You can look inside PluginDirectoryScanner::scanNextFile():
OwnedArray <PluginDescription> typesFound;
// Add this plugin to the end of the dead-man's pedal list in case it crashes...
StringArray crashedPlugins (getDeadMansPedalFile());
crashedPlugins.removeString (file);
crashedPlugins.add (file);
setDeadMansPedalFile (crashedPlugins);
list.scanAndAddFile (file,
dontRescanIfAlreadyInList,
typesFound,
format);
// Managed to load without crashing, so remove it from the dead-man's-pedal..
crashedPlugins.removeString (file);
setDeadMansPedalFile (crashedPlugins);
if (typesFound.size() == 0)
failedFiles.add (file);
It seems that if it doesn’t recognize a known plug-in type it adds it to the filedFiles