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>

1 files changed, 25 insertions, 0 deletions

diff --git a/rust/qemu-api-macros/meson.build b/rust/qemu-api-macros/meson.build
new file mode 100644
index 0000000..48af91e
--- /dev/null
+++ b/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,
+)