fix various subst_identity vs skip_binder

13 files changed, 29 insertions, 25 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index 7567a02d145..8d2cc70c05f 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -2066,7 +2066,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 };
 
                 self.one_bound_for_assoc_type(
-                    || traits::supertraits(tcx, ty::Binder::dummy(trait_ref.skip_binder())),
+                    || traits::supertraits(tcx, ty::Binder::dummy(trait_ref.subst_identity())),
                     || "Self".to_string(),
                     assoc_ident,
                     span,
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 7df19ba6d36..e58669433e2 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -540,7 +540,7 @@ fn check_item_type(tcx: TyCtxt<'_>, id: hir::ItemId) {
                     tcx,
                     it.span,
                     it.owner_id.def_id,
-                    impl_trait_ref.skip_binder(),
+                    impl_trait_ref.subst_identity(),
                     &impl_.items,
                 );
                 check_on_unimplemented(tcx, it);
diff --git a/compiler/rustc_hir_analysis/src/coherence/orphan.rs b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
index e8fe9281457..0aadc9f311b 100644
--- a/compiler/rustc_hir_analysis/src/coherence/orphan.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/orphan.rs
@@ -21,7 +21,7 @@ pub(crate) fn orphan_check_impl(
     tcx: TyCtxt<'_>,
     impl_def_id: LocalDefId,
 ) -> Result<(), ErrorGuaranteed> {
-    let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder();
+    let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
     trait_ref.error_reported()?;
 
     let ret = do_orphan_check_impl(tcx, trait_ref, impl_def_id);
diff --git a/compiler/rustc_hir_analysis/src/coherence/unsafety.rs b/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
index c7693cab474..a485768e37b 100644
--- a/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/unsafety.rs
@@ -13,7 +13,8 @@ pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
     let item = tcx.hir().expect_item(def_id);
     let hir::ItemKind::Impl(ref impl_) = item.kind else { bug!() };
 
-    if let Some(trait_ref) = tcx.impl_trait_ref(item.owner_id).map(|t| t.subst_identity()) {
+    if let Some(trait_ref) = tcx.impl_trait_ref(item.owner_id) {
+        let trait_ref = trait_ref.subst_identity();
         let trait_def = tcx.trait_def(trait_ref.def_id);
         let unsafe_attr =
             impl_.generics.params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index ba856a11890..a8000aa3c8a 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1898,9 +1898,9 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
 
         for id in tcx.hir().items() {
             if matches!(tcx.def_kind(id.owner_id), DefKind::Impl) {
-                if let Some(trait_ref) =
-                    tcx.impl_trait_ref(id.owner_id).map(ty::EarlyBinder::subst_identity)
-                {
+                if let Some(trait_ref) = tcx.impl_trait_ref(id.owner_id) {
+                    let trait_ref = trait_ref.subst_identity();
+
                     let simplified_self_ty = fast_reject::simplify_type(
                         self.tcx,
                         trait_ref.self_ty(),
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 7cc4ad4ca46..e9bd0e9866f 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -2187,8 +2187,10 @@ impl<'tcx> TyCtxt<'tcx> {
     ) -> Option<ImplOverlapKind> {
         // If either trait impl references an error, they're allowed to overlap,
         // as one of them essentially doesn't exist.
-        if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.skip_binder().references_error())
-            || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.skip_binder().references_error())
+        if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.subst_identity().references_error())
+            || self
+                .impl_trait_ref(def_id2)
+                .map_or(false, |tr| tr.subst_identity().references_error())
         {
             return Some(ImplOverlapKind::Permitted { marker: false });
         }
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 3080248d508..ec1de305687 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -1351,9 +1351,9 @@ fn create_mono_items_for_default_impls<'tcx>(
                 tcx.def_path_str(item.owner_id.to_def_id())
             );
 
-            if let Some(trait_ref) =
-                tcx.impl_trait_ref(item.owner_id).map(ty::EarlyBinder::subst_identity)
-            {
+            if let Some(trait_ref) = tcx.impl_trait_ref(item.owner_id) {
+                let trait_ref = trait_ref.subst_identity();
+
                 let param_env = ty::ParamEnv::reveal_all();
                 let trait_ref = tcx.normalize_erasing_regions(param_env, trait_ref);
                 let overridden_methods = tcx.impl_item_implementor_ids(item.owner_id);
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index 185810ed3d8..0edae34190c 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -77,10 +77,10 @@ pub fn overlapping_impls(
     // a quick check via fast_reject to tell if the impl headers could possibly
     // unify.
     let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::AsInfer };
-    let impl1_ref = tcx.impl_trait_ref(impl1_def_id).map(ty::EarlyBinder::subst_identity);
-    let impl2_ref = tcx.impl_trait_ref(impl2_def_id).map(ty::EarlyBinder::subst_identity);
+    let impl1_ref = tcx.impl_trait_ref(impl1_def_id);
+    let impl2_ref = tcx.impl_trait_ref(impl2_def_id);
     let may_overlap = match (impl1_ref, impl2_ref) {
-        (Some(a), Some(b)) => iter::zip(a.substs, b.substs)
+        (Some(a), Some(b)) => iter::zip(a.skip_binder().substs, b.skip_binder().substs)
             .all(|(arg1, arg2)| drcx.generic_args_may_unify(arg1, arg2)),
         (None, None) => {
             let self_ty1 = tcx.type_of(impl1_def_id);
@@ -461,7 +461,7 @@ pub fn orphan_check(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Result<(), OrphanChe
 
