This is a poor way to handle library upgrades that are guaranteed to break any existing compiled binaries.
Frustrating that my PR to create readline@7 was rejected. https://github.com/Homebrew/homebrew-core/pull/36782
I would at least like to see some mechanism to exclude a Formula from automatic gc of old versions besides brew pin. Libraries don't take up significant space, and they cause a world of hurt to delete out from under compiled binaries, so there is not a good argument for automatically deleting them.
> Usage: brew extract [options] formula tap
> Look through repository history to find the most recent version of formula and create a copy in tap/Formula/[email protected]. If the tap is not installed yet, attempt to install/clone the tap before continuing.