Allow attribute does not surpress unknown_or_malformed_diagnostic_attributes

[SpecificProtagonist]

Code

trait _Trait {}
#[allow(unknown_or_malformed_diagnostic_attributes)]
#[diagnostic::abcdef]
impl _Trait for () {}

Current output

warning: unknown diagnostic attribute
 --> src/lib.rs:3:15
  |
3 | #[diagnostic::abcdef]
  |               ^^^^^^
  |
  = note: `#[warn(unknown_or_malformed_diagnostic_attributes)]` on by default

warning: `playground` (lib) generated 1 warning

Desired output

(no warning)

Rationale and extra context

See bevyengine/bevy#17441 for a case where this comes up, where it can't be worked around by introducing a module (because of #79260) or allowing it globally because the lint triggers in a macro.

Rust Version

rustc 1.86.0-nightly (9a1d156f3 2025-01-19)
binary: rustc
commit-hash: 9a1d156f38c51441ee51e5a068f1d0caf4bb0f27
commit-date: 2025-01-19
host: x86_64-unknown-linux-gnu
release: 1.86.0-nightly
LLVM version: 19.1.7