We have a `HOMEBREW_MACOS_NEWEST_UNSUPPORTED` environment variable
and this is used in `MacOSVersion` to determine prerelease versions
but we don't have a way of easily determining the newest supported
macOS version.
`bump-cask-pr` contains logic that assumes the first key/value in
`MacOSVersion::SYMBOLS` is the newest macOS version but it recently
became clear that this is a prerelease version between WWDC and the
subsequent macOS release. Similarly, `dev-cmd/generate-cask-api.rb`
tries to compute the newest stable macOS version as
`HOMEBREW_MACOS_NEWEST_UNSUPPORTED.to_i - 1` and this will fail
if/when we update that variable to `"26"`, as the macOS version
before 26 is 15, not 25.
This adds a `HOMEBREW_MACOS_NEWEST_SUPPORTED` environment variable,
so we have a straightforward way of quickly identifying the newest
supported macOS version without having to make potentially unreliable
assumptions or do computations to identify the latest non-prerelease
`MacOSVersion` value. This also updates the two aforementioned areas
to use this environment variable to produce the newest stable macOS
version symbol in a more reliable way.
This adds a new file to the output of `brew generate-cask-api` which
represents the new internal JSON v3 file. It involves removing
a bunch of unneeded hash keys while removing blank ones as well.
I've made some slight changes to the cask loader as well but more
might be necessary before this starts loading things correctly.
The full loader code will be added in a separate PR.
There are two reasons for this:
- Makes it easier to run this command as a sanity check without
having to create a temporary directory
- Is somewhat faster since you don't have to write thousands of files
