Rollup merge of #123900 - compiler-errors:nobound, r=lcnr

Stop using `PolyTraitRef` for closure/coroutine predicates already instantiated w placeholders

r? lcnr

compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs

@@ -367,7 +367,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }),
         ) = error.code
             && let ty::Closure(def_id, _) | ty::Coroutine(def_id, ..) =
-                expected_trait_ref.skip_binder().self_ty().kind()
+                expected_trait_ref.self_ty().kind()
             && span.overlaps(self.tcx.def_span(*def_id))
         {
             true

compiler/rustc_infer/src/infer/at.rs

@@ -424,25 +424,7 @@ impl<'tcx> ToTrace<'tcx> for ty::TraitRef<'tcx> {
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(
-                a_is_expected,
-                ty::Binder::dummy(a),
-                ty::Binder::dummy(b),
-            )),
-        }
-    }
-}
-
-impl<'tcx> ToTrace<'tcx> for ty::PolyTraitRef<'tcx> {
-    fn to_trace(
-        cause: &ObligationCause<'tcx>,
-        a_is_expected: bool,
-        a: Self,
-        b: Self,
-    ) -> TypeTrace<'tcx> {
-        TypeTrace {
-            cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 }

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -1653,7 +1653,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                             .report(diag);
                         (false, Mismatch::Fixed("signature"))
                     }
-                    ValuePairs::PolyTraitRefs(_) => (false, Mismatch::Fixed("trait")),
+                    ValuePairs::TraitRefs(_) => (false, Mismatch::Fixed("trait")),
                     ValuePairs::Aliases(infer::ExpectedFound { expected, .. }) => {
                         (false, Mismatch::Fixed(self.tcx.def_descr(expected.def_id)))
                     }
@@ -1969,8 +1969,8 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             self.note_and_explain_type_err(diag, exp_found, cause, span, cause.body_id.to_def_id());
         }
 
-        if let Some(ValuePairs::PolyTraitRefs(exp_found)) = values
-            && let ty::Closure(def_id, _) = exp_found.expected.skip_binder().self_ty().kind()
+        if let Some(ValuePairs::TraitRefs(exp_found)) = values
+            && let ty::Closure(def_id, _) = exp_found.expected.self_ty().kind()
             && let Some(def_id) = def_id.as_local()
             && terr.involves_regions()
         {
@@ -2188,7 +2188,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             infer::Aliases(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialTraitRef(exp_found) => self.expected_found_str(exp_found),
             infer::ExistentialProjection(exp_found) => self.expected_found_str(exp_found),
-            infer::PolyTraitRefs(exp_found) => {
+            infer::TraitRefs(exp_found) => {
                 let pretty_exp_found = ty::error::ExpectedFound {
                     expected: exp_found.expected.print_trait_sugared(),
                     found: exp_found.found.print_trait_sugared(),

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/placeholder_error.rs

@@ -195,13 +195,13 @@ impl<'tcx> NiceRegionError<'_, 'tcx> {
         value_pairs: &ValuePairs<'tcx>,
     ) -> Option<Diag<'tcx>> {
         let (expected_args, found_args, trait_def_id) = match value_pairs {
-            ValuePairs::PolyTraitRefs(ExpectedFound { expected, found })
-                if expected.def_id() == found.def_id() =>
+            ValuePairs::TraitRefs(ExpectedFound { expected, found })
+                if expected.def_id == found.def_id =>
             {
                 // It's possible that the placeholders come from a binder
                 // outside of this value pair. Use `no_bound_vars` as a
                 // simple heuristic for that.
-                (expected.no_bound_vars()?.args, found.no_bound_vars()?.args, expected.def_id())
+                (expected.args, found.args, expected.def_id)
             }
             _ => return None,
         };

compiler/rustc_infer/src/infer/error_reporting/suggest.rs

@@ -599,7 +599,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         span: Span,
         hir: hir::Node<'_>,
-        exp_found: &ty::error::ExpectedFound<ty::PolyTraitRef<'tcx>>,
+        exp_found: &ty::error::ExpectedFound<ty::TraitRef<'tcx>>,
         diag: &mut Diag<'_>,
     ) {
         // 0. Extract fn_decl from hir
@@ -614,10 +614,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         // 1. Get the args of the closure.
         // 2. Assume exp_found is FnOnce / FnMut / Fn, we can extract function parameters from [1].
-        let Some(expected) = exp_found.expected.skip_binder().args.get(1) else {
+        let Some(expected) = exp_found.expected.args.get(1) else {
             return;
         };
-        let Some(found) = exp_found.found.skip_binder().args.get(1) else {
+        let Some(found) = exp_found.found.args.get(1) else {
             return;
         };
         let expected = expected.unpack();

