Homebrew fails to run on Ubuntu 23.04

[nirvdrum]

Additional Info

• I am using Windows Subsystem for Linux

Output of brew config

/usr/lib/ruby/vendor_ruby/os.rb:7:in `<top (required)>': OS is not a class (TypeError)
/home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/macos_version.rb:168: previous definition of OS was here
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/global.rb:78:in `require'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/global.rb:78:in `<top (required)>'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/brew.rb:18:in `require_relative'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/brew.rb:18:in `<main>'

Output of brew doctor

/usr/lib/ruby/vendor_ruby/os.rb:7:in `<top (required)>': OS is not a class (TypeError)
/home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/macos_version.rb:168: previous definition of OS was here
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/global.rb:78:in `require'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/global.rb:78:in `<top (required)>'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/brew.rb:18:in `require_relative'
	from /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/brew.rb:18:in `<main>'

Description of issue

I'm running on a brand new Ubuntu 23.04 installation. I'll try again with Ubuntu 23.10. The system Ruby on this machine is 3.1.2p20, which is not EOL yet.

1. Create Ubuntu 23.04 machine.
2. Install pre-requisites: sudo apt-get install build-essential procps curl file git
3. Attempt to install Homebrew: /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

It looks to me like the vendor_ruby/os.rb file is conflicting with Homebrew. The former defines a class named OS, while the latter defines a module named OS. I don't know where that vendor_ruby file came from. It's basically a brand new machine so I'm guessing it got pulled in from a system package.

If I look at the $LOAD_PATH, I see:

["/usr/local/lib/site_ruby/3.1.0",
 "/usr/local/lib/x86_64-linux-gnu/site_ruby",
 "/usr/local/lib/site_ruby",
 "/usr/lib/ruby/vendor_ruby/3.1.0",
 "/usr/lib/x86_64-linux-gnu/ruby/vendor_ruby/3.1.0",
 "/usr/lib/ruby/vendor_ruby",
 "/usr/lib/ruby/3.1.0",
 "/usr/lib/x86_64-linux-gnu/ruby/3.1.0"]

Homebrew uses require "os" in a couple of locations and my best guess is it's supposed to be loading Homebrew's own os.rb. Replacing the require with a require_relative appears to fix the problem for me.

I can work on a PR, but is there a reason the project is using require rather than require_relative? The latter is safer and faster if you're looking to load files within your own project. But, using require allows for patching code by manipulating the $LOAD_PATH. I don't know if that's a use case we need to preserve.

[Bo98]

We configure the LOAD_PATH here: https://github.com/Homebrew/brew/blob/5a09a06512fae4c434503edf2f236d379f5bb70c/Library/Homebrew/standalone/init.rb#L42-L46

It seems the HOMEBREW_LIBRARY_PATH line should be unshift rather than push?

[nirvdrum]

I have a good grasp on the problem, less so on the test suite. Where should I pet a test like this? I don't see any existing tests for the $LOAD_PATH modifications. I could throw it any one of the CLI tests, I guess, since it impacts the application start-up. But, I'd appreciate any guidance you can provide.

[SMillerDev]

I'm not usually involved in that part of brew, but if you put it in a PR wherever you can think of I'm sure someone with more experience will express their opinion

[nirvdrum]

Thanks. I was hoping to avoid lengthy round-trips through the review phase for what amounts to a one-line change. But, I'll just open a PR and see what happens.

[alichtman]

I opened Homebrew/brew#16479 after running into this issue today.

[nirvdrum]

Thanks. Life came up and I haven't had the time to work out the tests yet. It's probably straightforward, but diving into a new code base involves some ramp up.