rust: add utility procedural macro crate

This commit adds a helper crate library, qemu-api-macros for derive (and
other procedural) macros to be used along qemu-api.

It needs to be a separate library because in Rust, procedural macros, or
macros that can generate arbitrary code, need to be special separate
compilation units.

Only one macro is introduced in this patch, #[derive(Object)]. It
generates a constructor to register a QOM TypeInfo on init and it must
be used on types that implement qemu_api::definitions::ObjectImpl trait.

Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Link: https://lore.kernel.org/r/dd645642406a6dc2060c6f3f17db2bc77ed67b59.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -3295,6 +3295,7 @@ Rust
 M: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
 S: Maintained
 F: rust/qemu-api
+F: rust/qemu-api-macros
 F: rust/rustfmt.toml
 
 SLIRP

rust/meson.build

@@ -1 +1,2 @@
+subdir('qemu-api-macros')
 subdir('qemu-api')

rust/qemu-api-macros/Cargo.lock

@@ -0,0 +1,47 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.86"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "qemu_api_macros"
+version = "0.1.0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.36"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "syn"
+version = "2.0.72"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc4b9b9bf2add8093d3f2c0204471e951b2285580335de42f9d2534f3ae7a8af"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"

rust/qemu-api-macros/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "qemu_api_macros"
+version = "0.1.0"
+edition = "2021"
+authors = ["Manos Pitsidianakis <manos.pitsidianakis@linaro.org>"]
+license = "GPL-2.0-or-later"
+readme = "README.md"
+homepage = "https://www.qemu.org"
+description = "Rust bindings for QEMU - Utility macros"
+repository = "https://gitlab.com/qemu-project/qemu/"
+resolver = "2"
+publish = false
+keywords = []
+categories = []
+
+[lib]
+proc-macro = true
+
+[dependencies]
+proc-macro2 = "1"
+quote = "1"
+syn = "2"
+
+# Do not include in any global workspace
+[workspace]

rust/qemu-api-macros/README.md

@@ -0,0 +1 @@
+# `qemu-api-macros` - Utility macros for defining QEMU devices

rust/qemu-api-macros/meson.build

@@ -0,0 +1,25 @@
+add_languages('rust', required: true, native: true)
+
+quote_dep = dependency('quote-1-rs', native: true)
+syn_dep = dependency('syn-2-rs', native: true)
+proc_macro2_dep = dependency('proc-macro2-1-rs', native: true)
+
+_qemu_api_macros_rs = import('rust').proc_macro(
+  'qemu_api_macros',
+  files('src/lib.rs'),
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_args: [
+    '--cfg', 'use_fallback',
+    '--cfg', 'feature="syn-error"',
+    '--cfg', 'feature="proc-macro"',
+  ],
+  dependencies: [
+    proc_macro2_dep,
+    quote_dep,
+    syn_dep,
+  ],
+)
+
+qemu_api_macros = declare_dependency(
+  link_with: _qemu_api_macros_rs,
+)

rust/qemu-api-macros/src/lib.rs

@@ -0,0 +1,43 @@
+// Copyright 2024, Linaro Limited
+// Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+use proc_macro::TokenStream;
+use quote::{format_ident, quote};
+use syn::{parse_macro_input, DeriveInput};
+
+#[proc_macro_derive(Object)]
+pub fn derive_object(input: TokenStream) -> TokenStream {
+    let input = parse_macro_input!(input as DeriveInput);
+
+    let name = input.ident;
+    let module_static = format_ident!("__{}_LOAD_MODULE", name);
+
+    let expanded = quote! {
+        #[allow(non_upper_case_globals)]
+        #[used]
+        #[cfg_attr(target_os = "linux", link_section = ".ctors")]
+        #[cfg_attr(target_os = "macos", link_section = "__DATA,__mod_init_func")]
+        #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
+        pub static #module_static: extern "C" fn() = {
+            extern "C" fn __register() {
+                unsafe {
+                    ::qemu_api::bindings::type_register_static(&<#name as ::qemu_api::definitions::ObjectImpl>::TYPE_INFO);
+                }
+            }
+
+            extern "C" fn __load() {
+                unsafe {
+                    ::qemu_api::bindings::register_module_init(
+                        Some(__register),
+                        ::qemu_api::bindings::module_init_type::MODULE_INIT_QOM
+                    );
+                }
+            }
+
+            __load
+        };
+    };
+
+    TokenStream::from(expanded)
+}

rust/qemu-api/meson.build

@@ -14,6 +14,9 @@ _qemu_api_rs = static_library(
     '--cfg', 'MESON',
     # '--cfg', 'feature="allocator"',
   ],
+  dependencies: [
+    qemu_api_macros,
+  ],
 )
 
 qemu_api = declare_dependency(

scripts/archive-source.sh

@@ -26,7 +26,9 @@ sub_file="${sub_tdir}/submodule.tar"
 # independent of what the developer currently has initialized
 # in their checkout, because the build environment is completely
 # different to the host OS.
-subprojects="keycodemapdb libvfio-user berkeley-softfloat-3 berkeley-testfloat-3"
+subprojects="keycodemapdb libvfio-user berkeley-softfloat-3
+  berkeley-testfloat-3 proc-macro2-1-rs quote-1-rs
+  syn-2-rs unicode-ident-1-rs"
 sub_deinit=""
 
 function cleanup() {

scripts/make-release

@@ -17,7 +17,9 @@ if [ $# -ne 2 ]; then
 fi
 
 # Only include wraps that are invoked with subproject()
-SUBPROJECTS="libvfio-user keycodemapdb berkeley-softfloat-3 berkeley-testfloat-3"
+SUBPROJECTS="libvfio-user keycodemapdb berkeley-softfloat-3
+  berkeley-testfloat-3 proc-macro2-1-rs quote-1-rs
+  syn-2-rs unicode-ident-1-rs"
 