compiler/rustc_infer/src/infer/mod.rs

@@ -403,7 +403,7 @@ pub enum ValuePairs<'tcx> {
     Regions(ExpectedFound<ty::Region<'tcx>>),
     Terms(ExpectedFound<ty::Term<'tcx>>),
     Aliases(ExpectedFound<ty::AliasTy<'tcx>>),
-    PolyTraitRefs(ExpectedFound<ty::PolyTraitRef<'tcx>>),
+    TraitRefs(ExpectedFound<ty::TraitRef<'tcx>>),
     PolySigs(ExpectedFound<ty::PolyFnSig<'tcx>>),
     ExistentialTraitRef(ExpectedFound<ty::PolyExistentialTraitRef<'tcx>>),
     ExistentialProjection(ExpectedFound<ty::PolyExistentialProjection<'tcx>>),
@@ -1882,15 +1882,15 @@ impl<'tcx> TypeTrace<'tcx> {
         }
     }
 
-    pub fn poly_trait_refs(
+    pub fn trait_refs(
         cause: &ObligationCause<'tcx>,
         a_is_expected: bool,
-        a: ty::PolyTraitRef<'tcx>,
-        b: ty::PolyTraitRef<'tcx>,
+        a: ty::TraitRef<'tcx>,
+        b: ty::TraitRef<'tcx>,
     ) -> TypeTrace<'tcx> {
         TypeTrace {
             cause: cause.clone(),
-            values: PolyTraitRefs(ExpectedFound::new(a_is_expected, a, b)),
+            values: TraitRefs(ExpectedFound::new(a_is_expected, a, b)),
         }
     }
 

compiler/rustc_middle/src/traits/mod.rs

@@ -620,11 +620,10 @@ pub enum SelectionError<'tcx> {
     OpaqueTypeAutoTraitLeakageUnknown(DefId),
 }
 
-// FIXME(@lcnr): The `Binder` here should be unnecessary. Just use `TraitRef` instead.
 #[derive(Clone, Debug, TypeVisitable)]
 pub struct SignatureMismatchData<'tcx> {
-    pub found_trait_ref: ty::PolyTraitRef<'tcx>,
-    pub expected_trait_ref: ty::PolyTraitRef<'tcx>,
+    pub found_trait_ref: ty::TraitRef<'tcx>,
+    pub expected_trait_ref: ty::TraitRef<'tcx>,
     pub terr: ty::error::TypeError<'tcx>,
 }
 

compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs

@@ -1879,19 +1879,19 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         span: Span,
         found_span: Option<Span>,
-        found: ty::PolyTraitRef<'tcx>,
-        expected: ty::PolyTraitRef<'tcx>,
+        found: ty::TraitRef<'tcx>,
+        expected: ty::TraitRef<'tcx>,
         cause: &ObligationCauseCode<'tcx>,
         found_node: Option<Node<'_>>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> Diag<'tcx> {
         pub(crate) fn build_fn_sig_ty<'tcx>(
             infcx: &InferCtxt<'tcx>,
-            trait_ref: ty::PolyTraitRef<'tcx>,
+            trait_ref: ty::TraitRef<'tcx>,
         ) -> Ty<'tcx> {
-            let inputs = trait_ref.skip_binder().args.type_at(1);
+            let inputs = trait_ref.args.type_at(1);
             let sig = match inputs.kind() {
-                ty::Tuple(inputs) if infcx.tcx.is_fn_trait(trait_ref.def_id()) => {
+                ty::Tuple(inputs) if infcx.tcx.is_fn_trait(trait_ref.def_id) => {
                     infcx.tcx.mk_fn_sig(
                         *inputs,
                         infcx.next_ty_var(TypeVariableOrigin {
@@ -1915,10 +1915,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                 ),
             };
 
