Add --analyze-only flag to dart2js

sdk/lib/_internal/compiler/implementation/dart2js.dart

 // Copyright (c) 2012, 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 dart2js;
 
 import 'dart:async';
 import 'dart:collection' show Queue, LinkedHashMap;
 import 'dart:io';
 import 'dart:uri';
@@ skipping 61 matching lines @@
   Uri cwd = getCurrentDirectory();
   Uri libraryRoot = cwd;
   Uri out = cwd.resolve('out.js');
   Uri sourceMapOut = cwd.resolve('out.js.map');
   Uri packageRoot = null;
   List<String> options = new List<String>();
   bool explicitOut = false;
   bool wantHelp = false;
   String outputLanguage = 'JavaScript';
   bool stripArgumentSet = false;
+  bool analyzeOnly = false;
   SourceFileProvider inputProvider = new SourceFileProvider();
   FormattingDiagnosticHandler diagnosticHandler =
       new FormattingDiagnosticHandler(inputProvider);
 
   passThrough(String argument) => options.add(argument);
 
   setLibraryRoot(String argument) {
     libraryRoot = cwd.resolve(extractPath(argument));
   }
 
@@ skipping 22 matching lines @@
     var filenames = new List.from(sourceFiles.keys);
     filenames.sort();
     return Strings.join(filenames, "\n");
   }
 
   setStrip(String argument) {
     stripArgumentSet = true;
     passThrough(argument);
   }
 
+  setAnalyzeOnly(String argument) {
+    analyzeOnly = true;
+    passThrough(argument);
+  }
+
   handleShortOptions(String argument) {
     var shortOptions = argument.substring(1).splitChars();
     for (var shortOption in shortOptions) {
       switch (shortOption) {
         case 'v':
           diagnosticHandler.verbose = true;
           break;
         case 'h':
         case '?':
           wantHelp = true;
@@ skipping 27 matching lines @@
     new OptionHandler('--enable-diagnostic-colors',
                       (_) => diagnosticHandler.enableColors = true),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked',
                       (_) => passThrough('--enable-checked-mode')),
     new OptionHandler('--enable-concrete-type-inference',
                       (_) => passThrough('--enable-concrete-type-inference')),
     new OptionHandler(r'--help|/\?|/h', (_) => wantHelp = true),
     new OptionHandler('--package-root=.+|-p.+', setPackageRoot),
     new OptionHandler('--disallow-unsafe-eval', passThrough),
     new OptionHandler('--analyze-all', passThrough),
+    new OptionHandler('--analyze-only', setAnalyzeOnly),
     new OptionHandler('--disable-native-live-type-analysis', passThrough),
     new OptionHandler('--enable-native-live-type-analysis', passThrough),
     new OptionHandler('--reject-deprecated-language-features', passThrough),
     new OptionHandler('--report-sdk-use-of-deprecated-language-features',
                       passThrough),
 
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail('Error: Unknown option "$argument".');
     }),
@@ skipping 35 matching lines @@
 
   diagnosticHandler.info('package root is $packageRoot');
 
   // TODO(ahe): We expect the future to be complete and call value
   // directly. In effect, we don't support truly asynchronous API.
   String code = deprecatedFutureValue(
       api.compile(uri, libraryRoot, packageRoot,
                   inputProvider.readStringFromUri,
                   handler,
                   options));
+  if (analyzeOnly) return;
+
   if (code == null) {
     fail('Error: Compilation failed.');
   }
   String sourceMapFileName =
       sourceMapOut.path.substring(sourceMapOut.path.lastIndexOf('/') + 1);
   code = '$code\n//@ sourceMappingURL=${sourceMapFileName}';
   writeString(out, code);
   writeString(new Uri.fromString('$out.deps'),
               getDepsOutput(inputProvider.sourceFiles));
   int dartBytesRead = inputProvider.dartBytesRead;
@@ skipping 72 matching lines @@
 
   -p<path>, --package-root=<path>
     Where to find packages, that is, "package:..." imports.
 
   --analyze-all
     Analyze all code.  Without this option, the compiler only analyzes
     code that is reachable from [main].  This option is useful for
     finding errors in libraries, but using it can result in bigger and
     slower output.
 
+  --analyze-only
+    Analyze but do not generate code.
+
   --minify
     Generate minified output.
 
   --suppress-warnings
     Do not display any warnings.
 
   --enable-diagnostic-colors
     Add colors to diagnostic messages.
 
 The following options are only used for compiler development and may
@@ skipping 65 matching lines @@
     } catch (ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }