Auto merge of #120919 - oli-obk:impl_polarity, r=compiler-errors

Merge `impl_polarity` and `impl_trait_ref` queries

Hopefully this is perf neutral. I want to finish https://github.com/rust-lang/rust/pull/120835 and stop using the HIR in `coherent_trait`, which should then give us a perf improvement.

21 files changed, 152 insertions, 127 deletions

diff --git a/compiler/rustc_hir_analysis/src/astconv/mod.rs b/compiler/rustc_hir_analysis/src/astconv/mod.rs
index cc1ccff1a1d..a001044c3e5 100644
--- a/compiler/rustc_hir_analysis/src/astconv/mod.rs
+++ b/compiler/rustc_hir_analysis/src/astconv/mod.rs
@@ -1673,9 +1673,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                         .is_accessible_from(self.item_def_id(), tcx)
                     && tcx.all_impls(*trait_def_id)
                         .any(|impl_def_id| {
-                            let trait_ref = tcx.impl_trait_ref(impl_def_id);
-                            trait_ref.is_some_and(|trait_ref| {
-                                let impl_ = trait_ref.instantiate(
+                            let impl_header = tcx.impl_trait_header(impl_def_id);
+                            impl_header.is_some_and(|header| {
+                                let header = header.instantiate(
                                     tcx,
                                     infcx.fresh_args_for_item(DUMMY_SP, impl_def_id),
                                 );
@@ -1687,11 +1687,10 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                                 infcx
                                     .can_eq(
                                         ty::ParamEnv::empty(),
-                                        impl_.self_ty(),
+                                        header.trait_ref.self_ty(),
                                         value,
-                                    )
+                                    ) && header.polarity != ty::ImplPolarity::Negative
                             })
-                            && tcx.impl_polarity(impl_def_id) != ty::ImplPolarity::Negative
                         })
             })
             .map(|trait_def_id| tcx.def_path_str(trait_def_id))
@@ -1737,13 +1736,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
             } else {
                 // Find all the types that have an `impl` for the trait.
                 tcx.all_impls(trait_def_id)
-                    .filter(|impl_def_id| {
+                    .filter_map(|impl_def_id| tcx.impl_trait_header(impl_def_id))
+                    .filter(|header| {
                         // Consider only accessible traits
                         tcx.visibility(trait_def_id).is_accessible_from(self.item_def_id(), tcx)
-                            && tcx.impl_polarity(impl_def_id) != ty::ImplPolarity::Negative
+                            && header.skip_binder().polarity != ty::ImplPolarity::Negative
                     })
-                    .filter_map(|impl_def_id| tcx.impl_trait_ref(impl_def_id))
-                    .map(|impl_| impl_.instantiate_identity().self_ty())
+                    .map(|header| header.instantiate_identity().trait_ref.self_ty())
                     // We don't care about blanket impls.
                     .filter(|self_ty| !self_ty.has_non_region_param())
                     .map(|self_ty| tcx.erase_regions(self_ty).to_string())
diff --git a/compiler/rustc_hir_analysis/src/check/check.rs b/compiler/rustc_hir_analysis/src/check/check.rs
index 88800491ba2..b693d7201c1 100644
--- a/compiler/rustc_hir_analysis/src/check/check.rs
+++ b/compiler/rustc_hir_analysis/src/check/check.rs
@@ -527,8 +527,12 @@ pub(crate) fn check_item_type(tcx: TyCtxt<'_>, def_id: LocalDefId) {
         }
         DefKind::Fn => {} // entirely within check_item_body
         DefKind::Impl { of_trait } => {
-            if of_trait && let Some(impl_trait_ref) = tcx.impl_trait_ref(def_id) {
-                check_impl_items_against_trait(tcx, def_id, impl_trait_ref.instantiate_identity());
+            if of_trait && let Some(impl_trait_header) = tcx.impl_trait_header(def_id) {
+                check_impl_items_against_trait(
+                    tcx,
+                    def_id,
+                    impl_trait_header.instantiate_identity(),
+                );
                 check_on_unimplemented(tcx, def_id);
             }
         }
@@ -719,19 +723,19 @@ pub(super) fn check_specialization_validity<'tcx>(
 fn check_impl_items_against_trait<'tcx>(
     tcx: TyCtxt<'tcx>,
     impl_id: LocalDefId,
-    impl_trait_ref: ty::TraitRef<'tcx>,
+    impl_trait_header: ty::ImplTraitHeader<'tcx>,
 ) {
     // If the trait reference itself is erroneous (so the compilation is going
     // to fail), skip checking the items here -- the `impl_item` table in `tcx`
     // isn't populated for such impls.
-    if impl_trait_ref.references_error() {
+    if impl_trait_header.references_error() {
         return;
     }
 
     let impl_item_refs = tcx.associated_item_def_ids(impl_id);
 
     // Negative impls are not expected to have any items
-    match tcx.impl_polarity(impl_id) {
+    match impl_trait_header.polarity {
         ty::ImplPolarity::Reservation | ty::ImplPolarity::Positive => {}
         ty::ImplPolarity::Negative => {
             if let [first_item_ref, ..] = impl_item_refs {
@@ -748,7 +752,7 @@ fn check_impl_items_against_trait<'tcx>(
         }
     }
 
