tonic::Result and tonic::Status trigger clippy::result_large_err on rust 1.87

[eric-seppanen]

Bug Report

While testing the rust 1.87 beta toolchain, I noticed that clippy now raises warnings on any code that uses tonic::Result or otherwise contains a tonic::Status in its Err variant. The result_large_err lint is enabled by default.

I don't have an opinion about whether clippy's thresholds are correct; just wanted to give the tonic developers a heads-up as this will probably trigger warnings in a lot of downstream code that uses tonic.

Version

tonic v0.13.0 (also happens with tonic 0.12.3).

Description

Here's a trivial example that shows the warnings:

pub fn thing1() -> tonic::Result<()> {
    Ok(())
}

cargo +beta clippy says:

warning: the `Err`-variant returned from this function is very large
 --> src/lib.rs:1:19
  |
1 | pub fn hello() -> tonic::Result<()> {
  |                   ^^^^^^^^^^^^^^^^^ the `Err`-variant is at least 176 bytes
  |
  = help: try reducing the size of `tonic::Status`, for example by boxing large elements or replacing it with `Box<tonic::Status>`
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#result_large_err
  = note: `#[warn(clippy::result_large_err)]` on by default

Or alternatively, without explicitly using tonic::Result but propagating the error type:

pub enum MyError {
    Oops,
    Tonic(tonic::Status),
}

pub fn thing2() -> Result<(), MyError> {
    Ok(())
}

warning: the `Err`-variant returned from this function is very large
 --> src/lib.rs:6:20
  |
3 |     Tonic(tonic::Status),
  |     -------------------- the largest variant contains at least 176 bytes
...
6 | pub fn thing2() -> Result<(), MyError> {
  |                    ^^^^^^^^^^^^^^^^^^^
  |
  = help: try reducing the size of `MyError`, for example by boxing large elements or replacing it with `Box<MyError>`
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#result_large_err
  = note: `#[warn(clippy::result_large_err)]` on by default

[LucioFranco]

We can add this lint to codegen. I would welcome a PR.

[tustvold]

Have we considered extracting an inner boxed type, e.g. how reqwest handles this - https://docs.rs/reqwest/latest/src/reqwest/error.rs.html#17

[LucioFranco]

Yeah, my suggestion above was wrong, I think you're probably right @tustvold I would accept a PR for this and I can get a patch release out.