[PATCH v2 08/13] rust: cleanup module_init!, use it from #[derive(Object)]

[Paolo Bonzini <pbonzini@redhat.com>]

Remove the duplicate code by using the module_init! macro; at the same time,
simplify how module_init! is used, by taking inspiration from the implementation
of #[derive(Object)].

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/qemu-api-macros/src/lib.rs  | 33 +++-------------
 rust/qemu-api/src/definitions.rs | 66 ++++++++++++++------------------
 2 files changed, 33 insertions(+), 66 deletions(-)

diff --git a/rust/qemu-api-macros/src/lib.rs b/rust/qemu-api-macros/src/lib.rs
index 70e3f920460..a4bc5d01ee8 100644
--- a/rust/qemu-api-macros/src/lib.rs
+++ b/rust/qemu-api-macros/src/lib.rs
@@ -3,43 +3,20 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 
 use proc_macro::TokenStream;
-use quote::{format_ident, quote};
+use quote::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(
-            not(any(target_vendor = "apple", target_os = "windows")),
-            link_section = ".init_array"
-        )]
-        #[cfg_attr(target_vendor = "apple", 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);
-                }
+        ::qemu_api::module_init! {
+            MODULE_INIT_QOM => 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)
diff --git a/rust/qemu-api/src/definitions.rs b/rust/qemu-api/src/definitions.rs
index 3323a665d92..f180c38bfb2 100644
--- a/rust/qemu-api/src/definitions.rs
+++ b/rust/qemu-api/src/definitions.rs
@@ -29,51 +29,40 @@ pub trait Class {
 
 #[macro_export]
 macro_rules! module_init {
-    ($func:expr, $type:expr) => {
-        #[used]
-        #[cfg_attr(
-            not(any(target_vendor = "apple", target_os = "windows")),
-            link_section = ".init_array"
-        )]
-        #[cfg_attr(target_vendor = "apple", link_section = "__DATA,__mod_init_func")]
-        #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
-        pub static LOAD_MODULE: extern "C" fn() = {
-            extern "C" fn __load() {
-                unsafe {
-                    $crate::bindings::register_module_init(Some($func), $type);
-                }
-            }
-
-            __load
-        };
-    };
-    (qom: $func:ident => $body:block) => {
-        // NOTE: To have custom identifiers for the ctor func we need to either supply
-        // them directly as a macro argument or create them with a proc macro.
-        #[used]
-        #[cfg_attr(
-            not(any(target_vendor = "apple", target_os = "windows")),
-            link_section = ".init_array"
-        )]
-        #[cfg_attr(target_vendor = "apple", link_section = "__DATA,__mod_init_func")]
-        #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
-        pub static LOAD_MODULE: extern "C" fn() = {
-            extern "C" fn __load() {
-                unsafe extern "C" fn $func() {
+    ($type:ident => $body:block) => {
+        const _: () = {
+            #[used]
+            #[cfg_attr(
+                not(any(target_vendor = "apple", target_os = "windows")),
+                link_section = ".init_array"
+            )]
+            #[cfg_attr(target_vendor = "apple", link_section = "__DATA,__mod_init_func")]
+            #[cfg_attr(target_os = "windows", link_section = ".CRT$XCU")]
+            pub static LOAD_MODULE: extern "C" fn() = {
+                extern "C" fn init_fn() {
                     $body
                 }
 
-                unsafe {
-                    $crate::bindings::register_module_init(
-                        Some($func),
-                        $crate::bindings::module_init_type::MODULE_INIT_QOM,
-                    );
+                extern "C" fn ctor_fn() {
+                    unsafe {
+                        $crate::bindings::register_module_init(
+                            Some(init_fn),
+                            $crate::bindings::module_init_type::$type,
+                        );
+                    }
                 }
-            }
 
-            __load
+                ctor_fn
+            };
         };
     };
+
+    // shortcut because it's quite common that $body needs unsafe {}
+    ($type:ident => unsafe $body:block) => {
+        $crate::module_init! {
+            $type => { unsafe { $body } }
+        }
+    };
 }
 
 #[macro_export]
-- 
2.46.2