Move `msg.merge_from(othermsg)` onto a trait fn

PiperOrigin-RevId: 659662640

rust/codegen_traits.rs

@@ -14,7 +14,7 @@ use create::Parse;
 use interop::{MessageMutInterop, MessageViewInterop, OwnedMessageInterop};
 use read::Serialize;
 use std::fmt::Debug;
-use write::{Clear, ClearAndParse};
+use write::{Clear, ClearAndParse, MergeFrom};
 
 /// A trait that all generated owned message types implement.
 pub trait Message: SealedInternal
@@ -24,7 +24,7 @@ pub trait Message: SealedInternal
   // Read traits:
   + Debug + Serialize
   // Write traits:
-  + Clear + ClearAndParse
+  + Clear + ClearAndParse + MergeFrom
   // Thread safety:
   + Send + Sync
   // Copy/Clone:
@@ -57,7 +57,7 @@ pub trait MessageMut<'msg>: SealedInternal
     + Debug + Serialize
     // Write traits:
     // TODO: MsgMut should impl ClearAndParse.
-    + Clear
+    + Clear + MergeFrom
     // Thread safety:
     + Sync
     // Copy/Clone:
@@ -94,6 +94,7 @@ pub(crate) mod read {
 /// traits.
 pub(crate) mod write {
     use super::SealedInternal;
+    use crate::AsView;
 
     pub trait Clear: SealedInternal {
         fn clear(&mut self);
@@ -102,6 +103,10 @@ pub(crate) mod write {
     pub trait ClearAndParse: SealedInternal {
         fn clear_and_parse(&mut self, data: &[u8]) -> Result<(), crate::ParseError>;
     }
+
+    pub trait MergeFrom: AsView + SealedInternal {
+        fn merge_from(&mut self, src: impl AsView<Proxied = Self::Proxied>);
+    }
 }
 
 /// Traits related to interop with C or C++.

rust/prelude.rs

@@ -11,6 +11,6 @@
 //! or less common items should be imported normally.
 
 pub use crate::{
-    proto, AsMut, AsView, Clear, ClearAndParse, IntoMut, IntoView, Message, MessageMut,
+    proto, AsMut, AsView, Clear, ClearAndParse, IntoMut, IntoView, MergeFrom, Message, MessageMut,
     MessageView, Parse, Serialize,
 };

rust/proto_macro.rs

@@ -50,7 +50,7 @@ macro_rules! proto_internal {
     };
 
     (@merge $msg:ident ..$expr:expr) => {
-        $msg.merge_from($expr);
+        $crate::MergeFrom::merge_from(&mut $msg, $expr);
     };
 
     // @msg rules are used to set the fields of the message. There is a lot of duplication here

rust/shared.rs

@@ -26,7 +26,7 @@ pub mod __public {
         create::Parse,
         interop::{MessageMutInterop, MessageViewInterop, OwnedMessageInterop},
         read::Serialize,
-        write::{Clear, ClearAndParse},
+        write::{Clear, ClearAndParse, MergeFrom},
         Message, MessageMut, MessageView,
     };
     pub use crate::cord::{ProtoBytesCow, ProtoStringCow};

rust/test/shared/merge_from_test.rs

@@ -1,5 +1,5 @@
 use googletest::prelude::*;
-use protobuf::proto;
+use protobuf::prelude::*;
 use unittest_rust_proto::{NestedTestAllTypes, TestAllTypes};
 
 #[googletest::test]

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

@@ -334,7 +334,7 @@ void UpbGeneratedMessageTraitImpls(Context& ctx, const Descriptor& msg) {
   }
 }
 
