Bug2592: should clean old temp directory at exit after prefs change

src/AudacityApp.cpp

@@ -1637,6 +1637,7 @@ bool AudacityApp::InitTempDir()
    chmod(OSFILENAME(temp), 0755);
    #endif
 
+   FileNames::ResetTempDir();
    FileNames::UpdateDefaultPath(FileNames::Operation::Temp, temp);
 
    // Make sure the temp dir isn't locked by another process.

src/FileNames.cpp

@@ -196,13 +196,28 @@ wxString FileNames::MkDir(const wxString &Str)
    return Str;
 }
 
+static wxString &TempDirPath()
+{
+   static wxString path;
+   return path;
+}
+
 /// Returns the directory used for temp files.
 /// \todo put a counter in here to see if it gets used a lot.
 /// if it does, then maybe we should cache the path name
 /// each time.
 wxString FileNames::TempDir()
 {
-   return FileNames::MkDir(gPrefs->Read(PreferenceKey(Operation::Temp, PathType::_None), wxT("")));
+   auto &path = TempDirPath();
+   if (gPrefs && path.empty())
+      path =
+         gPrefs->Read(PreferenceKey(Operation::Temp, PathType::_None), wxT(""));
+   return FileNames::MkDir(path);
+}
+
+void FileNames::ResetTempDir()
+{
+   TempDirPath().clear();
 }
 
 // originally an ExportMultipleDialog method. Append suffix if newName appears in otherNames.

src/FileNames.h

@@ -66,6 +66,7 @@ namespace FileNames
 
    wxString MkDir(const wxString &Str);
    wxString TempDir();
+   void ResetTempDir();
 
    const FilePath &DefaultTempDir();
    void SetDefaultTempDir( const FilePath &tempDir );

src/ProjectFileIO.cpp

@@ -1014,8 +1014,7 @@ bool ProjectFileIO::RenameOrWarn(const FilePath &src, const FilePath &dst)
 
 bool ProjectFileIO::MoveProject(const FilePath &src, const FilePath &dst)
 {
-   // Assume the src database file is not busy.
-   if (!RenameOrWarn(src, dst))
+   // Assume the src database file is not busy.   if (!RenameOrWarn(src, dst))
       return false;
 
    // So far so good, but the separate -wal and -shm files might yet exist,