Rollup merge of #161330 - zakrad:regr-test-159559, r=JohnTitor

Add regression test for nested RPIT not an iterator ICE

Closes #159559

Author: jhpratt

tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.rs

@@ -0,0 +1,19 @@
+//! Regression test for <https://github.com/rust-lang/rust/issues/159559>.
+//! Reporting the `E0277` for the unsatisfied `IntoIterator` bound on the
+//! nested opaque type used to ICE ("Normalizing ... without wrapping in a
+//! `Binder`") in the RPIT method-chain suggestion when the return type
+//! captures a lifetime.
+
+trait Cap<'a> {}
+
+impl<T> Cap<'_> for T {}
+
+fn fail_late_bound<'a>(
+    a: &u8,
+    _: &'a u8,
+) -> impl IntoIterator<Item = impl Cap<'a> + IntoIterator<Item = impl Cap<'a>>> {
+    //~^ ERROR `&u8` is not an iterator
+    [a]
+}
+
+fn main() {}

tests/ui/impl-trait/nested-rpit-not-iterator-ice-159559.stderr

@@ -0,0 +1,12 @@
+error[E0277]: `&u8` is not an iterator
+  --> $DIR/nested-rpit-not-iterator-ice-159559.rs:14:31
+   |
+LL | ) -> impl IntoIterator<Item = impl Cap<'a> + IntoIterator<Item = impl Cap<'a>>> {
+   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `&u8` is not an iterator
+   |
+   = help: the trait `Iterator` is not implemented for `&u8`
+   = note: required for `&u8` to implement `IntoIterator`
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0277`.