Mac OS build failing. No error messages but multiple warnings for Apple old code

@jeroen and @jimhester my build at
is failing with the message “No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.”

Prior to that the following warnings were issued:
==> Installing java…
67 Warning: You are using macOS 10.13.
68 We (and Apple) do not provide support for this old version.
69 You will encounter build failures with some formulae.
Warning: Your Xcode (9.4.1) is outdated.
76 Please update to Xcode 10.1 (or delete it).
77 Xcode can be updated from the App Store.
79 Warning: A newer Command Line Tools release is available.
80 Update them from Software Update in the App Store or run:
81 softwareupdate --all --install --force

brew update >/dev/null

That’s to be expected if this command takes longer than 10 minutes.

Which it is now because the above message means that the Homebrew project lo longer provides prebuilt bottles for this OSX version so brew has to build them from source.
And a very outdated preintalled Homewbrew means that brew update will be likely installing stuff like a new Ruby version.

@rmsharp you can skip brew update by specifying

disable_homebrew: true

in .travis.yml.

This can cause problems if you need to install something from Homebrew in the build.

I apologize for my ignorance on this, but I do not think my .travis.yml file has anything that specifies the use of an unsupported OS (EOL). I added the “osx_image: xcode12.2” line to the matrix section of the .travis.yml file and that has worked. Thank you again for your informative guidance.

         - os: osx
           osx_image: xcode12.2
           fortran: false`

@jeroen Is there a something I can add to the YAML file that will not require hard coding an OSX image but will limit the tests to supported images?