Add --version option to dart2js and add version information (if available) to generated code.

Remove the 'Using snapshot ...' comment from sdk/bin/dart2js since we are
now relatively sure it works.

R=ahe@google.com, ngeoffray@google.com
BUG=http://dartbug.com/4439, http://dartbug.com/9848

Review URL: https://codereview.chromium.org//15957006

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@23355 260f80e4-7a28-3924-810f-c04153c831b5

sdk/bin/dart2js

@@ -41,9 +41,6 @@ unset EXTRA_VM_OPTIONS
 declare -a EXTRA_VM_OPTIONS
 
 if test -f "$SNAPSHOT"; then
-  # TODO(ahe): Remove the following line when we are relatively sure it works.
-  echo Using snapshot "$SNAPSHOT" 1>&2
-
   EXTRA_OPTIONS[${#EXTRA_OPTIONS[@]}]="--library-root=$SDK_DIR"
 fi
 

sdk/bin/dart2js.bat

@@ -29,7 +29,6 @@ if _%DART2JS_DEVELOPER_MODE%_ == _1_ (
 )
 
 if exist "%SNAPSHOT%" (
-  echo Using snapshot "%SNAPSHOT%" >&2
   set EXTRA_OPTIONS=%EXTRA_OPTIONS% "--library-root=%SDK_DIR%"
 )
 

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

@@ -86,6 +86,7 @@ void compile(List<String> argv) {
   List<String> options = new List<String>();
   bool explicitOut = false;
   bool wantHelp = false;
+  bool wantVersion = false;
   String outputLanguage = 'JavaScript';
   bool stripArgumentSet = false;
   bool analyzeOnly = false;
@@ -197,6 +198,7 @@ void compile(List<String> argv) {
                       (_) => diagnosticHandler.showWarnings = false),
     new OptionHandler('--output-type=dart|--output-type=js', setOutputType),
     new OptionHandler('--verbose', setVerbose),
+    new OptionHandler('--version', (_) => wantVersion = true),
     new OptionHandler('--library-root=.+', setLibraryRoot),
     new OptionHandler('--out=.+|-o.+', setOutput),
     new OptionHandler('--allow-mock-compilation', passThrough),
@@ -235,7 +237,9 @@ void compile(List<String> argv) {
   ];
 
   parseCommandLine(handlers, argv);
-  if (wantHelp) helpAndExit(diagnosticHandler.verbose);
+  if (wantHelp || wantVersion) {
+    helpAndExit(wantHelp, wantVersion, diagnosticHandler.verbose);
+  }
 
   if (outputLanguage != OUTPUT_LANGUAGE_DART && stripArgumentSet) {
     helpAndFail('Error: --force-strip may only be used with '
@@ -413,6 +417,9 @@ Supported options:
   -v, --verbose
     Display verbose information.
 
+  --version
+    Display version information.
+
   -p<path>, --package-root=<path>
     Where to find packages, that is, "package:..." imports.
 
@@ -487,11 +494,19 @@ be removed in a future version:
 '''.trim());
 }
 
-void helpAndExit(bool verbose) {
-  if (verbose) {
-    verboseHelp();
-  } else {
-    help();
+void helpAndExit(bool wantHelp, bool wantVersion, bool verbose) {
+  if (wantVersion) {
+    var version = (BUILD_ID == null)
+        ? '<non-SDK build>'
+        : BUILD_ID;
+    print('Dart-to-JavaScript compiler (dart2js) version: $version');
+  }
+  if (wantHelp) {
+    if (verbose) {
+      verboseHelp();
+    } else {
+      help();
+    }
   }
   exit(0);
 }

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

@@ -2948,7 +2948,7 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
 
       computeNeededClasses();
 
-      mainBuffer.add(GENERATED_BY);
+      mainBuffer.add(buildGeneratedBy());
       addComment(HOOKS_API_USAGE, mainBuffer);
       mainBuffer.add('function ${namer.isolateName}()$_{}\n');
       mainBuffer.add('init()$N$n');
@@ -3173,7 +3173,7 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
   void emitDeferredPreambleWhenEmpty(CodeBuffer buffer) {
     if (!buffer.isEmpty) return;
 
-    buffer.write(GENERATED_BY);
+    buffer.write(buildGeneratedBy());
 
     buffer.write('var old${namer.CURRENT_ISOLATE}$_='
                  '$_${namer.CURRENT_ISOLATE}$N');
@@ -3186,6 +3186,12 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
                  '$_${namer.isolateName}.prototype$N$n');
   }
 
+  String buildGeneratedBy() {
+    var suffix = '';
+    if (BUILD_ID != null) suffix = ' version: $BUILD_ID';
+    return '// Generated by dart2js, the Dart to JavaScript compiler$suffix.\n';
+  }
+
   String buildSourceMap(CodeBuffer buffer, SourceFile compiledFile) {
     SourceMapBuilder sourceMapBuilder =
         new SourceMapBuilder(compiler.sourceMapUri);
@@ -3214,10 +3220,6 @@ if (typeof document !== "undefined" && document.readyState !== "complete") {
   }
 }
 
-const String GENERATED_BY = """
-// Generated by dart2js, the Dart to JavaScript compiler.
-""";
-
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called

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

@@ -13,6 +13,7 @@ import '../elements/modelx.dart' show FunctionElementX;
 
 // TODO(ahe): There seems to be a bug in the VM, so we have to hide "js".
 import '../dart2jslib.dart' hide Selector, TypedSelector, js;
+import '../dart2js.dart' show BUILD_ID;
 import '../dart_types.dart';
 import '../js/js.dart' as jsAst;
 import '../js/js.dart' show js; // TODO(ahe): VM bug, see above.