-    let trait_def = tcx.trait_def(impl_trait_ref.def_id);
+    let trait_def = tcx.trait_def(impl_trait_header.trait_ref.def_id);
 
     for &impl_item in impl_item_refs {
         let ty_impl_item = tcx.associated_item(impl_item);
@@ -767,10 +771,10 @@ fn check_impl_items_against_trait<'tcx>(
                 ));
             }
             ty::AssocKind::Fn => {
-                compare_impl_method(tcx, ty_impl_item, ty_trait_item, impl_trait_ref);
+                compare_impl_method(tcx, ty_impl_item, ty_trait_item, impl_trait_header.trait_ref);
             }
             ty::AssocKind::Type => {
-                compare_impl_ty(tcx, ty_impl_item, ty_trait_item, impl_trait_ref);
+                compare_impl_ty(tcx, ty_impl_item, ty_trait_item, impl_trait_header.trait_ref);
             }
         }
 
@@ -790,7 +794,7 @@ fn check_impl_items_against_trait<'tcx>(
         let mut must_implement_one_of: Option<&[Ident]> =
             trait_def.must_implement_one_of.as_deref();
 
-        for &trait_item_id in tcx.associated_item_def_ids(impl_trait_ref.def_id) {
+        for &trait_item_id in tcx.associated_item_def_ids(impl_trait_header.trait_ref.def_id) {
             let leaf_def = ancestors.leaf_def(tcx, trait_item_id);
 
             let is_implemented = leaf_def
@@ -868,7 +872,7 @@ fn check_impl_items_against_trait<'tcx>(
 
         if let Some(missing_items) = must_implement_one_of {
             let attr_span = tcx
-                .get_attr(impl_trait_ref.def_id, sym::rustc_must_implement_one_of)
+                .get_attr(impl_trait_header.trait_ref.def_id, sym::rustc_must_implement_one_of)
                 .map(|attr| attr.span);
 
             missing_items_must_implement_one_of_err(
diff --git a/compiler/rustc_hir_analysis/src/check/wfcheck.rs b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
index 9541a0bcc48..7f674a1e7e4 100644
--- a/compiler/rustc_hir_analysis/src/check/wfcheck.rs
+++ b/compiler/rustc_hir_analysis/src/check/wfcheck.rs
@@ -245,9 +245,9 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
         // won't be allowed unless there's an *explicit* implementation of `Send`
         // for `T`
         hir::ItemKind::Impl(impl_) => {
-            let is_auto = tcx
-                .impl_trait_ref(def_id)
-                .is_some_and(|trait_ref| tcx.trait_is_auto(trait_ref.skip_binder().def_id));
+            let header = tcx.impl_trait_header(def_id);
+            let is_auto = header
+                .is_some_and(|header| tcx.trait_is_auto(header.skip_binder().trait_ref.def_id));
             let mut res = Ok(());
             if let (hir::Defaultness::Default { .. }, true) = (impl_.defaultness, is_auto) {
                 let sp = impl_.of_trait.as_ref().map_or(item.span, |t| t.path.span);
@@ -259,11 +259,12 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
                     .emit());
             }
             // We match on both `ty::ImplPolarity` and `ast::ImplPolarity` just to get the `!` span.
-            match tcx.impl_polarity(def_id) {
-                ty::ImplPolarity::Positive => {
+            match header.map(|h| h.skip_binder().polarity) {
+                // `None` means this is an inherent impl
+                Some(ty::ImplPolarity::Positive) | None => {
                     res = res.and(check_impl(tcx, item, impl_.self_ty, &impl_.of_trait));
                 }
-                ty::ImplPolarity::Negative => {
+                Some(ty::ImplPolarity::Negative) => {
                     let ast::ImplPolarity::Negative(span) = impl_.polarity else {
                         bug!("impl_polarity query disagrees with impl's polarity in AST");
                     };
@@ -280,7 +281,7 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
                         .emit());
                     }
                 }
-                ty::ImplPolarity::Reservation => {
+                Some(ty::ImplPolarity::Reservation) => {
                     // FIXME: what amount of WF checking do we need for reservation impls?
                 }
             }
diff --git a/compiler/rustc_hir_analysis/src/collect.rs b/compiler/rustc_hir_analysis/src/collect.rs
index d92e1a14151..e8787d159ae 100644
--- a/compiler/rustc_hir_analysis/src/collect.rs
+++ b/compiler/rustc_hir_analysis/src/collect.rs
@@ -79,8 +79,7 @@ pub fn provide(providers: &mut Providers) {
         trait_def,
         adt_def,
         fn_sig,
-        impl_trait_ref,
-        impl_polarity,
+        impl_trait_header,
         coroutine_kind,
         coroutine_for_closure,
         collect_mod_item_types,
@@ -600,7 +599,7 @@ fn convert_item(tcx: TyCtxt<'_>, item_id: hir::ItemId) {
         hir::ItemKind::Impl { .. } => {
             tcx.ensure().generics_of(def_id);
             tcx.ensure().type_of(def_id);
-            tcx.ensure().impl_trait_ref(def_id);
+            tcx.ensure().impl_trait_header(def_id);
             tcx.ensure().predicates_of(def_id);
         }
         hir::ItemKind::Trait(..) => {
@@ -1499,19 +1498,20 @@ fn suggest_impl_trait<'tcx>(
     None
 }
 
-fn impl_trait_ref(
+fn impl_trait_header(
     tcx: TyCtxt<'_>,
     def_id: LocalDefId,
-) -> Option<ty::EarlyBinder<ty::TraitRef<'_>>> {
+) -> Option<ty::EarlyBinder<ty::ImplTraitHeader<'_>>> {
     let icx = ItemCtxt::new(tcx, def_id);
-    let impl_ = tcx.hir().expect_item(def_id).expect_impl();
+    let item = tcx.hir().expect_item(def_id);
+    let impl_ = item.expect_impl();
     impl_
         .of_trait
         .as_ref()
         .map(|ast_trait_ref| {
             let selfty = tcx.type_of(def_id).instantiate_identity();
 
-            if let Some(ErrorGuaranteed { .. }) = check_impl_constness(
+            let trait_ref = if let Some(ErrorGuaranteed { .. }) = check_impl_constness(
                 tcx,
                 tcx.is_const_trait_impl_raw(def_id.to_def_id()),
                 ast_trait_ref,
@@ -1536,9 +1536,12 @@ fn impl_trait_ref(
                 icx.astconv().instantiate_mono_trait_ref(trait_ref, selfty)
             } else {
                 icx.astconv().instantiate_mono_trait_ref(ast_trait_ref, selfty)
-            }
+            };
+            ty::EarlyBinder::bind(ty::ImplTraitHeader {
+                trait_ref,
+                polarity: polarity_of_impl(tcx, def_id,  impl_, item.span)
+            })
         })
-        .map(ty::EarlyBinder::bind)
 }
 
 fn check_impl_constness(
@@ -1566,43 +1569,34 @@ fn check_impl_constness(
     }))
 }
 
-fn impl_polarity(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::ImplPolarity {
+fn polarity_of_impl(
+    tcx: TyCtxt<'_>,
+    def_id: LocalDefId,
+    impl_: &hir::Impl<'_>,
+    span: Span,
+) -> ty::ImplPolarity {
     let is_rustc_reservation = tcx.has_attr(def_id, sym::rustc_reservation_impl);
-    let item = tcx.hir().expect_item(def_id);
-    match &item.kind {
-        hir::ItemKind::Impl(hir::Impl {
-            polarity: hir::ImplPolarity::Negative(span),
-            of_trait,
-            ..
-        }) => {
+    match &impl_ {
+        hir::Impl { polarity: hir::ImplPolarity::Negative(span), of_trait, .. } => {
             if is_rustc_reservation {
                 let span = span.to(of_trait.as_ref().map_or(*span, |t| t.path.span));
                 tcx.dcx().span_err(span, "reservation impls can't be negative");
             }
             ty::ImplPolarity::Negative
         }
-        hir::ItemKind::Impl(hir::Impl {
-            polarity: hir::ImplPolarity::Positive,
-            of_trait: None,
-            ..
-        }) => {
+        hir::Impl { polarity: hir::ImplPolarity::Positive, of_trait: None, .. } => {
             if is_rustc_reservation {
-                tcx.dcx().span_err(item.span, "reservation impls can't be inherent");
+                tcx.dcx().span_err(span, "reservation impls can't be inherent");
             }
             ty::ImplPolarity::Positive
         }
-        hir::ItemKind::Impl(hir::Impl {
-            polarity: hir::ImplPolarity::Positive,
-            of_trait: Some(_),
-            ..
-        }) => {
+        hir::Impl { polarity: hir::ImplPolarity::Positive, of_trait: Some(_), .. } => {
             if is_rustc_reservation {
                 ty::ImplPolarity::Reservation
             } else {
                 ty::ImplPolarity::Positive
             }
         }
-        item => bug!("impl_polarity: {:?} not an impl", item),
     }
 }
 
