clippy::needless_return quick fix changes functionality of code

[DusterTheFirst]

rust-analyzer version: 0.3.1293-standalone

rustc version: rustc 1.66.0-beta.2 (0040709e3 2022-11-20)

Reproduction code:

use std::process::ExitCode;

fn main() -> ExitCode {
    return ExitCode::SUCCESS;
}

Quick fix in question:

The quick ""Fix"" removes the return, but not the semicolon, thus making the value no longer get returned:

[bjorn3]

Does the suggestion returned by clippy remove the semicolon? If not, this is a clippy bug.

[DusterTheFirst]

cargo clippy --fix produces

use std::process::ExitCode;

fn main() -> ExitCode {
    ExitCode::SUCCESS
}

[lowr]

You need the following settings to reproduce (with beta toolchain installed):

{
    "rust-analyzer.checkOnSave.command": "clippy",
    "rust-analyzer.server.extraEnv": { "RUSTUP_TOOLCHAIN": "beta" }
}

The problem is that, due to rust-lang/rust-clippy#9497, needless_return now produces multiple subdiagnostics, one for removing return and others for removing (possibly multiple) semicolons. If you hover on the line, you can see "remove this semicolon" message, and you can actually apply the quick fix if you place your cursor around the semicolon.

"remove this semicolon" diagnostics are hidden when you run clippy in terminal (see Diagnostic::tool_only_span_suggestion()) so ideally we'd want to coalesce them into the "primary" quickfix (remove return), but I'm not sure if we have any way to distinguish those hidden ones from others without special-casing every such diagnostic. Or can we just coalesce all subdiagnostics that have machine-applicable fix into one?

[kpreid]

I remember seeing this misbehavior myself, but I cannot reproduce it now (Rust 1.77.0 and RA 0.3.1896-standalone (6f6b03f 2024-03-24)) — the only relevant quick fix option removes both the "return" and the ";". Perhaps this issue can be closed as fixed.

[DusterTheFirst]

I can agree. With rust-analyzer 1.78.0-beta.2 (277d06b 2024-03-23) and rustc 1.78.0-beta.2 (277d06bc9 2024-03-23) the quick fix removes both the semicolon and the return statement. I will close this as resolved.