Downcase internal commands

[cocateh]

Since APFS is case-insensitive by default, Ruby will load the command file if user passes it mixed-case, but invoking it later will fail.

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

[ZhongRuoyu]

Thanks for the PR @cocateh, but can you please elaborate what your intended use case is? Is it something like brew INSTALL? Why not invoke it with the correct letter case?

This does matter in case-sensitive filesystems where you can technically have brew INSTALL as an external command. I don't think we make assumptions on the filesystem like this.

[cocateh]

Hi!

That's not the point of the PR, if you have a mixed-case command then brew crashes saying that it can't find an internal command.

This is because of what I described, because APFS is by default case-insensitive, if you pass something like upgrAde, then valid_internal_cmd? passes because it checks whether there is such command in brew's load path by doing require.

Because of the case-insensitivity, this returns true, so it loaded the command file, however, brew won't be able to find a proper handler in AbstractCommand nor do Command.method_name (it crashes on this one), because cmd is still mixed-case.

Since all of brew's internal commands are lower-case, I don't see a reason why shouldn't it be downcased by default for the sole convenience of a user :-)

[cocateh]

This is a minor issue, though, I just saw my Homebrew crash when I miss-spelled my command so that was a quick fix I think is sensible.

[cocateh]

This does matter in case-sensitive filesystems where you can technically have brew INSTALL as an external command. I don't think we make assumptions on the filesystem like this.

This change applies only to internal commands. It wouldn't make much sense to make two internal commands, both with different capitalisation.

[MikeMcQuaid]

@cocateh Thanks for the PR! I like the idea but not the implementation. I've adjusted it to improve the error messaging instead.