 src="$1"
 version="$2"

subprojects/.gitignore

@@ -6,3 +6,7 @@
 /keycodemapdb
 /libvfio-user
 /slirp
+/proc-macro2-1.0.84
+/quote-1.0.36
+/syn-2.0.66
+/unicode-ident-1.0.12

subprojects/packagefiles/proc-macro2-1-rs/meson.build

@@ -0,0 +1,31 @@
+project('proc-macro2-1-rs', 'rust',
+  version: '1.0.84',
+  license: 'MIT OR Apache-2.0',
+  default_options: [])
+
+subproject('unicode-ident-1-rs', required: true)
+
+unicode_ident_dep = dependency('unicode-ident-1-rs', native: true)
+
+_proc_macro2_rs = static_library(
+  'proc_macro2',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  rust_args: [
+    '--cfg', 'feature="proc-macro"',
+    '--cfg', 'span_locations',
+    '--cfg', 'wrap_proc_macro',
+  ],
+  dependencies: [
+    unicode_ident_dep,
+  ],
+  native: true,
+)
+
+proc_macro2_dep = declare_dependency(
+  link_with: _proc_macro2_rs,
+)
+
+meson.override_dependency('proc-macro2-1-rs', proc_macro2_dep, native: true)

subprojects/packagefiles/quote-1-rs/meson.build

@@ -0,0 +1,29 @@
+project('quote-1-rs', 'rust',
+  version: '1.12.0',
+  license: 'MIT OR Apache-2.0',
+  default_options: [])
+
+subproject('proc-macro2-1-rs', required: true)
+
+proc_macro2_dep = dependency('proc-macro2-1-rs', native: true)
+
+_quote_rs = static_library(
+  'quote',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  rust_args: [
+    '--cfg', 'feature="proc-macro"',
+  ],
+  dependencies: [
+    proc_macro2_dep,
+  ],
+  native: true,
+)
+
+quote_dep = declare_dependency(
+  link_with: _quote_rs,
+)
+
+meson.override_dependency('quote-1-rs', quote_dep, native: true)

subprojects/packagefiles/syn-2-rs/meson.build

@@ -0,0 +1,40 @@
+project('syn-2-rs', 'rust',
+  version: '2.0.66',
+  license: 'MIT OR Apache-2.0',
+  default_options: [])
+
+subproject('proc-macro2-1-rs', required: true)
+subproject('quote-1-rs', required: true)
+subproject('unicode-ident-1-rs', required: true)
+
+proc_macro2_dep = dependency('proc-macro2-1-rs', native: true)
+quote_dep = dependency('quote-1-rs', native: true)
+unicode_ident_dep = dependency('unicode-ident-1-rs', native: true)
+
+_syn_rs = static_library(
+  'syn',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  rust_args: [
+    '--cfg', 'feature="full"',
+    '--cfg', 'feature="derive"',
+    '--cfg', 'feature="parsing"',
+    '--cfg', 'feature="printing"',
+    '--cfg', 'feature="clone-impls"',
+    '--cfg', 'feature="proc-macro"',
+  ],
+  dependencies: [
+    quote_dep,
+    proc_macro2_dep,
+    unicode_ident_dep,
+  ],
+  native: true,
+)
+
+syn_dep = declare_dependency(
+  link_with: _syn_rs,
+)
+
+meson.override_dependency('syn-2-rs', syn_dep, native: true)

subprojects/proc-macro2-1-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = proc-macro2-1.0.84
+source_url = https://crates.io/api/v1/crates/proc-macro2/1.0.84/download
+source_filename = proc-macro2-1.0.84.0.tar.gz
+source_hash = ec96c6a92621310b51366f1e28d05ef11489516e93be030060e5fc12024a49d6
+#method = cargo
+patch_directory = proc-macro2-1-rs

subprojects/quote-1-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = quote-1.0.36
+source_url = https://crates.io/api/v1/crates/quote/1.0.36/download
+source_filename = quote-1.0.36.0.tar.gz
+source_hash = 0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7
+#method = cargo
+patch_directory = quote-1-rs

subprojects/syn-2-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = syn-2.0.66
+source_url = https://crates.io/api/v1/crates/syn/2.0.66/download
+source_filename = syn-2.0.66.0.tar.gz
+source_hash = c42f3f41a2de00b01c0aaad383c5a45241efc8b2d1eda5661812fda5f3cdcff5
+#method = cargo
+patch_directory = syn-2-rs

subprojects/unicode-ident-1-rs.wrap

@@ -0,0 +1,7 @@
+[wrap-file]
+directory = unicode-ident-1.0.12
+source_url = https://crates.io/api/v1/crates/unicode-ident/1.0.12/download
+source_filename = unicode-ident-1.0.12.tar.gz
+source_hash = 3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b
+#method = cargo
+patch_directory = unicode-ident-1-rs

subprojects/unicode-ident-1-rs/meson.build

@@ -0,0 +1,20 @@
+project('unicode-ident-1-rs', 'rust',
+  version: '1.0.12',
+  license: '(MIT OR Apache-2.0) AND Unicode-DFS-2016',
+  default_options: [])
+
+_unicode_ident_rs = static_library(
+  'unicode_ident',
+  files('src/lib.rs'),
+  gnu_symbol_visibility: 'hidden',
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  dependencies: [],
+  native: true,
+)
+
+unicode_ident_dep = declare_dependency(
+  link_with: _unicode_ident_rs,
+)
+
+meson.override_dependency('unicode-ident-1-rs', unicode_ident_dep, native: true)