Auto merge of #8737 - smoelius:extra-impl-lifetimes, r=giraffate

Extend `extra_unused_lifetimes` to handle impl lifetimes

Fixes #6437 (cc: `@carols10cents)`

changelog: fix #6437

tests/ui/crashes/ice-2865.rs

@@ -1,4 +1,4 @@
-#[allow(dead_code)]
+#![allow(dead_code, clippy::extra_unused_lifetimes)]
 
 /// Test for https://github.com/rust-lang/rust-clippy/issues/2865
 

tests/ui/crashes/ice-3151.rs

@@ -1,4 +1,4 @@
-/// Test for https://github.com/rust-lang/rust-clippy/issues/2865
+/// Test for https://github.com/rust-lang/rust-clippy/issues/3151
 
 #[derive(Clone)]
 pub struct HashMap<V, S> {

tests/ui/extra_unused_lifetimes.rs

@@ -72,4 +72,46 @@ mod issue4291 {
     }
 }
 
+mod issue6437 {
+    pub struct Scalar;
+
+    impl<'a> std::ops::AddAssign<&Scalar> for &mut Scalar {
+        fn add_assign(&mut self, _rhs: &Scalar) {
+            unimplemented!();
+        }
+    }
+
+    impl<'b> Scalar {
+        pub fn something<'c>() -> Self {
+            Self
+        }
+    }
+}
+
+// https://github.com/rust-lang/rust-clippy/pull/8737#pullrequestreview-951268213
+mod first_case {
+    use serde::de::Visitor;
+    pub trait Expected {
+        fn fmt(&self, formatter: &mut std::fmt::Formatter);
+    }
+
+    impl<'de, T> Expected for T
+    where
+        T: Visitor<'de>,
+    {
+        fn fmt(&self, formatter: &mut std::fmt::Formatter) {}
+    }
+}
+
+// https://github.com/rust-lang/rust-clippy/pull/8737#pullrequestreview-951268213
+mod second_case {
+    pub trait Source {
+        fn hey();
+    }
+
+    impl<'a, T: Source + ?Sized + 'a> Source for Box<T> {
+        fn hey() {}
+    }
+}
+
 fn main() {}

tests/ui/extra_unused_lifetimes.stderr

@@ -24,5 +24,23 @@ error: this lifetime isn't used in the function definition
 LL |         fn unused_lt<'a>(x: u8) {}
    |                      ^^
 
-error: aborting due to 4 previous errors
+error: this lifetime isn't used in the impl
+  --> $DIR/extra_unused_lifetimes.rs:78:10
+   |
+LL |     impl<'a> std::ops::AddAssign<&Scalar> for &mut Scalar {
+   |          ^^
+
+error: this lifetime isn't used in the impl
+  --> $DIR/extra_unused_lifetimes.rs:84:10
+   |
+LL |     impl<'b> Scalar {
+   |          ^^
+
+error: this lifetime isn't used in the function definition
+  --> $DIR/extra_unused_lifetimes.rs:85:26
+   |
+LL |         pub fn something<'c>() -> Self {
+   |                          ^^
+
+error: aborting due to 7 previous errors
 

tests/ui/impl.rs

@@ -1,4 +1,4 @@
-#![allow(dead_code)]
+#![allow(dead_code, clippy::extra_unused_lifetimes)]
 #![warn(clippy::multiple_inherent_impl)]
 
 struct MyStruct;

tests/ui/new_without_default.rs

@@ -1,4 +1,4 @@
-#![allow(dead_code, clippy::missing_safety_doc)]
+#![allow(dead_code, clippy::missing_safety_doc, clippy::extra_unused_lifetimes)]
 #![warn(clippy::new_without_default)]
 
 pub struct Foo;