I agree that storing generated stuff in the source directory should not
be encouraged.

Just want to mention that such changes can lead to trouble to
rust-analyzer. Today there are two ways to inform rust-analyzer of the
project structure:

  1. Use rust/Cargo.toml. In this case we'll hit an issue in
  rust-analyzer [1] that prevents it from including sources outside the
  crate directory. Thus, definitions in the bindgen-generated code
  cannot be found.

  2. Use the meson-generated rust-project.json. Due to the use of
  structured_sources(), that json file refers to the copied sources of
  qemu-api in the build directory. Rust-analyzer can find every symbol
  in the qemu-api crate but will jump to those copied files, making it a
  bit more annoying when developing the crate.

We can perhaps leave it as a separate topic for another series.

[1] https://github.com/rust-lang/rust-analyzer/issues/17040

--
Best Regards
Junjie Mao

> +    let path = env::var("MESON_BUILD_ROOT")
> +        .unwrap_or_else(|_| format!("{}/src", env!("CARGO_MANIFEST_DIR")));
> +
> +    let file = format!("{}/bindings.rs.inc", path);
> +    if !Path::new(&file).exists() {
> +        panic!(concat!(
> +            "No generated C bindings found! If you want to run `cargo`, start a subshell\n",
> +            "with `meson devenv`, or point MESON_BUILD_ROOT to the top of the build tree."
> +        ));
>      }
>
> +    println!("cargo:rustc-env=BINDINGS_RS_INC={}", file);
> +
>      // Check for available rustc features
>      if rustc::is_min_version("1.77.0").unwrap_or(false) {
>          println!("cargo:rustc-cfg=has_offset_of");
> diff --git a/rust/qemu-api/meson.build b/rust/qemu-api/meson.build
> index 6f637af7b1b..e3870e901e3 100644
> --- a/rust/qemu-api/meson.build
> +++ b/rust/qemu-api/meson.build
> @@ -9,6 +9,7 @@ _qemu_api_rs = static_library(
>    structured_sources(
>      [
>        'src/lib.rs',
> +      'src/bindings.rs',
>        'src/c_str.rs',
>        'src/definitions.rs',
>        'src/device_class.rs',
> diff --git a/rust/qemu-api/src/bindings.rs b/rust/qemu-api/src/bindings.rs
> new file mode 100644
> index 00000000000..1dac310594d
> --- /dev/null
> +++ b/rust/qemu-api/src/bindings.rs
> @@ -0,0 +1,29 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +#![allow(
> +    dead_code,
> +    improper_ctypes_definitions,
> +    improper_ctypes,
> +    non_camel_case_types,
> +    non_snake_case,
> +    non_upper_case_globals,
> +    unsafe_op_in_unsafe_fn,
> +    clippy::missing_const_for_fn,
> +    clippy::too_many_arguments,
> +    clippy::approx_constant,
> +    clippy::use_self,
> +    clippy::useless_transmute,
> +    clippy::missing_safety_doc
> +)]
> +
> +#[cfg(MESON)]
> +include!("bindings.rs.inc");
> +
> +#[cfg(not(MESON))]
> +include!(env!("BINDINGS_RS_INC"));
> +
> +unsafe impl Send for Property {}
> +unsafe impl Sync for Property {}
> +unsafe impl Sync for TypeInfo {}
> +unsafe impl Sync for VMStateDescription {}
> +unsafe impl Sync for VMStateField {}
> +unsafe impl Sync for VMStateInfo {}
> diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs
> index aa8d16ec94b..440aff3817d 100644
> --- a/rust/qemu-api/src/lib.rs
> +++ b/rust/qemu-api/src/lib.rs
> @@ -4,31 +4,9 @@
>
>  #![cfg_attr(not(MESON), doc = include_str!("../README.md"))]
>
> -#[allow(
> -    dead_code,
> -    improper_ctypes_definitions,
> -    improper_ctypes,
> -    non_camel_case_types,
> -    non_snake_case,
> -    non_upper_case_globals,
> -    unsafe_op_in_unsafe_fn,
> -    clippy::missing_const_for_fn,
> -    clippy::too_many_arguments,
> -    clippy::approx_constant,
> -    clippy::use_self,
> -    clippy::useless_transmute,
> -    clippy::missing_safety_doc,
> -)]
>  #[rustfmt::skip]
>  pub mod bindings;
>
> -unsafe impl Send for bindings::Property {}
> -unsafe impl Sync for bindings::Property {}
> -unsafe impl Sync for bindings::TypeInfo {}
> -unsafe impl Sync for bindings::VMStateDescription {}
> -unsafe impl Sync for bindings::VMStateField {}
> -unsafe impl Sync for bindings::VMStateInfo {}
> -
>  pub mod c_str;
>  pub mod definitions;
>  pub mod device_class;