Introduce weirder names for the oneof generated structs to minimize collisions.

Given:
oneof hello_world {}

We now generate:
fn hello_world(&self) -> HelloWorldOneof
fn hello_world_case(&self) -> HelloWorldCase

This change is to help mitigate a realistic risk of collisions in cases like:

message M {
  oneof x { ... }
  enum X { ... }
}

PiperOrigin-RevId: 714998247

rust/test/shared/accessors_proto3_test.rs

@@ -173,7 +173,7 @@ fn test_foreign_enum_accessors() {
 
 #[gtest]
 fn test_oneof_accessors() {
-    use test_all_types::OneofField::*;
+    use test_all_types::OneofFieldOneof::*;
 
     let mut msg = TestAllTypes::new();
     assert_that!(msg.oneof_field(), matches_pattern!(not_set(_)));
@@ -202,7 +202,7 @@ fn test_oneof_accessors() {
 
 #[gtest]
 fn test_oneof_accessors_view_long_lifetime() {
-    use test_all_types::OneofField::*;
+    use test_all_types::OneofFieldOneof::*;
 
     let mut msg = TestAllTypes::new();
     msg.set_oneof_uint32(7);
@@ -219,18 +219,18 @@ fn test_oneof_accessors_view_long_lifetime() {
 #[gtest]
 fn test_oneof_enum_accessors() {
     use unittest_proto3_rust_proto::{
-        test_oneof2::{Foo, FooCase, NestedEnum},
+        test_oneof2::{FooCase, FooOneof, NestedEnum},
         TestOneof2,
     };
 
     let mut msg = TestOneof2::new();
     assert_that!(msg.foo_enum_opt(), eq(Optional::Unset(NestedEnum::Unknown)));
-    assert_that!(msg.foo(), matches_pattern!(Foo::not_set(_)));
+    assert_that!(msg.foo(), matches_pattern!(FooOneof::not_set(_)));
     assert_that!(msg.foo_case(), matches_pattern!(FooCase::not_set));
 
     msg.set_foo_enum(NestedEnum::Bar);
     assert_that!(msg.foo_enum_opt(), eq(Optional::Set(NestedEnum::Bar)));
-    assert_that!(msg.foo(), matches_pattern!(Foo::FooEnum(eq(NestedEnum::Bar))));
+    assert_that!(msg.foo(), matches_pattern!(FooOneof::FooEnum(eq(NestedEnum::Bar))));
     assert_that!(msg.foo_case(), matches_pattern!(FooCase::FooEnum));
 }
 

rust/test/shared/accessors_test.rs

@@ -767,7 +767,7 @@ fn test_default_import_enum_accessors() {
 
 #[gtest]
 fn test_oneof_accessors() {
-    use unittest_rust_proto::test_oneof2::{Foo::*, FooCase, NestedEnum};
+    use unittest_rust_proto::test_oneof2::{FooCase, FooOneof::*, NestedEnum};
     use unittest_rust_proto::TestOneof2;
 
     let mut msg = TestOneof2::new();
@@ -818,7 +818,7 @@ fn test_oneof_accessors() {
 
 #[gtest]
 fn test_msg_oneof_default_accessors() {
-    use unittest_rust_proto::test_oneof2::{Bar::*, BarCase, NestedEnum};
+    use unittest_rust_proto::test_oneof2::{BarCase, BarOneof::*, NestedEnum};
 
     let mut msg = unittest_rust_proto::TestOneof2::new();
     assert_that!(msg.bar(), matches_pattern!(not_set(_)));

rust/test/shared/fields_with_imported_types_test.rs

@@ -30,13 +30,21 @@ fn test_enum_field_generated() {
 
 #[gtest]
 fn test_oneof_message_field_generated() {
-    use fields_with_imported_types_rust_proto::msg_with_fields_with_imported_types::ImportedTypesOneof::not_set;
-    use fields_with_imported_types_rust_proto::MsgWithFieldsWithImportedTypes;
+    use fields_with_imported_types_rust_proto::{
+        msg_with_fields_with_imported_types, MsgWithFieldsWithImportedTypes,
+    };
     use imported_types_rust_proto::ImportedEnum;
     use imported_types_rust_proto::ImportedMessageView;
 
     let msg = MsgWithFieldsWithImportedTypes::new();
     assert_that!(msg.imported_message_oneof(), matches_pattern!(ImportedMessageView { .. }));
     assert_that!(msg.imported_enum_oneof(), eq(ImportedEnum::Unknown));
-    assert_that!(msg.imported_types_oneof(), matches_pattern!(not_set(_)));
+    assert_that!(
+        msg.imported_types_oneof(),
+        matches_pattern!(msg_with_fields_with_imported_types::ImportedTypesOneofOneof::not_set(_))
+    );
+    assert_that!(
+        msg.imported_types_oneof_case(),
+        matches_pattern!(msg_with_fields_with_imported_types::ImportedTypesOneofCase::not_set)
+    );
 }

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

@@ -333,13 +333,19 @@ std::string EnumValueRsName(const MultiCasePrefixStripper& stripper,
   return RsSafeName(name);
 }
 
-std::string OneofViewEnumRsName(const OneofDescriptor& oneof) {
+std::string DeprecatedOneofViewEnumRsName(const OneofDescriptor& oneof) {
   return RsSafeName(SnakeToUpperCamelCase(oneof.name()));
 }
 
