about summary refs log tree commit diff
diff options
context:
space:
mode:
-rw-r--r--compiler/rustc_hir_analysis/src/astconv/errors.rs230
-rw-r--r--compiler/rustc_hir_analysis/src/astconv/mod.rs266
-rw-r--r--compiler/rustc_hir_typeck/src/method/probe.rs30
-rw-r--r--tests/ui/associated-inherent-types/ambiguity.rs16
-rw-r--r--tests/ui/associated-inherent-types/ambiguity.stderr20
-rw-r--r--tests/ui/associated-inherent-types/bugs/ice-substitution.rs23
-rw-r--r--tests/ui/associated-inherent-types/bugs/ice-substitution.stderr6
-rw-r--r--tests/ui/associated-inherent-types/bugs/inference-fail.rs15
-rw-r--r--tests/ui/associated-inherent-types/bugs/inference-fail.stderr9
-rw-r--r--tests/ui/associated-inherent-types/bugs/lack-of-regionck.rs19
-rw-r--r--tests/ui/associated-inherent-types/dispatch-on-self-type-0.rs41
-rw-r--r--tests/ui/associated-inherent-types/dispatch-on-self-type-1.rs39
-rw-r--r--tests/ui/associated-inherent-types/dispatch-on-self-type-2.rs17
-rw-r--r--tests/ui/associated-inherent-types/dispatch-on-self-type-2.stderr19
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.rs31
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.shadowed.stderr15
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr9
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs.alias.stderr16
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs.local.stderr16
-rw-r--r--tests/ui/associated-inherent-types/not-found-self-type-differs.rs22
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.rs21
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.stderr27
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.rs18
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.stderr14
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.rs20
-rw-r--r--tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.stderr20
-rw-r--r--tests/ui/associated-inherent-types/substitute-params-bad.rs23
-rw-r--r--tests/ui/associated-inherent-types/substitute-params-bad.stderr20
-rw-r--r--tests/ui/associated-inherent-types/substitute-params.rs (renamed from tests/ui/associated-inherent-types/struct-generics.rs)8
29 files changed, 946 insertions, 84 deletions
diff --git a/compiler/rustc_hir_analysis/src/astconv/errors.rs b/compiler/rustc_hir_analysis/src/astconv/errors.rs
index 232ef2079d6..a9c2886b414 100644
--- a/compiler/rustc_hir_analysis/src/astconv/errors.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/errors.rs
@@ -1,10 +1,11 @@
 use crate::astconv::AstConv;
 use crate::errors::{ManualImplementation, MissingTypeParams};
 use rustc_data_structures::fx::FxHashMap;
-use rustc_errors::{pluralize, struct_span_err, Applicability, ErrorGuaranteed};
+use rustc_errors::{pluralize, struct_span_err, Applicability, Diagnostic, ErrorGuaranteed};
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
-use rustc_middle::ty;
+use rustc_infer::traits::FulfillmentError;
+use rustc_middle::ty::{self, Ty};
 use rustc_session::parse::feature_err;
 use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::symbol::{sym, Ident};
@@ -221,6 +222,231 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         err.emit()
     }
 
+    pub(crate) fn complain_about_ambiguous_inherent_assoc_type(
+        &self,
+        name: Ident,
+        candidates: Vec<DefId>,
+        span: Span,
+    ) -> ErrorGuaranteed {
+        let mut err = struct_span_err!(
+            self.tcx().sess,
+            name.span,
+            E0034,
+            "multiple applicable items in scope"
+        );
+        err.span_label(name.span, format!("multiple `{name}` found"));
+        self.note_ambiguous_inherent_assoc_type(&mut err, candidates, span);
+        err.emit()
+    }
+
+    // FIXME(fmease): Heavily adapted from `rustc_hir_typeck::method::suggest`. Deduplicate.
+    fn note_ambiguous_inherent_assoc_type(
+        &self,
+        err: &mut Diagnostic,
+        candidates: Vec<DefId>,
+        span: Span,
+    ) {
+        let tcx = self.tcx();
+
+        // Dynamic limit to avoid hiding just one candidate, which is silly.
+        let limit = if candidates.len() == 5 { 5 } else { 4 };
+
+        for (index, &item) in candidates.iter().take(limit).enumerate() {
+            let impl_ = tcx.impl_of_method(item).unwrap();
+
+            let note_span = if item.is_local() {
+                Some(tcx.def_span(item))
+            } else if impl_.is_local() {
+                Some(tcx.def_span(impl_))
+            } else {
+                None
+            };
+
+            let title = if candidates.len() > 1 {
+                format!("candidate #{}", index + 1)
+            } else {
+                "the candidate".into()
+            };
+
+            let impl_ty = tcx.at(span).type_of(impl_).subst_identity();
+            let note = format!("{title} is defined in an impl for the type `{impl_ty}`");
+
+            if let Some(span) = note_span {
+                err.span_note(span, &note);
+            } else {
+                err.note(&note);
+            }
+        }
+        if candidates.len() > limit {
+            err.note(&format!("and {} others", candidates.len() - limit));
+        }
+    }
+
+    // FIXME(inherent_associated_types): Find similarly named associated types and suggest them.
+    pub(crate) fn complain_about_inherent_assoc_type_not_found(
+        &self,
+        name: Ident,
+        self_ty: Ty<'tcx>,
+        candidates: Vec<(DefId, (DefId, DefId))>,
+        fulfillment_errors: Vec<FulfillmentError<'tcx>>,
+        span: Span,
+    ) -> ErrorGuaranteed {
+        // FIXME(fmease): This was copied in parts from an old version of `rustc_hir_typeck::method::suggest`.
+        // Either
+        // * update this code by applying changes similar to #106702 or by taking a
+        //   Vec<(DefId, (DefId, DefId), Option<Vec<FulfillmentError<'tcx>>>)> or
+        // * deduplicate this code across the two crates.
