nit: continue using from_str_and_span as requested

Author: IntegralPilot

compiler/rustc_builtin_macros/src/test.rs

@@ -209,7 +209,7 @@ pub(crate) fn expand_test_or_bench(
     let test_fn = if is_bench {
         // A simple ident for a lambda, using the user's function name within it to avoid collisions.
         let param_name = format!("__bench_{}", fn_.ident.name);
-        let bencher_param = Ident::new(Symbol::intern(&param_name), attr_sp);
+        let bencher_param = Ident::from_str_and_span(&param_name, attr_sp);
         cx.expr_call(
             sp,
             cx.expr_path(test_path("StaticBenchFn")),