formula: configure git/npm to ignore .brew_home

[branchvincent]

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In core, there's 4 formulae that rm_rf ".brew_home" to ensure git status reports no changes (for some reason, code search is missing helm).

Let's handle this here directly instead with a ~/.gitignore since imo formulae shouldn't even be aware of .brew_home. And because npm respects .gitignore files (as long as there is not also an .npmignore file in the same directory), this removes the need for std_npm_install_args to append to .npmignore.

To demonstrate this shouldn't change anything:

$ cd "$(brew --repo homebrew/core)"

# for git
$ sed -i "" 's/rm_rf ".brew_home"//' Formula/h/helm.rb
$ brew install -s helm && helm version
version.BuildInfo{Version:"v3.14.4", GitCommit:"81c902a123462fd4052bc5e9aa9c513c4c8fc142", GitTreeState:"clean", GoVersion:"go1.22.2"}

# for npm
$ sed -i "" 's/def install/def install\n\t\ttouch ".npmignore"/' Formula/b/bower.rb
$ brew install -s bower && ls "$(brew --prefix bower)"/libexec/lib/node_modules/bower/.brew_home
ls: /opt/homebrew/opt/bower/libexec/lib/node_modules/bower/.brew_home: No such file or directory

[ZhongRuoyu]

Makes sense to me!

[MikeMcQuaid]

Great idea, thanks again @branchvincent!

[cho-m]

This impacts formulae tests that run git add as it now errors. Not sure if there is a way to restrict to build only. Otherwise will need to update formulae, e.g.

  ==> Testing git-series
  ==> git init
  Initialized empty Git repository in /private/tmp/git-series-test-20240423-56212-o7xmxo/.git/
  ==> git add test
  The following paths are ignored by one of your .gitignore files:
  test
  hint: Use -f if you really want to add them.
  hint: Turn this message off by running
  hint: "git config advice.addIgnoredFile false"
  ==> Testing git-series (again)

[MikeMcQuaid]

@cho-m Yeh, making this build-only with a parameter probably makes sense 👍🏻

[Bo98]

Bit odd ~/.gitignore is being read here. Is core.excludesFile set or something?

[cho-m]

Bit odd ~/.gitignore is being read here. Is core.excludesFile set or something?

It is possible this isn't working as intended then.

• In test, we use HOME=testpath, so ~/.gitignore is often <repo>/.gitignore.
• In build, we use HOME=buildpath/.brew_home, so it may not actually be used.

Sadly, this is reverse of what we want. EDIT: For npm, this is probably behaving okay in build phase as it looks like they are specifically searching for .gitignore. If we don't care about other git usage, then we can keep installing it as it. I don't know if npm is aware of "modern" git files (e.g. ~/.config/git/ignore)

[Bo98]

Ohh right I had in my head for some reason that .brew_home existed in tests too. Makes sense moving this out of setup_home to be in stage only then as it's specific to that surrounding setup.

[cho-m]

One thing is whether we only care about npm or want to also deal with all git repos. ~/.gitignore works for npm. ~/.config/git/ignore works for git. However, neither works for both by default.

We would need to write two separate files to support both (in which case we may want to use ~/.npmignore if only used by npm). Alternatively, we would need to write core.excludesFile into ~/.gitconfig or ~/.config/git/config, but the non-standard format (in-house ini variant) makes it less ideal to manually modify.

[MikeMcQuaid]

For now: reverting in #17131. Would appreciate a ✅

[branchvincent]

Oops! Thanks for the quick revert @MikeMcQuaid, sorry didn't realize our test directory structure was different. Trying again with #17141