+
+        let tcx = self.tcx();
+
+        let adt_did = self_ty.ty_adt_def().map(|def| def.did());
+        let add_def_label = |err: &mut Diagnostic| {
+            if let Some(did) = adt_did {
+                err.span_label(
+                    tcx.def_span(did),
+                    format!(
+                        "associated item `{name}` not found for this {}",
+                        tcx.def_kind(did).descr(did)
+                    ),
+                );
+            }
+        };
+
+        if fulfillment_errors.is_empty() {
+            // FIXME(fmease): Copied from `rustc_hir_typeck::method::probe`. Deduplicate.
+
+            let limit = if candidates.len() == 5 { 5 } else { 4 };
+            let type_candidates = candidates
+                .iter()
+                .take(limit)
+                .map(|&(impl_, _)| format!("- `{}`", tcx.at(span).type_of(impl_).subst_identity()))
+                .collect::<Vec<_>>()
+                .join("\n");
+            let additional_types = if candidates.len() > limit {
+                format!("\nand {} more types", candidates.len() - limit)
+            } else {
+                String::new()
+            };
+
+            let mut err = struct_span_err!(
+                tcx.sess,
+                name.span,
+                E0220,
+                "associated type `{name}` not found for `{self_ty}` in the current scope"
+            );
+            err.span_label(name.span, format!("associated item not found in `{self_ty}`"));
+            err.note(&format!(
+                "the associated type was found for\n{type_candidates}{additional_types}",
+            ));
+            add_def_label(&mut err);
+            return err.emit();
+        }
+
+        let mut bound_spans = Vec::new();
+
+        let mut bound_span_label = |self_ty: Ty<'_>, obligation: &str, quiet: &str| {
+            let msg = format!(
+                "doesn't satisfy `{}`",
+                if obligation.len() > 50 { quiet } else { obligation }
+            );
+            match &self_ty.kind() {
+                // Point at the type that couldn't satisfy the bound.
+                ty::Adt(def, _) => bound_spans.push((tcx.def_span(def.did()), msg)),
+                // Point at the trait object that couldn't satisfy the bound.
+                ty::Dynamic(preds, _, _) => {
+                    for pred in preds.iter() {
+                        match pred.skip_binder() {
+                            ty::ExistentialPredicate::Trait(tr) => {
+                                bound_spans.push((tcx.def_span(tr.def_id), msg.clone()))
+                            }
+                            ty::ExistentialPredicate::Projection(_)
+                            | ty::ExistentialPredicate::AutoTrait(_) => {}
+                        }
+                    }
+                }
+                // Point at the closure that couldn't satisfy the bound.
+                ty::Closure(def_id, _) => {
+                    bound_spans.push((tcx.def_span(*def_id), format!("doesn't satisfy `{quiet}`")))
+                }
+                _ => {}
+            }
+        };
+
+        let format_pred = |pred: ty::Predicate<'tcx>| {
+            let bound_predicate = pred.kind();
+            match bound_predicate.skip_binder() {
+                ty::PredicateKind::Clause(ty::Clause::Projection(pred)) => {
+                    let pred = bound_predicate.rebind(pred);
+                    // `<Foo as Iterator>::Item = String`.
+                    let projection_ty = pred.skip_binder().projection_ty;
+
+                    let substs_with_infer_self = tcx.mk_substs(
+                        std::iter::once(tcx.mk_ty_var(ty::TyVid::from_u32(0)).into())
+                            .chain(projection_ty.substs.iter().skip(1)),
+                    );
+
+                    let quiet_projection_ty =
+                        tcx.mk_alias_ty(projection_ty.def_id, substs_with_infer_self);
+
+                    let term = pred.skip_binder().term;
+
+                    let obligation = format!("{projection_ty} = {term}");
+                    let quiet = format!("{quiet_projection_ty} = {term}");
+
+                    bound_span_label(projection_ty.self_ty(), &obligation, &quiet);
+                    Some((obligation, projection_ty.self_ty()))
+                }
+                ty::PredicateKind::Clause(ty::Clause::Trait(poly_trait_ref)) => {
+                    let p = poly_trait_ref.trait_ref;
+                    let self_ty = p.self_ty();
+                    let path = p.print_only_trait_path();
+                    let obligation = format!("{self_ty}: {path}");
+                    let quiet = format!("_: {path}");
+                    bound_span_label(self_ty, &obligation, &quiet);
+                    Some((obligation, self_ty))
+                }
+                _ => None,
+            }
+        };
+
+        // FIXME(fmease): `rustc_hir_typeck::method::suggest` uses a `skip_list` to filter out some bounds.
+        // I would do the same here if it didn't mean more code duplication.
+        let mut bounds: Vec<_> = fulfillment_errors
+            .into_iter()
+            .map(|error| error.root_obligation.predicate)
+            .filter_map(format_pred)
+            .map(|(p, _)| format!("`{}`", p))
+            .collect();
+        bounds.sort();
+        bounds.dedup();
+
+        let mut err = tcx.sess.struct_span_err(
+            name.span,
+            &format!("the associated type `{name}` exists for `{self_ty}`, but its trait bounds were not satisfied")
+        );
+        if !bounds.is_empty() {
+            err.note(&format!(
+                "the following trait bounds were not satisfied:\n{}",
+                bounds.join("\n")
+            ));
+        }
+        err.span_label(
+            name.span,
+            format!("associated type cannot be referenced on `{self_ty}` due to unsatisfied trait bounds")
+        );
+
+        bound_spans.sort();
+        bound_spans.dedup();
+        for (span, msg) in bound_spans {
+            if !tcx.sess.source_map().is_span_accessible(span) {
+                continue;
+            }
+            err.span_label(span, &msg);
+        }
+        add_def_label(&mut err);
+        err.emit()
+    }
+
     /// When there are any missing associated types, emit an E0191 error and attempt to supply a
     /// reasonable suggestion on how to write it. For the case of multiple associated types in the
     /// same trait bound have the same name (as they come from different supertraits), we instead
diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 2ff47237b1b..716b4fc6ae3 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -27,7 +27,10 @@ use rustc_hir::def::{CtorOf, DefKind, Namespace, Res};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::intravisit::{walk_generics, Visitor as _};
 use rustc_hir::{GenericArg, GenericArgs, OpaqueTyOrigin};
+use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 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::subst::{self, GenericArgKind, InternalSubsts, SubstsRef};
 use rustc_middle::ty::DynKind;
@@ -39,12 +42,11 @@ use rustc_span::lev_distance::find_best_match_for_name;
 use rustc_span::symbol::{kw, Ident, Symbol};
 use rustc_span::{sym, Span, DUMMY_SP};
 use rustc_target::spec::abi;
-use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::astconv_object_safety_violations;
 use rustc_trait_selection::traits::error_reporting::{
     report_object_safety_error, suggestions::NextTypeParamName,
 };
 use rustc_trait_selection::traits::wf::object_region_bounds;
+use rustc_trait_selection::traits::{self, astconv_object_safety_violations, ObligationCtxt};
 
 use smallvec::{smallvec, SmallVec};
 use std::collections::BTreeSet;
@@ -1944,7 +1946,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             Res::Err
         };
 
-        // Check if we have an enum variant.
