Fix for issue 23908 - error message reports the exact error when a native extension fails to load.

runtime/bin/main.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "include/dart_tools_api.h"
@@ skipping 1074 matching lines @@
   DartUtils::ReadFile(buffer, &len, file);
   if (*buffer == NULL || len == -1) {
     ErrorExit(kErrorExitCode,
               "Error: Unable to read snapshot file %s\n", filename);
   }
   DartUtils::CloseFile(file);
 }
 
 
 static void* LoadLibrarySymbol(const char* libname, const char* symname) {
-  void* library = Extensions::LoadExtensionLibrary(libname);
-  if (library == NULL) {
-    Log::PrintErr("Error: Failed to load library '%s'\n", libname);
-    exit(kErrorExitCode);
+  void* library = NULL;
+  Dart_Handle result = Extensions::LoadExtensionLibrary(libname, &library);
+  if (Dart_IsError(result)) {
+    ErrorExit(kErrorExitCode,
+              "Error: Failed to load library '%s' - '%s'\n",
+              libname,
+              Dart_GetError(result));
   }
-  void* symbol = Extensions::ResolveSymbol(library, symname);
-  if (symbol == NULL) {
-    Log::PrintErr("Error: Failed to load symbol '%s'\n", symname);
-    exit(kErrorExitCode);
+  void* symbol = NULL;
+  result = Extensions::ResolveSymbol(library, symname, &symbol);
+  if (Dart_IsError(result)) {
+    ErrorExit(kErrorExitCode,
+              "Error: Failed to load symbol '%s' - '%s'\n",
+              symname,
+              Dart_GetError(result));
   }
   return symbol;
 }
 
 
 #define CHECK_RESULT(result)                                                   \
   if (Dart_IsError(result)) {                                                  \
     if (Dart_IsVMRestartRequest(result)) {                                     \
       Dart_ExitScope();                                                        \
       Dart_ShutdownIsolate();                                                  \
@@ skipping 342 matching lines @@
   exit(Process::GlobalExitCode());
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   dart::bin::main(argc, argv);
   UNREACHABLE();
 }