Change the Rust > C++ interop fns to be consuming-self, add a 'leak' to the name and a ManuallyDrop(self) on the owned message case.

PiperOrigin-RevId: 622159280

rust/test/cpp/interop/main.rs

@@ -23,6 +23,7 @@ macro_rules! proto_assert_eq {
 // Helper functions invoking C++ Protobuf APIs directly in C++.
 // Defined in `test_utils.cc`.
 extern "C" {
+    fn TakeOwnershipAndGetOptionalInt32(msg: RawMessage) -> i32;
     fn DeserializeTestAllTypes(data: *const u8, len: usize) -> RawMessage;
     fn MutateTestAllTypes(msg: RawMessage);
     fn SerializeTestAllTypes(msg: RawMessage) -> protobuf_cpp::__runtime::SerializedData;
@@ -33,26 +34,20 @@ extern "C" {
 }
 
 #[test]
-fn mutate_message_in_cpp() {
+fn send_to_cpp() {
     let mut msg1 = TestAllTypes::new();
-    unsafe {
-        MutateTestAllTypes(msg1.__unstable_cpp_repr_grant_permission_to_break());
-    }
-
-    let mut msg2 = TestAllTypes::new();
-    msg2.set_optional_int64(42);
-    msg2.set_optional_bytes(b"something mysterious");
-    msg2.set_optional_bool(false);
-
-    proto_assert_eq!(msg1, msg2);
+    msg1.set_optional_int32(7);
+    let i = unsafe {
+        TakeOwnershipAndGetOptionalInt32(msg1.__unstable_leak_cpp_repr_grant_permission_to_break())
+    };
+    assert_eq!(i, 7);
 }
 
 #[test]
 fn mutate_message_mut_in_cpp() {
     let mut msg1 = TestAllTypes::new();
-    let mut msg_mut = msg1.as_mut();
     unsafe {
-        MutateTestAllTypes(msg_mut.__unstable_cpp_repr_grant_permission_to_break());
+        MutateTestAllTypes(msg1.as_mut().__unstable_cpp_repr_grant_permission_to_break());
     }
 
     let mut msg2 = TestAllTypes::new();
@@ -139,7 +134,8 @@ fn smuggle_extension() {
     let data = msg1.serialize();
 
     let mut msg2 = TestAllExtensions::parse(&data).unwrap();
-    let bytes =
-        unsafe { GetBytesExtension(msg2.__unstable_cpp_repr_grant_permission_to_break()).as_ref() };
-    assert_eq!(&*bytes, b"smuggled");
+    let bytes = unsafe {
+        GetBytesExtension(msg2.as_mut().__unstable_cpp_repr_grant_permission_to_break()).as_ref()
+    };
+    assert_eq!(bytes, b"smuggled");
 }

rust/test/cpp/interop/test_utils.cc

@@ -6,6 +6,7 @@
 // https://developers.google.com/open-source/licenses/bsd
 
 #include <cstddef>
+#include <cstdint>
 
 #include "absl/strings/string_view.h"
 #include "rust/cpp_kernel/cpp_api.h"
@@ -44,3 +45,10 @@ extern "C" google::protobuf::rust_internal::PtrAndLen GetBytesExtension(
       proto->GetExtension(protobuf_unittest::optional_bytes_extension);
   return {bytes.data(), bytes.size()};
 }
+
+extern "C" int32_t TakeOwnershipAndGetOptionalInt32(
+    protobuf_unittest::TestAllTypes* msg) {
+  int32_t i = msg->optional_int32();
+  delete msg;
+  return i;
+}

src/google/protobuf/compiler/rust/message.cc

@@ -1102,8 +1102,9 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
         pub fn __unstable_wrap_cpp_grant_permission_to_break(msg: $pbi$::RawMessage) -> Self {
           Self { inner: $pbr$::MessageInner { msg } }
         }
-        pub fn __unstable_cpp_repr_grant_permission_to_break(&mut self) -> $pbi$::RawMessage {
-          self.raw_msg()
+        pub fn __unstable_leak_cpp_repr_grant_permission_to_break(self) -> $pbi$::RawMessage {
+          let s = std::mem::ManuallyDrop::new(self);
+          s.raw_msg()
         }
       }
 
@@ -1116,7 +1117,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             inner: $pbr$::MutatorMessageRef::from_raw_msg($pbi$::Private, msg)
           }
         }
-        pub fn __unstable_cpp_repr_grant_permission_to_break(&mut self) -> $pbi$::RawMessage {
+        pub fn __unstable_cpp_repr_grant_permission_to_break(self) -> $pbi$::RawMessage {
           self.raw_msg()
         }
       }
@@ -1128,7 +1129,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
           msg: &'a $pbi$::RawMessage) -> Self {
           Self::new($pbi$::Private, *msg)
         }
-        pub fn __unstable_cpp_repr_grant_permission_to_break(&self) -> $pbi$::RawMessage {
+        pub fn __unstable_cpp_repr_grant_permission_to_break(self) -> $pbi$::RawMessage {
           self.msg
         }
       }