+        // Check if we have an enum variant or an inherent associated type.
         let mut variant_resolution = None;
         if let Some(adt_def) = self.probe_adt(span, qself_ty) {
             if adt_def.is_enum() {
@@ -2043,23 +2045,15 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 }
             }
 
-            // see if we can satisfy using an inherent associated type
-            for &impl_ in tcx.inherent_impls(adt_def.did()) {
-                let Some(assoc_ty_did) = self.lookup_assoc_ty(assoc_ident, hir_ref_id, span, impl_) else {
-                    continue;
-                };
-                let ty::Adt(_, adt_substs) = qself_ty.kind() else {
-                    // FIXME(inherent_associated_types)
-                    bug!("unimplemented: non-adt self of inherent assoc ty");
-                };
-                let item_substs = self.create_substs_for_associated_item(
-                    span,
-                    assoc_ty_did,
-                    assoc_segment,
-                    adt_substs,
-                );
-                let ty = tcx.type_of(assoc_ty_did).subst(tcx, item_substs);
-                return Ok((ty, DefKind::AssocTy, assoc_ty_did));
+            if let Some((ty, did)) = self.lookup_inherent_assoc_ty(
+                assoc_ident,
+                assoc_segment,
+                adt_def.did(),
+                qself_ty,
+                hir_ref_id,
+                span,
+            )? {
+                return Ok((ty, DefKind::AssocTy, did));
             }
         }
 
@@ -2202,6 +2196,172 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         Ok((ty, DefKind::AssocTy, assoc_ty_did))
     }
 
+    fn lookup_inherent_assoc_ty(
+        &self,
+        name: Ident,
+        segment: &hir::PathSegment<'_>,
+        adt_did: DefId,
+        self_ty: Ty<'tcx>,
+        block: hir::HirId,
+        span: Span,
+    ) -> Result<Option<(Ty<'tcx>, DefId)>, ErrorGuaranteed> {
+        let tcx = self.tcx();
+
+        let candidates: Vec<_> = tcx
+            .inherent_impls(adt_did)
+            .iter()
+            .filter_map(|&impl_| Some((impl_, self.lookup_assoc_ty_unchecked(name, block, impl_)?)))
+            .collect();
+
+        if candidates.is_empty() {
+            return Ok(None);
+        }
+
+        // In contexts that have no inference context, just make a new one.
+        // We do need a local variable to store it, though.
+        let infcx_;
+        let infcx = match self.infcx() {
+            Some(infcx) => infcx,
+            None => {
+                assert!(!self_ty.needs_infer());
+                infcx_ = tcx.infer_ctxt().ignoring_regions().build();
+                &infcx_
+            }
+        };
+
+        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
+            .iter()
+            .filter_map(|&(impl_, (assoc_item, def_scope))| {
+                infcx.probe(|_| {
+                    let ocx = ObligationCtxt::new_in_snapshot(&infcx);
+
+                    let impl_ty = tcx.type_of(impl_);
+                    let impl_substs = infcx.fresh_item_substs(impl_);
+                    let impl_ty = impl_ty.subst(tcx, impl_substs);
+                    let impl_ty = ocx.normalize(&cause, param_env, impl_ty);
+
+                    // Check that the Self-types can be related.
+                    // FIXME(fmease): Should we use `eq` here?
+                    ocx.sup(&ObligationCause::dummy(), param_env, impl_ty, self_ty).ok()?;
+
+                    // Check whether the impl imposes obligations we have to worry about.
+                    let impl_bounds = tcx.predicates_of(impl_);
+                    let impl_bounds = impl_bounds.instantiate(tcx, impl_substs);
+
+                    let impl_bounds = ocx.normalize(&cause, param_env, impl_bounds);
+
+                    let impl_obligations = traits::predicates_for_generics(
+                        |_, _| cause.clone(),
+                        param_env,
+                        impl_bounds,
+                    );
+
+                    ocx.register_obligations(impl_obligations);
+
+                    let mut errors = ocx.select_where_possible();
+                    if !errors.is_empty() {
+                        fulfillment_errors.append(&mut errors);
+                        return None;
+                    }
+
+                    // FIXME(fmease): Unsolved vars can escape this InferCtxt snapshot.
+                    Some((assoc_item, def_scope, infcx.resolve_vars_if_possible(impl_substs)))
+                })
+            })
+            .collect();
+
+        if applicable_candidates.len() > 1 {
+            return Err(self.complain_about_ambiguous_inherent_assoc_type(
+                name,
+                applicable_candidates.into_iter().map(|(candidate, ..)| candidate).collect(),
+                span,
+            ));
+        }
+
+        if let Some((assoc_item, def_scope, impl_substs)) = applicable_candidates.pop() {
+            self.check_assoc_ty(assoc_item, name, def_scope, block, span);
+
+            // FIXME(inherent_associated_types): To fully *confirm* the *probed* candidate, we still
+            // need to relate the Self-type with fresh item substs & register region obligations for
+            // regionck to prove/disprove.
