Controlling where to look for files - make distcheck and VPATH builds, finding config.h and other includes

Intro

SentryPeer is being extended using Rust as a lib. This Rust lib also uses SentryPeer via a C lib it generates, hence the use of cbindgen and bindgen in the same build.rs. This is all driven by autotools.

Input C/C++ Header

https://github.com/SentryPeer/SentryPeer/blob/main/sentrypeer_rust/wrapper.h

/* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only  */
/* Copyright (c) 2021 - 2024 Gavin Henry <ghenry@sentrypeer.org> */
/* 
   _____            _              _____
  / ____|          | |            |  __ \
 | (___   ___ _ __ | |_ _ __ _   _| |__) |__  ___ _ __
  \___ \ / _ \ '_ \| __| '__| | | |  ___/ _ \/ _ \ '__|
  ____) |  __/ | | | |_| |  | |_| | |  |  __/  __/ |
 |_____/ \___|_| |_|\__|_|   \__, |_|   \___|\___|_|
                              __/ |
                             |___/
*/

#include "../src/conf.h"
#include "../src/sip_message_event.h"
#include "../src/sip_daemon.h"

Bindgen Invocation

https://github.com/SentryPeer/SentryPeer/blob/main/sentrypeer_rust/build.rs

    // 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")
        // Pick the functions we want to generate bindings for
        .allowlist_function("sentrypeer_config_new|sentrypeer_config_destroy")
        .allowlist_function("sip_message_event_new|sip_message_event_destroy")
        .allowlist_function("sip_log_event")
        // Tell cargo to invalidate the built crate whenever any of the
        // included header files changed.
        .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
        // 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.join("bindings.rs"))
        .expect("Couldn't write bindings.rs, so can't use SentryPeer C lib!");

What options do I have for setting where we look for files?

Output

  --- stderr
  src_dir: ../..
  ./../src/conf.h:21:10: fatal error: '../config.h' file not found
  thread 'main' panicked at build.rs:60:10:
  Unable to generate bindings: ClangDiagnostic("./../src/conf.h:21:10: fatal error: '../config.h' file not found\n")
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
make[2]: *** [Makefile:2850: /home/ghenry/src/sentrypeer/sentrypeer-4.0.0/_build/sub/sentrypeer_rust/target/release/libsentrypeer_rust.a] Error 101
make[2]: Leaving directory '/home/ghenry/src/sentrypeer/sentrypeer-4.0.0/_build/sub'
make[1]: *** [Makefile:942: all] Error 2
make[1]: Leaving directory '/home/ghenry/src/sentrypeer/sentrypeer-4.0.0/_build/sub'

I'm passing in SRC_DIR from my makefile here:

https://github.com/SentryPeer/SentryPeer/blob/main/Makefile.am#L273

This is all to try and get make distcheck to work for VPATH

Maybe I just can't. make dist and running all the usual works:

./configure
make
make check
make install

Thanks.

Start with sentrypeer_rust/build.rs and wrapper.h, then inspect Makefile.am and src/conf.h to trace include paths during a VPATH build. Reproduce the reported failure with make distcheck and determine how generated config.h and other headers should be located. Done means the Rust bindings build successfully in the VPATH/distcheck setup.