Add --build-summary-only-diet option.

pkg/analyzer_cli/lib/src/options.dart

Index: pkg/analyzer_cli/lib/src/options.dart
diff --git a/pkg/analyzer_cli/lib/src/options.dart b/pkg/analyzer_cli/lib/src/options.dart
index bf1aa686fe122261372ee6f1390f2ad2c1be1eb4..d6e78fc53e2a43e44b2eb06130bf2328a114ef0d 100644
--- a/pkg/analyzer_cli/lib/src/options.dart
+++ b/pkg/analyzer_cli/lib/src/options.dart
@@ -45,6 +45,10 @@ class CommandLineOptions {
   /// Whether to skip analysis when creating summaries in build mode.
   final bool buildSummaryOnly;
 
+  /// Whether to use diet parsing, i.e. skip function bodies. We don't need to
+  /// analyze function bodies to use summaries during future compilation steps.
+  final bool buildSummaryOnlyDiet;
+
   /// The path to output the summary when creating summaries in build mode.
   final String buildSummaryOutput;
 
@@ -133,6 +137,7 @@ class CommandLineOptions {
         buildMode = args['build-mode'],
         buildSummaryInputs = args['build-summary-input'],
         buildSummaryOnly = args['build-summary-only'],
+        buildSummaryOnlyDiet = args['build-summary-only-diet'],
         buildSummaryOutput = args['build-summary-output'],
         buildSuppressExitCode = args['build-suppress-exit-code'],
         dartSdkPath = args['dart-sdk'],
@@ -209,6 +214,12 @@ class CommandLineOptions {
           "Null aware operators are supported by default.");
     }
 
+    // Build mode.
+    if (options.buildSummaryOnlyDiet && !options.buildSummaryOnly) {
+      printAndFail('The option --build-summary-only-diet can be used only '
+          'together with --build-summary-only.');
+    }
+
     return options;
   }
 
@@ -330,6 +341,11 @@ class CommandLineOptions {
           defaultsTo: false,
           negatable: false,
           hide: true)
+      ..addFlag('build-summary-only-diet',
+          help: 'Diet parse function bodies.',
+          defaultsTo: false,
+          negatable: false,
+          hide: true)
       ..addFlag('build-suppress-exit-code',
           help: 'Exit with code 0 even if errors are found.',
           defaultsTo: false,