3 files changed, 23 insertions, 1 deletions
diff --git a/clippy_lints/src/methods/unnecessary_to_owned.rs b/clippy_lints/src/methods/unnecessary_to_owned.rs
index b32e5d8d421..8e9ed33e009 100644
--- a/clippy_lints/src/methods/unnecessary_to_owned.rs
+++ b/clippy_lints/src/methods/unnecessary_to_owned.rs
@@ -8,7 +8,7 @@ use clippy_utils::visitors::find_all_ret_expressions;
 use clippy_utils::{fn_def_id, get_parent_expr, is_diag_item_method, is_diag_trait_item, return_ty};
 use clippy_utils::{meets_msrv, msrvs};
 use rustc_errors::Applicability;
-use rustc_hir::{def_id::DefId, BorrowKind, Expr, ExprKind, ItemKind, Node};
+use rustc_hir::{def_id::DefId, BorrowKind, Expr, ExprKind, ItemKind, LangItem, Node};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::LateContext;
 use rustc_middle::mir::Mutability;
@@ -380,6 +380,10 @@ fn can_change_type<'a>(cx: &LateContext<'a>, mut expr: &'a Expr<'a>, mut ty: Ty<
             Node::Expr(parent_expr) => {
                 if let Some((callee_def_id, call_substs, recv, call_args)) = get_callee_substs_and_args(cx, parent_expr)
                 {
+                    if cx.tcx.lang_items().require(LangItem::IntoFutureIntoFuture) == Ok(callee_def_id) {
+                        return false;
+                    }
+
                     let fn_sig = cx.tcx.fn_sig(callee_def_id).skip_binder();
                     if let Some(arg_index) = recv.into_iter().chain(call_args).position(|arg| arg.hir_id == expr.hir_id)
                         && let Some(param_ty) = fn_sig.inputs().get(arg_index)
diff --git a/tests/ui/unnecessary_to_owned.fixed b/tests/ui/unnecessary_to_owned.fixed
index a920c63b199..f97583aa22f 100644
--- a/tests/ui/unnecessary_to_owned.fixed
+++ b/tests/ui/unnecessary_to_owned.fixed
@@ -417,3 +417,12 @@ mod issue_9351 {
         predicates_are_satisfied(id("abc".to_string()));
     }
 }
+
+mod issue_9504 {
+    #![allow(dead_code)]
+
+    async fn foo<S: AsRef<str>>(_: S) {}
+    async fn bar() {
+        foo(std::path::PathBuf::new().to_string_lossy().to_string()).await;
+    }
+}
diff --git a/tests/ui/unnecessary_to_owned.rs b/tests/ui/unnecessary_to_owned.rs
index 2128bdacdda..aa5394a5657 100644
--- a/tests/ui/unnecessary_to_owned.rs
+++ b/tests/ui/unnecessary_to_owned.rs
@@ -417,3 +417,12 @@ mod issue_9351 {
         predicates_are_satisfied(id("abc".to_string()));
     }
 }
+
+mod issue_9504 {
+    #![allow(dead_code)]
+
+    async fn foo<S: AsRef<str>>(_: S) {}
+    async fn bar() {
+        foo(std::path::PathBuf::new().to_string_lossy().to_string()).await;
+    }
+}