WebAssembly ABI mismatch between clang and rust

When I compile this C code to wasm32-wasi:

typedef struct Vector {
    int a;
    int b;
} Vector;

extern int extract_a(Vector v) {
    return v.a;
}

And this Rust code to wasm32-wasi:

#[repr(C)]
struct Vector {
    a: i32,
    b: i32,
}

extern "C" {
    fn extract_a(v: Vector) -> i32;
}

fn main() {
    unsafe {
        extract_a(Vector { a: 5, b: 4 });
    }
}

And try link them together, I'm getting linking errors:

  = note: lld: error: function signature mismatch: extract_a
          >>> defined as (i32, i32) -> i32 in /home/pierre/Projets/wasm-abi-test/target/wasm32-wasi/debug/deps/wasm_abi_test.67xpw7l331r9o5x.rcgu.o
          >>> defined as (i32) -> i32 in /home/pierre/Projets/wasm-abi-test/target/wasm32-wasi/debug/build/wasm-abi-test-9c49ce7f6c5ca031/out/libfoo.a(test.o)

It seems that, according to clang, passing a struct by value should inline the fields, while for Rust it should be passed by pointer.

I uploaded an example project here: https://github.com/tomaka/wasm-abi-test
It can be built with something like:

AR_wasm32_wasi=/path/to/wasi-sdk-10.0/bin/ar CC_wasm32_wasi=/path/to/wasi-sdk-10.0/bin/clang cargo run --target=wasm32-wasi

Rust version: rustc 1.44.0-nightly (38114ff 2020-03-21)