rust: move rust.bindgen to qemu-api crate

Once qemu-api is split in multiple crates, each of them will have
its own invocation of bindgen.  There cannot be only one, because
there are occasional "impl" blocks for the bindgen-generated
structs (e.g. VMStateFlags or QOM classes) that have to
reside in the same crate as the bindgen-generated code.

For now, prepare for this new organization by invoking bindgen
within the qemu-api crate's build definitions; it's also a
much better place to list enums that need specific treatment
from bindgen.

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

rust/meson.build

@@ -20,6 +20,8 @@ proc_macro2_rs_native = dependency('proc-macro2-1-rs', native: true)
 
 qemuutil_rs = qemuutil.partial_dependency(link_args: true, links: true)
 
+genrs = []
+
 subdir('qemu-api-macros')
 subdir('bits')
 subdir('qemu-api')
@@ -33,5 +35,5 @@ if cargo.found()
     command: [config_host['MESON'], 'devenv',
               '--workdir', '@CURRENT_SOURCE_DIR@',
               cargo, 'fmt'],
-    depends: _qemu_api_bindings_inc_rs)
+    depends: genrs)
 endif

rust/qemu-api/build.rs

@@ -14,7 +14,7 @@ fn main() -> Result<()> {
     let path = env::var("MESON_BUILD_ROOT")
         .unwrap_or_else(|_| format!("{}/src", env!("CARGO_MANIFEST_DIR")));
 
-    let file = format!("{path}/bindings.inc.rs");
+    let file = format!("{path}/rust/qemu-api/bindings.inc.rs");
     let file = Path::new(&file);
     if !Path::new(&file).exists() {
         panic!(concat!(

rust/qemu-api/meson.build

@@ -7,6 +7,47 @@ if get_option('debug_mutex')
   _qemu_api_cfg += ['--cfg', 'feature="debug_cell"']
 endif
 
+c_enums = [
+  'DeviceCategory',
+  'GpioPolarity',
+  'MachineInitPhase',
+  'MemoryDeviceInfoKind',
+  'MigrationPolicy',
+  'MigrationPriority',
+  'QEMUChrEvent',
+  'QEMUClockType',
+  'ResetType',
+  'device_endian',
+  'module_init_type',
+]
+_qemu_api_bindgen_args = []
+foreach enum : c_enums
+  _qemu_api_bindgen_args += ['--rustified-enum', enum]
+endforeach
+c_bitfields = [
+  'ClockEvent',
+  'VMStateFlags',
+]
+foreach enum : c_bitfields
+  _qemu_api_bindgen_args += ['--bitfield-enum', enum]
+endforeach
+
+# TODO: Remove this comment when the clang/libclang mismatch issue is solved.
+#
+# Rust bindings generation with `bindgen` might fail in some cases where the
+# detected `libclang` does not match the expected `clang` version/target. In
+# this case you must pass the path to `clang` and `libclang` to your build
+# command invocation using the environment variables CLANG_PATH and
+# LIBCLANG_PATH
+_qemu_api_bindings_inc_rs = rust.bindgen(
+  input: 'wrapper.h',
+  dependencies: common_ss.all_dependencies(),
+  output: 'bindings.inc.rs',
+  include_directories: bindings_incdir,
+  bindgen_version: ['>=0.60.0'],
+  args: bindgen_args_common + _qemu_api_bindgen_args,
+  )
+
 _qemu_api_rs = static_library(
   'qemu_api',
   structured_sources(