Bug fixes for hot reload

runtime/vm/service.cc

 // Copyright (c) 2013, 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 "vm/service.h"
 
 #include "include/dart_api.h"
 #include "include/dart_native_api.h"
 #include "platform/globals.h"
 
@@ skipping 2466 matching lines @@
   if (handler == NULL) {
     js->PrintError(kFeatureDisabled,
                    "A library tag handler must be installed.");
     return true;
   }
   if (isolate->IsReloading()) {
     js->PrintError(kIsolateIsReloading,
                    "This isolate is being reloaded.");
     return true;
   }
-  DebuggerStackTrace* stack = isolate->debugger()->StackTrace();
-  ASSERT(isolate->CanReload());
-
-  if (stack->Length() > 0) {
-    // TODO(turnidge): We need to support this case.
+  if (!isolate->CanReload()) {
     js->PrintError(kFeatureDisabled,
-                   "Source can only be reloaded when stack is empty.");
+                   "This isolate cannot reload sources right now.");
     return true;
-  } else {
-    isolate->ReloadSources();
   }
 
-  PrintSuccess(js);
+  isolate->ReloadSources();
+
+  const Error& error = Error::Handle(isolate->sticky_reload_error());
+
+  if (error.IsNull()) {
+    PrintSuccess(js);
+  } else {
+    // Clear the sticky error.
+    isolate->clear_sticky_reload_error();
+    js->PrintError(kIsolateReloadFailed,
+                   "Isolate reload failed: %s", error.ToErrorCString());
+  }
   return true;

[Florian Schneider, 2016/06/16 17:30:00]

This function never seems to return false. Is the result used at all? If not,
you should make it return void.

[Cutch, 2016/06/16 18:02:26]

A service protocol handler can return false if they have not directly handled
the request (possibly sending it to another isolate for processing).

 }
 
 
 static bool AddBreakpointCommon(Thread* thread,
                                 JSONStream* js,
                                 const String& script_uri) {
   if (!thread->isolate()->compilation_allowed()) {
     js->PrintError(kFeatureDisabled,
         "Cannot use breakpoints when running a precompiled program.");
     return true;
@@ skipping 1750 matching lines @@
     if (strcmp(method_name, method.name) == 0) {
       return &method;
     }
   }
   return NULL;
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart