multiple_unsafe_ops_per_block should not warn external macros

[taiki-e]

Summary

multiple_unsafe_ops_per_block currently warns of unsafe code generated by external macros, but it should not. (there is no way for the user to fix it.)

Mentioning @Niki4tap who implemented this lint in #10206.

Lint Name

multiple_unsafe_ops_per_block

Reproducer

I tried this code:

# Cargo.toml
[package]
name = "repro"
version = "0.1.0"
edition = "2021"

[dependencies]
pin-project = "=1.0.12"

// src/lib.rs
#![warn(clippy::multiple_unsafe_ops_per_block)]

#[pin_project::pin_project(project_replace)]
struct S {
    f: (),
}

I saw this happen:

warning: this `unsafe` block contains 4 unsafe operations, expected only one
 --> src/lib.rs:3:1
  |
3 | #[pin_project::pin_project(project_replace)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
note: unsafe method call occurs here
 --> src/lib.rs:3:1
  |
3 | #[pin_project::pin_project(project_replace)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: unsafe function call occurs here
 --> src/lib.rs:3:1
  |
3 | #[pin_project::pin_project(project_replace)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: raw pointer dereference occurs here
 --> src/lib.rs:3:1
  |
3 | #[pin_project::pin_project(project_replace)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: unsafe function call occurs here
 --> src/lib.rs:3:1
  |
3 | #[pin_project::pin_project(project_replace)]
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#multiple_unsafe_ops_per_block
note: the lint level is defined here
 --> src/lib.rs:1:9
  |
1 | #![warn(clippy::multiple_unsafe_ops_per_block)]
  |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  = note: this warning originates in the derive macro `::pin_project::__private::__PinProjectInternalDerive` (in Nightly builds, run with -Z macro-backtrace for more info)

I expected to see this happen: no warnings

Version

rustc 1.69.0-nightly (e972bc808 2023-01-29)
binary: rustc
commit-hash: e972bc8083d5228536dfd42913c8778b6bb04c8e
commit-date: 2023-01-29
host: aarch64-apple-darwin
release: 1.69.0-nightly
LLVM version: 15.0.7

Additional Labels

No response

[Niki4tap]

@rustbot claim

Thanks for the report!

To be honest, I didn't even consider the lint triggering in external macros, but after this report it seems so obvious, sorry for overlooking this :v

The fix should be pretty simple, I'll PR it asap.

[taiki-e]

Thanks for the quick fix!