rust: prepare variable definitions for multiple bindgen invocations

When splitting the QEMU Rust bindings into multiple crates, the
bindgen-generated structs also have to be split so that it's
possible to add "impl" blocks (e.g. for Sync/Send or Default,
or even for utility methods in cases such as VMStateFlags).

Tweak various variable definitions in meson.build, to avoid naming
conflicts once there will be multiple bindgen invocations.

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

meson.build

@@ -4200,10 +4200,11 @@ foreach target_base_arch, config_base_arch : config_base_arch_mak
 endforeach
 
 if have_rust
+  bindings_incdir = include_directories('.', 'include')
   # We would like to use --generate-cstr, but it is only available
   # starting with bindgen 0.66.0.  The oldest supported versions
   # is 0.60.x (Debian 12 has 0.60.1) which introduces --allowlist-file.
-  bindgen_args = [
+  bindgen_args_common = [
     '--disable-header-comment',
     '--raw-line', '// @generated',
     '--ctypes-prefix', 'std::os::raw',
@@ -4219,20 +4220,22 @@ if have_rust
     ]
   if not rustfmt.found()
     if bindgen.version().version_compare('<0.65.0')
-      bindgen_args += ['--no-rustfmt-bindings']
+      bindgen_args_common += ['--no-rustfmt-bindings']
     else
-      bindgen_args += ['--formatter', 'none']
+      bindgen_args_common += ['--formatter', 'none']
     endif
   endif
   if bindgen.version().version_compare('>=0.66.0')
-    bindgen_args += ['--rust-target', '1.59']
+    bindgen_args_common += ['--rust-target', '1.59']
   endif
   if bindgen.version().version_compare('<0.61.0')
     # default in 0.61+
-    bindgen_args += ['--size_t-is-usize']
+    bindgen_args_common += ['--size_t-is-usize']
   else
-    bindgen_args += ['--merge-extern-blocks']
+    bindgen_args_common += ['--merge-extern-blocks']
   endif
+
+  bindgen_args = []
   c_enums = [
     'DeviceCategory',
     'GpioPolarity',
@@ -4264,13 +4267,13 @@ if have_rust
   # 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
-  bindings_rs = rust.bindgen(
+  _qemu_api_bindings_inc_rs = rust.bindgen(
     input: 'rust/wrapper.h',
     dependencies: common_ss.all_dependencies(),
     output: 'bindings.inc.rs',
-    include_directories: include_directories('.', 'include'),
+    include_directories: bindings_incdir,
     bindgen_version: ['>=0.60.0'],
-    args: bindgen_args,
+    args: bindgen_args_common + bindgen_args,
     )
   subdir('rust')
 endif

rust/meson.build

@@ -33,5 +33,5 @@ if cargo.found()
     command: [config_host['MESON'], 'devenv',
               '--workdir', '@CURRENT_SOURCE_DIR@',
               cargo, 'fmt'],
-    depends: bindings_rs)
+    depends: _qemu_api_bindings_inc_rs)
 endif

rust/qemu-api/meson.build

@@ -32,7 +32,7 @@ _qemu_api_rs = static_library(
       'src/vmstate.rs',
       'src/zeroable.rs',
     ],
-    {'.' : bindings_rs},
+    {'.' : _qemu_api_bindings_inc_rs},
   ),
   override_options: ['rust_std=2021', 'build.rust_std=2021'],
   rust_abi: 'rust',