Currently the listing key of kio protocols has type stringlist, but it's currently used only to figure out if the slave supports listing (i.e. m_supportsListing = (m_listing.count() > 0);).
We could make the key just a boolean and simplify the protocol definitions.
It's also used to define extra columns.
trash.json:
"listing": [
"Name",
"Type",
"Size",
"Extra1",
"Extra2",
"Date",
"Access",
"Owner",
"Group",
"Link"
],This is accessible via QStringList KProtocolManager::listing(const QUrl &url) (which ends up using that m_listing variable you mention)
I'm not sure if anyone is still using KProtocolManager::listing(). This used to be the case....
Yeah I could not find any usage of KProtocolManager::listing(), not even in KIO...
What was used for?
As I said, it was used to define extra columns.
It appears that it was used in konqueror before konqueror's file management views were replaced with Dolphin's.
See http://www.davidfaure.fr/2020/konq_listviewwidget.cc
I see, so I guess it doesn't hurt to keep KProtocolManager::listing() around and the gain wouldn't be worth the effort.