rust: build integration test for the qemu_api crate

Adjust the integration test to compile with a subset of QEMU object
files, and make it actually create an object of the class it defines.

Follow the Rust filesystem conventions, where tests go in tests/ if
they use the library in the same way any other code would.

Reviewed-by: Junjie Mao <junjie.mao@hotmail.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -3345,7 +3345,15 @@ if have_rust and have_system
 
   # Prohibit code that is forbidden in Rust 2024
   rustc_args += ['-D', 'unsafe_op_in_unsafe_fn']
-  add_project_arguments(rustc_args, native: false, language: 'rust')
+
+  # Apart from procedural macros, our Rust executables will often link
+  # with C code, so include all the libraries that C code needs.  This
+  # is safe; https://github.com/rust-lang/rust/pull/54675 says that
+  # passing -nodefaultlibs to the linker "was more ideological to
+  # start with than anything".
+  add_project_arguments(rustc_args + ['-C', 'default-linker-libraries'],
+      native: false, language: 'rust')
+
   add_project_arguments(rustc_args, native: true, language: 'rust')
 endif
 

rust/qemu-api/meson.build

@@ -14,11 +14,31 @@ _qemu_api_rs = static_library(
     '--cfg', 'MESON',
     # '--cfg', 'feature="allocator"',
   ],
-  dependencies: [
-    qemu_api_macros,
-  ],
 )
 
 qemu_api = declare_dependency(
   link_with: _qemu_api_rs,
+  dependencies: qemu_api_macros,
 )
+
+# Rust executables do not support objects, so add an intermediate step.
+rust_qemu_api_objs = static_library(
+    'rust_qemu_api_objs',
+    objects: [libqom.extract_all_objects(recursive: false),
+              libhwcore.extract_all_objects(recursive: false)])
+
+test('rust-qemu-api-integration',
+    executable(
+        'rust-qemu-api-integration',
+        'tests/tests.rs',
+        override_options: ['rust_std=2021', 'build.rust_std=2021'],
+        rust_args: ['--test'],
+        install: false,
+        dependencies: [qemu_api, qemu_api_macros],
+        link_whole: [rust_qemu_api_objs, libqemuutil]),
+    args: [
+        '--test',
+        '--format', 'pretty',
+    ],
+    protocol: 'rust',
+    suite: ['unit', 'rust'])

rust/qemu-api/src/lib.rs

@@ -30,9 +30,6 @@ unsafe impl Sync for bindings::VMStateDescription {}
 pub mod definitions;
 pub mod device_class;
 
-#[cfg(test)]
-mod tests;
-
 use std::alloc::{GlobalAlloc, Layout};
 
 #[cfg(HAVE_GLIB_WITH_ALIGNED_ALLOC)]

rust/qemu-api/src/tests.rs

@@ -1,49 +0,0 @@
-// Copyright 2024, Linaro Limited
-// Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
-// SPDX-License-Identifier: GPL-2.0-or-later
-
-use crate::{
-    bindings::*, declare_properties, define_property, device_class_init, vm_state_description,
-};
-
-#[test]
-fn test_device_decl_macros() {
-    // Test that macros can compile.
-    vm_state_description! {
-        VMSTATE,
-        name: c"name",
-        unmigratable: true,
-    }
-
-    #[repr(C)]
-    pub struct DummyState {
-        pub char_backend: CharBackend,
-        pub migrate_clock: bool,
-    }
-
-    declare_properties! {
-        DUMMY_PROPERTIES,
-            define_property!(
-                c"chardev",
-                DummyState,
-                char_backend,
-                unsafe { &qdev_prop_chr },
-                CharBackend
-            ),
-            define_property!(
-                c"migrate-clk",
-                DummyState,
-                migrate_clock,
-                unsafe { &qdev_prop_bool },
-                bool
-            ),
-    }
-
-    device_class_init! {
-        dummy_class_init,
-        props => DUMMY_PROPERTIES,
-        realize_fn => None,
-        reset_fn => None,
-        vmsd => VMSTATE,
-    }
-}

rust/qemu-api/tests/tests.rs

@@ -0,0 +1,78 @@
+// Copyright 2024, Linaro Limited
+// Author(s): Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+use core::ffi::CStr;
+
+use qemu_api::{
+    bindings::*,
+    declare_properties, define_property,
+    definitions::{Class, ObjectImpl},
+    device_class_init, vm_state_description,
+};
+
+#[test]
+fn test_device_decl_macros() {
+    // Test that macros can compile.
+    vm_state_description! {
+        VMSTATE,
+        name: c"name",
+        unmigratable: true,
+    }
+
+    #[repr(C)]
+    #[derive(qemu_api_macros::Object)]
+    pub struct DummyState {
+        pub _parent: DeviceState,
+        pub migrate_clock: bool,
+    }
+
+    #[repr(C)]
+    pub struct DummyClass {
+        pub _parent: DeviceClass,
+    }
+
+    declare_properties! {
+        DUMMY_PROPERTIES,
+            define_property!(
+                c"migrate-clk",
+                DummyState,
+                migrate_clock,
+                unsafe { &qdev_prop_bool },
+                bool
+            ),
+    }
+
+    device_class_init! {
+        dummy_class_init,
+        props => DUMMY_PROPERTIES,
+        realize_fn => None,
+        legacy_reset_fn => None,
+        vmsd => VMSTATE,
+    }
+
+    impl ObjectImpl for DummyState {
+        type Class = DummyClass;
+        const TYPE_INFO: qemu_api::bindings::TypeInfo = qemu_api::type_info! { Self };
+        const TYPE_NAME: &'static CStr = c"dummy";
+        const PARENT_TYPE_NAME: Option<&'static CStr> = Some(TYPE_DEVICE);
+        const ABSTRACT: bool = false;
+        const INSTANCE_INIT: Option<unsafe extern "C" fn(obj: *mut Object)> = None;
+        const INSTANCE_POST_INIT: Option<unsafe extern "C" fn(obj: *mut Object)> = None;
+        const INSTANCE_FINALIZE: Option<unsafe extern "C" fn(obj: *mut Object)> = None;
+    }
+
+    impl Class for DummyClass {
+        const CLASS_INIT: Option<
+            unsafe extern "C" fn(klass: *mut ObjectClass, data: *mut core::ffi::c_void),
+        > = Some(dummy_class_init);
+        const CLASS_BASE_INIT: Option<
+            unsafe extern "C" fn(klass: *mut ObjectClass, data: *mut core::ffi::c_void),
+        > = None;
+    }
+
+    unsafe {
+        module_call_init(module_init_type::MODULE_INIT_QOM);
+        object_unref(object_new(DummyState::TYPE_NAME.as_ptr()) as *mut _);
+    }
+}