-void MessageMergeFrom(Context& ctx, const Descriptor& msg) {
+void MessageMutMergeFrom(Context& ctx, const Descriptor& msg) {
   switch (ctx.opts().kernel) {
     case Kernel::kCpp:
       ctx.Emit(
@@ -342,10 +342,12 @@ void MessageMergeFrom(Context& ctx, const Descriptor& msg) {
               {"merge_from_thunk", ThunkName(ctx, msg, "merge_from")},
           },
           R"rs(
-          pub fn merge_from(&mut self, src: impl $pb$::AsView<Proxied = $Msg$>) {
-            // SAFETY: self and src are both valid `$Msg$`s.
-            unsafe {
-              $merge_from_thunk$(self.raw_msg(), src.as_view().raw_msg());
+          impl $pb$::MergeFrom for $Msg$Mut<'_> {
+            fn merge_from(&mut self, src: impl $pb$::AsView<Proxied = $Msg$>) {
+              // SAFETY: self and src are both valid `$Msg$`s.
+              unsafe {
+                $merge_from_thunk$(self.raw_msg(), src.as_view().raw_msg());
+              }
             }
           }
         )rs");
@@ -353,17 +355,19 @@ void MessageMergeFrom(Context& ctx, const Descriptor& msg) {
     case Kernel::kUpb:
       ctx.Emit(
           R"rs(
-          pub fn merge_from(&mut self, src: impl $pb$::AsView<Proxied = $Msg$>) {
-            // SAFETY: self and src are both valid `$Msg$`s.
-            unsafe {
-              assert!(
-                $pbr$::upb_Message_MergeFrom(self.raw_msg(),
-                  src.as_view().raw_msg(),
-                  <Self as $pbr$::AssociatedMiniTable>::MINI_TABLE,
-                  // Use a nullptr for the ExtensionRegistry.
-                  $std$::ptr::null(),
-                  self.arena().raw())
-              );
+          impl $pb$::MergeFrom for $Msg$Mut<'_> {
+            fn merge_from(&mut self, src: impl $pb$::AsView<Proxied = $Msg$>) {
+              // SAFETY: self and src are both valid `$Msg$`s.
+              unsafe {
+                assert!(
+                  $pbr$::upb_Message_MergeFrom(self.raw_msg(),
+                    src.as_view().raw_msg(),
+                    <Self as $pbr$::AssociatedMiniTable>::MINI_TABLE,
+                    // Use a nullptr for the ExtensionRegistry.
+                    $std$::ptr::null(),
+                    self.arena().raw())
+                );
+              }
             }
           }
         )rs");
@@ -853,6 +857,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
        {"Msg::clear_and_parse", [&] { MessageClearAndParse(ctx, msg); }},
        {"Msg::drop", [&] { MessageDrop(ctx, msg); }},
        {"Msg::debug", [&] { MessageDebug(ctx, msg); }},
+       {"MsgMut::merge_from", [&] { MessageMutMergeFrom(ctx, msg); }},
        {"Msg_externs", [&] { MessageExterns(ctx, msg); }},
        {"accessor_fns",
         [&] {
@@ -955,7 +960,6 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
        {"into_proxied_impl", [&] { IntoProxiedForMessage(ctx, msg); }},
        {"upb_generated_message_trait_impls",
         [&] { UpbGeneratedMessageTraitImpls(ctx, msg); }},
-       {"msg_merge_from", [&] { MessageMergeFrom(ctx, msg); }},
        {"repeated_impl", [&] { MessageProxiedInRepeated(ctx, msg); }},
        {"map_value_impl", [&] { MessageProxiedInMapValue(ctx, msg); }},
        {"unwrap_upb",
@@ -998,6 +1002,13 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
           }
         }
 
+        impl $pb$::MergeFrom for $Msg$ {
+          fn merge_from<'src>(&mut self, src: impl $pb$::AsView<Proxied = Self>) {
+            let mut m = self.as_mut();
+            $pb$::MergeFrom::merge_from(&mut m, src)
+          }
+        }
+
         impl $pb$::Serialize for $Msg$ {
           fn serialize(&self) -> Result<Vec<u8>, $pb$::SerializeError> {
             $pb$::AsView::as_view(self).serialize()
@@ -1141,6 +1152,8 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
           }
         }
 
+        $MsgMut::merge_from$
+
         #[allow(dead_code)]
         impl<'msg> $Msg$Mut<'msg> {
           #[doc(hidden)]
@@ -1173,8 +1186,6 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             $pb$::AsView::as_view(self).to_owned()
           }
 
-          $msg_merge_from$
-
           $raw_arena_getter_for_msgmut$
 
           $accessor_fns_for_muts$
@@ -1248,10 +1259,6 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             $Msg$Mut::new($pbi$::Private, &mut self.inner)
           }
 
-          pub fn merge_from<'src>(&mut self, src: impl $pb$::Proxy<'src, Proxied = $Msg$>) {
-            self.as_mut().merge_from(src);
-          }
-
           $accessor_fns$
         }  // impl $Msg$