Add and use generics.is_empty() and generics.is_own_empty, rather than using generics' attributes

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -432,7 +432,7 @@ fn check_gat_where_clauses(tcx: TyCtxt<'_>, trait_def_id: LocalDefId) {
             }
             let gat_generics = tcx.generics_of(gat_def_id);
             // FIXME(jackh726): we can also warn in the more general case
-            if gat_generics.own_params.is_empty() {
+            if gat_generics.is_own_empty() {
                 continue;
             }
 

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -1409,7 +1409,7 @@ fn generics_args_err_extend<'a>(
             // it was done based on the end of assoc segment but that sometimes
             // led to impossible spans and caused issues like #116473
             let args_span = args.span_ext.with_lo(args.span_ext.lo() - BytePos(2));
-            if tcx.generics_of(adt_def.did()).count() == 0 {
+            if tcx.generics_of(adt_def.did()).is_empty() {
                 // FIXME(estebank): we could also verify that the arguments being
                 // work for the `enum`, instead of just looking if it takes *any*.
                 err.span_suggestion_verbose(

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -412,7 +412,7 @@ fn lower_generic_args_of_path(
         // Traits always have `Self` as a generic parameter, which means they will not return early
         // here and so associated type bindings will be handled regardless of whether there are any
         // non-`Self` generic parameters.
-        if generics.own_params.is_empty() {
+        if generics.is_own_empty() {
             return (tcx.mk_args(parent_args), arg_count);
         }
 

compiler/rustc_hir_analysis/src/lib.rs

@@ -181,7 +181,7 @@ pub fn check_crate(tcx: TyCtxt<'_>) {
         let def_kind = tcx.def_kind(item_def_id);
         match def_kind {
             DefKind::Static { .. } => tcx.ensure().eval_static_initializer(item_def_id),
-            DefKind::Const if tcx.generics_of(item_def_id).own_params.is_empty() => {
+            DefKind::Const if tcx.generics_of(item_def_id).is_empty() => {
                 let instance = ty::Instance::new(item_def_id.into(), ty::GenericArgs::empty());
                 let cid = GlobalId { instance, promoted: None };
                 let param_env = ty::ParamEnv::reveal_all();

compiler/rustc_hir_analysis/src/variance/constraints.rs

@@ -99,7 +99,7 @@ fn build_constraints_for_item(&mut self, def_id: LocalDefId) {
         debug!("build_constraints_for_item({})", tcx.def_path_str(def_id));
 
         // Skip items with no generics - there's nothing to infer in them.
-        if tcx.generics_of(def_id).count() == 0 {
+        if tcx.generics_of(def_id).is_empty() {
             return;
         }
 

compiler/rustc_hir_analysis/src/variance/mod.rs

@@ -41,7 +41,7 @@ fn crate_variances(tcx: TyCtxt<'_>, (): ()) -> CrateVariancesMap<'_> {
 
 fn variances_of(tcx: TyCtxt<'_>, item_def_id: LocalDefId) -> &[ty::Variance] {
     // Skip items with no generics - there's nothing to infer in them.
-    if tcx.generics_of(item_def_id).count() == 0 {
+    if tcx.generics_of(item_def_id).is_empty() {
         return &[];
     }
 

compiler/rustc_hir_typeck/src/method/confirm.rs

@@ -451,7 +451,7 @@ fn inferred_kind(
         // `foo.bar::<u32>(...)` -- the `Self` type here will be the
         // type of `foo` (possibly adjusted), but we don't want to
         // include that. We want just the `[_, u32]` part.
-        if !args.is_empty() && !generics.own_params.is_empty() {
+        if !args.is_empty() && !generics.is_own_empty() {
             let user_type_annotation = self.probe(|_| {
                 let user_args = UserArgs {
                     args: GenericArgs::for_item(self.tcx, pick.item.def_id, |param, _| {

compiler/rustc_hir_typeck/src/method/prelude2021.rs

@@ -279,7 +279,7 @@ pub(super) fn lint_fully_qualified_call_from_2018(
                 if !self_ty_name.contains('<') {
                     if let ty::Adt(def, _) = self_ty.kind() {
                         let generics = self.tcx.generics_of(def.did());
-                        if !generics.own_params.is_empty() {
+                        if !generics.is_own_empty() {
                             let counts = generics.own_counts();
                             self_ty_name += &format!(
                                 "<{}>",

compiler/rustc_hir_typeck/src/method/probe.rs

@@ -1754,7 +1754,7 @@ fn xform_method_sig(&self, method: DefId, args: GenericArgsRef<'tcx>) -> ty::FnS
         let generics = self.tcx.generics_of(method);
         assert_eq!(args.len(), generics.parent_count);
 
