hpb: Introduce set_alias on maps for (k,v) where v is a message

PiperOrigin-RevId: 684446420

hpb_generator/gen_accessors.cc

@@ -181,6 +181,8 @@ void WriteMapFieldAccessors(const protobuf::Descriptor* desc,
         R"cc(
           bool set_$0($1 key, $3 value);
           bool set_$0($1 key, $4 value);
+          bool set_alias_$0($1 key, $3 value);
+          bool set_alias_$0($1 key, $4 value);
           absl::StatusOr<$3> get_$0($1 key);
         )cc",
         resolved_field_name, CppConstType(key), CppConstType(val),
@@ -338,6 +340,28 @@ void WriteMapAccessorDefinitions(const protobuf::Descriptor* message,
         converted_key_name, upbc_name,
         ::upb::generator::MiniTableMessageVarName(
             val->message_type()->full_name()));
+    output(
+        R"cc(
+          bool $0::set_alias_$1($2 key, $3 value) {
+            $6return $4_$8_set(
+                msg_, $7, ($5*)hpb::interop::upb::GetMessage(value), arena_);
+          }
+        )cc",
+        class_name, resolved_field_name, CppConstType(key),
+        MessagePtrConstType(val, /* is_const */ true), MessageName(message),
+        MessageName(val->message_type()), optional_conversion_code,
+        converted_key_name, upbc_name);
+    output(
+        R"cc(
+          bool $0::set_alias_$1($2 key, $3 value) {
+            $6return $4_$8_set(
+                msg_, $7, ($5*)hpb::interop::upb::GetMessage(value), arena_);
+          }
+        )cc",
+        class_name, resolved_field_name, CppConstType(key),
+        MessagePtrConstType(val, /* is_const */ false), MessageName(message),
+        MessageName(val->message_type()), optional_conversion_code,
+        converted_key_name, upbc_name);
     output(
         R"cc(
           absl::StatusOr<$3> $0::get_$1($2 key) {
@@ -462,6 +486,15 @@ void WriteUsingAccessorsInHeader(const protobuf::Descriptor* desc,
               using $0Access::set_$1;
             )cc",
             class_name, resolved_field_name);
+        // only emit set_alias for maps when value is a message
+        if (field->message_type()->FindFieldByNumber(2)->cpp_type() ==
+            protobuf::FieldDescriptor::CPPTYPE_MESSAGE) {
+          output(
+              R"cc(
+                using $0Access::set_alias_$1;
+              )cc",
+              class_name, resolved_field_name);
+        }
       }
     } else if (desc->options().map_entry()) {
       // TODO Implement map entry

hpb_generator/tests/set_alias.proto

@@ -21,3 +21,7 @@ message Parent {
 message ParentWithRepeated {
   repeated Child children = 1;
 }
+
+message ParentWithMap {
+  map<int32, Child> child_map = 1;
+}

hpb_generator/tests/test_generated.cc

@@ -41,6 +41,7 @@ using ::hpb_unittest::protos::container_ext;
 using ::hpb_unittest::protos::ContainerExtension;
 using ::hpb_unittest::protos::other_ext;
 using ::hpb_unittest::protos::Parent;
+using ::hpb_unittest::protos::ParentWithMap;
 using ::hpb_unittest::protos::ParentWithRepeated;
 using ::hpb_unittest::protos::RED;
 using ::hpb_unittest::protos::TestEnum;
@@ -1299,4 +1300,23 @@ TEST(CppGeneratedCode, SetAliasRepeatedFailsForDifferentArena) {
   EXPECT_DEATH(parent.add_alias_children(child), "hpb::interop::upb::GetArena");
 }
 
+TEST(CppGeneratedCode, SetAliasMap) {
+  hpb::Arena arena;
+  auto parent1 = hpb::CreateMessage<ParentWithMap>(arena);
+  auto parent2 = hpb::CreateMessage<ParentWithMap>(arena);
+
+  auto child = hpb::CreateMessage<Child>(arena);
+
+  constexpr int key = 1;
+  parent1.set_alias_child_map(key, child);
+  parent2.set_alias_child_map(key, child);
+  auto c1 = parent1.get_child_map(key);
+  auto c2 = parent2.get_child_map(key);
+
+  EXPECT_TRUE(c1.ok());
+  EXPECT_TRUE(c2.ok());
+  ASSERT_EQ(hpb::interop::upb::GetMessage(c1.value()),
+            hpb::interop::upb::GetMessage(c2.value()));
+}
+
 }  // namespace