-            Ty::new_fn_ptr(infcx.tcx, trait_ref.rebind(sig))
+            Ty::new_fn_ptr(infcx.tcx, ty::Binder::dummy(sig))
         }
 
-        let argument_kind = match expected.skip_binder().self_ty().kind() {
+        let argument_kind = match expected.self_ty().kind() {
             ty::Closure(..) => "closure",
             ty::Coroutine(..) => "coroutine",
             _ => "function",

compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs

@@ -3380,11 +3380,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
     fn report_cyclic_signature_error(
         &self,
         obligation: &PredicateObligation<'tcx>,
-        found_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
-        expected_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
+        found_trait_ref: ty::TraitRef<'tcx>,
+        expected_trait_ref: ty::TraitRef<'tcx>,
         terr: TypeError<'tcx>,
     ) -> Diag<'tcx> {
-        let self_ty = found_trait_ref.self_ty().skip_binder();
+        let self_ty = found_trait_ref.self_ty();
         let (cause, terr) = if let ty::Closure(def_id, _) = self_ty.kind() {
             (
                 ObligationCause::dummy_with_span(self.tcx.def_span(def_id)),
@@ -3394,7 +3394,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
             (obligation.cause.clone(), terr)
         };
         self.report_and_explain_type_error(
-            TypeTrace::poly_trait_refs(&cause, true, expected_trait_ref, found_trait_ref),
+            TypeTrace::trait_refs(&cause, true, expected_trait_ref, found_trait_ref),
             terr,
         )
     }
@@ -3434,17 +3434,14 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         &self,
         obligation: &PredicateObligation<'tcx>,
         span: Span,
-        found_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
-        expected_trait_ref: ty::Binder<'tcx, ty::TraitRef<'tcx>>,
+        found_trait_ref: ty::TraitRef<'tcx>,
+        expected_trait_ref: ty::TraitRef<'tcx>,
     ) -> Result<Diag<'tcx>, ErrorGuaranteed> {
         let found_trait_ref = self.resolve_vars_if_possible(found_trait_ref);
         let expected_trait_ref = self.resolve_vars_if_possible(expected_trait_ref);
 
         expected_trait_ref.self_ty().error_reported()?;
-
-        let Some(found_trait_ty) = found_trait_ref.self_ty().no_bound_vars() else {
-            self.dcx().bug("bound vars outside binder");
-        };
+        let found_trait_ty = found_trait_ref.self_ty();
 
         let found_did = match *found_trait_ty.kind() {
             ty::Closure(did, _) | ty::FnDef(did, _) | ty::Coroutine(did, ..) => Some(did),
@@ -3462,15 +3459,15 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 
         let mut not_tupled = false;
 
-        let found = match found_trait_ref.skip_binder().args.type_at(1).kind() {
+        let found = match found_trait_ref.args.type_at(1).kind() {
             ty::Tuple(tys) => vec![ArgKind::empty(); tys.len()],
             _ => {
                 not_tupled = true;
                 vec![ArgKind::empty()]
             }
         };
 
-        let expected_ty = expected_trait_ref.skip_binder().args.type_at(1);
+        let expected_ty = expected_trait_ref.args.type_at(1);
         let expected = match expected_ty.kind() {
             ty::Tuple(tys) => {
                 tys.iter().map(|t| ArgKind::from_expected_ty(t, Some(span))).collect()
@@ -3487,11 +3484,11 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
         // traits manually, but don't make it more confusing when it does
         // happen.
         Ok(
-            if Some(expected_trait_ref.def_id()) != self.tcx.lang_items().coroutine_trait()
+            if Some(expected_trait_ref.def_id) != self.tcx.lang_items().coroutine_trait()
                 && not_tupled
             {
                 self.report_and_explain_type_error(
-                    TypeTrace::poly_trait_refs(
+                    TypeTrace::trait_refs(
                         &obligation.cause,
                         true,
                         expected_trait_ref,

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -1079,8 +1079,8 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             })
             .map_err(|terr| {
                 SignatureMismatch(Box::new(SignatureMismatchData {
-                    expected_trait_ref: ty::Binder::dummy(obligation_trait_ref),
-                    found_trait_ref: ty::Binder::dummy(found_trait_ref),
+                    expected_trait_ref: obligation_trait_ref,
+                    found_trait_ref,
                     terr,
                 }))
             })