diff --git a/compiler/rustc_hir_typeck/src/method/suggest.rs b/compiler/rustc_hir_typeck/src/method/suggest.rs
index 7fc51e36a2b..ab5c0f32705 100644
--- a/compiler/rustc_hir_typeck/src/method/suggest.rs
+++ b/compiler/rustc_hir_typeck/src/method/suggest.rs
@@ -3134,12 +3134,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     if self
                         .tcx
                         .all_impls(candidate.def_id)
-                        .filter(|imp_did| {
-                            self.tcx.impl_polarity(*imp_did) == ty::ImplPolarity::Negative
+                        .map(|imp_did| {
+                            self.tcx.impl_trait_header(imp_did).expect(
+                                "inherent impls can't be candidates, only trait impls can be",
+                            )
+                        })
+                        .filter(|header| {
+                            header.skip_binder().polarity == ty::ImplPolarity::Negative
                         })
-                        .any(|imp_did| {
-                            let imp =
-                                self.tcx.impl_trait_ref(imp_did).unwrap().instantiate_identity();
+                        .any(|header| {
+                            let imp = header.instantiate_identity().trait_ref;
                             let imp_simp =
                                 simplify_type(self.tcx, imp.self_ty(), TreatParams::ForLookup);
                             imp_simp.is_some_and(|s| s == simp_rcvr_ty)
diff --git a/compiler/rustc_incremental/src/persist/dirty_clean.rs b/compiler/rustc_incremental/src/persist/dirty_clean.rs
index 14cc8c260e2..8311a735133 100644
--- a/compiler/rustc_incremental/src/persist/dirty_clean.rs
+++ b/compiler/rustc_incremental/src/persist/dirty_clean.rs
@@ -63,7 +63,7 @@ const BASE_HIR: &[&str] = &[
 
 /// `impl` implementation of struct/trait
 const BASE_IMPL: &[&str] =
-    &[label_strs::associated_item_def_ids, label_strs::generics_of, label_strs::impl_trait_ref];
+    &[label_strs::associated_item_def_ids, label_strs::generics_of, label_strs::impl_trait_header];
 
 /// DepNodes for mir_built/Optimized, which is relevant in "executable"
 /// code, i.e., functions+methods
diff --git a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
index 988388edfd5..d79d4b226a5 100644
--- a/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
+++ b/compiler/rustc_metadata/src/rmeta/decoder/cstore_impl.rs
@@ -215,7 +215,7 @@ provide! { tcx, def_id, other, cdata,
     variances_of => { table }
     fn_sig => { table }
     codegen_fn_attrs => { table }
-    impl_trait_ref => { table }
+    impl_trait_header => { table }
     const_param_default => { table }
     object_lifetime_default => { table }
     thir_abstract_const => { table }
@@ -234,7 +234,6 @@ provide! { tcx, def_id, other, cdata,
     unused_generic_params => { cdata.root.tables.unused_generic_params.get(cdata, def_id.index) }
     def_kind => { cdata.def_kind(def_id.index) }
     impl_parent => { table }
-    impl_polarity => { table_direct }
     defaultness => { table_direct }
     constness => { table_direct }
     coerce_unsized_info => {
diff --git a/compiler/rustc_metadata/src/rmeta/encoder.rs b/compiler/rustc_metadata/src/rmeta/encoder.rs
index 6ca1973396f..4a24c038f7a 100644
--- a/compiler/rustc_metadata/src/rmeta/encoder.rs
+++ b/compiler/rustc_metadata/src/rmeta/encoder.rs
@@ -1969,10 +1969,10 @@ impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
             let def_id = id.owner_id.to_def_id();
 
             self.tables.defaultness.set_some(def_id.index, tcx.defaultness(def_id));
-            self.tables.impl_polarity.set_some(def_id.index, tcx.impl_polarity(def_id));
 
-            if of_trait && let Some(trait_ref) = tcx.impl_trait_ref(def_id) {
-                record!(self.tables.impl_trait_ref[def_id] <- trait_ref);
+            if of_trait && let Some(header) = tcx.impl_trait_header(def_id) {
+                record!(self.tables.impl_trait_header[def_id] <- header);
+                let trait_ref = header.map_bound(|h| h.trait_ref);
 
                 let trait_ref = trait_ref.instantiate_identity();
                 let simplified_self_ty = fast_reject::simplify_type(
diff --git a/compiler/rustc_metadata/src/rmeta/mod.rs b/compiler/rustc_metadata/src/rmeta/mod.rs
index 8205e995c19..4d0a6cb60ee 100644
--- a/compiler/rustc_metadata/src/rmeta/mod.rs
+++ b/compiler/rustc_metadata/src/rmeta/mod.rs
@@ -423,7 +423,7 @@ define_tables! {
     variances_of: Table<DefIndex, LazyArray<ty::Variance>>,
     fn_sig: Table<DefIndex, LazyValue<ty::EarlyBinder<ty::PolyFnSig<'static>>>>,
     codegen_fn_attrs: Table<DefIndex, LazyValue<CodegenFnAttrs>>,
-    impl_trait_ref: Table<DefIndex, LazyValue<ty::EarlyBinder<ty::TraitRef<'static>>>>,
+    impl_trait_header: Table<DefIndex, LazyValue<ty::EarlyBinder<ty::ImplTraitHeader<'static>>>>,
     const_param_default: Table<DefIndex, LazyValue<ty::EarlyBinder<rustc_middle::ty::Const<'static>>>>,
     object_lifetime_default: Table<DefIndex, LazyValue<ObjectLifetimeDefault>>,
     optimized_mir: Table<DefIndex, LazyValue<mir::Body<'static>>>,
@@ -433,7 +433,6 @@ define_tables! {
     promoted_mir: Table<DefIndex, LazyValue<IndexVec<mir::Promoted, mir::Body<'static>>>>,
     thir_abstract_const: Table<DefIndex, LazyValue<ty::EarlyBinder<ty::Const<'static>>>>,
     impl_parent: Table<DefIndex, RawDefId>,
-    impl_polarity: Table<DefIndex, ty::ImplPolarity>,
     constness: Table<DefIndex, hir::Constness>,
     defaultness: Table<DefIndex, hir::Defaultness>,
     // FIXME(eddyb) perhaps compute this on the fly if cheap enough?
diff --git a/compiler/rustc_middle/src/query/erase.rs b/compiler/rustc_middle/src/query/erase.rs
index 7039749b1b7..5666a59e38e 100644
--- a/compiler/rustc_middle/src/query/erase.rs
+++ b/compiler/rustc_middle/src/query/erase.rs
@@ -177,8 +177,8 @@ impl EraseType for Option<mir::DestructuredConstant<'_>> {
     type Result = [u8; size_of::<Option<mir::DestructuredConstant<'static>>>()];
 }
 
