Throw if there is no compiler context available

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

 // Copyright (c) 2016, 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.
 
 library fasta.compiler_command_line;
 
 import 'dart:io' show exit;
 
+import 'dart:async' show runZoned;
+
 import 'package:kernel/target/targets.dart'
     show Target, getTarget, TargetFlags, targets;
 
 import 'command_line.dart' show CommandLine, deprecated_argumentError;
 
-import 'compiler_context.dart' show CompilerContext;
+import 'compiler_context.dart' show CompilerContext, compilerContextKey;
 
 import 'command_line_reporting.dart' as command_line_reporting;
 
 import 'fasta_codes.dart'
     show
         LocatedMessage,
         Message,
         messageFastaUsageLong,
         messageFastaUsageShort,
         templateUnspecified;
@@ skipping 121 matching lines @@
     return options["format"] ?? command_line_reporting.format;
   }
 
   String Function(Message, Severity) get formatWithoutLocation {
     return options["formatWithoutLocation"] ??
         command_line_reporting.formatWithoutLocation;
   }
 
   static dynamic withGlobalOptions(String programName, List<String> arguments,
       dynamic f(CompilerContext context)) {
-    return CompilerContext.withGlobalOptions(
-        new CompilerCommandLine(programName, arguments), f);
+    CompilerCommandLine cl = deprecated_withDefaultOptions(
+        () => new CompilerCommandLine(programName, arguments));
+    return CompilerContext.withGlobalOptions(cl, f);
   }
 
-  static CompilerCommandLine forRootContext() {
-    return new CompilerCommandLine("", [""]);
+  // TODO(sigmund, ahe): delete. We use this to wrap places where we require a
+  // context but we shoudln't. Right now this includes:
+  //   - constructor calls to CompilerCommandLine (because it is calling
+  //   [validate] which may report errors). This should be fixed by doing
+  //   validation after creating these objects.
+  //   - top-level try-catch in command-line tools that capture
+  //   deprecated_InputError, and then report errors using fasta's error
+  //   reporting mechanism. Those should be unnecessary once we get rid of all
+  //   deprecated_InputErrors.
+  static dynamic deprecated_withDefaultOptions(dynamic f()) {
+    var defaultContext = new CompilerContext(new CompilerCommandLine("", [""]));
+    return runZoned(f, zoneValues: {compilerContextKey: defaultContext});
   }
 }
 
 Message computeUsage(String programName, bool verbose) {
   String basicUsage = "Usage: $programName [options] dartfile\n";
   String summary;
   String options =
       (verbose ? messageFastaUsageLong.message : messageFastaUsageShort.message)
           .trim();
   switch (programName) {
@@ skipping 18 matching lines @@
   StringBuffer sb = new StringBuffer(basicUsage);
   if (summary != null) {
     sb.writeln();
     sb.writeln(summary);
     sb.writeln();
   }
   sb.write(options);
   // TODO(ahe): Don't use [templateUnspecified].
   return templateUnspecified.withArguments("$sb");
 }