Bindgen and Bzlmod

[sonoclock110]

Hello Q&A,
I try to use bindgen with bzlmod.

In MODULE.bazel I added:
bazel_dep(name = "rules_rust", version = "0.51.0")

Within a BUILD file I use bindgen:
load("@rules_rust//bindgen:defs.bzl", "rust_bindgen")
cc_library( name = "hello_bindgen", srcs = ["hello_bindgen.c"], hdrs = ["hello_bindgen.h"], linkstatic = True, visibility = ["//visibility:public"], )
rust_bindgen( name = "hello_rust_bindgen", cc_lib = ":hello_bindgen", header = ":hello_bindgen.h", )

When try to build the target I get the error:

ERROR: no such package '@@[unknown repo 'llvm-project' requested from @@rules_rust~]//clang': The repository '@@[unknown repo 'llvm-project' requested from @@rules_rust~]' could not be resolved: No repository visible as '@llvm-project' from repository '@@rules_rust~'

Do you have any idea what I have forgotten here?
Thanks!!!

[YuhanunCitgez]

Same issue, anyone?

[jayakasadev]

follow the example here

you need a llvm toolchain that you can use to create a custom bindgen toolchain

[UebelAndre]

I also think the issue of missing llvm-project was resolved in a newer version but you still need to configure your own toolchain

[bertulli]

When using bindgen, you need to provide an LLVM toolchain to bazel. On the docs there are listed two methods: either compile libllvm from source :

register_toolchains("@rules_rust_bindgen//:default_bindgen_toolchain")

or use a precompiled version, fetched from the web, which should be similar to (but please CHECK!):

# MODULE.bazel
bazel_dep(name = "rules_rust", version = "0.59.2")
bazel_dep(name = "rules_cc", version = "0.1.1")
bazel_dep(name = "rules_rust_bindgen", version = "0.59.2")
bazel_dep(name = "bazel_skylib", version = "1.7.1")
bazel_dep(name = "toolchains_llvm", version = "1.3.0")

llvm = use_extension("@toolchains_llvm//toolchain/extensions:llvm.bzl", "llvm")
llvm.toolchain(llvm_version = "17.0.6")
use_repo(llvm, "llvm_toolchain_llvm")

register_toolchains("//my_package:my_bindgen_toolchain")

# BUILD file of my_package
load("@bazel_skylib//rules:native_binary.bzl", "native_binary")
load("@rules_cc//cc:defs.bzl", "cc_import")
load("@rules_rust_bindgen//:defs.bzl", "rust_bindgen_toolchain")

native_binary(
    name = "clang",
    src = "@llvm_toolchain_llvm//:bin/clang",
)

cc_import(
    name = "libclang",
    shared_library = "@llvm_toolchain_llvm//:libclang",
)

rust_bindgen_toolchain(
    name = "rust_bindgen_toolchain",
    bindgen = "@rules_rust_bindgen//3rdparty:bindgen",
    clang = ":clang",
    libclang = ":libclang",
)

toolchain(
    name = "my_bindgen_toolchain",
    toolchain = ":rust_bindgen_toolchain",
    toolchain_type = "@rules_rust_bindgen//:toolchain_type",
)

After this you should be able to load and call the bindgen functions, though i didn't manage to find how to link everything toghether