fix: parameterless function does not compile with r2g (#10)

examples/example-monoio/build.rs

@@ -1,6 +1,13 @@
+use rust2go::RegenArgs;
+
 fn main() {
     rust2go::Builder::new()
         .with_go_src("./go")
-        // .with_regen("./src/user.rs", "./go/gen.go")
+        .with_regen_arg(RegenArgs {
+            src: "./src/user.rs".into(),
+            dst: "./go/gen.go".into(),
+            go118: true,
+            ..Default::default()
+        })
         .build();
 }

examples/example-monoio/go/gen.go

@@ -8,11 +8,6 @@ package main
 #include <stdint.h>
 #include <stdlib.h>
 
-typedef struct StringRef {
-  const uint8_t *ptr;
-  uintptr_t len;
-} StringRef;
-
 typedef struct ListRef {
   const void *ptr;
   uintptr_t len;
@@ -23,15 +18,20 @@ typedef struct DemoComplicatedRequestRef {
   struct ListRef balabala;
 } DemoComplicatedRequestRef;
 
+typedef struct DemoResponseRef {
+  bool pass;
+} DemoResponseRef;
+
+typedef struct StringRef {
+  const uint8_t *ptr;
+  uintptr_t len;
+} StringRef;
+
 typedef struct DemoUserRef {
   struct StringRef name;
   uint8_t age;
 } DemoUserRef;
 
-typedef struct DemoResponseRef {
-  bool pass;
-} DemoResponseRef;
-
 // hack from: https://stackoverflow.com/a/69904977
 __attribute__((weak))
 inline void DemoCall_demo_check_cb(const void *f_ptr, struct DemoResponseRef resp, const void *slot) {
@@ -49,6 +49,18 @@ __attribute__((weak))
 inline void DemoCall_demo_check_async_safe_cb(const void *f_ptr, struct DemoResponseRef resp, const void *slot) {
 ((void (*)(struct DemoResponseRef, const void*))f_ptr)(resp, slot);
 }
+
+// hack from: https://stackoverflow.com/a/69904977
+__attribute__((weak))
+inline void DemoCall_demo_get_n_cb(const void *f_ptr, int32_t resp, const void *slot) {
+((void (*)(int32_t, const void*))f_ptr)(resp, slot);
+}
+
+// hack from: https://stackoverflow.com/a/69904977
+__attribute__((weak))
+inline void DemoCall_demo_sum_cb(const void *f_ptr, int32_t resp, const void *slot) {
+((void (*)(int32_t, const void*))f_ptr)(resp, slot);
+}
 */
 import "C"
 import (
@@ -64,6 +76,8 @@ type DemoCall interface {
 	demo_check(req DemoComplicatedRequest) DemoResponse
 	demo_check_async(req DemoComplicatedRequest) DemoResponse
 	demo_check_async_safe(req DemoComplicatedRequest) DemoResponse
+	demo_get_n() int32
+	demo_sum(a int32, b int32) int32
 }
 
 //export CDemoCall_demo_oneway
@@ -104,6 +118,24 @@ func CDemoCall_demo_check_async_safe(req C.DemoComplicatedRequestRef, slot *C.vo
 	}()
 }
 
+//export CDemoCall_demo_get_n
+func CDemoCall_demo_get_n(slot *C.void, cb *C.void) {
+	resp := DemoCallImpl.demo_get_n()
+	resp_ref, buffer := cvt_ref(cntC_int32_t, refC_int32_t)(&resp)
+	C.DemoCall_demo_get_n_cb(unsafe.Pointer(cb), resp_ref, unsafe.Pointer(slot))
+	runtime.KeepAlive(resp)
+	runtime.KeepAlive(buffer)
+}
+
+//export CDemoCall_demo_sum
+func CDemoCall_demo_sum(a C.int32_t, b C.int32_t, slot *C.void, cb *C.void) {
+	resp := DemoCallImpl.demo_sum(newC_int32_t(a), newC_int32_t(b))
+	resp_ref, buffer := cvt_ref(cntC_int32_t, refC_int32_t)(&resp)
+	C.DemoCall_demo_sum_cb(unsafe.Pointer(cb), resp_ref, unsafe.Pointer(slot))
+	runtime.KeepAlive(resp)
+	runtime.KeepAlive(buffer)
+}
+
 // An alternative impl of unsafe.String for go1.18
 func unsafeString(ptr *byte, length int) string {
 	sliceHeader := &reflect.SliceHeader{

examples/example-monoio/go/impl.go

@@ -35,3 +35,11 @@ func (Demo) demo_check_async_safe(req DemoComplicatedRequest) DemoResponse {
 	fmt.Printf("[Go-call async drop_safe] Golang returned result, pass: %v\n", req.balabala[0] == 1)
 	return resp
 }
+
+func (Demo) demo_get_n() int32 {
+	return 8
+}
+
+func (Demo) demo_sum(a int32, b int32) int32 {
+	return a + b
+}

examples/example-monoio/src/main.rs

@@ -14,6 +14,12 @@ async fn main() {
         name: "chihai".to_string(),
         age: 28,
     };
+    println!("========== Start get_n demo ==========");
+    let n = DemoCallImpl::demo_get_n();
+    println!("[Rust-get_n] n={n}");
+    println!("========== Start sum demo ==========");
+    let sum = DemoCallImpl::demo_sum(1, 2);
+    println!("[Rust-get_n] 1+2={sum}");
     println!("========== Start oneway demo ==========");
     DemoCallImpl::demo_oneway(&user);
     println!("[Rust-oneway] done");

examples/example-monoio/src/user.rs

@@ -57,4 +57,6 @@ pub trait DemoCall {
     fn demo_check_async_safe(
         req: DemoComplicatedRequest,
     ) -> impl std::future::Future<Output = DemoResponse>;
+    fn demo_get_n() -> i32;
+    fn demo_sum(a: i32, b: i32) -> i32;
 }