Auto merge of #17190 - dfireBird:dyn_trait_with_lifetimes_in_rpit, r=Veykril

Fix: Lifetime's Bound Var Debrujin Index in Dyn Traits

Surely fixes #17182

I have tried running the analysis-stats in some of the repos mentioned in #17080. No panic in almost all of them.

Author: bors

crates/hir-ty/src/lower.rs

@@ -1311,11 +1311,10 @@ impl<'a> TyLoweringContext<'a> {
                 bounds,
                 lifetime: match lifetime {
                     Some(it) => match it.bound_var(Interner) {
-                        Some(bound_var) => LifetimeData::BoundVar(BoundVar::new(
-                            DebruijnIndex::INNERMOST,
-                            bound_var.index,
-                        ))
-                        .intern(Interner),
+                        Some(bound_var) => bound_var
+                            .shifted_out_to(DebruijnIndex::new(2))
+                            .map(|bound_var| LifetimeData::BoundVar(bound_var).intern(Interner))
+                            .unwrap_or(it),
                         None => it,
                     },
                     None => static_lifetime(),

crates/hir-ty/src/tests/traits.rs

@@ -4803,3 +4803,24 @@ fn foo() {
 "#,
     );
 }
+
+#[test]
+fn dyn_trait_with_lifetime_in_rpit() {
+    check_types(
+        r#"
+//- minicore: future
+pub struct Box<T> {}
+
+trait Trait {}
+
+pub async fn foo_async<'a>() -> Box<dyn Trait + 'a>  {
+    Box {}
+}
+
+fn foo() {
+    foo_async();
+  //^^^^^^^^^^^impl Future<Output = Box<dyn Trait>> + ?Sized
+}
+"#,
+    )
+}