-        let xform_fn_sig = if generics.own_params.is_empty() {
+        let xform_fn_sig = if generics.is_own_empty() {
             fn_sig.instantiate(self.tcx, args)
         } else {
             let args = GenericArgs::for_item(self.tcx, method, |param, _| {

compiler/rustc_middle/src/ty/generics.rs

@@ -391,6 +391,14 @@ pub fn check_concrete_type_after_default(
         }
         false
     }
+
+    pub fn is_empty(&'tcx self) -> bool {
+        self.count() == 0
+    }
+
+    pub fn is_own_empty(&'tcx self) -> bool {
+        self.own_params.is_empty()
+    }
 }
 
 /// Bounds on generics.

compiler/rustc_middle/src/ty/print/mod.rs

@@ -160,7 +160,7 @@ fn default_print_def_path(
                         // If we have any generic arguments to print, we do that
                         // on top of the same path, but without its own generics.
                         _ => {
-                            if !generics.own_params.is_empty() && args.len() >= generics.count() {
+                            if !generics.is_own_empty() && args.len() >= generics.count() {
                                 let args = generics.own_args_no_defaults(self.tcx(), args);
                                 return self.path_generic_args(
                                     |cx| cx.print_def_path(def_id, parent_args),

compiler/rustc_monomorphize/src/collector.rs

@@ -1429,7 +1429,7 @@ fn process_item(&mut self, id: hir::ItemId) {
         match self.tcx.def_kind(id.owner_id) {
             DefKind::Enum | DefKind::Struct | DefKind::Union => {
                 if self.strategy == MonoItemCollectionStrategy::Eager
-                    && self.tcx.generics_of(id.owner_id).count() == 0
+                    && self.tcx.generics_of(id.owner_id).is_empty()
                 {
                     debug!("RootCollector: ADT drop-glue for `{id:?}`",);
 

compiler/rustc_monomorphize/src/polymorphize.rs

@@ -51,7 +51,7 @@ fn unused_generic_params<'tcx>(
     debug!(?generics);
 
     // Exit early when there are no parameters to be unused.
-    if generics.count() == 0 {
+    if generics.is_empty() {
         return UnusedGenericParams::new_all_used();
     }
 

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -398,7 +398,7 @@ pub fn object_safety_violations_for_assoc_item(
         // Associated types can only be object safe if they have `Self: Sized` bounds.
         ty::AssocKind::Type => {
             if !tcx.features().generic_associated_types_extended
-                && !tcx.generics_of(item.def_id).own_params.is_empty()
+                && !tcx.generics_of(item.def_id).is_own_empty()
                 && !item.is_impl_trait_in_trait()
             {
                 vec![ObjectSafetyViolation::GAT(item.name, item.ident(tcx).span)]

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

@@ -619,7 +619,7 @@ fn confirm_object_candidate(
             // higher-ranked things.
             // Prevent, e.g., `dyn Iterator<Item = str>`.
             for bound in self.tcx().item_bounds(assoc_type).transpose_iter() {
-                let arg_bound = if defs.count() == 0 {
+                let arg_bound = if defs.is_empty() {
                     bound.instantiate(tcx, trait_predicate.trait_ref.args)
                 } else {
                     let mut args = smallvec::SmallVec::with_capacity(defs.count());

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

@@ -1781,7 +1781,7 @@ pub(super) fn match_projection_projections(
             // FIXME(generic-associated-types): This only detects one layer of inference,
             // which is probably not what we actually want, but fixing it causes some ambiguity:
             // <https://github.com/rust-lang/rust/issues/125196>.
-            if !generics.own_params.is_empty()
+            if !generics.is_own_empty()
                 && obligation.predicate.args[generics.parent_count..].iter().any(|&p| {
                     p.has_non_region_infer()
                         && match p.unpack() {

src/tools/clippy/clippy_lints/src/iter_without_into_iter.rs

@@ -225,7 +225,7 @@ fn check_impl_item(&mut self, cx: &LateContext<'_>, item: &rustc_hir::ImplItem<'
             && let ImplItemKind::Fn(sig, _) = item.kind
             && let FnRetTy::Return(ret) = sig.decl.output
             && is_nameable_in_impl_trait(ret)
-            && cx.tcx.generics_of(item_did).own_params.is_empty()
+            && cx.tcx.generics_of(item_did).is_own_empty()
             && sig.decl.implicit_self == expected_implicit_self
             && sig.decl.inputs.len() == 1
             && let Some(imp) = get_parent_as_impl(cx.tcx, item.hir_id())

src/tools/clippy/clippy_utils/src/ty/type_certainty/mod.rs

@@ -176,7 +176,7 @@ fn qpath_certainty(cx: &LateContext<'_>, qpath: &QPath<'_>, resolves_to_type: bo
             .get(*lang_item)
             .map_or(Certainty::Uncertain, |def_id| {
                 let generics = cx.tcx.generics_of(def_id);
-                if generics.parent_count == 0 && generics.own_params.is_empty() {
+                if generics.is_empty() {
                     Certainty::Certain(if resolves_to_type { Some(def_id) } else { None })
                 } else {
                     Certainty::Uncertain