next-solver hang: infinite recursion during hidden type inference for TAIT

I tried this code:（auto-reduced）

#![feature(type_alias_impl_trait)]
trait UnwrapItemsExt {
    type Iter;
}
trait MyTrait<'a> {}
impl<'a> MyTrait<'a> for <() as UnwrapItemsExt>::Iter {}
impl<'a, I> UnwrapItemsExt for I {
    type Iter = impl MyTrait<'a>;
    fn unwrap_items() -> Self::Iter {
    }
}
fn main(){}

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rustc --version --verbose:

rustc 1.95.0-nightly (e96bb7e44 2026-01-27)
binary: rustc
commit-hash: e96bb7e44fbcc23c1e6009e8d0ee8ab208668fb4
commit-date: 2026-01-27
host: x86_64-unknown-linux-gnu
release: 1.95.0-nightly
LLVM version: 21.1.8

error[E0407]: method `unwrap_items` is not a member of trait `UnwrapItemsExt`
  --> bug.rs:9:5
   |
 9 | /     fn unwrap_items() -> Self::Iter {
10 | |     }
   | |_____^ not a member of trait `UnwrapItemsExt`

error[E0658]: `impl Trait` in associated types is unstable
 --> bug.rs:8:17
  |
8 |     type Iter = impl MyTrait<'a>;
  |                 ^^^^^^^^^^^^^^^^
  |
  = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information
  = help: add `#![feature(impl_trait_in_assoc_type)]` to the crate attributes to enable
  = note: this compiler was built on 2026-01-27; consider upgrading it if it is out of date

error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
 --> bug.rs:7:6
  |
7 | impl<'a, I> UnwrapItemsExt for I {
  |      ^^ unconstrained lifetime parameter

hang.

Reproduce the minimized case in bug.rs with a nightly rustc and -Znext-solver=globally, then compare it with the default solver's diagnostics. Trace the hidden type inference path for TAIT to identify the recursion, and consider how to cover this reproducer in compiler regression testing. Done means the case terminates with an appropriate error instead of hanging.