avoid using format!("{}", ..)

Author: TaKO8Ki

compiler/rustc_infer/src/infer/error_reporting/note_and_explain.rs

@@ -139,7 +139,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                     tcx,
                                     generics,
                                     diag,
-                                    &format!("{}", proj.self_ty()),
+                                    &proj.self_ty().to_string(),
                                     &path,
                                     None,
                                     matching_span,
@@ -153,7 +153,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                                     tcx,
                                     generics,
                                     diag,
-                                    &format!("{}", proj.self_ty()),
+                                    &proj.self_ty().to_string(),
                                     &path,
                                     None,
                                     matching_span,