+
+            let item_substs =
+                self.create_substs_for_associated_item(span, assoc_item, segment, impl_substs);
+
+            // FIXME(fmease, #106722): Check if the bounds on the parameters of the
+            // associated type hold, if any.
+            let ty = tcx.type_of(assoc_item).subst(tcx, item_substs);
+
+            return Ok(Some((ty, assoc_item)));
+        }
+
+        Err(self.complain_about_inherent_assoc_type_not_found(
+            name,
+            self_ty,
+            candidates,
+            fulfillment_errors,
+            span,
+        ))
+    }
+
+    fn lookup_assoc_ty(
+        &self,
+        name: Ident,
+        block: hir::HirId,
+        span: Span,
+        scope: DefId,
+    ) -> Option<DefId> {
+        let (item, def_scope) = self.lookup_assoc_ty_unchecked(name, block, scope)?;
+        self.check_assoc_ty(item, name, def_scope, block, span);
+        Some(item)
+    }
+
+    fn lookup_assoc_ty_unchecked(
+        &self,
+        name: Ident,
+        block: hir::HirId,
+        scope: DefId,
+    ) -> Option<(DefId, DefId)> {
+        let tcx = self.tcx();
+        let (ident, def_scope) = tcx.adjust_ident_and_get_scope(name, scope, block);
+
+        // We have already adjusted the item name above, so compare with `ident.normalize_to_macros_2_0()` instead
+        // of calling `find_by_name_and_kind`.
+        let item = tcx.associated_items(scope).in_definition_order().find(|i| {
+            i.kind.namespace() == Namespace::TypeNS
+                && i.ident(tcx).normalize_to_macros_2_0() == ident
+        })?;
+
+        Some((item.def_id, def_scope))
+    }
+
+    fn check_assoc_ty(
+        &self,
+        item: DefId,
+        name: Ident,
+        def_scope: DefId,
+        block: hir::HirId,
+        span: Span,
+    ) {
+        let tcx = self.tcx();
+        let kind = DefKind::AssocTy;
+
+        if !tcx.visibility(item).is_accessible_from(def_scope, tcx) {
+            let kind = kind.descr(item);
+            let msg = format!("{kind} `{name}` is private");
+            let def_span = tcx.def_span(item);
+            tcx.sess
+                .struct_span_err_with_code(span, &msg, rustc_errors::error_code!(E0624))
+                .span_label(span, &format!("private {kind}"))
+                .span_label(def_span, &format!("{kind} defined here"))
+                .emit();
+        }
+        tcx.check_stability(item, Some(block), span, None);
+    }
+
     fn probe_traits_that_match_assoc_ty(
         &self,
         qself_ty: Ty<'tcx>,
@@ -2255,39 +2415,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             .collect()
     }
 
-    fn lookup_assoc_ty(
-        &self,
-        ident: Ident,
-        block: hir::HirId,
-        span: Span,
-        scope: DefId,
-    ) -> Option<DefId> {
-        let tcx = self.tcx();
-        let (ident, def_scope) = tcx.adjust_ident_and_get_scope(ident, scope, block);
-
-        // We have already adjusted the item name above, so compare with `ident.normalize_to_macros_2_0()` instead
-        // of calling `find_by_name_and_kind`.
-        let item = tcx.associated_items(scope).in_definition_order().find(|i| {
-            i.kind.namespace() == Namespace::TypeNS
-                && i.ident(tcx).normalize_to_macros_2_0() == ident
-        })?;
-
-        let kind = DefKind::AssocTy;
-        if !item.visibility(tcx).is_accessible_from(def_scope, tcx) {
-            let kind = kind.descr(item.def_id);
-            let msg = format!("{kind} `{ident}` is private");
-            let def_span = self.tcx().def_span(item.def_id);
-            tcx.sess
-                .struct_span_err_with_code(span, &msg, rustc_errors::error_code!(E0624))
-                .span_label(span, &format!("private {kind}"))
-                .span_label(def_span, &format!("{kind} defined here"))
-                .emit();
-        }
-        tcx.check_stability(item.def_id, Some(block), span, None);
-
-        Some(item.def_id)
-    }
-
     fn qpath_to_ty(
         &self,
         span: Span,
@@ -3375,3 +3502,36 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         }
     }
 }
+
+pub trait InferCtxtExt<'tcx> {
+    fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx>;
+}
+
+impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
+    fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx> {
+        InternalSubsts::for_item(self.tcx, def_id, |param, _| match param.kind {
+            GenericParamDefKind::Lifetime => self.tcx.lifetimes.re_erased.into(),
+            GenericParamDefKind::Type { .. } => self
+                .next_ty_var(TypeVariableOrigin {
+                    kind: TypeVariableOriginKind::SubstitutionPlaceholder,
+                    span: self.tcx.def_span(def_id),
+                })
+                .into(),
+            GenericParamDefKind::Const { .. } => {
+                let span = self.tcx.def_span(def_id);
+                let origin = ConstVariableOrigin {
+                    kind: ConstVariableOriginKind::SubstitutionPlaceholder,
+                    span,
+                };
+                self.next_const_var(
+                    self.tcx
+                        .type_of(param.def_id)
+                        .no_bound_vars()
+                        .expect("const parameter types cannot be generic"),
+                    origin,
+                )
+                .into()
