Re: [lldb-dev] Help with C++ API

[Jakob Leben]

On Wed, Aug 28, 2013 at 11:25 AM, Enrico Granata <egran...@apple.com> wrote:
> 2. For std::vector, GetNumChildren() returns -1 (with preference for
> synthetic)! However, reading children using GetChildAtIndex() etc.
> still succeeds.
>
>
> Interesting. Test case?

See attached files for debugger and debugee programs.

The output of debugger is always:
count = -1
val = 11
val = 12
val = 13

This is when both debugger and debugee are built either with clang or gcc.

#include <vector>
int main()
{
  std::vector<int> foo {11,12,13};
  return 0;
}

#include <iostream>
#include <string>
#include <lldb/API/LLDB.h>

using namespace lldb;
using namespace std;

const int BREAKPOINT_LINE = 5;

bool breakpoint_callback (void *baton, SBProcess &process, SBThread &thread, SBBreakpointLocation &location);

int main(int argc, char *argv[])
{
  SBDebugger::Initialize();

  SBError error;

  SBDebugger debugger = SBDebugger::Create(false);
  if (!debugger.IsValid())
  {
    cerr << "Error creating debugger." << endl;
    return 1;
  }

  SBTarget target ( debugger.CreateTarget("./debugee", "", "", true, error) );
  if (!error.Success())
  {
    cerr << "Error creating target: " << error.GetCString() << endl;
    return 1;
  }
  if (!target.IsValid())
  {
    cerr << "Error: target invalid." << endl;
    return 1;
  }

  SBBreakpoint bp;

  bp = target.BreakpointCreateByLocation("debugee.cpp", BREAKPOINT_LINE);
  bp.SetCallback( breakpoint_callback, nullptr );

  SBProcess process = target.LaunchSimple(nullptr, nullptr, nullptr);
  if (!process.IsValid())
  {
    cerr << "Error: Invalid process." << endl;
    return 1;
  }

  SBListener listener = debugger.GetListener();
  assert(listener.IsValid());

  bool running = true;
  while (running)
  {
    SBEvent event;
    bool ok = listener.WaitForEvent(UINT32_MAX, event);
    if (!ok || !event.IsValid())
      continue;

    const uint32_t event_type = event.GetType();

    if (SBProcess::EventIsProcessEvent (event))
    {
      if (event_type & SBProcess::eBroadcastBitStateChanged)
      {
        StateType event_state = SBProcess::GetStateFromEvent (event);
        switch (event_state)
        {
        case eStateExited:
        case eStateCrashed:
          running = false;
          break;
        default:
          break;
        }
      }
    }
  }

  return 0;
}

bool breakpoint_callback (void *baton, SBProcess &process, SBThread &thread, SBBreakpointLocation &location)
{
  SBError error;

  SBFrame frame( thread.GetSelectedFrame() );
  assert(frame.IsValid());

  {
    SBValue foo_value = frame.FindVariable("foo");
    foo_value.SetPreferSyntheticValue(true);

    int count = foo_value.GetNumChildren();
    cout << "count = " << count << endl;
    count = 3;
    for (int i = 0; i < count; ++i)
    {
      SBError error;
      int x = 0;
      SBValue child = foo_value.GetChildAtIndex(i, eNoDynamicValues, false);
      if (child.IsValid())
      {
        x = child.GetValueAsSigned();
      }
      cout << "val = " << x << endl;
    }
  }

  return false;
}

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