The trait `Message` is not implemented

[kurudj]

Bug Report

Version

│ │ └── tonic v0.12.1 │ │ └── tonic-build v0.12.1 │ ├── tonic v0.12.1 (*)

Platform

6.1.82-99.168.amzn2023.x86_64

Description

Upon generating Rust files from proto files as well as a service, the service build yields an issue with Message trait not being implemented for a struct generated from a proto message, despite the Rust file explicitly having a ::prost::Message derive.

I tried this code:

tonic_build::configure()
        .build_server(true)
        .out_dir("src")
        .type_attribute(".", "#[derive(serde::Serialize, serde::Deserialize)]")
        .compile(&["MyStruct.proto"], &["src/raw/structs"])?;*/

tonic_build::configure().build_server(true).out_dir("src").compile(&["MyStructService.proto"], &["src/raw/structs"])?;

Where the Cargo.toml is:

[dependencies]
tonic = "0.12"
prost = "0.13"
serde = { version = "1.0", features = ["derive"] }

[build-dependencies]
tonic-build = "0.12"

This yields a MyStruct.rs with my main message as a struct:

#[derive(serde::Serialize, serde::Deserialize)]
#[allow(clippy::derive_partial_eq_without_eq)]
#[derive(Clone, PartialEq, ::prost::Message)]
pub struct MyStruct {

Within the service the following code throws the following errors:

error[E0277]: the trait bound `MyStruct: Message` is not satisfied
    |
242 |                         let mut grpc = tonic::server::Grpc::new(codec)
    |                                        ------------------------ ^^^^^ the trait `Message` is not implemented for `MyStruct`, which is required by `ProstCodec<_, _>: Codec`
    |                                        |
    |                                        required by a bound introduced by this call

[Frank-Krick]

I had a similar issue, with 170 or so build errors related to prost::Message and other traits. What solved it for me was adding prost to the project dependencies. Looks like a similar thing to me, so maybe that'll help.

[dmitrygrigoryev]

Have the same problem in my project. Maybe somebody can share an any workaround to fix this problem?

[Frank-Krick]

Does adding prost to your dependencies help? cargo add prost

[dmitrygrigoryev]

Combination of tonic 0.9.2 and prost/prost-types 0.11.9 works! I think there were a mess between dependencies, cause one of my dependencies locks the tonic version to 0.9.2. It is just proposal.

My Cargo.toml with newest versions of dependencies was:

[dependencies]
prost = "0.13.3"
prost-types = "0.13.3"
dependency_with_tonic0.9.2 = { path = "../../libraries/dependency_with_tonic0.9.2", default-features = false}
tonic = "0.12.3"

So, yes I've tried to add prost to dependencies, in my case it did not help(.

[H-0-O]

Just adding prost then everything works in 0.12.3

[p-kraszewski]

I know this is well past due time: I was hit by same problem "the trait Message is not implemented for...".

In my case it was tonic and tonic-build in v0.13.1, but prost in v0.14.1. The cause was version mismatch between prost and tonic*. When I forced prost to v.0.13, the project built flawlessly.

[LucioFranco]

This is an expected error message when prost and tonic do not match. Not much we can do to improve this message as it comes from the compiler.

[p-kraszewski]

I wish https://docs.rs/tonic-build/latest/tonic_build/ was explicit about that versions must match.

My understanding of the

[dependencies]
tonic = <tonic-version>
prost = <prost-version>

[build-dependencies]
tonic-build = <tonic-version>

was that they don't have to - that's why they used separate <tonic-version> and <prost-version>. There is not a single word about version matching throughout the docs.