How can I compile a static c++ library from MediaPipe (it uses bazel) to use in Rust

I'm trying to integrate MediaPipe (https://github.com/google/mediapipe) which uses the google build system Bazel. I'm trying to figure out how to get a static library out of it. I've searched around and found people saying they've tried it and done it, but nobody has posted what they've done. I know there's no standard rule for doing so.

My attempt thus far has been to make bazel verbose (run with -s) and then see what commands it passes to compiling the final binary so I could take it and modify it to build a static library. I've tried parsing the compiler command args to pick out all the object files (.o) and link them with ar like so ar rcs gpu.a $(grep -E '\.o' bazel-bin/custom/run_gpu-2.params)

That command works, but when I try to link it to Rust with rust fails.

Here's my build.rs

fn main() {
    println!("cargo:rustc-link-search=/home/me/dev/mediapipe");
}

And here's my main

#[link(name = "gpu")]
extern "C" {
    fn square(val: i32) -> i32;
}

fn main() {
    let r = unsafe { square(3) };
    println!("3 squared is {}", r);
}

And here's the error I get:

   Compiling my-mediapipe-project v0.1.0 (/home/me/dev/my-mediapipe-project)
error: linking with `cc` failed: exit code: 1
  |
  = note: "cc""-Wl,--as-needed""-Wl,-z,noexecstack""-m64""-L""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.1fmokwdndpsbxaxm.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.2j9fb5mr4wpkcnpp.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.3bpsevdikgyu7tj9.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.48fsbok7dmpjlo4o.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.4ezfxccf1xedvrna.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.577bi7s5mtonhdwp.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.qpj0hauia5ocv8m.rcgu.o""-o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.22pad9p4rf6ea56q.rcgu.o""-Wl,--gc-sections""-pie""-Wl,-zrelro""-Wl,-znow""-nodefaultlibs""-L""/home/me/dev/my-mediapipe-project/target/debug/deps""-L""/home/me/dev/mediapipe""-L""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib""-lgpu""-Wl,--start-group""-Wl,-Bstatic""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-c32b051c3aafd36c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libpanic_unwind-eabf8b29c0a244dd.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libhashbrown-5c336cc1b5ec2048.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_std_workspace_alloc-c7631f762b1ba6d9.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libbacktrace-db0f6c539591c951.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libbacktrace_sys-32c2dc6fbc292c9c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_demangle-84e9c510dc249620.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-13bc027534de0b4c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcfg_if-b3c13ecda1794c6c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-72dc11de859645e9.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liballoc-a78b04f112feb31a.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_std_workspace_core-29469f6c53ac35f8.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-0eb3c513c640c4a6.rlib""-Wl,--end-group""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-0b278345638bce90.rlib""-Wl,-Bdynamic""-ldl""-lrt""-lpthread""-lgcc_s""-lc""-lm""-lrt""-lpthread""-lutil""-lutil"
  = note: /usr/bin/ld: cannot find -lgpu
          collect2: error: ld returned 1 exit status

Here it is manually line-wrapped:

error: linking with `cc` failed: exit code: 1
  |
  = note: "cc""-Wl,--as-needed""-Wl,-z,noexecstack""-m64""-L""/home/me/.rustup/toolchains
/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib""/home/me/dev/my-
mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.1fmokwdndpsbxaxm.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-
a37e83e58c99436c.2j9fb5mr4wpkcnpp.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug
/deps/rust_whiteboard-a37e83e58c99436c.3bpsevdikgyu7tj9.rcgu.o""/home/me/dev/my-mediapipe-
project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.48fsbok7dmpjlo4o.rcgu.o""/home
/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-
a37e83e58c99436c.4ezfxccf1xedvrna.rcgu.o""/home/me/dev/my-mediapipe-project/target/debug
/deps/rust_whiteboard-a37e83e58c99436c.577bi7s5mtonhdwp.rcgu.o""/home/me/dev/my-mediapipe-
project/target/debug/deps/rust_whiteboard-a37e83e58c99436c.qpj0hauia5ocv8m.rcgu.o""-o""/home
/me/dev/my-mediapipe-project/target/debug/deps/rust_whiteboard-a37e83e58c99436c""/home/me/dev
/my-mediapipe-project/target/debug/deps/rust_whiteboard-
a37e83e58c99436c.22pad9p4rf6ea56q.rcgu.o""-Wl,--gc-sections""-pie""-Wl,-zrelro""-Wl,-znow""-nodefaultlibs""-L""/home/me/dev/my-mediapipe-project/target/debug/deps""-L""/home/me/dev
/mediapipe""-L""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib""-lgpu""-Wl,--start-group""-Wl,-Bstatic""/home/me/.rustup
/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-
c32b051c3aafd36c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/libpanic_unwind-eabf8b29c0a244dd.rlib""/home/me/.rustup
/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib
/libhashbrown-5c336cc1b5ec2048.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-
gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_std_workspace_alloc-
c7631f762b1ba6d9.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/libbacktrace-db0f6c539591c951.rlib""/home/me/.rustup/toolchains
/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libbacktrace_sys-
32c2dc6fbc292c9c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/librustc_demangle-84e9c510dc249620.rlib""/home/me/.rustup
/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libunwind-
13bc027534de0b4c.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/libcfg_if-b3c13ecda1794c6c.rlib""/home/me/.rustup/toolchains
/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/liblibc-
72dc11de859645e9.rlib""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/liballoc-a78b04f112feb31a.rlib""/home/me/.rustup/toolchains
/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib
/librustc_std_workspace_core-29469f6c53ac35f8.rlib""/home/me/.rustup/toolchains/stable-x86_64-
unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/libcore-0eb3c513c640c4a6.rlib""-Wl,--end-group""/home/me/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib
/x86_64-unknown-linux-gnu/lib/libcompiler_builtins-0b278345638bce90.rlib""-Wl,-Bdynamic""-ldl""-lrt""-lpthread""-lgcc_s""-lc""-lm""-lrt""-lpthread""-lutil""-lutil"
  = note: /usr/bin/ld: cannot find -lgpu
          collect2: error: ld returned 1 exit status

I'm on Arch Linux if it helps. MediaPipe does compile correctly for me - I had to modify a few definitions relating to OpenCV to get it to work properly, I found that documented in a GitHub issue.

I really don't want to have to manage my Rust code through Bazel. I'd really like to just be able to produce a static binary, and then consume it through Rust/Cargo.

I'd really love it if there was a cross platform solution for this too...