From 2063056243f3d67c6f5124b4075c0054dbae2f3f Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Mon, 10 Sep 2018 17:50:10 -0400
Subject: [PATCH] Bug221 re-fixed with better exception safety: see commit
 1deff18...

... in case only some tracks successfully allocate, de-allocate all before
propagating the exception.
---
 src/toolbars/ControlToolBar.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/toolbars/ControlToolBar.cpp b/src/toolbars/ControlToolBar.cpp
index 29a874e25..20a586d9f 100644
--- a/src/toolbars/ControlToolBar.cpp
+++ b/src/toolbars/ControlToolBar.cpp
@@ -1399,7 +1399,7 @@ void ControlToolBar::SetupCutPreviewTracks(double WXUNUSED(playStart), double cu
    ClearCutPreviewTracks();
    AudacityProject *p = GetActiveProject();
    if (p) {
-      mCutPreviewTracks = TrackList::Create();
+      auto cutPreviewTracks = TrackList::Create();
       // Find first selected track (stereo or mono) and duplicate it
       const Track *track1 = NULL, *track2 = NULL;
       TrackListIterator it(p->GetTracks());
@@ -1426,13 +1426,13 @@ void ControlToolBar::SetupCutPreviewTracks(double WXUNUSED(playStart), double cu
             }
 
             // use NOTHROW-GUARANTEE:
-            mCutPreviewTracks->Add(std::move(new1));
+            cutPreviewTracks->Add(std::move(new1));
             if (track2)
-               mCutPreviewTracks->Add(std::move(new2));
+               cutPreviewTracks->Add(std::move(new2));
          }
       }
-      if( !track1 )
-         ClearCutPreviewTracks();
+      if( track1 )
+         mCutPreviewTracks = cutPreviewTracks;
    }
 }