unable to use type_attribute multiple times

[horacimacias]

Bug Report

I'm building .rs files from .proto files and using type_attribute to add some extra attributes to the .rs files.
Trying to use type_attribute multiple times seems to not work. Only the last type_attribute set is kept.
I'm using the same path on both type attributes; not sure if this is related to the issue or this is a misuse of such method.

Doing the same using tonic-build 0.4 shows the expected behaviour.

Version

tonic-build v0.5.0

Platform

Darwin computer.local 19.2.0 Darwin Kernel Version 19.2.0: Sat Nov 9 03:47:04 PST 2019; root:xnu-6153.61.1~20/RELEASE_X86_64 x86_64

Crates

tonic-build

Description

I tried this code:

fn main() -> Result<(), Box<dyn std::error::Error>> {
    tonic_build::configure()
        .out_dir("proto/helloworld/")
        .type_attribute(".", "// first attribute")
        .type_attribute(".", "// second attribute")
        .build_server(false)
        .compile(
            &["proto/helloworld/helloworld.proto"],
            &["proto/helloworld"],
        )?;
    Ok(())
}

This is a brand new cargo new tonic-build project with only tonic-build as dependency:

[package]
name = "tonic-build"
version = "0.1.0"
edition = "2018"

[dependencies]
tonic-build = "0.5.0"

I expected to see both "// first attribute" and "// second attribute" on the generated code.

Instead, I only see "// second attribute" on the generated code.
If I swap the type_attribute invocations, I only see "// first attribute" and not "// second attribute".

am I doing something wrong? Same code is working on tonic-build 0.4

as a workaround, I'm using something like:

.type_attribute(".", "// first attribute\n// second attribute")

[davidpdrsn]

That appears to be a bug in prost then. Tonic just forwards those attributes directly here. If you use prost-build directly, without tonic-build, does it work as expected?

[horacimacias]

thanks, and sorry I did not realise that.

Indeed, using the same sample project with prost-build = "0.8.0" dependency shows the same issue, so it does not look like it's caused by tonic.

I'll open an issue on prost.

[horacimacias]

FYI, issue already existed in prost: tokio-rs/prost#502

[davidpdrsn]

Thanks! It can sometimes be hard to know where the boundaries is between prost and tonic.