Move dual blanket impl logic from source analyzer to goto_def

crates/hir/src/lib.rs

@@ -2756,6 +2756,15 @@ impl Trait {
         traits.iter().map(|tr| Trait::from(*tr)).collect()
     }
 
+    pub fn function(self, db: &dyn HirDatabase, name: impl PartialEq<Name>) -> Option<Function> {
+        db.trait_data(self.id).items.iter().find(|(n, _)| name == *n).and_then(
+            |&(_, it)| match it {
+                AssocItemId::FunctionId(id) => Some(Function { id }),
+                _ => None,
+            },
+        )
+    }
+
     pub fn items(self, db: &dyn HirDatabase) -> Vec<AssocItem> {
         db.trait_data(self.id).items.iter().map(|(_name, it)| (*it).into()).collect()
     }

crates/hir/src/semantics.rs

@@ -1439,8 +1439,20 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(call.syntax())?.resolve_method_call_fallback(self.db, call)
     }
 
-    pub fn resolve_known_blanket_dual_impls(&self, call: &ast::MethodCallExpr) -> Option<Function> {
-        self.analyze(call.syntax())?.resolve_known_blanket_dual_impls(self.db, call)
+    /// Env is used to derive the trait environment
+    // FIXME: better api for the trait environment
+    pub fn resolve_impl_method(
+        &self,
+        env: Type,
+        trait_: Trait,
+        func: Function,
+        subst: impl IntoIterator<Item = Type>,
+    ) -> Option<Function> {
+        let mut substs = hir_ty::TyBuilder::subst_for_def(self.db, TraitId::from(trait_), None);
+        for s in subst {
+            substs = substs.push(s.ty);
+        }
+        Some(self.db.lookup_impl_method(env.env, func.into(), substs.build()).0.into())
     }
 
     fn resolve_range_pat(&self, range_pat: &ast::RangePat) -> Option<StructId> {

crates/hir/src/source_analyzer.rs

@@ -322,68 +322,6 @@ impl SourceAnalyzer {
         }
     }
 
-    // If the method is into(), try_into(), parse(), resolve it to from, try_from, from_str.
-    pub(crate) fn resolve_known_blanket_dual_impls(
-        &self,
-        db: &dyn HirDatabase,
-        call: &ast::MethodCallExpr,
-    ) -> Option<Function> {
-        // e.g. if the method call is let b = a.into(),
-        // - receiver_type is A (type of a)
-        // - return_type is B (type of b)
-        // We will find the definition of B::from(a: A).
-        let callable = self.resolve_method_call_as_callable(db, call)?;
-        let (_, receiver_type) = callable.receiver_param(db)?;
-        let return_type = callable.return_type();
-        let (search_method, substs) = match call.name_ref()?.text().as_str() {
-            "into" => {
-                let trait_ =
-                    self.resolver.resolve_known_trait(db.upcast(), &path![core::convert::From])?;
-                (
-                    self.trait_fn(db, trait_, "from")?,
-                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
-                        .push(return_type.ty)
-                        .push(receiver_type.ty)
-                        .build(),
-                )
-            }
-            "try_into" => {
-                let trait_ = self
-                    .resolver
-                    .resolve_known_trait(db.upcast(), &path![core::convert::TryFrom])?;
-                (
-                    self.trait_fn(db, trait_, "try_from")?,
-                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
-                        // If the method is try_into() or parse(), return_type is Result<T, Error>.
-                        // Get T from type arguments of Result<T, Error>.
-                        .push(return_type.type_arguments().next()?.ty)
-                        .push(receiver_type.ty)
-                        .build(),
-                )
-            }
-            "parse" => {
-                let trait_ =
-                    self.resolver.resolve_known_trait(db.upcast(), &path![core::str::FromStr])?;
-                (
-                    self.trait_fn(db, trait_, "from_str")?,
-                    hir_ty::TyBuilder::subst_for_def(db, trait_, None)
-                        .push(return_type.type_arguments().next()?.ty)
-                        .build(),
-                )
-            }
-            _ => return None,
-        };
-
-        let found_method = self.resolve_impl_method_or_trait_def(db, search_method, substs);
-        // If found_method == search_method, the method in trait itself is resolved.
-        // It means the blanket dual impl is not found.
-        if found_method == search_method {
-            None
-        } else {
-            Some(found_method.into())
-        }
-    }
-
     pub(crate) fn resolve_expr_as_callable(
         &self,
         db: &dyn HirDatabase,
@@ -1309,18 +1247,6 @@ impl SourceAnalyzer {
         Some((trait_id, fn_id))
     }
 
-    fn trait_fn(
-        &self,
-        db: &dyn HirDatabase,
-        trait_id: TraitId,
-        method_name: &str,
-    ) -> Option<FunctionId> {
-        db.trait_data(trait_id).items.iter().find_map(|(item_name, item)| match item {
-            AssocItemId::FunctionId(t) if item_name.as_str() == method_name => Some(*t),
-            _ => None,
-        })
-    }
-
     fn ty_of_expr(&self, db: &dyn HirDatabase, expr: &ast::Expr) -> Option<&Ty> {
         self.infer.as_ref()?.type_of_expr_or_pat(self.expr_id(db, expr)?)
     }