hang in <clippy_lints::needless_pass_by_ref_mut::MutablyUsedVariablesCtxt>::add_mutably_used_var

[matthiaskrgr]

Summary

I don't have any code yet, I noticed this checking rustc_mir_dataflow with clippy that it seemed to hang.

Reproducer

I tried this code:

<code>

I expected to see this happen:

Instead, this happened:

Version

rustc 1.73.0-nightly (4eaad89dc 2023-07-17)
binary: rustc
commit-hash: 4eaad89dce57da09cebbf651e9ac3bd3292b4725
commit-date: 2023-07-17
host: x86_64-unknown-linux-gnu
release: 1.73.0-nightly
LLVM version: 16.0.5

Additional Labels

No response

[matthiaskrgr]

rust-clippy/clippy_lints/src/needless_pass_by_ref_mut.rs

Line 205 in d4a6634

while let Some(id) = self.aliases.get(&used_id) {

there's a suspicious while loop there but I'm not sure it would seemingly loop infinitly (for 20+ minutes on a single crate)

[GuillaumeGomez]

Is the problem still present?

EDIT: forgot to precise: I added a cycle check to prevent this problem so if it's still present, I need to fix it.