     // We only except this routine to be invoked on implementations
     // of a trait, not inherent implementations.
-    let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder();
+    let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
     debug!("orphan_check: trait_ref={:?}", trait_ref);
 
     // If the *trait* is local to the crate, ok.
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 5d2e0bd5afa..052db2cfe7b 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -1940,7 +1940,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     return None;
                 }
 
-                let imp = self.tcx.impl_trait_ref(def_id).unwrap().subst_identity();
+                let imp = self.tcx.impl_trait_ref(def_id).unwrap().skip_binder();
 
                 self.fuzzy_match_tys(trait_pred.skip_binder().self_ty(), imp.self_ty(), false)
                     .map(|similarity| ImplCandidate { trait_ref: imp, similarity })
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index 69b671b27bd..3b796c623c0 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -431,7 +431,7 @@ fn report_conflicting_impls<'tcx>(
 pub(crate) fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
     use std::fmt::Write;
 
-    let trait_ref = tcx.impl_trait_ref(impl_def_id)?.skip_binder();
+    let trait_ref = tcx.impl_trait_ref(impl_def_id)?.subst_identity();
     let mut w = "impl".to_owned();
 
     let substs = InternalSubsts::identity_for_item(tcx, impl_def_id);
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
index eb4815122c3..6411206a5a4 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/specialization_graph.rs
@@ -48,7 +48,7 @@ trait ChildrenExt<'tcx> {
 impl<'tcx> ChildrenExt<'tcx> for Children {
     /// Insert an impl into this set of children without comparing to any existing impls.
     fn insert_blindly(&mut self, tcx: TyCtxt<'tcx>, impl_def_id: DefId) {
-        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
+        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder();
         if let Some(st) = fast_reject::simplify_type(tcx, trait_ref.self_ty(), TreatParams::AsInfer)
         {
             debug!("insert_blindly: impl_def_id={:?} st={:?}", impl_def_id, st);
@@ -63,7 +63,7 @@ impl<'tcx> ChildrenExt<'tcx> for Children {
     /// an impl with a parent. The impl must be present in the list of
     /// children already.
     fn remove_existing(&mut self, tcx: TyCtxt<'tcx>, impl_def_id: DefId) {
-        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
+        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder();
         let vec: &mut Vec<DefId>;
         if let Some(st) = fast_reject::simplify_type(tcx, trait_ref.self_ty(), TreatParams::AsInfer)
         {
@@ -275,7 +275,8 @@ impl<'tcx> GraphExt<'tcx> for Graph {
     ) -> Result<Option<FutureCompatOverlapError<'tcx>>, OverlapError<'tcx>> {
         assert!(impl_def_id.is_local());
 
-        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().subst_identity();
+        // FIXME: use `EarlyBinder` in `self.children`
+        let trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder();
         let trait_def_id = trait_ref.def_id;
 
         debug!(
@@ -388,7 +389,7 @@ pub(crate) fn assoc_def(
     impl_def_id: DefId,
     assoc_def_id: DefId,
 ) -> Result<LeafDef, ErrorGuaranteed> {
-    let trait_def_id = tcx.impl_trait_ref(impl_def_id).unwrap().skip_binder().def_id;
+    let trait_def_id = tcx.trait_id_of_impl(impl_def_id).unwrap();
     let trait_def = tcx.trait_def(trait_def_id);
 
     // This function may be called while we are still building the
diff --git a/compiler/rustc_ty_utils/src/implied_bounds.rs b/compiler/rustc_ty_utils/src/implied_bounds.rs
index 7a9c1d8ffe7..7a24645803c 100644
--- a/compiler/rustc_ty_utils/src/implied_bounds.rs
+++ b/compiler/rustc_ty_utils/src/implied_bounds.rs
@@ -22,9 +22,9 @@ fn assumed_wf_types(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::List<Ty<'_>> {
             tcx.intern_type_list(&assumed_wf_types)
         }
         DefKind::Impl => {
-            match tcx.impl_trait_ref(def_id).map(ty::EarlyBinder::subst_identity) {
+            match tcx.impl_trait_ref(def_id) {
                 Some(trait_ref) => {
-                    let types: Vec<_> = trait_ref.substs.types().collect();
+                    let types: Vec<_> = trait_ref.skip_binder().substs.types().collect();
                     tcx.intern_type_list(&types)
                 }
                 // Only the impl self type
diff --git a/src/librustdoc/passes/collect_intra_doc_links.rs b/src/librustdoc/passes/collect_intra_doc_links.rs
index 62588040685..075951312a6 100644
--- a/src/librustdoc/passes/collect_intra_doc_links.rs
+++ b/src/librustdoc/passes/collect_intra_doc_links.rs
@@ -786,7 +786,7 @@ fn trait_impls_for<'a>(
         tcx.find_map_relevant_impl(trait_, ty, |impl_| {
             let trait_ref = tcx.impl_trait_ref(impl_).expect("this is not an inherent impl");
             // Check if these are the same type.
-            let impl_type = trait_ref.subst_identity().self_ty();
+            let impl_type = trait_ref.skip_binder().self_ty();
             trace!(
                 "comparing type {} with kind {:?} against type {:?}",
                 impl_type,