Auto merge of #13257 - rust-lang:revert-13147-fix/dyn-ty-inherent-methods, r=lnicola

Revert "fix: handle trait methods as inherent methods for trait-related types"

Reverts #13147

https://github.com/rust-lang/rust-analyzer/actions/runs/3041499441/jobs/4898678721#step:18:62

Author: bors

crates/hir-ty/src/method_resolution.rs

@@ -914,10 +914,22 @@ fn iterate_trait_method_candidates(
     let db = table.db;
     let env = table.trait_env.clone();
     let self_is_array = matches!(self_ty.kind(Interner), chalk_ir::TyKind::Array(..));
+    // if ty is `dyn Trait`, the trait doesn't need to be in scope
+    let inherent_trait =
+        self_ty.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t));
+    let env_traits = matches!(self_ty.kind(Interner), TyKind::Placeholder(_))
+        // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
+        .then(|| {
+            env.traits_in_scope_from_clauses(self_ty.clone())
+                .flat_map(|t| all_super_traits(db.upcast(), t))
+        })
+        .into_iter()
+        .flatten();
+    let traits = inherent_trait.chain(env_traits).chain(traits_in_scope.iter().copied());
 
     let canonical_self_ty = table.canonicalize(self_ty.clone()).value;
 
-    'traits: for &t in traits_in_scope {
+    'traits: for t in traits {
         let data = db.trait_data(t);
 
         // Traits annotated with `#[rustc_skip_array_during_method_dispatch]` are skipped during
@@ -967,43 +979,6 @@ fn iterate_inherent_methods(
 ) -> ControlFlow<()> {
     let db = table.db;
     let env = table.trait_env.clone();
-
-    // For trait object types and placeholder types with trait bounds, the methods of the trait and
-    // its super traits are considered inherent methods. This matters because these methods have
-    // higher priority than the other traits' methods, which would be considered in
-    // `iterate_trait_method_candidates()` only after this function.
-    match self_ty.kind(Interner) {
-        TyKind::Placeholder(_) => {
-            let env = table.trait_env.clone();
-            let traits = env
-                .traits_in_scope_from_clauses(self_ty.clone())
-                .flat_map(|t| all_super_traits(db.upcast(), t));
-            iterate_inherent_trait_methods(
-                self_ty,
-                table,
-                name,
-                receiver_ty,
-                receiver_adjustments.clone(),
-                callback,
-                traits,
-            )?;
-        }
-        TyKind::Dyn(_) => {
-            let principal_trait = self_ty.dyn_trait().unwrap();
-            let traits = all_super_traits(db.upcast(), principal_trait);
-            iterate_inherent_trait_methods(
-                self_ty,
-                table,
-                name,
-                receiver_ty,
-                receiver_adjustments.clone(),
-                callback,
-                traits.into_iter(),
-            )?;
-        }
-        _ => {}
-    }
-
     let def_crates = match def_crates(db, self_ty, env.krate) {
         Some(k) => k,
         None => return ControlFlow::Continue(()),
@@ -1045,28 +1020,6 @@ fn iterate_inherent_methods(
     }
     return ControlFlow::Continue(());
 
-    fn iterate_inherent_trait_methods(
-        self_ty: &Ty,
-        table: &mut InferenceTable<'_>,
-        name: Option<&Name>,
-        receiver_ty: Option<&Ty>,
-        receiver_adjustments: Option<ReceiverAdjustments>,
-        callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>,
-        traits: impl Iterator<Item = TraitId>,
-    ) -> ControlFlow<()> {
-        let db = table.db;
-        for t in traits {
-            let data = db.trait_data(t);
-            for &(_, item) in data.items.iter() {
-                // We don't pass `visible_from_module` as all trait items should be visible.
-                if is_valid_candidate(table, name, receiver_ty, item, self_ty, None) {
-                    callback(receiver_adjustments.clone().unwrap_or_default(), item)?;
-                }
-            }
-        }
-        ControlFlow::Continue(())
-    }
-
     fn impls_for_self_ty(
         impls: &InherentImpls,
         self_ty: &Ty,

crates/hir-ty/src/tests/method_resolution.rs

@@ -1218,40 +1218,6 @@ fn main() {
     );
 }
 
-#[test]
-fn dyn_trait_method_priority() {
-    check_types(
-        r#"
-//- minicore: from
-trait Trait {
-    fn into(&self) -> usize { 0 }
-}
-
-fn foo(a: &dyn Trait) {
-    let _ = a.into();
-      //^usize
-}
-        "#,
-    );
-}
-
-#[test]
-fn trait_method_priority_for_placeholder_type() {
-    check_types(
-        r#"
-//- minicore: from
-trait Trait {
-    fn into(&self) -> usize { 0 }
-}
-
-fn foo<T: Trait>(a: &T) {
-    let _ = a.into();
-      //^usize
-}
-        "#,
-    );
-}
-
 #[test]
 fn autoderef_visibility_field() {
     check(