I’ve gotten past it by logging into my Apple Developer account and manually downloading/installing the command line tools.
I can tell you what I was running and saw (based on scrollback) was:
[tvon:~] % brew upgrade azure-cli neovim terraform
==> Auto-updated Homebrew!
Updated 1 tap (homebrew/core).
==> Updated Formulae
fn gnunet istioctl joplin
Error: azure-cli 2.0.66 already installed
==> Upgrading 2 outdated packages:
neovim 0.3.5 -> 0.3.7, terraform 0.12.0 -> 0.12.1
==> Upgrading neovim
Error: Xcode alone is not sufficient on Mojave.
Install the Command Line Tools:
I already had xcode installed. I tried uninstall/reinstall to no avail.
brew doctor output warned of not using
/usr/local (I never have) and gave the
xcode-select --install error (I’d paste but that is no longer in scrollback).
Probably of no use now but for kicks here is my current
[tvon:~] 1 % brew config
Last commit: 20 hours ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: c58dce188e274656041f0dd72aca59a8a968248d
Core tap last commit: 17 hours ago
CPU: octa-core 64-bit haswell
Homebrew Ruby: 2.3.7 => /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby
Clang: 10.0 build 1001
Git: 2.21.0 => /opt/homebrew/bin/git
Curl: 7.54.0 => /usr/bin/curl
CLT headers: 10.2.1.0.1.1554506761
XQuartz: 2.7.11 => /opt/X11