Rollup merge of #113698 - compiler-errors:rpitit-check, r=spastorino

Make it clearer that we're just checking for an RPITIT

Tiny nit to use `is_impl_trait_in_trait` more, to make it clearer that we're just checking whether a def-id is an RPITIT, rather than doing something meaningful with the `opt_rpitit_info`.

r? `@spastorino`

Author: matthiaskrgr

compiler/rustc_hir_analysis/src/astconv/errors.rs

@@ -123,7 +123,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         let all_candidate_names: Vec<_> = all_candidates()
             .flat_map(|r| self.tcx().associated_items(r.def_id()).in_definition_order())
             .filter_map(|item| {
-                if item.opt_rpitit_info.is_none() && item.kind == ty::AssocKind::Type {
+                if !item.is_impl_trait_in_trait() && item.kind == ty::AssocKind::Type {
                     Some(item.name)
                 } else {
                     None
@@ -164,7 +164,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 self.tcx().associated_items(*trait_def_id).in_definition_order()
             })
             .filter_map(|item| {
-                if item.opt_rpitit_info.is_none() && item.kind == ty::AssocKind::Type {
+                if !item.is_impl_trait_in_trait() && item.kind == ty::AssocKind::Type {
                     Some(item.name)
                 } else {
                     None

compiler/rustc_hir_analysis/src/astconv/object_safety.rs

@@ -173,7 +173,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                             tcx.associated_items(pred.def_id())
                                 .in_definition_order()
                                 .filter(|item| item.kind == ty::AssocKind::Type)
-                                .filter(|item| item.opt_rpitit_info.is_none())
+                                .filter(|item| !item.is_impl_trait_in_trait())
                                 .map(|item| item.def_id),
                         );
                     }

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1322,7 +1322,7 @@ fn compare_number_of_generics<'tcx>(
     // has mismatched type or const generic arguments, then the method that it's
     // inheriting the generics from will also have mismatched arguments, and
     // we'll report an error for that instead. Delay a bug for safety, though.
-    if trait_.opt_rpitit_info.is_some() {
+    if trait_.is_impl_trait_in_trait() {
         return Err(tcx.sess.delay_span_bug(
             rustc_span::DUMMY_SP,
             "errors comparing numbers of generics of trait/impl functions were not emitted",
@@ -2116,7 +2116,7 @@ pub(super) fn check_type_bounds<'tcx>(
     // A synthetic impl Trait for RPITIT desugaring has no HIR, which we currently use to get the
     // span for an impl's associated type. Instead, for these, use the def_span for the synthesized
     // associated type.
-    let impl_ty_span = if impl_ty.opt_rpitit_info.is_some() {
+    let impl_ty_span = if impl_ty.is_impl_trait_in_trait() {
         tcx.def_span(impl_ty_def_id)
     } else {
         match tcx.hir().get_by_def_id(impl_ty_def_id) {

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -188,7 +188,7 @@ fn missing_items_err(
     full_impl_span: Span,
 ) {
     let missing_items =
-        missing_items.iter().filter(|trait_item| trait_item.opt_rpitit_info.is_none());
+        missing_items.iter().filter(|trait_item| !trait_item.is_impl_trait_in_trait());
 
     let missing_items_msg = missing_items
         .clone()

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1136,7 +1136,7 @@ fn should_encode_type(tcx: TyCtxt<'_>, def_id: LocalDefId, def_kind: DefKind) ->
                 // the default projection predicates in default trait methods
                 // with RPITITs.
                 ty::AssocItemContainer::TraitContainer => {
-                    assoc_item.defaultness(tcx).has_value() || assoc_item.opt_rpitit_info.is_some()
+                    assoc_item.defaultness(tcx).has_value() || assoc_item.is_impl_trait_in_trait()
                 }
             }
         }

compiler/rustc_middle/src/ty/assoc.rs

@@ -96,6 +96,10 @@ impl AssocItem {
             }
         }
     }
+
+    pub fn is_impl_trait_in_trait(&self) -> bool {
+        self.opt_rpitit_info.is_some()
+    }
 }
 
 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash, Encodable, Decodable)]

compiler/rustc_passes/src/dead.rs

@@ -276,7 +276,7 @@ impl<'tcx> MarkSymbolVisitor<'tcx> {
             }
 
             // Avoid accessing the HIR for the synthesized associated type generated for RPITITs.
-            if self.tcx.opt_rpitit_info(id.to_def_id()).is_some() {
+            if self.tcx.is_impl_trait_in_trait(id.to_def_id()) {
                 self.live_symbols.insert(id);
                 continue;
             }

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

@@ -435,7 +435,7 @@ fn suggest_restriction<'tcx>(
 ) {
     if hir_generics.where_clause_span.from_expansion()
         || hir_generics.where_clause_span.desugaring_kind().is_some()
-        || projection.is_some_and(|projection| tcx.opt_rpitit_info(projection.def_id).is_some())
+        || projection.is_some_and(|projection| tcx.is_impl_trait_in_trait(projection.def_id))
     {
         return;
     }

compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -393,7 +393,7 @@ fn object_safety_violation_for_assoc_item(
         ty::AssocKind::Type => {
             if !tcx.features().generic_associated_types_extended
                 && !tcx.generics_of(item.def_id).params.is_empty()
-                && item.opt_rpitit_info.is_none()
+                && !item.is_impl_trait_in_trait()
             {
                 Some(ObjectSafetyViolation::GAT(item.name, item.ident(tcx).span))
             } else {