Yggdrasil and jlrs

In the previous chapter we saw how we could write a recipe to build a Rust crate and contribute it to Yggdrasil to distribute it as a JLL package. When the crate we want to build depends on jlrs, we have to deal with a complication: we need to build the library against every version of Julia that we want to support, and enable the correct version feature at compile time. We'll also need to enable the yggdrasil feature. This requires a few adjustments to the recipe.

We're going to assume the crate re-exposes the version and yggdrasil features:

[features]
julia-1-6 = ["jlrs/julia-1-6"]
julia-1-7 = ["jlrs/julia-1-7"]
julia-1-8 = ["jlrs/julia-1-8"]
julia-1-9 = ["jlrs/julia-1-9"]
julia-1-10 = ["jlrs/julia-1-10"]
julia-1-11 = ["jlrs/julia-1-11"]
yggdrasil = ["jlrs/yggdrasil"]

The recipe should look as follows:

# Note that this script can accept some limited command-line arguments, run
# `julia build_tarballs.jl --help` to see a usage message.
using BinaryBuilder, Pkg

# See https://github.com/JuliaLang/Pkg.jl/issues/2942
# Once this Pkg issue is resolved, this must be removed
uuid = Base.UUID("a83860b7-747b-57cf-bf1f-3e79990d037f")
delete!(Pkg.Types.get_last_stdlibs(v"1.6.3"), uuid)

name = "{{crate_name}}"
version = v"0.1.0"
julia_versions = [v"1.6.3", v"1.7", v"1.8", v"1.9", v"1.10", v"1.11"]

# Collection of sources required to complete build
sources = [
    GitSource("https://github.com/{{user}}/{{crate_name}}.git",
              "{full commit hash, e.g.: 52ab80563a07d02e3d142f85101853bbf5c0a8a1}"),
]

# Bash recipe for building across all platforms
script = raw"""
cd $WORKSPACE/srcdir/{{crate_name}}

# This program prints the version feature that must be passed to `cargo build`
# Adapted from ../../G/GAP/build_tarballs.jl
# HACK: determine Julia version
cat > version.c <<EOF
#include <stdio.h>
#include "julia/julia_version.h"
int main(int argc, char**argv)
{
    printf("julia-%d-%d", JULIA_VERSION_MAJOR, JULIA_VERSION_MINOR);
    return 0;
}
EOF
${CC_BUILD} -I${includedir} -Wall version.c -o julia_version
julia_version=$(./julia_version)

cargo build --features yggdrasil,${julia_version} --release --verbose
install_license LICENSE
install -Dvm 0755 "target/${rust_target}/release/"*{{crate_name}}".${dlext}" "${libdir}/lib{{crate_name}}.${dlext}"
"""

include("../../L/libjulia/common.jl")
platforms = vcat(libjulia_platforms.(julia_versions)...)

# Rust toolchain for i686 Windows is unusable
is_excluded(p) = Sys.iswindows(p) && nbits(p) == 32
filter!(!is_excluded, platforms)

# The products that we will ensure are always built
products = [
    LibraryProduct("lib{{crate_name}}", :librustfft),
]

# Dependencies that must be installed before this package can be built
dependencies = [
    BuildDependency("libjulia_jll"),
    Dependency("Libiconv_jll"; platforms=filter(Sys.isapple, platforms)),
]

# Build the tarballs.
build_tarballs(ARGS, name, version, sources, script, platforms, products, dependencies;
               preferred_gcc_version=v"10", julia_compat="1.6", compilers=[:c, :rust])

The main differences with the recipe for a crate that doesn't depend on jlrs are:

• The workaround for issue #2942.
• The supported versions of Julia are set.
• A small executable that prints the version feature we need to enable is built and executed as part of the build script.
• libjulia/common.jl is included.
• Supported platforms are acquired via libjulia_platforms, not supported_platforms.
• libjulia_jll is added to the dependencies as a build dependency.