-impl EraseType for Option<ty::EarlyBinder<ty::TraitRef<'_>>> {
-    type Result = [u8; size_of::<Option<ty::EarlyBinder<ty::TraitRef<'static>>>>()];
+impl EraseType for Option<ty::EarlyBinder<ty::ImplTraitHeader<'_>>> {
+    type Result = [u8; size_of::<Option<ty::EarlyBinder<ty::ImplTraitHeader<'static>>>>()];
 }
 
 impl EraseType for Option<ty::EarlyBinder<Ty<'_>>> {
diff --git a/compiler/rustc_middle/src/query/mod.rs b/compiler/rustc_middle/src/query/mod.rs
index 5a158edab72..60d195e4d3e 100644
--- a/compiler/rustc_middle/src/query/mod.rs
+++ b/compiler/rustc_middle/src/query/mod.rs
@@ -846,17 +846,13 @@ rustc_queries! {
         cache_on_disk_if { true }
     }
 
-    /// Given an `impl_id`, return the trait it implements.
+    /// Given an `impl_id`, return the trait it implements along with some header information.
     /// Return `None` if this is an inherent impl.
-    query impl_trait_ref(impl_id: DefId) -> Option<ty::EarlyBinder<ty::TraitRef<'tcx>>> {
+    query impl_trait_header(impl_id: DefId) -> Option<ty::EarlyBinder<ty::ImplTraitHeader<'tcx>>> {
         desc { |tcx| "computing trait implemented by `{}`", tcx.def_path_str(impl_id) }
         cache_on_disk_if { impl_id.is_local() }
         separate_provide_extern
     }
-    query impl_polarity(impl_id: DefId) -> ty::ImplPolarity {
-        desc { |tcx| "computing implementation polarity of `{}`", tcx.def_path_str(impl_id) }
-        separate_provide_extern
-    }
 
     query issue33140_self_ty(key: DefId) -> Option<ty::EarlyBinder<ty::Ty<'tcx>>> {
         desc { |tcx| "computing Self type wrt issue #33140 `{}`", tcx.def_path_str(key) }
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 9a0eea6592f..bd86c1c284e 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -2316,6 +2316,20 @@ impl<'tcx> TyCtxt<'tcx> {
     pub fn module_children_local(self, def_id: LocalDefId) -> &'tcx [ModChild] {
         self.resolutions(()).module_children.get(&def_id).map_or(&[], |v| &v[..])
     }
+
+    /// Given an `impl_id`, return the trait it implements.
+    /// Return `None` if this is an inherent impl.
+    pub fn impl_trait_ref(
+        self,
+        def_id: impl IntoQueryParam<DefId>,
+    ) -> Option<ty::EarlyBinder<ty::TraitRef<'tcx>>> {
+        Some(self.impl_trait_header(def_id)?.map_bound(|h| h.trait_ref))
+    }
+
+    pub fn impl_polarity(self, def_id: impl IntoQueryParam<DefId>) -> ty::ImplPolarity {
+        self.impl_trait_header(def_id)
+            .map_or(ty::ImplPolarity::Positive, |h| h.skip_binder().polarity)
+    }
 }
 
 /// Parameter attributes that can only be determined by examining the body of a function instead
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index af77ba02ad2..6ee74ef2fb6 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -248,6 +248,12 @@ pub struct ImplHeader<'tcx> {
     pub predicates: Vec<Predicate<'tcx>>,
 }
 
+#[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, TyEncodable, TyDecodable, HashStable)]
+pub struct ImplTraitHeader<'tcx> {
+    pub trait_ref: ty::TraitRef<'tcx>,
+    pub polarity: ImplPolarity,
+}
+
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]
 pub enum ImplSubject<'tcx> {
     Trait(TraitRef<'tcx>),
@@ -1602,17 +1608,16 @@ impl<'tcx> TyCtxt<'tcx> {
         def_id1: DefId,
         def_id2: DefId,
     ) -> Option<ImplOverlapKind> {
-        let impl_trait_ref1 = self.impl_trait_ref(def_id1);
-        let impl_trait_ref2 = self.impl_trait_ref(def_id2);
+        let impl1 = self.impl_trait_header(def_id1).unwrap().instantiate_identity();
+        let impl2 = self.impl_trait_header(def_id2).unwrap().instantiate_identity();
+
         // If either trait impl references an error, they're allowed to overlap,
         // as one of them essentially doesn't exist.
-        if impl_trait_ref1.is_some_and(|tr| tr.instantiate_identity().references_error())
-            || impl_trait_ref2.is_some_and(|tr| tr.instantiate_identity().references_error())
-        {
+        if impl1.references_error() || impl2.references_error() {
             return Some(ImplOverlapKind::Permitted { marker: false });
         }
 
