case it is of any use in debugging and/or reproducing this.

My workflow looks like this:

cd cxxtest
julia build_tarballs.jl --deploy=local
julia --project=.

Then inside Julia:

] add CxxWrap
] dev libcxxtest_jl
include("CxxTest.jl")

The error message:

julia> include("CxxTest.jl")
C++ exception while wrapping module CxxTest: invalid subtyping in definition of Rectangle with supertype Any
ERROR: LoadError: invalid subtyping in definition of Rectangle with supertype Any
Stacktrace:
 [1] register_julia_module
   @ ~/.julia/packages/CxxWrap/IdOJa/src/CxxWrap.jl:405 [inlined]
 [2] readmodule(so_path::String, funcname::Symbol, m::Module, flags::Nothing)
   @ CxxWrap.CxxWrapCore ~/.julia/packages/CxxWrap/IdOJa/src/CxxWrap.jl:734
 [3] wrapmodule(so_path::String, funcname::Symbol, m::Module, flags::Nothing)
   @ CxxWrap.CxxWrapCore ~/.julia/packages/CxxWrap/IdOJa/src/CxxWrap.jl:738
 [4] include(fname::String)
   @ Base.MainInclude ./client.jl:476
in expression starting at /home/torrance/cxxtest/CxxTest.jl:1

[benlorenz]

This error often happens when running and building with different julia / libjulia versions.
Even if the log says libjulia_jll v1.8.0 it might be using binaries for 1.6, 1.7 or even 1.9, they are all under the same release but with different platforms: https://github.com/JuliaBinaryWrappers/libjulia_jll.jl/releases/tag/libjulia-v1.8.0%2B2
You might see the version that is really used in the cmake output when running the build with --verbose.

You need to build separate binaries for each minor julia version using L/libjulia/common.jl, the version will then be included in a platform-tag. You can look at some examples on Yggdrasil: https://github.com/JuliaPackaging/Yggdrasil/search?q=libjulia

[torrance]

That's it! For anyone else encountering this problem when doing local development with build_tarballs.jl, I used an additional julia_version key in my Platforms list, e.g.:

platforms = [Platform("x86_64", "linux"; libc="glibc", julia_version="1.8")]

For supporting a range of versions, see the search listing @benlorenz provided: https://github.com/JuliaPackaging/Yggdrasil/search?q=libjulia

[j-hayes]

Just adding my comment for others who might come across this. Make sure that the version of julia you are using is the one that comes out of your $PATH variable. I.e. I ran /opt/julia-1.x.0/bin/julia but my default julia in my $PATH is /opt/julia-1.y.0/bin

[divital-coder]

@benlorenz Thank you so much, I admire your comment so much, u have no idea how much time i spent headbutting this issue, until i finally realised it was simply a julia version compat issue, hope u have an awesome day on your side of the screen :)