I don't really understand the MacOS build system so this is half feature request and half general whiney plea for help for the ignorant.

Often I see this error when running the ./configure script after upgrading Mac OS (or "randomly", not sure why):

    checking for metal... [not found]
    checking if metal can be run using xcrun... no
    configure: A full XCode is required to build the JDK (not only command line tools)
    configure: If you have XCode installed, you might need to reset the Xcode active developer directory
    configure: using 'sudo xcode-select -r'
    configure: error: XCode tool 'metal' neither found in path nor with xcrun

Unfortunately, the suggested action does not solve the problem. Each time, having forgotten what works, I have to google around and try a bunch of different things like upgrading Xcode, etc.

This past time, the command below is what actually worked:

    xcodebuild -downloadComponent MetalToolchain

Feature request: add the above command to the suggestions output by ./configure when "metal" is not found.