-        match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
+        match (impl1.polarity, impl2.polarity) {
             (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
                 // `#[rustc_reservation_impl]` impls don't overlap with anything
                 return Some(ImplOverlapKind::Permitted { marker: false });
@@ -1627,10 +1632,9 @@ impl<'tcx> TyCtxt<'tcx> {
         };
 
         let is_marker_overlap = {
-            let is_marker_impl = |trait_ref: Option<EarlyBinder<TraitRef<'_>>>| -> bool {
-                trait_ref.is_some_and(|tr| self.trait_def(tr.skip_binder().def_id).is_marker)
-            };
-            is_marker_impl(impl_trait_ref1) && is_marker_impl(impl_trait_ref2)
+            let is_marker_impl =
+                |trait_ref: TraitRef<'_>| -> bool { self.trait_def(trait_ref.def_id).is_marker };
+            is_marker_impl(impl1.trait_ref) && is_marker_impl(impl2.trait_ref)
         };
 
         if is_marker_overlap {
diff --git a/compiler/rustc_middle/src/ty/parameterized.rs b/compiler/rustc_middle/src/ty/parameterized.rs
index 47f9d9e61ad..045856dd9cd 100644
--- a/compiler/rustc_middle/src/ty/parameterized.rs
+++ b/compiler/rustc_middle/src/ty/parameterized.rs
@@ -134,4 +134,5 @@ parameterized_over_tcx! {
     ty::Predicate,
     ty::Clause,
     ty::ClauseKind,
+    ty::ImplTraitHeader
 }
diff --git a/compiler/rustc_monomorphize/src/collector.rs b/compiler/rustc_monomorphize/src/collector.rs
index 8ae9457ff76..1c9913fa203 100644
--- a/compiler/rustc_monomorphize/src/collector.rs
+++ b/compiler/rustc_monomorphize/src/collector.rs
@@ -1347,18 +1347,17 @@ fn create_mono_items_for_default_impls<'tcx>(
     item: hir::ItemId,
     output: &mut MonoItems<'tcx>,
 ) {
-    let polarity = tcx.impl_polarity(item.owner_id);
-    if matches!(polarity, ty::ImplPolarity::Negative) {
+    let Some(impl_) = tcx.impl_trait_header(item.owner_id) else {
         return;
-    }
+    };
 
-    if tcx.generics_of(item.owner_id).own_requires_monomorphization() {
+    if matches!(impl_.skip_binder().polarity, ty::ImplPolarity::Negative) {
         return;
     }
 
-    let Some(trait_ref) = tcx.impl_trait_ref(item.owner_id) else {
+    if tcx.generics_of(item.owner_id).own_requires_monomorphization() {
         return;
-    };
+    }
 
     // Lifetimes never affect trait selection, so we are allowed to eagerly
     // instantiate an instance of an impl method if the impl (and method,
@@ -1376,7 +1375,7 @@ fn create_mono_items_for_default_impls<'tcx>(
         }
     };
     let impl_args = GenericArgs::for_item(tcx, item.owner_id.to_def_id(), only_region_params);
-    let trait_ref = trait_ref.instantiate(tcx, impl_args);
+    let trait_ref = impl_.instantiate(tcx, impl_args).trait_ref;
 
     // Unlike 'lazy' monomorphization that begins by collecting items transitively
     // called by `main` or other global items, when eagerly monomorphizing impl
diff --git a/compiler/rustc_trait_selection/src/solve/trait_goals.rs b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
index 32b46c7ac44..7a466241bfa 100644
--- a/compiler/rustc_trait_selection/src/solve/trait_goals.rs
+++ b/compiler/rustc_trait_selection/src/solve/trait_goals.rs
@@ -39,15 +39,18 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
     ) -> Result<Candidate<'tcx>, NoSolution> {
         let tcx = ecx.tcx();
 
-        let impl_trait_ref = tcx.impl_trait_ref(impl_def_id).unwrap();
+        let impl_trait_header = tcx.impl_trait_header(impl_def_id).unwrap();
         let drcx = DeepRejectCtxt { treat_obligation_params: TreatParams::ForLookup };
-        if !drcx.args_may_unify(goal.predicate.trait_ref.args, impl_trait_ref.skip_binder().args) {
+        if !drcx.args_may_unify(
+            goal.predicate.trait_ref.args,
+            impl_trait_header.skip_binder().trait_ref.args,
+        ) {
             return Err(NoSolution);
         }
 
