Loosen aggressive assert in debugger stack trace code

runtime/vm/debugger.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 "vm/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 882 matching lines @@
 }
 
 
 DebuggerStackTrace* Debugger::CollectStackTrace() {
   Isolate* isolate = Isolate::Current();
   DebuggerStackTrace* stack_trace = new DebuggerStackTrace(8);
   Context& ctx = Context::Handle(isolate->top_context());
   Code& code = Code::Handle(isolate);
   StackFrameIterator iterator(false);
   StackFrame* frame = iterator.NextFrame();
+  ActivationFrame* callee_activation = NULL;
   bool optimized_frame_found = false;
   while (frame != NULL) {
     ASSERT(frame->IsValid());
     if (frame->IsDartFrame()) {
       code = frame->LookupDartCode();
       ActivationFrame* activation = new ActivationFrame(frame->pc(),
                                                         frame->fp(),
                                                         frame->sp(),
                                                         code);
       // If this activation frame called a closure, the function has
       // saved its context before the call.
-      if (stack_trace->Length() > 0) {
-        ActivationFrame* callee_frame =
-            stack_trace->ActivationFrameAt(stack_trace->Length() - 1);
-        if (callee_frame->function().IsClosureFunction()) {
-          ctx = activation->GetSavedCurrentContext();
-          if (FLAG_verbose_debug && ctx.IsNull()) {
-            const Function& caller = activation->function();
-            const Function& callee = callee_frame->function();
-            const Script& script =
-                Script::Handle(Class::Handle(caller.Owner()).script());
-            intptr_t line, col;
-            script.GetTokenLocation(activation->TokenPos(), &line, &col);
-            printf("CollectStackTrace error: no saved context in function "
-                "'%s' which calls closure '%s' "
-                " in line %"Pd" column %"Pd"\n",
-                caller.ToFullyQualifiedCString(),
-                callee.ToFullyQualifiedCString(),
-                line, col);
-          }
-          ASSERT(!ctx.IsNull());
+      if ((callee_activation != NULL) &&
+          (callee_activation->function().IsClosureFunction())) {
+        ctx = activation->GetSavedCurrentContext();
+        if (FLAG_verbose_debug && ctx.IsNull()) {
+          const Function& caller = activation->function();
+          const Function& callee = callee_activation->function();
+          const Script& script =
+              Script::Handle(Class::Handle(caller.Owner()).script());
+          intptr_t line, col;
+          script.GetTokenLocation(activation->TokenPos(), &line, &col);
+          printf("CollectStackTrace error: no saved context in function "

[siva, 2013/05/01 18:21:19]

maybe use OS::Print here.

[hausner, 2013/05/01 18:32:53]

Yes.

+              "'%s' which calls closure '%s' "
+              " in line %"Pd" column %"Pd"\n",
+              caller.ToFullyQualifiedCString(),
+              callee.ToFullyQualifiedCString(),
+              line, col);
         }
+        ASSERT(!ctx.IsNull());
       }
       if (optimized_frame_found || code.is_optimized()) {
         // Set context to null, to avoid returning bad context variable values.
         activation->SetContext(Context::Handle());
         optimized_frame_found = true;
       } else {
         activation->SetContext(ctx);
       }
       stack_trace->AddActivation(activation);
+      callee_activation = activation;
       // Get caller's context if this function saved it on entry.
       ctx = activation->GetSavedEntryContext(ctx);
     } else if (frame->IsEntryFrame()) {
       ctx = reinterpret_cast<EntryFrame*>(frame)->SavedContext();
+      callee_activation = NULL;
     }
     frame = iterator.NextFrame();
   }
   return stack_trace;
 }
 
 
 void Debugger::SetExceptionPauseInfo(Dart_ExceptionPauseInfo pause_info) {
   ASSERT((pause_info == kNoPauseOnExceptions) ||
          (pause_info == kPauseOnUnhandledExceptions) ||
@@ skipping 823 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart