From 2d6db518fa00f1f6175189d66d5a1cfdfda39606 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Sun, 22 Nov 2020 19:54:14 -0500
Subject: [PATCH] Prevent dangling pointers to meters...

... This stops a crash that might occur when the checkpoint thread causes
ProjectAudioManager::Stop() to execute but the project is in the process of
closing.
---
 src/ProjectAudioIO.cpp | 1 +
 src/ProjectAudioIO.h   | 5 +++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/ProjectAudioIO.cpp b/src/ProjectAudioIO.cpp
index 9f541df7a..9dafaee5c 100644
--- a/src/ProjectAudioIO.cpp
+++ b/src/ProjectAudioIO.cpp
@@ -12,6 +12,7 @@ Paul Licameli split from AudacityProject.cpp
 
 #include "AudioIOBase.h"
 #include "Project.h"
+#include "widgets/MeterPanelBase.h"
 
 static const AudacityProject::AttachedObjects::RegisteredFactory sAudioIOKey{
   []( AudacityProject &parent ){
diff --git a/src/ProjectAudioIO.h b/src/ProjectAudioIO.h
index 85c7c976f..bee522795 100644
--- a/src/ProjectAudioIO.h
+++ b/src/ProjectAudioIO.h
@@ -12,6 +12,7 @@ Paul Licameli split from AudacityProject.h
 #define __PROJECT_AUDIO_IO__
 
 #include "ClientData.h" // to inherit
+#include <wx/weakref.h>
 
 class AudacityProject;
 class MeterPanelBase;
@@ -43,8 +44,8 @@ private:
    AudacityProject &mProject;
 
    // Project owned meters
-   MeterPanelBase *mPlaybackMeter{};
-   MeterPanelBase *mCaptureMeter{};
+   wxWeakRef<MeterPanelBase> mPlaybackMeter{};
+   wxWeakRef<MeterPanelBase> mCaptureMeter{};
 
    int  mAudioIOToken{ -1 };
 };