Don't check RPITITs that are Self:Sized for PointerLike

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -1197,6 +1197,11 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                                 continue;
                             }
 
+                            // RPITITs with `Self: Sized` don't need to be checked.
+                            if tcx.generics_require_sized_self(assoc_item) {
+                                continue;
+                            }
+
                             let pointer_like_goal = pointer_like_goal_for_rpitit(
                                 tcx,
                                 supertrait,

tests/ui/impl-trait/in-trait/sized-rpits-dont-need-pointer-like.rs

@@ -0,0 +1,13 @@
+//@ check-pass
+
+// Make sure that we don't enforce that an RPIT that has `where Self: Sized` is pointer-like.
+
+trait Foo {
+    fn foo() -> impl Sized where Self: Sized {}
+}
+
+impl Foo for () {}
+
+fn main() {
+    let x: &dyn Foo = &();
+}