add test for #[expect]ing unsafe_derive_deserialize

Adding `#![feature(lint_reasons)]` to the top of the file
also changed the line numbers in the expected error output.

Author: B14CK313

tests/ui/unsafe_derive_deserialize.rs

@@ -1,3 +1,4 @@
+#![feature(lint_reasons)]
 #![warn(clippy::unsafe_derive_deserialize)]
 #![allow(unused, clippy::missing_safety_doc)]
 
@@ -71,4 +72,14 @@ impl G {
     }
 }
 
+// Check that we honor the `expect` attribute on the ADT
+#[expect(clippy::unsafe_derive_deserialize)]
+#[derive(Deserialize)]
+pub struct H;
+impl H {
+    pub fn unsafe_block(&self) {
+        unsafe {}
+    }
+}
+
 fn main() {}

tests/ui/unsafe_derive_deserialize.stderr

@@ -1,5 +1,5 @@
 error: you are deriving `serde::Deserialize` on a type that has methods using `unsafe`
-  --> tests/ui/unsafe_derive_deserialize.rs:8:10
+  --> tests/ui/unsafe_derive_deserialize.rs:9:10
    |
 LL | #[derive(Deserialize)]
    |          ^^^^^^^^^^^
@@ -10,7 +10,7 @@ LL | #[derive(Deserialize)]
    = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: you are deriving `serde::Deserialize` on a type that has methods using `unsafe`
-  --> tests/ui/unsafe_derive_deserialize.rs:17:10
+  --> tests/ui/unsafe_derive_deserialize.rs:18:10
    |
 LL | #[derive(Deserialize)]
    |          ^^^^^^^^^^^
@@ -19,7 +19,7 @@ LL | #[derive(Deserialize)]
    = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: you are deriving `serde::Deserialize` on a type that has methods using `unsafe`
-  --> tests/ui/unsafe_derive_deserialize.rs:24:10
+  --> tests/ui/unsafe_derive_deserialize.rs:25:10
    |
 LL | #[derive(Deserialize)]
    |          ^^^^^^^^^^^
@@ -28,7 +28,7 @@ LL | #[derive(Deserialize)]
    = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: you are deriving `serde::Deserialize` on a type that has methods using `unsafe`
-  --> tests/ui/unsafe_derive_deserialize.rs:33:10
+  --> tests/ui/unsafe_derive_deserialize.rs:34:10
    |
 LL | #[derive(Deserialize)]
    |          ^^^^^^^^^^^