Detect and warn about missing scripts (rather than fail during the build)

pkg/polymer/lib/src/build/script_compactor.dart

Index: pkg/polymer/lib/src/build/script_compactor.dart
diff --git a/pkg/polymer/lib/src/build/script_compactor.dart b/pkg/polymer/lib/src/build/script_compactor.dart
index 0af62005d1065a4e596edd0373b63b93c616331d..4ca5537ba8845a6dd335b9b72211313931341da0 100644
--- a/pkg/polymer/lib/src/build/script_compactor.dart
+++ b/pkg/polymer/lib/src/build/script_compactor.dart
@@ -139,12 +139,8 @@ class _ScriptCompactor extends PolymerTransformer {
   /// Emits the main HTML and Dart bootstrap code for the application. If there
   /// were not Dart entry point files, then this simply emits the original HTML.
   Future _emitNewEntrypoint(_) {
-    if (entryLibraries.isEmpty) {
-      // We didn't find code, nothing to do.
-      transform.addOutput(transform.primaryInput);
-      return null;
-    }
-
+    // If we don't find code, there is nothing to do.
+    if (entryLibraries.isEmpty) return null;
     return _initResolver()
         .then(_extractUsesOfMirrors)
         .then(_emitFiles)
@@ -157,10 +153,17 @@ class _ScriptCompactor extends PolymerTransformer {
   /// [entryLibraries], then use it to initialize the [recorder] (for import
   /// resolution) and to resolve specific elements (for analyzing the user's
   /// code).
-  Future _initResolver() => resolvers.get(transform, entryLibraries).then((r) {
-    resolver = r;
-    types = new _ResolvedTypes(resolver);
-  });
+  Future _initResolver() {
+    // We include 'polymer.dart' to simplify how we do resolution below. This
+    // way we can assume polymer is there, even if the user didn't include an
+    // import to it.
+    var libsToLoad = [new AssetId('polymer', 'lib/polymer.dart')]

[Jennifer Messerly, 2014/04/18 00:53:33]

based on the test, is the idea here that we don't want to blow up if no polymer
import is there?
if so maybe note that without this code, it throws?

[Siggi Cherem (dart-lang), 2014/04/18 01:05:16]

Right
Done.

+        ..addAll(entryLibraries);
+    return resolvers.get(transform, libsToLoad).then((r) {
+      resolver = r;
+      types = new _ResolvedTypes(resolver);
+    });
+  }
 
   /// Inspects the entire program to find out anything that polymer accesses
   /// using mirrors and produces static information that can be used to replace
@@ -345,15 +348,21 @@ class _ScriptCompactor extends PolymerTransformer {
     generator.writeTopLevelDeclarations(code);
     code.writeln('\nvoid main() {');
     generator.writeInitCall(code);
-    code.writeln('  startPolymer([');
+    code.write('  startPolymer([');
 
     // Include initializers to switch from mirrors_loader to static_loader.
-    for (var init in initializers) {
-      var initCode = init.asCode(prefixes[init.assetId]);
-      code.write("      $initCode,\n");
+    if (!initializers.isEmpty) {
+      code.writeln();
+      for (var init in initializers) {
+        var initCode = init.asCode(prefixes[init.assetId]);
+        code.write("      $initCode,\n");
+      }
+      code.writeln('    ]);');
+    } else {
+      logger.warning('no polymer initializers were found.');

[Jennifer Messerly, 2014/04/18 00:53:33]

I wonder if we should add more to this msg about how to fix this, if it happens?

[Siggi Cherem (dart-lang), 2014/04/18 01:05:16]

Good idea. Done.

+      code.writeln(']);');
     }
-    code..writeln('    ]);')
-        ..writeln('}');
+    code.writeln('}');
     transform.addOutput(new Asset.fromString(bootstrapId, code.toString()));