fix(prost-build): Remove derived(Copy) on boxed fields

Author: ldm0

prost-build/src/code_generator.rs

@@ -230,7 +230,7 @@ impl<'a> CodeGenerator<'a> {
         self.push_indent();
         self.buf.push_str(&format!(
             "#[derive(Clone, {}PartialEq, {}::Message)]\n",
-            if self.message_graph.can_message_derive_copy(&fq_message_name) {
+            if self.can_message_derive_copy(&fq_message_name) {
                 "Copy, "
             } else {
                 ""
@@ -615,10 +615,10 @@ impl<'a> CodeGenerator<'a> {
         self.append_enum_attributes(&oneof_name);
         self.push_indent();
 
-        let can_oneof_derive_copy = oneof.fields.iter().all(|field| {
-            self.message_graph
-                .can_field_derive_copy(fq_message_name, &field.descriptor)
-        });
+        let can_oneof_derive_copy = oneof
+            .fields
+            .iter()
+            .all(|field| self.can_field_derive_copy(fq_message_name, &field.descriptor));
         self.buf.push_str(&format!(
             "#[derive(Clone, {}PartialEq, {}::Oneof)]\n",
             if can_oneof_derive_copy { "Copy, " } else { "" },
@@ -1120,6 +1120,60 @@ impl<'a> CodeGenerator<'a> {
             message_name,
         )
     }
+
+    /// Returns `true` if this message can automatically derive Copy trait.
+    fn can_message_derive_copy(&self, fq_message_name: &str) -> bool {
+        assert_eq!(".", &fq_message_name[..1]);
+        self.message_graph
+            .get_message(fq_message_name)
+            .unwrap()
+            .field
+            .iter()
+            .all(|field| self.can_field_derive_copy(fq_message_name, field))
+    }
+
+    /// Returns `true` if the type of this field allows deriving the Copy trait.
+    fn can_field_derive_copy(&self, fq_message_name: &str, field: &FieldDescriptorProto) -> bool {
+        assert_eq!(".", &fq_message_name[..1]);
+
+        // repeated field cannot derive Copy
+        if field.label() == Label::Repeated {
+            false
+        } else if field.r#type() == Type::Message {
+            // nested and boxed messages cannot derive Copy
+            if self
+                .message_graph
+                .is_nested(field.type_name(), fq_message_name)
+                || self
+                    .config
+                    .boxed
+                    .get_first_field(fq_message_name, field.name())
+                    .is_some()
+            {
+                false
+            } else {
+                self.can_message_derive_copy(field.type_name())
+            }
+        } else {
+            matches!(
+                field.r#type(),
+                Type::Float
+                    | Type::Double
+                    | Type::Int32
+                    | Type::Int64
+                    | Type::Uint32
+                    | Type::Uint64
+                    | Type::Sint32
+                    | Type::Sint64
+                    | Type::Fixed32
+                    | Type::Fixed64
+                    | Type::Sfixed32
+                    | Type::Sfixed64
+                    | Type::Bool
+                    | Type::Enum
+            )
+        }
+    }
 }
 
 /// Returns `true` if the repeated field type can be packed.

prost-build/src/fixtures/field_attributes/_expected_field_attributes.rs

@@ -19,7 +19,7 @@ pub struct Foo {
     #[prost(string, tag="1")]
     pub foo: ::prost::alloc::string::String,
 }
-#[derive(Clone, Copy, PartialEq, ::prost::Message)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct Bar {
     #[prost(message, optional, boxed, tag="1")]
     pub qux: ::core::option::Option<::prost::alloc::boxed::Box<Qux>>,

prost-build/src/fixtures/field_attributes/_expected_field_attributes_formatted.rs

@@ -19,7 +19,7 @@ pub struct Foo {
     #[prost(string, tag = "1")]
     pub foo: ::prost::alloc::string::String,
 }
-#[derive(Clone, Copy, PartialEq, ::prost::Message)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct Bar {
     #[prost(message, optional, boxed, tag = "1")]
     pub qux: ::core::option::Option<::prost::alloc::boxed::Box<Qux>>,

prost-build/src/message_graph.rs

@@ -6,7 +6,7 @@ use petgraph::Graph;
 
 use prost_types::{
     field_descriptor_proto::{Label, Type},
-    DescriptorProto, FieldDescriptorProto, FileDescriptorProto,
+    DescriptorProto, FileDescriptorProto,
 };
 
 /// `MessageGraph` builds a graph of messages whose edges correspond to nesting.
@@ -74,6 +74,11 @@ impl MessageGraph {
         }
     }
 
+    /// Try get a message descriptor from current message graph
+    pub fn get_message(&self, message: &str) -> Option<&DescriptorProto> {
+        self.messages.get(message)
+    }
+
     /// Returns true if message type `inner` is nested in message type `outer`.
     pub fn is_nested(&self, outer: &str, inner: &str) -> bool {
         let outer = match self.index.get(outer) {
@@ -87,50 +92,4 @@ impl MessageGraph {
 
         has_path_connecting(&self.graph, outer, inner, None)
     }
-
-    /// Returns `true` if this message can automatically derive Copy trait.
-    pub fn can_message_derive_copy(&self, fq_message_name: &str) -> bool {
-        assert_eq!(".", &fq_message_name[..1]);
-        let msg = self.messages.get(fq_message_name).unwrap();
-        msg.field
-            .iter()
-            .all(|field| self.can_field_derive_copy(fq_message_name, field))
-    }
-
-    /// Returns `true` if the type of this field allows deriving the Copy trait.
-    pub fn can_field_derive_copy(
-        &self,
-        fq_message_name: &str,
-        field: &FieldDescriptorProto,
-    ) -> bool {
-        assert_eq!(".", &fq_message_name[..1]);
-
-        if field.label() == Label::Repeated {
-            false
-        } else if field.r#type() == Type::Message {
-            if self.is_nested(field.type_name(), fq_message_name) {
-                false
-            } else {
-                self.can_message_derive_copy(field.type_name())
-            }
-        } else {
-            matches!(
-                field.r#type(),
-                Type::Float
-                    | Type::Double
-                    | Type::Int32
-                    | Type::Int64
-                    | Type::Uint32
-                    | Type::Uint64
-                    | Type::Sint32
-                    | Type::Sint64
-                    | Type::Fixed32
-                    | Type::Fixed64
-                    | Type::Sfixed32
-                    | Type::Sfixed64
-                    | Type::Bool
-                    | Type::Enum
-            )
-        }
-    }
 }