[lldb/Target] Fix event handling during process launch

[mib]

Summary

This patch fixes process event handling when the events are broadcasted
at launch. To do so, the patch introduces a new listener to ensure the
event ordering.

Signed-off-by: Med Ismail Bennani <[e-mail]>

[jingham]

This LGTM. This code is fetching events by hand off the event queue and then resending them, so it makes sense that it should stop the ones it is handling from leaking out to the Process listener.

[mib]

Landed in 8266b7ea7dac95b60843a1fdde31b42475687fe5

lldb/source/Target/Process.cpp

 //===-- Process.cpp -------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include <atomic>
 #include <memory>
 #include <mutex>
 
+#include "llvm/ADT/ScopeExit.h"
 #include "llvm/Support/ScopedPrinter.h"
 #include "llvm/Support/Threading.h"
 
 #include "lldb/Breakpoint/BreakpointLocation.h"
 #include "lldb/Breakpoint/StoppointCallbackContext.h"
 #include "lldb/Core/Debugger.h"
 #include "lldb/Core/Module.h"
 #include "lldb/Core/ModuleSpec.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Core/StreamFile.h"
 #include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/DynamicCheckerFunctions.h"
Status Process::Launch(ProcessLaunchInfo &launch_info) {
   if (FileSystem::Instance().Exists(exe_module->GetFileSpec())) {
     // Install anything that might need to be installed prior to launching.
     // For host systems, this will do nothing, but if we are connected to a
     // remote platform it will install any needed binaries
     error = GetTarget().Install(&launch_info);
     if (error.Fail())
       return error;
 
+    // Listen and queue events that are broadcasted during the process launch.
+    ListenerSP listener_sp(Listener::MakeListener("LaunchEventHijack"));
+    HijackProcessEvents(listener_sp);
+    auto on_exit = llvm::make_scope_exit([this]() { RestoreProcessEvents(); });
+
     if (PrivateStateThreadIsValid())
       PausePrivateStateThread();
 
     error = WillLaunch(exe_module);
     if (error.Success()) {
       const bool restarted = false;
       SetPublicState(eStateLaunching, restarted);
       m_should_detach = false;