remove dependencies to analyzer from lib/src/fasta

pkg/front_end/lib/src/fasta/patched_sdk_location.dart

+// Copyright (c) 2017, 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.md file.
+
+/// Utility for locating the patched_sdk. This is temporarily used to run fasta
+/// until patching support is added.
+library front_end.src.fasta.patched_sdk_location;

[Siggi Cherem (dart-lang), 2017/04/19 20:46:18]

I extracted this code out of kernel_chain in the process, probably unnecessary
now that I see where everything settled, but it still feels like a separate
piece.

[ahe, 2017/04/20 09:24:50]

As for the library name, I'd prefer to shorten "front_end.src.fasta" to "fasta".

[ahe, 2017/04/20 09:24:50]

Agreed, but I think it should be moved to the testing subpackage.

[Siggi Cherem (dart-lang), 2017/04/21 04:29:23]

Done.

[Siggi Cherem (dart-lang), 2017/04/21 04:29:23]

Done.

+
+import 'dart:async';
+import 'dart:io' show File, Platform;
+
+import 'environment_variable.dart' show EnvironmentVariable;

[ahe, 2017/04/20 09:24:50]

We should now be able to move this to testing as well.

[Siggi Cherem (dart-lang), 2017/04/21 04:29:22]

Done.

+
+Future<Uri> computePatchedSdk() async {
+  String config = await testConfigVariable.value;
+  String path;
+  switch (Platform.operatingSystem) {
+    case "linux":
+      path = "out/$config/patched_sdk";
+      break;
+
+    case "macos":
+      path = "xcodebuild/$config/patched_sdk";
+      break;
+
+    case "windows":
+      path = "build/$config/patched_sdk";
+      break;
+
+    default:
+      throw "Unsupported operating system: '${Platform.operatingSystem}'.";
+  }
+  Uri sdk = Uri.base.resolve("$path/");
+  const String asyncDart = "lib/async/async.dart";
+  if (!await fileExists(sdk, asyncDart)) {
+    throw "Couldn't find '$asyncDart' in '$sdk'.";
+  }
+  const String asyncSources = "lib/async/async_sources.gypi";
+  if (await fileExists(sdk, asyncSources)) {
+    throw "Found '$asyncSources' in '$sdk', so it isn't a patched SDK.";
+  }
+  return sdk;
+}
+
+Uri computeDartVm(Uri patchedSdk) {
+  return patchedSdk.resolve(Platform.isWindows ? "../dart.exe" : "../dart");
+}
+
+Future<bool> fileExists(Uri base, String path) async {
+  return await new File.fromUri(base.resolve(path)).exists();
+}
+
+final EnvironmentVariable testConfigVariable = new EnvironmentVariable(
+    "DART_CONFIGURATION",
+    "It should be something like 'ReleaseX64', depending on which"
+    " configuration you're testing.");