+            }
+        })
+    }
+}
diff --git a/compiler/rustc_hir_typeck/src/method/probe.rs b/compiler/rustc_hir_typeck/src/method/probe.rs
index 0b9226802cf..eb6c0b7686b 100644
--- a/compiler/rustc_hir_typeck/src/method/probe.rs
+++ b/compiler/rustc_hir_typeck/src/method/probe.rs
@@ -9,12 +9,11 @@ use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::def::DefKind;
+use rustc_hir_analysis::astconv::InferCtxtExt as _;
 use rustc_hir_analysis::autoderef::{self, Autoderef};
 use rustc_infer::infer::canonical::OriginalQueryValues;
 use rustc_infer::infer::canonical::{Canonical, QueryResponse};
-use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc_infer::infer::{self, InferOk, TyCtxtInferExt};
-use rustc_middle::infer::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use rustc_middle::middle::stability;
 use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::AssocItem;
@@ -1941,33 +1940,6 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
         (self.tcx.type_of(impl_def_id), self.fresh_item_substs(impl_def_id))
     }
 
-    fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx> {
-        InternalSubsts::for_item(self.tcx, def_id, |param, _| match param.kind {
-            GenericParamDefKind::Lifetime => self.tcx.lifetimes.re_erased.into(),
-            GenericParamDefKind::Type { .. } => self
-                .next_ty_var(TypeVariableOrigin {
-                    kind: TypeVariableOriginKind::SubstitutionPlaceholder,
-                    span: self.tcx.def_span(def_id),
-                })
-                .into(),
-            GenericParamDefKind::Const { .. } => {
-                let span = self.tcx.def_span(def_id);
-                let origin = ConstVariableOrigin {
-                    kind: ConstVariableOriginKind::SubstitutionPlaceholder,
-                    span,
-                };
-                self.next_const_var(
-                    self.tcx
-                        .type_of(param.def_id)
-                        .no_bound_vars()
-                        .expect("const parameter types cannot be generic"),
-                    origin,
-                )
-                .into()
-            }
-        })
-    }
-
     /// Replaces late-bound-regions bound by `value` with `'static` using
     /// `ty::erase_late_bound_regions`.
     ///
diff --git a/tests/ui/associated-inherent-types/ambiguity.rs b/tests/ui/associated-inherent-types/ambiguity.rs
new file mode 100644
index 00000000000..73920555b3e
--- /dev/null
+++ b/tests/ui/associated-inherent-types/ambiguity.rs
@@ -0,0 +1,16 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Wrapper<T>(T);
+
+impl Wrapper<i32> {
+    type Foo = i32;
+}
+
+impl Wrapper<()> {
+    type Foo = ();
+}
+
+fn main() {
+    let _: Wrapper<_>::Foo = (); //~ ERROR multiple applicable items in scope
+}
diff --git a/tests/ui/associated-inherent-types/ambiguity.stderr b/tests/ui/associated-inherent-types/ambiguity.stderr
new file mode 100644
index 00000000000..155c296cbb3
--- /dev/null
+++ b/tests/ui/associated-inherent-types/ambiguity.stderr
@@ -0,0 +1,20 @@
+error[E0034]: multiple applicable items in scope
+  --> $DIR/ambiguity.rs:15:24
+   |
+LL |     let _: Wrapper<_>::Foo = ();
+   |                        ^^^ multiple `Foo` found
+   |
+note: candidate #1 is defined in an impl for the type `Wrapper<i32>`
+  --> $DIR/ambiguity.rs:7:5
+   |
+LL |     type Foo = i32;
+   |     ^^^^^^^^
+note: candidate #2 is defined in an impl for the type `Wrapper<()>`
+  --> $DIR/ambiguity.rs:11:5
+   |
+LL |     type Foo = ();
+   |     ^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0034`.
diff --git a/tests/ui/associated-inherent-types/bugs/ice-substitution.rs b/tests/ui/associated-inherent-types/bugs/ice-substitution.rs
new file mode 100644
index 00000000000..53ac79e0561
--- /dev/null
+++ b/tests/ui/associated-inherent-types/bugs/ice-substitution.rs
@@ -0,0 +1,23 @@
+// known-bug: unknown
+// failure-status: 101
+// normalize-stderr-test "note: .*\n\n" -> ""
+// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
+// rustc-env:RUST_BACKTRACE=0
+
+// FIXME: I presume a type variable that couldn't be solved by `resolve_vars_if_possible`
+//        escapes the InferCtxt snapshot.
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Cont<T>(T);
+
+impl<T: Copy> Cont<T> {
+    type Out = Vec<T>;
+}
+
+pub fn weird<T: Copy>(x: T) {
+    let _: Cont<_>::Out = vec![true];
+}
+
+fn main() {}
diff --git a/tests/ui/associated-inherent-types/bugs/ice-substitution.stderr b/tests/ui/associated-inherent-types/bugs/ice-substitution.stderr
new file mode 100644
index 00000000000..7b0d1c50516
--- /dev/null
+++ b/tests/ui/associated-inherent-types/bugs/ice-substitution.stderr
@@ -0,0 +1,6 @@
+error: the compiler unexpectedly panicked. this is a bug.
+
+query stack during panic:
+#0 [typeck] type-checking `weird`
+#1 [typeck_item_bodies] type-checking all item bodies
+end of query stack
diff --git a/tests/ui/associated-inherent-types/bugs/inference-fail.rs b/tests/ui/associated-inherent-types/bugs/inference-fail.rs
new file mode 100644
index 00000000000..a920b412b1a
--- /dev/null
+++ b/tests/ui/associated-inherent-types/bugs/inference-fail.rs
@@ -0,0 +1,15 @@
+// known-bug: unknown
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct S<T>(T);
+
+impl S<()> {
+    type P = i128;
+}
+
+fn main() {
+    // We fail to infer `_ == ()` here.
