Rust bindgen ignore include specific include from header file

Question

I have a header file lets say greetings.h:

include <hello.h>;
include <bye.h>;
include <hola.h>;
...

Im using bindgen in rust to generate those file from c header to rust. But I want to ignore generating the include <hola.h> header and generate the greeting.h only with helllo.h and bye.h. I have searched it in docs.rs bindgen documentation but not found any hint on that. or is there any option to do that with clang

Answer 1

I was able to solve this by guessing that my library that Im trying to bind from c to rust are "namespaced", in C language there is no actually namespaces but people that write open source code tend to prefix their code with "some_prefix*". So if the h file that I want to bind looks like:

mylib.h:

include <hello.h>;
include <bye.h>;
include <hola.h>;
...

mylib_add_value(...);
mylib_remove_value(...);
mylib_display_value(...);
...

and I don't want the hola.h to be generated, i can filter the output with allow and block functionality of bingden like:

build.rs:

fn main() {
    // Tell cargo to tell rustc to link the system nvpair of zfs
    // shared library.
    println!("cargo:rustc-link-lib=mylib");

    // The bindgen::Builder is the main entry point
    // to bindgen, and lets you build up options for
    // the resulting bindings.
    let bindings = bindgen::Builder::default()
        // The input header we would like to generate
        // bindings for.
        .header("wrapper.h")
        .allowlist_var(r#"(\w*mylib\w*)"#)
        .allowlist_type(r#"(\w*mylib\w*)"#)
        .allowlist_function(r#"(\w*mylib\w*)"#)
        .blocklist_item(r#"(\w*hola\w*)"#)
        .blocklist_type(r#"(\w*hola\w*)"#)
        .blocklist_function(r#"(\w*hola\w*)"#)
        .clang_args(vec!["-I/usr/include/mylib"])
        .default_enum_style(bindgen::EnumVariation::Rust {
            non_exhaustive: (true),
        })
        // Finish the builder and generate the bindings.
        .generate()
        // Unwrap the Result and panic on failure.
        .expect("Unable to generate bindings");

    // Write the bindings to the $OUT_DIR/bindings.rs file.
    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
    bindings
        //.write_to_file(out_path)
        .write_to_file(out_path.join("bindings.rs"))
        .expect("Couldn't write bindings!");
}

Bindgen will bring all dependencies of allowlist firstly and if some of the dependencies include *hola* it won't generate it.