Re: [PATCH 03/11] rust/qemu-api-macros: introduce Device proc macro

["Alex Bennée" <alex.bennee@linaro.org>]

Manos Pitsidianakis <manos.pitsidianakis@linaro.org> writes:

> Add a new derive procedural macro to declare device models. Add
> corresponding DeviceImpl trait after already existing ObjectImpl trait.
> At the same time, add instance_init, instance_post_init,
> instance_finalize methods to the ObjectImpl trait and call them from the
> ObjectImplUnsafe trait, which is generated by the procedural macro.
>
> This allows all the boilerplate device model registration to be handled
> by macros, and all pertinent details to be declared through proc macro
> attributes or trait associated constants and methods.
>
> The device class can now be generated automatically and the name can be
> optionally overridden:
>
>   ------------------------ >8 ------------------------
>  #[repr(C)]
>  #[derive(Debug, qemu_api_macros::Object, qemu_api_macros::Device)]
>  #[device(class_name_override = PL011Class)]
>  /// PL011 Device Model in QEMU
>  pub struct PL011State {
>   ------------------------ >8 ------------------------
>
> Properties are now marked as field attributes:
>
>   ------------------------ >8 ------------------------
>  #[property(name = c"chardev", qdev_prop = qdev_prop_chr)]
>  pub char_backend: CharBackend,
>   ------------------------ >8 ------------------------
>
> Object methods (instance_init, etc) methods are now trait methods:
>
>   ------------------------ >8 ------------------------
>  /// Trait a type must implement to be registered with QEMU.
>  pub trait ObjectImpl {
>      type Class: ClassImpl;
>      const TYPE_NAME: &'static CStr;
>      const PARENT_TYPE_NAME: Option<&'static CStr>;
>      const ABSTRACT: bool;
>
>      unsafe fn instance_init(&mut self) {}
>      fn instance_post_init(&mut self) {}
>      fn instance_finalize(&mut self) {}
>  }
>   ------------------------ >8 ------------------------
>
> Device methods (realize/reset etc) are now safe idiomatic trait methods:
>
>   ------------------------ >8 ------------------------
>  /// Implementation methods for device types.
>  pub trait DeviceImpl: ObjectImpl {
>      fn realize(&mut self) {}
>      fn reset(&mut self) {}
>  }
>   ------------------------ >8 ------------------------
>
> The derive Device macro is responsible for creating all the extern "C" FFI
> functions that QEMU needs to call these methods.
>
> Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
> ---
>  rust/hw/char/pl011/src/device.rs              | 124 +++-----
>  rust/hw/char/pl011/src/device_class.rs        |  70 -----
>  rust/hw/char/pl011/src/lib.rs                 |   1 -
>  rust/qemu-api-macros/src/device.rs            | 433 ++++++++++++++++++++++++++
>  rust/qemu-api-macros/src/lib.rs               |  45 +--
>  rust/qemu-api-macros/src/object.rs            | 107 +++++++
>  rust/qemu-api-macros/src/symbols.rs           |  55 ++++
>  rust/qemu-api-macros/src/utilities.rs         | 152 +++++++++
>  rust/qemu-api/meson.build                     |   3 +-
>  rust/qemu-api/src/definitions.rs              |  97 ------
>  rust/qemu-api/src/device_class.rs             | 128 --------
>  rust/qemu-api/src/lib.rs                      |   6 +-
>  rust/qemu-api/src/objects.rs                  |  90 ++++++
>  rust/qemu-api/src/tests.rs                    |  49 ---
>  subprojects/packagefiles/syn-2-rs/meson.build |   1 +
>  15 files changed, 902 insertions(+), 459 deletions(-)

My initial reaction is these patches are getting quite large because we
are doing several things at once. Is it possible to split them so:

  - we bring in one macro at a time (with unit tests)
  - we then convert pl011 to the new idiom

? 

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro