Allow excluding specific traits from completion

To be accurate, only their methods are excluded, the trait themselves are still available.

I also excluded a bunch of std traits by default. Some less opinionated, like `AsRef`, which should never be used directly except in generic scenarios (and won't be excluded there), some more opinionated, like the ops traits, which I know some users sometimes want to use directly. Either way it's configurable.

It should be pretty easy to extend support to excluding only specific methods, but I didn't do that currently.

Traits configured to be excluded are resolved in each completion request from scratch. If this proves too expensive, it is easy enough to cache them in the DB.

crates/hir-def/src/item_scope.rs

@@ -342,6 +342,13 @@ impl ItemScope {
             .chain(self.unnamed_trait_imports.keys().copied())
     }
 
+    pub fn trait_by_name(&self, name: &Name) -> Option<TraitId> {
+        self.types.get(name).and_then(|(def, _, _)| match def {
+            ModuleDefId::TraitId(it) => Some(*it),
+            _ => None,
+        })
+    }
+
     pub(crate) fn resolutions(&self) -> impl Iterator<Item = (Option<Name>, PerNs)> + '_ {
         self.entries().map(|(name, res)| (Some(name.clone()), res)).chain(
             self.unnamed_trait_imports.iter().map(|(tr, (vis, i))| {

crates/hir-ty/src/method_resolution.rs

@@ -914,7 +914,7 @@ pub fn iterate_path_candidates(
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
-    callback: &mut dyn FnMut(AssocItemId) -> ControlFlow<()>,
+    callback: &mut dyn MethodCandidateCallback,
 ) -> ControlFlow<()> {
     iterate_method_candidates_dyn(
         ty,
@@ -925,7 +925,7 @@ pub fn iterate_path_candidates(
         name,
         LookupMode::Path,
         // the adjustments are not relevant for path lookup
-        &mut |_, id, _| callback(id),
+        callback,
     )
 }
 
@@ -937,7 +937,7 @@ pub fn iterate_method_candidates_dyn(
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
     mode: LookupMode,
-    callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
+    callback: &mut dyn MethodCandidateCallback,
 ) -> ControlFlow<()> {
     let _p = tracing::info_span!(
         "iterate_method_candidates_dyn",
@@ -1007,7 +1007,7 @@ fn iterate_method_candidates_with_autoref(
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
-    mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
+    callback: &mut dyn MethodCandidateCallback,
 ) -> ControlFlow<()> {
     if receiver_ty.value.is_general_var(Interner, &receiver_ty.binders) {
         // don't try to resolve methods on unknown types
@@ -1022,7 +1022,7 @@ fn iterate_method_candidates_with_autoref(
             traits_in_scope,
             visible_from_module,
             name,
-            &mut callback,
+            callback,
         )
     };
 
@@ -1052,6 +1052,45 @@ fn iterate_method_candidates_with_autoref(
     iterate_method_candidates_by_receiver(ref_muted, first_adjustment.with_autoref(Mutability::Mut))
 }
 
+pub trait MethodCandidateCallback {
+    fn on_inherent_method(
+        &mut self,
+        adjustments: ReceiverAdjustments,
+        item: AssocItemId,
+        is_visible: bool,
+    ) -> ControlFlow<()>;
+
+    fn on_trait_method(
+        &mut self,
+        adjustments: ReceiverAdjustments,
+        item: AssocItemId,
+        is_visible: bool,
+    ) -> ControlFlow<()>;
+}
+
+impl<F> MethodCandidateCallback for F
+where
+    F: FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
+{
+    fn on_inherent_method(
+        &mut self,
+        adjustments: ReceiverAdjustments,
+        item: AssocItemId,
+        is_visible: bool,
+    ) -> ControlFlow<()> {
+        self(adjustments, item, is_visible)
+    }
+
+    fn on_trait_method(
+        &mut self,
+        adjustments: ReceiverAdjustments,
+        item: AssocItemId,
+        is_visible: bool,
+    ) -> ControlFlow<()> {
+        self(adjustments, item, is_visible)
+    }
+}
+
 #[tracing::instrument(skip_all, fields(name = ?name))]
 fn iterate_method_candidates_by_receiver(
     table: &mut InferenceTable<'_>,
@@ -1060,7 +1099,7 @@ fn iterate_method_candidates_by_receiver(
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
-    mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
+    callback: &mut dyn MethodCandidateCallback,
 ) -> ControlFlow<()> {
     let receiver_ty = table.instantiate_canonical(receiver_ty);
     // We're looking for methods with *receiver* type receiver_ty. These could
@@ -1076,7 +1115,9 @@ fn iterate_method_candidates_by_receiver(
                 Some(&receiver_ty),
                 Some(receiver_adjustments.clone()),
                 visible_from_module,
-                &mut callback,
+                &mut |adjustments, item, is_visible| {
+                    callback.on_inherent_method(adjustments, item, is_visible)
+                },
             )?
         }
         ControlFlow::Continue(())
@@ -1096,7 +1137,9 @@ fn iterate_method_candidates_by_receiver(
                 name,
                 Some(&receiver_ty),
                 Some(receiver_adjustments.clone()),
-                &mut callback,
+                &mut |adjustments, item, is_visible| {
+                    callback.on_trait_method(adjustments, item, is_visible)
+                },
             )?
         }
         ControlFlow::Continue(())
@@ -1111,7 +1154,7 @@ fn iterate_method_candidates_for_self_ty(
     traits_in_scope: &FxHashSet<TraitId>,
     visible_from_module: VisibleFromModule,
     name: Option<&Name>,
-    mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId, bool) -> ControlFlow<()>,
+    callback: &mut dyn MethodCandidateCallback,
 ) -> ControlFlow<()> {
     let mut table = InferenceTable::new(db, env);
     let self_ty = table.instantiate_canonical(self_ty.clone());
@@ -1122,7 +1165,9 @@ fn iterate_method_candidates_for_self_ty(
         None,
         None,
         visible_from_module,
-        &mut callback,
+        &mut |adjustments, item, is_visible| {
+            callback.on_inherent_method(adjustments, item, is_visible)
+        },
     )?;
     iterate_trait_method_candidates(
         &self_ty,
@@ -1131,7 +1176,9 @@ fn iterate_method_candidates_for_self_ty(
         name,
         None,
         None,
-        callback,
+        &mut |adjustments, item, is_visible| {
+            callback.on_trait_method(adjustments, item, is_visible)
+        },
     )
 }
 

crates/hir/src/attrs.rs

@@ -258,7 +258,7 @@ fn resolve_impl_trait_item(
         &traits_in_scope,
         method_resolution::VisibleFromModule::None,
         Some(name),
-        &mut |assoc_item_id| {
+        &mut |_, assoc_item_id: AssocItemId, _| {
             // If two traits in scope define the same item, Rustdoc links to no specific trait (for
             // instance, given two methods `a`, Rustdoc simply links to `method.a` with no
             // disambiguation) so we just pick the first one we find as well.