- Properly load the core libraries as libraries and not as scripts.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 18894)
+++ runtime/vm/parser.cc	(working copy)
@@ -4252,12 +4252,18 @@
 }
 
 
-Dart_Handle Parser::CallLibraryTagHandler(Dart_LibraryTag tag,
+RawObject* Parser::CallLibraryTagHandler(Dart_LibraryTag tag,
                                           intptr_t token_pos,
                                           const String& url) {
   Isolate* isolate = Isolate::Current();
   Dart_LibraryTagHandler handler = isolate->library_tag_handler();
   if (handler == NULL) {
+    if (url.StartsWith(Symbols::DartScheme())) {
+      if (tag == kCanonicalizeUrl) {
+        return url.raw();
+      }
+      return Object::null();
+    }
     ErrorMsg(token_pos, "no library handler registered");
   }
   Dart_Handle result = handler(tag,
@@ -4267,8 +4273,14 @@
     Error& prev_error = Error::Handle();
     prev_error ^= Api::UnwrapHandle(result);
     AppendErrorMsg(prev_error, token_pos, "library handler failed");
+    UNREACHABLE();

[siva, 2013/02/23 00:11:03]

Why UNREACHABLE here (AppendErrorMsg already has one)?

[Ivan Posva, 2013/02/25 22:20:14]

I wanted to make it clear that we will not be able to continue below. Instead I
will add an appropriate comment.

   }
-  return result;
+  if (tag == kCanonicalizeUrl) {
+    if (!Dart_IsString(result)) {
+      ErrorMsg(token_pos, "library handler failed URI canonicalization");
+    }
+  }
+  return Api::UnwrapHandle(result);
 }
 
 
@@ -4303,10 +4315,8 @@
     }
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
-    Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
-                                               import_pos,
-                                               url);
-    const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
+    const String& canon_url = String::CheckedHandle(
+        CallLibraryTagHandler(kCanonicalizeUrl, import_pos, url));
     // Lookup the library URL.
     Library& library = Library::Handle(Library::LookupLibrary(canon_url));
     if (library.IsNull()) {
@@ -4352,10 +4362,8 @@
     ConsumeToken();
     ExpectToken(Token::kRPAREN);
     ExpectToken(Token::kSEMICOLON);
-    Dart_Handle handle = CallLibraryTagHandler(kCanonicalizeUrl,
-                                               source_pos,
-                                               url);
-    const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
+    const String& canon_url = String::CheckedHandle(
+        CallLibraryTagHandler(kCanonicalizeUrl, source_pos, url));
     CallLibraryTagHandler(kSourceTag, source_pos, canon_url);
   }
 }
@@ -4442,9 +4450,8 @@
   ExpectSemicolon();
 
   // Canonicalize library URL.
-  Dart_Handle handle =
-      CallLibraryTagHandler(kCanonicalizeUrl, import_pos, url);
-  const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
+  const String& canon_url = String::CheckedHandle(
+      CallLibraryTagHandler(kCanonicalizeUrl, import_pos, url));
   // Lookup the library URL.
   Library& library = Library::Handle(Library::LookupLibrary(canon_url));
   if (library.IsNull()) {
@@ -4496,9 +4503,8 @@
   const String& url = *CurrentLiteral();
   ConsumeToken();
   ExpectSemicolon();
-  Dart_Handle handle =
-      CallLibraryTagHandler(kCanonicalizeUrl, source_pos, url);
-  const String& canon_url = String::CheckedHandle(Api::UnwrapHandle(handle));
+  const String& canon_url = String::CheckedHandle(
+      CallLibraryTagHandler(kCanonicalizeUrl, source_pos, url));
   CallLibraryTagHandler(kSourceTag, source_pos, canon_url);
 }