+    let _: S<_>::P;
+}
diff --git a/tests/ui/associated-inherent-types/bugs/inference-fail.stderr b/tests/ui/associated-inherent-types/bugs/inference-fail.stderr
new file mode 100644
index 00000000000..425691bd6c4
--- /dev/null
+++ b/tests/ui/associated-inherent-types/bugs/inference-fail.stderr
@@ -0,0 +1,9 @@
+error[E0282]: type annotations needed
+  --> $DIR/inference-fail.rs:14:14
+   |
+LL |     let _: S<_>::P;
+   |              ^ cannot infer type
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0282`.
diff --git a/tests/ui/associated-inherent-types/bugs/lack-of-regionck.rs b/tests/ui/associated-inherent-types/bugs/lack-of-regionck.rs
new file mode 100644
index 00000000000..632dbf3854b
--- /dev/null
+++ b/tests/ui/associated-inherent-types/bugs/lack-of-regionck.rs
@@ -0,0 +1,19 @@
+// known-bug: unknown
+// check-pass
+
+// We currently don't region-check inherent associated type projections at all.
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features, dead_code)]
+
+struct S<T>(T);
+
+impl S<&'static ()> {
+    type T = ();
+}
+
+fn usr<'a>() {
+    let _: S::<&'a ()>::T; // this should *fail* but it doesn't!
+}
+
+fn main() {}
diff --git a/tests/ui/associated-inherent-types/dispatch-on-self-type-0.rs b/tests/ui/associated-inherent-types/dispatch-on-self-type-0.rs
new file mode 100644
index 00000000000..f846bfa4168
--- /dev/null
+++ b/tests/ui/associated-inherent-types/dispatch-on-self-type-0.rs
@@ -0,0 +1,41 @@
+// check-pass
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+// Check that inherent associated types are dispatched on the concrete Self type.
+
+struct Select<T>(T);
+
+impl Select<u8> {
+    type Projection = ();
+}
+
+impl Select<String> {
+    type Projection = bool;
+}
+
+struct Choose<T>(T);
+struct NonCopy;
+
+impl<T: Copy> Choose<T> {
+    type Result = Vec<T>;
+}
+
+impl Choose<NonCopy> {
+    type Result = ();
+}
+
+fn main() {
+    let _: Select<String>::Projection = false;
+    let _: Select<u8>::Projection = ();
+
+    let _: Choose<NonCopy>::Result = ();
+    let _: Choose<bool>::Result = vec![true];
+}
+
+// Test if we use the correct `ParamEnv` when proving obligations.
+
+pub fn parameterized<T: Copy>(x: T) {
+    let _: Choose<T>::Result = vec![x];
+}
diff --git a/tests/ui/associated-inherent-types/dispatch-on-self-type-1.rs b/tests/ui/associated-inherent-types/dispatch-on-self-type-1.rs
new file mode 100644
index 00000000000..9b0fa8dc6f3
--- /dev/null
+++ b/tests/ui/associated-inherent-types/dispatch-on-self-type-1.rs
@@ -0,0 +1,39 @@
+// check-pass
+
+#![feature(inherent_associated_types, auto_traits, negative_impls)]
+#![allow(incomplete_features)]
+
+use std::cmp::Ordering;
+
+// Check that inherent associated types are dispatched on the concrete Self type.
+
+struct Select<T, U>(T, U);
+
+impl<T: Ordinary, U: Ordinary> Select<T, U> {
+    type Type = ();
+}
+
+impl<T: Ordinary> Select<T, Special> {
+    type Type = bool;
+}
+
+impl<T: Ordinary> Select<Special, T> {
+    type Type = Ordering;
+}
+
+impl Select<Special, Special> {
+    type Type = (bool, bool);
+}
+
+fn main() {
+    let _: Select<String, Special>::Type = false;
+    let _: Select<Special, Special>::Type = (true, false);
+    let _: Select<Special, u8>::Type = Ordering::Equal;
+    let _: Select<i128, ()>::Type = ();
+}
+
+enum Special {}
+
+impl !Ordinary for Special {}
+
+auto trait Ordinary {}
diff --git a/tests/ui/associated-inherent-types/dispatch-on-self-type-2.rs b/tests/ui/associated-inherent-types/dispatch-on-self-type-2.rs
new file mode 100644
index 00000000000..7b205952f52
--- /dev/null
+++ b/tests/ui/associated-inherent-types/dispatch-on-self-type-2.rs
@@ -0,0 +1,17 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Parameterized<T, U>(T, U);
+
+impl Parameterized<(), ()> {
+    type Output = bool;
+}
+
+impl<T> Parameterized<bool, T> {
+    type Result = T;
+}
+
+fn main() {
+    let _: Parameterized<(), ()>::Output = String::new(); //~ ERROR mismatched types
+    let _: Parameterized<bool, u32>::Result = (); //~ ERROR mismatched types
+}
diff --git a/tests/ui/associated-inherent-types/dispatch-on-self-type-2.stderr b/tests/ui/associated-inherent-types/dispatch-on-self-type-2.stderr
new file mode 100644
index 00000000000..c9a48872af4
--- /dev/null
+++ b/tests/ui/associated-inherent-types/dispatch-on-self-type-2.stderr
@@ -0,0 +1,19 @@
+error[E0308]: mismatched types
+  --> $DIR/dispatch-on-self-type-2.rs:15:44
+   |
+LL |     let _: Parameterized<(), ()>::Output = String::new();
+   |            -----------------------------   ^^^^^^^^^^^^^ expected `bool`, found `String`
+   |            |
+   |            expected due to this
+
+error[E0308]: mismatched types
+  --> $DIR/dispatch-on-self-type-2.rs:16:47
+   |
+LL |     let _: Parameterized<bool, u32>::Result = ();
+   |            --------------------------------   ^^ expected `u32`, found `()`
+   |            |
+   |            expected due to this
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.rs b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.rs
new file mode 100644
index 00000000000..d2efb24c666
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.rs
@@ -0,0 +1,31 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+// Check that it's okay to report “[inherent] associated type […] not found” for inherent associated
+// type candidates that are not applicable (due to unsuitable Self type) even if there exists a
+// “shadowed” associated type from a trait with the same name since its use would be ambiguous
+// anyway if the IAT didn't exist.
+// FIXME(inherent_associated_types): Figure out which error would be more helpful here.
