Auto merge of #113471 - compiler-errors:new-solver-norm-escaping, r=lcnr

Allow escaping bound vars during `normalize_erasing_regions` in new solver

Add `AllowEscapingBoundVars` to `deeply_normalize`, and use it in the new solver in the `query_normalize` routine.

Ideally, we'd make all `query_normalize` calls handle pass in `AllowEscapingBoundVars` individually, because really the only `query_normalize` call that needs `AllowEscapingBoundVars::Yes` is the one in `try_normalize_generic_arg_after_erasing_regions`, but I think that's kind of overkill. I am happy to be convinced otherwise, though.

r? `@lcnr`

compiler/rustc_trait_selection/src/solve/normalize.rs

@@ -19,9 +19,23 @@ use super::FulfillmentCtxt;
 pub(crate) fn deeply_normalize<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
     at: At<'_, 'tcx>,
     value: T,
+) -> Result<T, Vec<FulfillmentError<'tcx>>> {
+    assert!(!value.has_escaping_bound_vars());
+    deeply_normalize_with_skipped_universes(at, value, vec![])
+}
+
+/// Deeply normalize all aliases in `value`. This does not handle inference and expects
+/// its input to be already fully resolved.
+///
+/// Additionally takes a list of universes which represents the binders which have been
+/// entered before passing `value` to the function.
+pub(crate) fn deeply_normalize_with_skipped_universes<'tcx, T: TypeFoldable<TyCtxt<'tcx>>>(
+    at: At<'_, 'tcx>,
+    value: T,
+    universes: Vec<Option<UniverseIndex>>,
 ) -> Result<T, Vec<FulfillmentError<'tcx>>> {
     let fulfill_cx = FulfillmentCtxt::new(at.infcx);
-    let mut folder = NormalizationFolder { at, fulfill_cx, depth: 0, universes: Vec::new() };
+    let mut folder = NormalizationFolder { at, fulfill_cx, depth: 0, universes };
 
     value.try_fold_with(&mut folder)
 }