Rollup merge of #104732 - WaffleLapkin:from_def_idn't, r=compiler-errors

Refactor `ty::ClosureKind` related stuff

I've tried to fix all duplication and weirdness, but if I missed something do tell :p

r? `@compiler-errors`

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

@@ -357,7 +357,8 @@ impl<'tcx> InferCtxtExt<'tcx> for InferCtxt<'tcx> {
                 ocx.register_obligation(obligation);
                 if ocx.select_all_or_error().is_empty() {
                     return Ok((
-                        ty::ClosureKind::from_def_id(self.tcx, trait_def_id)
+                        self.tcx
+                            .fn_trait_kind_from_def_id(trait_def_id)
                             .expect("expected to map DefId to ClosureKind"),
                         ty.rebind(self.resolve_vars_if_possible(var)),
                     ));
@@ -686,7 +687,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                                 }
                                 ObligationCauseCode::BindingObligation(def_id, _)
                                 | ObligationCauseCode::ItemObligation(def_id)
-                                    if ty::ClosureKind::from_def_id(tcx, *def_id).is_some() =>
+                                    if tcx.is_fn_trait(*def_id) =>
                                 {
                                     err.code(rustc_errors::error_code!(E0059));
                                     err.set_primary_message(format!(
@@ -846,8 +847,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             );
                         }
 
-                        let is_fn_trait =
-                            ty::ClosureKind::from_def_id(tcx, trait_ref.def_id()).is_some();
+                        let is_fn_trait = tcx.is_fn_trait(trait_ref.def_id());
                         let is_target_feature_fn = if let ty::FnDef(def_id, _) =
                             *trait_ref.skip_binder().self_ty().kind()
                         {
@@ -877,7 +877,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                             // Note if the `FnMut` or `FnOnce` is less general than the trait we're trying
                             // to implement.
                             let selected_kind =
-                                ty::ClosureKind::from_def_id(self.tcx, trait_ref.def_id())
+                                self.tcx.fn_trait_kind_from_def_id(trait_ref.def_id())
                                     .expect("expected to map DefId to ClosureKind");
                             if !implemented_kind.extends(selected_kind) {
                                 err.note(
@@ -2155,7 +2155,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     if generics.params.iter().any(|p| p.name != kw::SelfUpper)
                         && !snippet.ends_with('>')
                         && !generics.has_impl_trait()
-                        && !self.tcx.fn_trait_kind_from_lang_item(def_id).is_some()
+                        && !self.tcx.is_fn_trait(def_id)
                     {
                         // FIXME: To avoid spurious suggestions in functions where type arguments
                         // where already supplied, we check the snippet to make sure it doesn't

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

@@ -1679,9 +1679,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
         ) -> Ty<'tcx> {
             let inputs = trait_ref.skip_binder().substs.type_at(1);
             let sig = match inputs.kind() {
-                ty::Tuple(inputs)
-                    if infcx.tcx.fn_trait_kind_from_lang_item(trait_ref.def_id()).is_some() =>
-                {
+                ty::Tuple(inputs) if infcx.tcx.is_fn_trait(trait_ref.def_id()) => {
                     infcx.tcx.mk_fn_sig(
                         inputs.iter(),
                         infcx.next_ty_var(TypeVariableOrigin {
@@ -1752,7 +1750,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
             && let predicates = self.tcx.predicates_of(def_id).instantiate_identity(self.tcx)
             && let Some(pred) = predicates.predicates.get(*idx)
             && let ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) = pred.kind().skip_binder()
-            && ty::ClosureKind::from_def_id(self.tcx, trait_pred.def_id()).is_some()
+            && self.tcx.is_fn_trait(trait_pred.def_id())
         {
             let expected_self =
                 self.tcx.anonymize_late_bound_regions(pred.kind().rebind(trait_pred.self_ty()));
@@ -1766,8 +1764,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                 .enumerate()
                 .find(|(other_idx, (pred, _))| match pred.kind().skip_binder() {
                     ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred))
-                        if ty::ClosureKind::from_def_id(self.tcx, trait_pred.def_id())
-                            .is_some()
+                        if self.tcx.is_fn_trait(trait_pred.def_id())
                             && other_idx != idx
                             // Make sure that the self type matches
                             // (i.e. constraining this closure)

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

@@ -451,7 +451,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         obligation: &TraitObligation<'tcx>,
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
-        let Some(kind) = self.tcx().fn_trait_kind_from_lang_item(obligation.predicate.def_id()) else {
+        let Some(kind) = self.tcx().fn_trait_kind_from_def_id(obligation.predicate.def_id()) else {
             return;
         };
 
@@ -489,7 +489,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         candidates: &mut SelectionCandidateSet<'tcx>,
     ) {
         // We provide impl of all fn traits for fn pointers.
-        if self.tcx().fn_trait_kind_from_lang_item(obligation.predicate.def_id()).is_none() {
+        if !self.tcx().is_fn_trait(obligation.predicate.def_id()) {
             return;
         }
 

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

@@ -735,7 +735,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
     ) -> Result<ImplSourceClosureData<'tcx, PredicateObligation<'tcx>>, SelectionError<'tcx>> {
         let kind = self
             .tcx()
-            .fn_trait_kind_from_lang_item(obligation.predicate.def_id())
+            .fn_trait_kind_from_def_id(obligation.predicate.def_id())
             .unwrap_or_else(|| bug!("closure candidate for non-fn trait {:?}", obligation));
 
         // Okay to skip binder because the substs on closure types never