+std::string OneofViewEnumRsName(const OneofDescriptor& oneof) {
+  return SnakeToUpperCamelCase(oneof.name()) + "Oneof";
+}
+
 std::string OneofCaseEnumRsName(const OneofDescriptor& oneof) {
-  // Note: This is the name used for the cpp Case enum, we use it for both
-  // the Rust Case enum as well as for the cpp case enum in the cpp thunk.
+  return SnakeToUpperCamelCase(oneof.name()) + "Case";
+}
+
+std::string OneofCaseEnumCppName(const OneofDescriptor& oneof) {
   return SnakeToUpperCamelCase(oneof.name()) + "Case";
 }
 

src/google/protobuf/compiler/rust/naming.h

@@ -63,8 +63,14 @@ std::string RsViewType(Context& ctx, const FieldDescriptor& field,
 std::string EnumRsName(const EnumDescriptor& desc);
 std::string EnumValueRsName(const EnumValueDescriptor& value);
 
+// The old names for these types, which we intend to imminently burn down
+// to avoid collisions.
+std::string DeprecatedOneofViewEnumRsName(const OneofDescriptor& oneof);
+
 std::string OneofViewEnumRsName(const OneofDescriptor& oneof);
 std::string OneofCaseEnumRsName(const OneofDescriptor& oneof);
+
+std::string OneofCaseEnumCppName(const OneofDescriptor& oneof);
 std::string OneofCaseRsName(const FieldDescriptor& oneof_field);
 
 std::string FieldInfoComment(Context& ctx, const FieldDescriptor& field);

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

@@ -37,7 +37,7 @@ namespace rust {
 // Example:
 // For this oneof:
 // message SomeMsg {
-//   oneof some_oneof {
+//   oneof some {
 //     int32 field_a = 7;
 //     SomeMsg field_b = 9;
 //   }
@@ -52,7 +52,7 @@ namespace rust {
 //   }
 //
 //   #[repr(C)]
-//   pub enum SomeOneofCase {
+//   pub enum SomeCase {
 //     FieldA = 7,
 //     FieldB = 9,
 //     not_set = 0
@@ -60,25 +60,15 @@ namespace rust {
 // }
 // impl SomeMsg {
 //   pub fn some_oneof(&self) -> SomeOneof {...}
-//   pub fn some_oneof_case(&self) -> SomeOneofCase {...}
+//   pub fn some_oneof_case(&self) -> SomeCase {...}
 // }
 // impl SomeMsgMut {
 //   pub fn some_oneof(&self) -> SomeOneof {...}
-//   pub fn some_oneof_case(&self) -> SomeOneofCase {...}
+//   pub fn some_oneof_case(&self) -> SomeCase {...}
 // }
 // impl SomeMsgView {
 //   pub fn some_oneof(self) -> SomeOneof {...}
-//   pub fn some_oneof_case(self) -> SomeOneofCase {...}
-// }
-//
-// An additional "Case" enum which just reflects the corresponding slot numbers
-// is emitted for usage with the FFI (exactly matching the Case struct that both
-// cpp and upb generate).
-//
-// #[repr(C)] pub(super) enum SomeOneofCase {
-//   FieldA = 7,
-//   FieldB = 9,
-//   not_set = 0
+//   pub fn some_oneof_case(self) -> SomeCase {...}
 // }
 
 namespace {
@@ -134,6 +124,7 @@ std::string RsTypeNameView(Context& ctx, const FieldDescriptor& field) {
 void GenerateOneofDefinition(Context& ctx, const OneofDescriptor& oneof) {
   ctx.Emit(
       {
+          {"deprecated_view_enum_name", DeprecatedOneofViewEnumRsName(oneof)},
           {"view_enum_name", OneofViewEnumRsName(oneof)},
           {"view_fields",
            [&] {
@@ -164,9 +155,11 @@ void GenerateOneofDefinition(Context& ctx, const OneofDescriptor& oneof) {
       pub enum $view_enum_name$<'msg> {
         $view_fields$
 
-        #[allow(non_camel_case_types)]
         not_set(std::marker::PhantomData<&'msg ()>) = 0
       }
+
+      #[deprecated(note="Use $view_enum_name$ instead (will be imminently moved)")]
+      pub use $view_enum_name$ as $deprecated_view_enum_name$;
       )rs");
 
   // Note: This enum is used as the Thunk return type for getting which case is
@@ -205,7 +198,6 @@ void GenerateOneofDefinition(Context& ctx, const OneofDescriptor& oneof) {
       pub enum $case_enum_name$ {
         $cases$
 
-        #[allow(non_camel_case_types)]
         not_set = 0
       }
 
@@ -313,7 +305,7 @@ void GenerateOneofThunkCc(Context& ctx, const OneofDescriptor& oneof) {
   ctx.Emit(
       {
           {"oneof_name", oneof.name()},
-          {"case_enum_name", OneofCaseEnumRsName(oneof)},
+          {"case_enum_name", OneofCaseEnumCppName(oneof)},
           {"case_thunk", ThunkName(ctx, oneof, "case")},
           {"QualifiedMsg", cpp::QualifiedClassName(oneof.containing_type())},
       },