Auto merge of #10481 - blyxyas:allow_attribute, r=xFrednet

Add `allow_attribute` lint

Fixes #10468

changelog: new lint: [`allow_attributes`]
[#10481](https://github.com/rust-lang/rust-clippy/pull/10481)

tests/ui/allow_attributes.fixed

@@ -0,0 +1,25 @@
+// run-rustfix
+#![allow(unused)]
+#![warn(clippy::allow_attributes)]
+#![feature(lint_reasons)]
+
+fn main() {}
+
+// Using clippy::needless_borrow just as a placeholder, it isn't relevant.
+
+// Should lint
+#[expect(dead_code)]
+struct T1;
+
+struct T2; // Should not lint
+#[deny(clippy::needless_borrow)] // Should not lint
+struct T3;
+#[warn(clippy::needless_borrow)] // Should not lint
+struct T4;
+// `panic = "unwind"` should always be true
+#[cfg_attr(panic = "unwind", expect(dead_code))]
+struct CfgT;
+
+fn ignore_inner_attr() {
+    #![allow(unused)] // Should not lint
+}

tests/ui/allow_attributes.rs

@@ -0,0 +1,25 @@
+// run-rustfix
+#![allow(unused)]
+#![warn(clippy::allow_attributes)]
+#![feature(lint_reasons)]
+
+fn main() {}
+
+// Using clippy::needless_borrow just as a placeholder, it isn't relevant.
+
+// Should lint
+#[allow(dead_code)]
+struct T1;
+
+struct T2; // Should not lint
+#[deny(clippy::needless_borrow)] // Should not lint
+struct T3;
+#[warn(clippy::needless_borrow)] // Should not lint
+struct T4;
+// `panic = "unwind"` should always be true
+#[cfg_attr(panic = "unwind", allow(dead_code))]
+struct CfgT;
+
+fn ignore_inner_attr() {
+    #![allow(unused)] // Should not lint
+}

tests/ui/allow_attributes.stderr

@@ -0,0 +1,16 @@
+error: #[allow] attribute found
+  --> $DIR/allow_attributes.rs:11:3
+   |
+LL | #[allow(dead_code)]
+   |   ^^^^^ help: replace it with: `expect`
+   |
+   = note: `-D clippy::allow-attributes` implied by `-D warnings`
+
+error: #[allow] attribute found
+  --> $DIR/allow_attributes.rs:20:30
+   |
+LL | #[cfg_attr(panic = "unwind", allow(dead_code))]
+   |                              ^^^^^ help: replace it with: `expect`
+
+error: aborting due to 2 previous errors
+