fix(use_self): descend into type's children when looking for lifetimes

This unfortunately breaks another test case -- it had only worked
because when we checked `!has_lifetime` on `S2<S<'a>>`, we only looked
for generic lifetime params on `S2`, forgetting to descend into `S`.

One thing that makes this a bit less sad is that this particular test
case doesn't come from a reported issue, but rather was added as a
miscellaneous check during a kind of unrelated PR.

Author: ada4a

clippy_lints/src/use_self.rs

@@ -323,10 +323,12 @@ fn same_lifetimes<'tcx>(a: MiddleTy<'tcx>, b: MiddleTy<'tcx>) -> bool {
 fn has_lifetime(ty: MiddleTy<'_>) -> bool {
     use rustc_middle::ty::{Adt, GenericArgKind};
     match ty.kind() {
-        Adt(_, args) => args
-            .iter()
+        Adt(_, args) => args.iter().any(|arg| match arg.kind() {
             // TODO: Handle inferred lifetimes
-            .any(|arg| matches!(arg.kind(), GenericArgKind::Lifetime(..))),
+            GenericArgKind::Lifetime(..) => true,
+            GenericArgKind::Type(ty) => has_lifetime(ty),
+            _ => false,
+        }),
         _ => false,
     }
 }

tests/ui/use_self.fixed

@@ -530,8 +530,8 @@ mod issue7206 {
 
     impl<'a> S2<S<'a>> {
         fn new_again() -> Self {
-            Self::new()
-            //~^ use_self
+            S2::new()
+            // FIXME: ^Broken by PR #15611
         }
     }
 }
@@ -755,3 +755,17 @@ mod crash_check_13128 {
         }
     }
 }
+
+mod issue_13277 {
+    trait Foo {
+        type Item<'foo>;
+    }
+    struct Bar<'b> {
+        content: &'b str,
+    }
+    impl<'b> Foo for Option<Bar<'b>> {
+        // when checking whether `Option<Bar<'foo>>` has a lifetime, check not only the outer
+        // `Option<T>`, but also the inner `Bar<'foo>`
+        type Item<'foo> = Option<Bar<'foo>>;
+    }
+}

tests/ui/use_self.rs

@@ -531,7 +531,7 @@ mod issue7206 {
     impl<'a> S2<S<'a>> {
         fn new_again() -> Self {
             S2::new()
-            //~^ use_self
+            // FIXME: ^Broken by PR #15611
         }
     }
 }
@@ -755,3 +755,17 @@ mod crash_check_13128 {
         }
     }
 }
+
+mod issue_13277 {
+    trait Foo {
+        type Item<'foo>;
+    }
+    struct Bar<'b> {
+        content: &'b str,
+    }
+    impl<'b> Foo for Option<Bar<'b>> {
+        // when checking whether `Option<Bar<'foo>>` has a lifetime, check not only the outer
+        // `Option<T>`, but also the inner `Bar<'foo>`
+        type Item<'foo> = Option<Bar<'foo>>;
+    }
+}

tests/ui/use_self.stderr

@@ -169,12 +169,6 @@ error: unnecessary structure name repetition
 LL |             A::new::<submod::B>(submod::B {})
    |             ^ help: use the applicable keyword: `Self`
 
-error: unnecessary structure name repetition
-  --> tests/ui/use_self.rs:533:13
-   |
-LL |             S2::new()
-   |             ^^ help: use the applicable keyword: `Self`
-
 error: unnecessary structure name repetition
   --> tests/ui/use_self.rs:571:17
    |
@@ -259,5 +253,5 @@ error: unnecessary structure name repetition
 LL |                 E::A => {},
    |                 ^ help: use the applicable keyword: `Self`
 
-error: aborting due to 43 previous errors
+error: aborting due to 42 previous errors