+
+// revisions: shadowed uncovered
+
+struct S<T>(T);
+
+trait Tr {
+    type Pr;
+}
+
+impl<T> Tr for S<T> {
+    type Pr = ();
+}
+
+#[cfg(shadowed)]
+impl S<()> {
+    type Pr = i32;
+}
+
+fn main() {
+    let _: S::<bool>::Pr = ();
+    //[shadowed]~^ ERROR associated type `Pr` not found
+    //[uncovered]~^^ ERROR ambiguous associated type
+}
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.shadowed.stderr b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.shadowed.stderr
new file mode 100644
index 00000000000..3561db354c0
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.shadowed.stderr
@@ -0,0 +1,15 @@
+error[E0220]: associated type `Pr` not found for `S<bool>` in the current scope
+  --> $DIR/not-found-self-type-differs-shadowing-trait-item.rs:28:23
+   |
+LL | struct S<T>(T);
+   | ----------- associated item `Pr` not found for this struct
+...
+LL |     let _: S::<bool>::Pr = ();
+   |                       ^^ associated item not found in `S<bool>`
+   |
+   = note: the associated type was found for
+           - `S<()>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr
new file mode 100644
index 00000000000..88c72042ce2
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs-shadowing-trait-item.uncovered.stderr
@@ -0,0 +1,9 @@
+error[E0223]: ambiguous associated type
+  --> $DIR/not-found-self-type-differs-shadowing-trait-item.rs:28:12
+   |
+LL |     let _: S::<bool>::Pr = ();
+   |            ^^^^^^^^^^^^^ help: use the fully-qualified path: `<S<bool> as Tr>::Pr`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0223`.
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs.alias.stderr b/tests/ui/associated-inherent-types/not-found-self-type-differs.alias.stderr
new file mode 100644
index 00000000000..4396435a6dd
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs.alias.stderr
@@ -0,0 +1,16 @@
+error[E0220]: associated type `Proj` not found for `Family<Option<()>>` in the current scope
+  --> $DIR/not-found-self-type-differs.rs:17:34
+   |
+LL | struct Family<T>(T);
+   | ---------------- associated item `Proj` not found for this struct
+...
+LL | type Alias = Family<Option<()>>::Proj;
+   |                                  ^^^^ associated item not found in `Family<Option<()>>`
+   |
+   = note: the associated type was found for
+           - `Family<()>`
+           - `Family<Result<T, ()>>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs.local.stderr b/tests/ui/associated-inherent-types/not-found-self-type-differs.local.stderr
new file mode 100644
index 00000000000..d527db02217
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs.local.stderr
@@ -0,0 +1,16 @@
+error[E0220]: associated type `Proj` not found for `Family<PathBuf>` in the current scope
+  --> $DIR/not-found-self-type-differs.rs:21:40
+   |
+LL | struct Family<T>(T);
+   | ---------------- associated item `Proj` not found for this struct
+...
+LL |     let _: Family<std::path::PathBuf>::Proj = ();
+   |                                        ^^^^ associated item not found in `Family<PathBuf>`
+   |
+   = note: the associated type was found for
+           - `Family<()>`
+           - `Family<Result<T, ()>>`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0220`.
diff --git a/tests/ui/associated-inherent-types/not-found-self-type-differs.rs b/tests/ui/associated-inherent-types/not-found-self-type-differs.rs
new file mode 100644
index 00000000000..93f58dcb6e6
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-self-type-differs.rs
@@ -0,0 +1,22 @@
+// revisions: local alias
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Family<T>(T);
+
+impl Family<()> {
+    type Proj = ();
+}
+
+impl<T> Family<Result<T, ()>> {
+    type Proj = Self;
+}
+
+#[cfg(alias)]
+type Alias = Family<Option<()>>::Proj; //[alias]~ ERROR associated type `Proj` not found for `Family<Option<()>>`
+
+fn main() {
+    #[cfg(local)]
+    let _: Family<std::path::PathBuf>::Proj = (); //[local]~ ERROR associated type `Proj` not found for `Family<PathBuf>`
+}
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.rs b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.rs
new file mode 100644
index 00000000000..b00830fa1c1
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.rs
@@ -0,0 +1,21 @@
+// Regression test for issue #104251.
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct Container<T: ?Sized>(T);
+
+impl<T> Container<T> {
+    type Yield = i32;
+}
+
+struct Duple<T, U>(T, U);
+
+impl<T: Copy, U: Send> Duple<T, U> {
+    type Combination = (T, U);
+}
+
+fn main() {
+    let _: Container<[u8]>::Yield = 1; //~ ERROR the associated type `Yield` exists for `Container<[u8]>`, but its trait bounds were not satisfied
+    let _: Duple<String, std::rc::Rc<str>>::Combination; //~ ERROR the associated type `Combination` exists for `Duple<String, Rc<str>>`, but its trait bounds were not satisfied
+}
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.stderr b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.stderr
new file mode 100644
index 00000000000..73657906761
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-0.stderr
@@ -0,0 +1,27 @@
+error: the associated type `Yield` exists for `Container<[u8]>`, but its trait bounds were not satisfied
+  --> $DIR/not-found-unsatisfied-bounds-0.rs:19:29
+   |
+LL | struct Container<T: ?Sized>(T);
+   | --------------------------- associated item `Yield` not found for this struct
+...
+LL |     let _: Container<[u8]>::Yield = 1;
+   |                             ^^^^^ associated type cannot be referenced on `Container<[u8]>` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `[u8]: Sized`
+
+error: the associated type `Combination` exists for `Duple<String, Rc<str>>`, but its trait bounds were not satisfied
+  --> $DIR/not-found-unsatisfied-bounds-0.rs:20:45
+   |
+LL | struct Duple<T, U>(T, U);
+   | ------------------ associated item `Combination` not found for this struct
+...
