Extend extra_unused_lifetimes to handle impl lifetimes

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 +72,20 @@ 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
+        }
+    }
+}
+
 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;