Merge pull request #18482 from regexident/hir_trait_supertraits_accessors

internal: Add public `direct_supertraits(…)` & `all_supertraits(…)` accessor methods to `hir::Trait`

Author: lnicola

Diff for: src/tools/rust-analyzer/crates/hir-ty/src/lib.rs

@@ -98,7 +98,7 @@ pub use mapping::{
 };
 pub use method_resolution::check_orphan_rules;
 pub use traits::TraitEnvironment;
-pub use utils::{all_super_traits, is_fn_unsafe_to_call};
+pub use utils::{all_super_traits, direct_super_traits, is_fn_unsafe_to_call};
 
 pub use chalk_ir::{
     cast::Cast,

Diff for: src/tools/rust-analyzer/crates/hir-ty/src/utils.rs

@@ -43,6 +43,17 @@ pub(crate) fn fn_traits(
         .flat_map(|it| it.as_trait())
 }
 
+/// Returns an iterator over the direct super traits (including the trait itself).
+pub fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> SmallVec<[TraitId; 4]> {
+    let mut result = smallvec![trait_];
+    direct_super_traits_cb(db, trait_, |tt| {
+        if !result.contains(&tt) {
+            result.push(tt);
+        }
+    });
+    result
+}
+
 /// Returns an iterator over the whole super trait hierarchy (including the
 /// trait itself).
 pub fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> SmallVec<[TraitId; 4]> {
@@ -54,7 +65,7 @@ pub fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> SmallVec<[Trai
     while let Some(&t) = result.get(i) {
         // yeah this is quadratic, but trait hierarchies should be flat
         // enough that this doesn't matter
-        direct_super_traits(db, t, |tt| {
+        direct_super_traits_cb(db, t, |tt| {
             if !result.contains(&tt) {
                 result.push(tt);
             }
@@ -153,7 +164,7 @@ impl Iterator for ClauseElaborator<'_> {
     }
 }
 
-fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId, cb: impl FnMut(TraitId)) {
+fn direct_super_traits_cb(db: &dyn DefDatabase, trait_: TraitId, cb: impl FnMut(TraitId)) {
     let resolver = trait_.resolver(db);
     let generic_params = db.generic_params(trait_.into());
     let trait_self = generic_params.trait_self_param();

Diff for: src/tools/rust-analyzer/crates/hir/src/lib.rs

@@ -68,7 +68,7 @@ use hir_ty::{
     all_super_traits, autoderef, check_orphan_rules,
     consteval::{try_const_usize, unknown_const_as_generic, ConstExt},
     diagnostics::BodyValidationDiagnostic,
-    error_lifetime, known_const_to_ast,
+    direct_super_traits, error_lifetime, known_const_to_ast,
     layout::{Layout as TyLayout, RustcEnumVariantIdx, RustcFieldIdx, TagEncoding},
     method_resolution,
     mir::{interpret_mir, MutBorrowKind},
@@ -2704,13 +2704,22 @@ impl Trait {
         db.trait_data(self.id).name.clone()
     }
 
+    pub fn direct_supertraits(self, db: &dyn HirDatabase) -> Vec<Trait> {
+        let traits = direct_super_traits(db.upcast(), self.into());
+        traits.iter().map(|tr| Trait::from(*tr)).collect()
+    }
+
+    pub fn all_supertraits(self, db: &dyn HirDatabase) -> Vec<Trait> {
+        let traits = all_super_traits(db.upcast(), self.into());
+        traits.iter().map(|tr| Trait::from(*tr)).collect()
+    }
+
     pub fn items(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
         db.trait_data(self.id).items.iter().map(|(_name, it)| (*it).into()).collect()
     }
 
     pub fn items_with_supertraits(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
-        let traits = all_super_traits(db.upcast(), self.into());
-        traits.iter().flat_map(|tr| Trait::from(*tr).items(db)).collect()
+        self.all_supertraits(db).into_iter().flat_map(|tr| tr.items(db)).collect()
     }
 
     pub fn is_auto(self, db: &dyn HirDatabase) -> bool {