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

Index: sdk/lib/_internal/compiler/implementation/apiimpl.dart
diff --git a/sdk/lib/_internal/compiler/implementation/apiimpl.dart b/sdk/lib/_internal/compiler/implementation/apiimpl.dart
index 2b56ac00003095c547ef53a3d9f48f088646d33d..72f05a1c835e05e20f0af78b1731b39ad1b36f0e 100644
--- a/sdk/lib/_internal/compiler/implementation/apiimpl.dart
+++ b/sdk/lib/_internal/compiler/implementation/apiimpl.dart
@@ -15,7 +15,7 @@ import '../../libraries.dart';
 import 'source_file.dart';
 
 class Compiler extends leg.Compiler {
-  api.ReadStringFromUri provider;
+  api.CompilerInputProvider provider;
   api.DiagnosticHandler handler;
   final Uri libraryRoot;
   final Uri packageRoot;
@@ -176,8 +176,16 @@ class Compiler extends leg.Compiler {
     // [Future] to ensure that we never execute an asynchronous action without setting
     // up the current element of the compiler.
     return new Future.sync(() => callUserProvider(resourceUri))
-        .then((String text) {
-      SourceFile sourceFile = new SourceFile(resourceUri.toString(), text);
+        .then((data) {
+      SourceFile sourceFile;
+      if (data is List<int>) {
+        sourceFile = new Utf8BytesSourceFile(resourceUri.toString(), data);
+      } else if (data is String) {
+        sourceFile = new StringSourceFile(resourceUri.toString(), data);
+      } else {
+        String tp = data.runtimeType.toString();

[ahe, 2013/10/16 14:26:04]

Please don't abbreviate. Also, don't use runtimeType, it is expensive in
dart2js.

[lukas, 2013/10/17 07:21:25]

Done.

+        reportReadError("The CompilerInputProvider returned a $tp.");

[ahe, 2013/10/16 14:26:04]

This error message should be something like:

"Expected a 'String' or a 'List<int>' from input provider, but got:
${Error.safeToString(data)}.".

This follows the recommendation from warnings.dart:

 * Generally, we want to provide messages that consists of three sentences:
 * 1. what is wrong, 2. why is it wrong, 3. how do I fix it. However, we
 * combine the first two in [template] and the last in [howToFix].

In addition, this should be reported as an exception in user code, not a
compile-time error.

[lukas, 2013/10/17 07:21:25]

How do I do that?

+      }
       // We use [readableUri] as the URI for the script since need to preserve
       // the scheme in the script because [Script.uri] is used for resolving
       // relative URIs mentioned in the script. See the comment on