Prefixed attributes are not detected as duplicated

[samueltardieu]

Summary

Although the mechanism for checking inner meta items is present in the lint logic, it doesn't properly account for the fact that inner meta items will not have their name (which contains, e.g., allow, deny, etc.) set when recursing.

Found while working on #14855.

@rustbot label "+good first issue"

Lint Name

duplicated_attributes

Reproducer

I tried this code:

#![deny(unused, unused, clippy::duplicated_attributes, clippy::duplicated_attributes)]

fn main() {}

I expected to see this happen: two errors, one for the duplication of #![deny(unused)], and one for the duplication of #![deny(clippy::dupplicated_attributes)].

Instead, this happened:

Only the duplication of #[deny(unused)] is detected.

error: duplicated attribute
 --> /tmp/t.rs:1:17
  |
1 | #![deny(unused, unused, clippy::duplicated_attributes, clippy::duplicated_attributes)]
  |                 ^^^^^^
  |
note: first defined here
 --> /tmp/t.rs:1:9
  |
1 | #![deny(unused, unused, clippy::duplicated_attributes, clippy::duplicated_attributes)]
  |         ^^^^^^
help: remove this attribute
 --> /tmp/t.rs:1:17
  |
1 | #![deny(unused, unused, clippy::duplicated_attributes, clippy::duplicated_attributes)]
  |                 ^^^^^^
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#duplicated_attributes
note: the lint level is defined here
 --> /tmp/t.rs:1:56
  |
1 | #![deny(unused, unused, clippy::duplicated_attributes, clippy::duplicated_attributes)]
  |                                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: aborting due to 1 previous error

Version

rustc 1.89.0-nightly (70b3f4666 2025-05-30)
binary: rustc
commit-hash: 70b3f4666e24ce22fc32f5e357dbcf85d3254e63
commit-date: 2025-05-30
host: x86_64-unknown-linux-gnu
release: 1.89.0-nightly
LLVM version: 20.1.5

[a-yossy]

@rustbot claim