accept ReStatic for RPITIT

add an ui test for #112094

Author: TaKO8Ki

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1550,7 +1550,7 @@ impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for ImplTraitInTraitFinder<'_, 'tcx> {
         {
             let opaque_ty = tcx.fold_regions(unshifted_opaque_ty, |re, _depth| {
                 match re.kind() {
-                    ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReError(_) => re,
+                    ty::ReEarlyBound(_) | ty::ReFree(_) | ty::ReError(_) | ty::ReStatic => re,
                     r => bug!("unexpected region: {r:?}"),
                 }
             });

tests/ui/impl-trait/static-lifetime-return-position-impl-trait.rs

@@ -0,0 +1,12 @@
+// check-pass
+
+#![allow(incomplete_features)]
+#![feature(adt_const_params, return_position_impl_trait_in_trait)]
+
+pub struct Element;
+
+pub trait Node {
+    fn elements<const T: &'static str>(&self) -> impl Iterator<Item = Element>;
+}
+
+fn main() {}