+LL |     let _: Duple<String, std::rc::Rc<str>>::Combination;
+   |                                             ^^^^^^^^^^^ associated type cannot be referenced on `Duple<String, Rc<str>>` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `Rc<str>: Send`
+           `String: Copy`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.rs b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.rs
new file mode 100644
index 00000000000..c80b1364ae3
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.rs
@@ -0,0 +1,18 @@
+// fail-check
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+// Test if we use the correct `ParamEnv` when proving obligations.
+
+fn parameterized<T>() {
+    let _: Container<T>::Proj = String::new(); //~ ERROR the associated type `Proj` exists for `Container<T>`, but its trait bounds were not satisfied
+}
+
+struct Container<T>(T);
+
+impl<T: Clone> Container<T> {
+    type Proj = String;
+}
+
+fn main() {}
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.stderr b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.stderr
new file mode 100644
index 00000000000..230bfa538b4
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-1.stderr
@@ -0,0 +1,14 @@
+error: the associated type `Proj` exists for `Container<T>`, but its trait bounds were not satisfied
+  --> $DIR/not-found-unsatisfied-bounds-1.rs:9:26
+   |
+LL |     let _: Container<T>::Proj = String::new();
+   |                          ^^^^ associated type cannot be referenced on `Container<T>` due to unsatisfied trait bounds
+...
+LL | struct Container<T>(T);
+   | ------------------- associated item `Proj` not found for this struct
+   |
+   = note: the following trait bounds were not satisfied:
+           `T: Clone`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.rs b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.rs
new file mode 100644
index 00000000000..5b0e8de9c58
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.rs
@@ -0,0 +1,20 @@
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct S<A, B>(A, B);
+struct Featureless;
+
+trait One {}
+trait Two {}
+
+impl<T: One> S<Featureless, T> {
+    type X = ();
+}
+
+impl<T: Two> S<T, Featureless> {
+    type X = String;
+}
+
+fn main() {
+    let _: S::<Featureless, Featureless>::X; //~ ERROR the associated type `X` exists for `S<Featureless, Featureless>`, but its trait bounds were not satisfied
+}
diff --git a/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.stderr b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.stderr
new file mode 100644
index 00000000000..3ddab25deb5
--- /dev/null
+++ b/tests/ui/associated-inherent-types/not-found-unsatisfied-bounds-in-multiple-impls.stderr
@@ -0,0 +1,20 @@
+error: the associated type `X` exists for `S<Featureless, Featureless>`, but its trait bounds were not satisfied
+  --> $DIR/not-found-unsatisfied-bounds-in-multiple-impls.rs:19:43
+   |
+LL | struct S<A, B>(A, B);
+   | -------------- associated item `X` not found for this struct
+LL | struct Featureless;
+   | ------------------
+   | |
+   | doesn't satisfy `Featureless: One`
+   | doesn't satisfy `Featureless: Two`
+...
+LL |     let _: S::<Featureless, Featureless>::X;
+   |                                           ^ associated type cannot be referenced on `S<Featureless, Featureless>` due to unsatisfied trait bounds
+   |
+   = note: the following trait bounds were not satisfied:
+           `Featureless: One`
+           `Featureless: Two`
+
+error: aborting due to previous error
+
diff --git a/tests/ui/associated-inherent-types/substitute-params-bad.rs b/tests/ui/associated-inherent-types/substitute-params-bad.rs
new file mode 100644
index 00000000000..00eb1a14da4
--- /dev/null
+++ b/tests/ui/associated-inherent-types/substitute-params-bad.rs
@@ -0,0 +1,23 @@
+// Regression test for issue #105305 and for
+// https://github.com/rust-lang/rust/issues/107468#issuecomment-1409096700
+
+#![feature(inherent_associated_types)]
+#![allow(incomplete_features)]
+
+struct S<T>(T);
+
+impl<T, 'a> S<T> { //~ ERROR lifetime parameters must be declared prior to type and const parameters
+    type P = T;
+}
+
+struct Subj<T>(T);
+
+impl<T, S> Subj<(T, S)> {
+    type Un = (T, S);
+}
+
+fn main() {
+    type A = S<()>::P;
+
+    let _: Subj<(i32, i32)>::Un = 0i32; //~ ERROR mismatched types
+}
diff --git a/tests/ui/associated-inherent-types/substitute-params-bad.stderr b/tests/ui/associated-inherent-types/substitute-params-bad.stderr
new file mode 100644
index 00000000000..7a7808ba67b
--- /dev/null
+++ b/tests/ui/associated-inherent-types/substitute-params-bad.stderr
@@ -0,0 +1,20 @@
+error: lifetime parameters must be declared prior to type and const parameters
+  --> $DIR/substitute-params-bad.rs:9:9
+   |
+LL | impl<T, 'a> S<T> {
+   |     ----^^- help: reorder the parameters: lifetimes, then consts and types: `<'a, T>`
+
+error[E0308]: mismatched types
+  --> $DIR/substitute-params-bad.rs:22:35
+   |
+LL |     let _: Subj<(i32, i32)>::Un = 0i32;
+   |            --------------------   ^^^^ expected `(i32, i32)`, found `i32`
+   |            |
+   |            expected due to this
+   |
+   = note: expected tuple `(i32, i32)`
+               found type `i32`
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0308`.
diff --git a/tests/ui/associated-inherent-types/struct-generics.rs b/tests/ui/associated-inherent-types/substitute-params.rs
index 8952b379173..e94d6833159 100644
--- a/tests/ui/associated-inherent-types/struct-generics.rs
+++ b/tests/ui/associated-inherent-types/substitute-params.rs
@@ -9,7 +9,15 @@ impl<T> S<T> {
     type P = T;
 }
 
+impl<T> S<(T,)> {
+    type Un = T;
+}
+
 fn main() {
+    // Regression test for issue #104240.
     type A = S<()>::P;
     let _: A = ();
+
+    // Regression test for issue #107468.
+    let _: S<(i32,)>::Un = 0i32;
 }