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// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart = 2.9
/// @assertion Metadata can appear before ... parameter ...
/// @description Check that metadata is allowed before typedef declaration
/// parameter
/// @author
import 'dart:mirrors';
import '../../Utils/expect.dart';
class A {
const A();
typedef void f(@A() int, String);
main() {
// This is a case where the documentation of `reflectType` isn't sufficiently
// detailed to preclude any behavior. Initially the test seems to have been
// written under the assumption that we would always get a `TypedefMirror`
// when call `reflectType(f)`, and that's probably also how it used to work.
// Today, implementations will often expand type aliases at compile-time
// (which is always possible, now that we have the inline syntax
// `R Function(...)` for function types). That is probably a worthwhile
// optimization, because we don't have to look up the meaning of that typedef
// each time it is needed at run time. In any case, it does happen (for
// instance: right here), and we can't say that it is wrong, so we need to
// deal with it.
// So here we preserve the support for the old behavior and add support for
// the current behavior, i.e. assume that it can be either `TypedMirror` or
// `TypedefMirror` here.
ParameterMirror paramMirror =
reflectType(f) is TypedefMirror ?
(reflectType(f) as TypedefMirror).referent.parameters[0] :
(reflectType(f) as FunctionTypeMirror).parameters[0];
// Cf., the language team
// decided that we would not support metadata on type parameters of a function
// type. Nothing was said about parameters that are not type parameters (that
// is, "normal" parameters like `x` and `y` in `X Function<X>(X x, int y)`),
// and nothing was said about whether the response from tools should be to
// emit a compile-time error. It would make sense to simply skip unsupported
// metadata silently, because it could then be allowed to exist in source
// code, and there could be other tools (say, code generators) that would take
// that metadata into account.
if(paramMirror.metadata.length > 0) {