Avoid going through queries if a value of type AssocItem is already available

Author: oli-obk

Diff for: compiler/rustc_hir_analysis/src/astconv/mod.rs

@@ -1601,7 +1601,7 @@ 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| tcx.opt_rpitit_info(item.def_id).is_none())
+                                .filter(|item| item.opt_rpitit_info.is_none())
                                 .map(|item| item.def_id),
                         );
                     }

Diff for: compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1216,7 +1216,7 @@ 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 tcx.opt_rpitit_info(trait_.def_id).is_some() {
+    if trait_.opt_rpitit_info.is_some() {
         return Err(tcx.sess.delay_span_bug(
             rustc_span::DUMMY_SP,
             "errors comparing numbers of generics of trait/impl functions were not emitted",
@@ -2006,7 +2006,7 @@ 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 tcx.opt_rpitit_info(impl_ty.def_id).is_some() {
+    let impl_ty_span = if impl_ty.opt_rpitit_info.is_some() {
         tcx.def_span(impl_ty_def_id)
     } else {
         match tcx.hir().get_by_def_id(impl_ty_def_id) {

Diff for: 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| tcx.opt_rpitit_info(trait_item.def_id).is_none());
+        missing_items.iter().filter(|trait_item| trait_item.opt_rpitit_info.is_none());
 
     let missing_items_msg = missing_items
         .clone()

Diff for: compiler/rustc_trait_selection/src/traits/object_safety.rs

@@ -161,7 +161,7 @@ fn object_safety_violations_for_trait(
                 .in_definition_order()
                 .filter(|item| item.kind == ty::AssocKind::Type)
                 .filter(|item| !tcx.generics_of(item.def_id).params.is_empty())
-                .filter(|item| tcx.opt_rpitit_info(item.def_id).is_none())
+                .filter(|item| item.opt_rpitit_info.is_none())
                 .map(|item| {
                     let ident = item.ident(tcx);
                     ObjectSafetyViolation::GAT(ident.name, ident.span)