-        let impl_polarity = tcx.impl_polarity(impl_def_id);
         // An upper bound of the certainty of this goal, used to lower the certainty
         // of reservation impl to ambiguous during coherence.
+        let impl_polarity = impl_trait_header.skip_binder().polarity;
         let maximal_certainty = match impl_polarity {
             ty::ImplPolarity::Positive | ty::ImplPolarity::Negative => {
                 match impl_polarity == goal.predicate.polarity {
@@ -63,7 +66,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
 
         ecx.probe_trait_candidate(CandidateSource::Impl(impl_def_id)).enter(|ecx| {
             let impl_args = ecx.fresh_args_for_item(impl_def_id);
-            let impl_trait_ref = impl_trait_ref.instantiate(tcx, impl_args);
+            let impl_trait_ref = impl_trait_header.instantiate(tcx, impl_args).trait_ref;
 
             ecx.eq(goal.param_env, goal.predicate.trait_ref, impl_trait_ref)?;
             let where_clause_bounds = tcx
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
index f3b6dd0a8d4..c5ee0391682 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
@@ -1976,13 +1976,13 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             .tcx
             .all_impls(trait_pred.def_id())
             .filter_map(|def_id| {
-                if self.tcx.impl_polarity(def_id) == ty::ImplPolarity::Negative
+                let imp = self.tcx.impl_trait_header(def_id).unwrap().skip_binder();
+                if imp.polarity == ty::ImplPolarity::Negative
                     || !self.tcx.is_user_visible_dep(def_id.krate)
                 {
                     return None;
                 }
-
-                let imp = self.tcx.impl_trait_ref(def_id).unwrap().skip_binder();
+                let imp = imp.trait_ref;
 
                 self.fuzzy_match_tys(trait_pred.skip_binder().self_ty(), imp.self_ty(), false).map(
                     |similarity| ImplCandidate { trait_ref: imp, similarity, impl_def_id: def_id },
@@ -2161,12 +2161,13 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 .tcx
                 .all_impls(def_id)
                 // Ignore automatically derived impls and `!Trait` impls.
-                .filter(|&def_id| {
-                    self.tcx.impl_polarity(def_id) != ty::ImplPolarity::Negative
+                .filter_map(|def_id| self.tcx.impl_trait_header(def_id))
+                .map(ty::EarlyBinder::instantiate_identity)
+                .filter(|header| {
+                    header.polarity != ty::ImplPolarity::Negative
                         || self.tcx.is_automatically_derived(def_id)
                 })
-                .filter_map(|def_id| self.tcx.impl_trait_ref(def_id))
-                .map(ty::EarlyBinder::instantiate_identity)
+                .map(|header| header.trait_ref)
                 .filter(|trait_ref| {
                     let self_ty = trait_ref.self_ty();
                     // Avoid mentioning type parameters.
diff --git a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
index bafb8c10bf1..31a0d6271fa 100644
--- a/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
@@ -560,20 +560,22 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 // Before we create the generic parameters and everything, first
                 // consider a "quick reject". This avoids creating more types
                 // and so forth that we need to.
-                let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap();
-                if !drcx.args_may_unify(obligation_args, impl_trait_ref.skip_binder().args) {
+                let impl_trait_header = self.tcx().impl_trait_header(impl_def_id).unwrap();
+                if !drcx
+                    .args_may_unify(obligation_args, impl_trait_header.skip_binder().trait_ref.args)
+                {
                     return;
                 }
                 if self.reject_fn_ptr_impls(
                     impl_def_id,
                     obligation,
-                    impl_trait_ref.skip_binder().self_ty(),
+                    impl_trait_header.skip_binder().trait_ref.self_ty(),
                 ) {
                     return;
                 }
 
                 self.infcx.probe(|_| {
-                    if let Ok(_args) = self.match_impl(impl_def_id, impl_trait_ref, obligation) {
+                    if let Ok(_args) = self.match_impl(impl_def_id, impl_trait_header, obligation) {
                         candidates.vec.push(ImplCandidate(impl_def_id));
                     }
                 });
diff --git a/compiler/rustc_trait_selection/src/traits/select/mod.rs b/compiler/rustc_trait_selection/src/traits/select/mod.rs
index b7c37431a21..185b735594f 100644
--- a/compiler/rustc_trait_selection/src/traits/select/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/mod.rs
@@ -2412,8 +2412,8 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
         impl_def_id: DefId,
         obligation: &PolyTraitObligation<'tcx>,
     ) -> Normalized<'tcx, GenericArgsRef<'tcx>> {
-        let impl_trait_ref = self.tcx().impl_trait_ref(impl_def_id).unwrap();
-        match self.match_impl(impl_def_id, impl_trait_ref, obligation) {
+        let impl_trait_header = self.tcx().impl_trait_header(impl_def_id).unwrap();
+        match self.match_impl(impl_def_id, impl_trait_header, obligation) {
             Ok(args) => args,
             Err(()) => {
                 // FIXME: A rematch may fail when a candidate cache hit occurs
@@ -2446,7 +2446,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
     fn match_impl(
         &mut self,
         impl_def_id: DefId,
-        impl_trait_ref: EarlyBinder<ty::TraitRef<'tcx>>,
+        impl_trait_header: EarlyBinder<ty::ImplTraitHeader<'tcx>>,
         obligation: &PolyTraitObligation<'tcx>,
     ) -> Result<Normalized<'tcx, GenericArgsRef<'tcx>>, ()> {
         let placeholder_obligation =
@@ -2455,12 +2455,12 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
 
         let impl_args = self.infcx.fresh_args_for_item(obligation.cause.span, impl_def_id);
 
