iat selection: erase regions in self type

compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -31,6 +31,7 @@ use rustc_infer::infer::{InferCtxt, TyCtxtInferExt};
 use rustc_infer::traits::ObligationCause;
 use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::middle::stability::AllowUnstable;
+use rustc_middle::ty::fold::FnMutDelegate;
 use rustc_middle::ty::subst::{self, GenericArgKind, InternalSubsts, SubstsRef};
 use rustc_middle::ty::DynKind;
 use rustc_middle::ty::GenericParamDefKind;
@@ -2226,8 +2227,26 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
         let param_env = tcx.param_env(block.owner.to_def_id());
         let cause = ObligationCause::misc(span, block.owner.def_id);
+
         let mut fulfillment_errors = Vec::new();
-        let mut applicable_candidates: Vec<_> = candidates
+        let mut applicable_candidates: Vec<_> = infcx.probe(|_| {
+            let universe = infcx.create_next_universe();
+
+            // Regions are not considered during selection.
+            let self_ty = tcx.replace_escaping_bound_vars_uncached(
+                self_ty,
+                FnMutDelegate {
+                    regions: &mut |_| tcx.lifetimes.re_erased,
+                    types: &mut |bv| {
+                        tcx.mk_placeholder(ty::PlaceholderType { universe, name: bv.kind })
+                    },
+                    consts: &mut |bv, ty| {
+                        tcx.mk_const(ty::PlaceholderConst { universe, name: bv }, ty)
+                    },
+                },
+            );
+
+            candidates
                 .iter()
                 .filter_map(|&(impl_, (assoc_item, def_scope))| {
                     infcx.probe(|_| {
@@ -2266,7 +2285,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         Some((assoc_item, def_scope, infcx.resolve_vars_if_possible(impl_substs)))
                     })
                 })
-            .collect();
+                .collect()
+        });
 
         if applicable_candidates.len() > 1 {
             return Err(self.complain_about_ambiguous_inherent_assoc_type(

tests/ui/associated-inherent-types/issue-109299-1.rs

@@ -0,0 +1,12 @@
+#![feature(inherent_associated_types, non_lifetime_binders, type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+struct Lexer<T>(T);
+
+impl Lexer<i32> {
+    type Cursor = ();
+}
+
+type X = impl for<T> Fn() -> Lexer<T>::Cursor; //~ ERROR associated type `Cursor` not found for `Lexer<T>` in the current scope
+
+fn main() {}

tests/ui/associated-inherent-types/issue-109299-1.stderr

@@ -0,0 +1,15 @@
+error[E0220]: associated type `Cursor` not found for `Lexer<T>` in the current scope
+  --> $DIR/issue-109299-1.rs:10:40
+   |
+LL | struct Lexer<T>(T);
+   | --------------- associated item `Cursor` not found for this struct
+...
+LL | type X = impl for<T> Fn() -> Lexer<T>::Cursor;
+   |                                        ^^^^^^ associated item not found in `Lexer<T>`
+   |
+   = note: the associated type was found for
+           - `Lexer<i32>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.

tests/ui/associated-inherent-types/issue-109299.rs

@@ -0,0 +1,12 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Lexer<'d>(&'d ());
+
+impl Lexer<'d> { //~ ERROR use of undeclared lifetime name `'d`
+    type Cursor = ();
+}
+
+fn test(_: Lexer::Cursor) {}
+
+fn main() {}

tests/ui/associated-inherent-types/issue-109299.stderr

@@ -0,0 +1,11 @@
+error[E0261]: use of undeclared lifetime name `'d`
+  --> $DIR/issue-109299.rs:6:12
+   |
+LL | impl Lexer<'d> {
+   |     -      ^^ undeclared lifetime
+   |     |
+   |     help: consider introducing lifetime `'d` here: `<'d>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0261`.