-        let impl_trait_ref = impl_trait_ref.instantiate(self.tcx(), impl_args);
-        if impl_trait_ref.references_error() {
+        let impl_trait_header = impl_trait_header.instantiate(self.tcx(), impl_args);
+        if impl_trait_header.references_error() {
             return Err(());
         }
 
-        debug!(?impl_trait_ref);
+        debug!(?impl_trait_header);
 
         let Normalized { value: impl_trait_ref, obligations: mut nested_obligations } =
             ensure_sufficient_stack(|| {
@@ -2469,7 +2469,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
                     obligation.param_env,
                     obligation.cause.clone(),
                     obligation.recursion_depth + 1,
-                    impl_trait_ref,
+                    impl_trait_header.trait_ref,
                 )
             });
 
@@ -2490,9 +2490,7 @@ impl<'tcx> SelectionContext<'_, 'tcx> {
             })?;
         nested_obligations.extend(obligations);
 
-        if !self.is_intercrate()
-            && self.tcx().impl_polarity(impl_def_id) == ty::ImplPolarity::Reservation
-        {
+        if !self.is_intercrate() && impl_trait_header.polarity == ty::ImplPolarity::Reservation {
             debug!("reservation impls only apply in intercrate mode");
             return Err(());
         }
diff --git a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
index be066e45d0a..73df1be6b55 100644
--- a/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/specialize/mod.rs
@@ -168,6 +168,8 @@ pub(super) fn specializes(tcx: TyCtxt<'_>, (impl1_def_id, impl2_def_id): (DefId,
         }
     }
 
+    let impl1_trait_header = tcx.impl_trait_header(impl1_def_id).unwrap().instantiate_identity();
+
     // We determine whether there's a subset relationship by:
     //
     // - replacing bound vars with placeholders in impl1,
@@ -181,21 +183,25 @@ pub(super) fn specializes(tcx: TyCtxt<'_>, (impl1_def_id, impl2_def_id): (DefId,
     // See RFC 1210 for more details and justification.
 
     // Currently we do not allow e.g., a negative impl to specialize a positive one
-    if tcx.impl_polarity(impl1_def_id) != tcx.impl_polarity(impl2_def_id) {
+    if impl1_trait_header.polarity != tcx.impl_polarity(impl2_def_id) {
         return false;
     }
 
     // create a parameter environment corresponding to a (placeholder) instantiation of impl1
     let penv = tcx.param_env(impl1_def_id);
-    let impl1_trait_ref = tcx.impl_trait_ref(impl1_def_id).unwrap().instantiate_identity();
 
     // Create an infcx, taking the predicates of impl1 as assumptions:
     let infcx = tcx.infer_ctxt().build();
 
     // Attempt to prove that impl2 applies, given all of the above.
-    fulfill_implication(&infcx, penv, impl1_trait_ref, impl1_def_id, impl2_def_id, |_, _| {
-        ObligationCause::dummy()
-    })
+    fulfill_implication(
+        &infcx,
+        penv,
+        impl1_trait_header.trait_ref,
+        impl1_def_id,
+        impl2_def_id,
+        |_, _| ObligationCause::dummy(),
+    )
     .is_ok()
 }
 
diff --git a/compiler/rustc_ty_utils/src/ty.rs b/compiler/rustc_ty_utils/src/ty.rs
index 60b1bbe8c2a..b725eda33ce 100644
--- a/compiler/rustc_ty_utils/src/ty.rs
+++ b/compiler/rustc_ty_utils/src/ty.rs
@@ -257,14 +257,15 @@ fn param_env_reveal_all_normalized(tcx: TyCtxt<'_>, def_id: DefId) -> ty::ParamE
 fn issue33140_self_ty(tcx: TyCtxt<'_>, def_id: DefId) -> Option<EarlyBinder<Ty<'_>>> {
     debug!("issue33140_self_ty({:?})", def_id);
 
-    let trait_ref = tcx
-        .impl_trait_ref(def_id)
+    let impl_ = tcx
+        .impl_trait_header(def_id)
         .unwrap_or_else(|| bug!("issue33140_self_ty called on inherent impl {:?}", def_id))
         .skip_binder();
 
+    let trait_ref = impl_.trait_ref;
     debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref);
 
-    let is_marker_like = tcx.impl_polarity(def_id) == ty::ImplPolarity::Positive
+    let is_marker_like = impl_.polarity == ty::ImplPolarity::Positive
         && tcx.associated_item_def_ids(trait_ref.def_id).is_empty();
 
     // Check whether these impls would be ok for a marker trait.