Can we make HB flags not interfere with cask?

[vitorgalvao]

I’m building an external command for cask. However, I’m running into a snag caused by Homebrew (related: #16265). Basically, short flag options become not viable.

Steps to reproduce:

# Make a simple temporary executable script
echo '#!/bin/bash
[[ "${1}" == "--flag" ]] && echo "long flag given"
[[ "${1}" == "-a" ]] && echo "short flag given"
[[ -z "${1}" ]] && echo "no flag given"' > /tmp/brewcask-example
chmod +x /tmp/brewcask-example

# Add its directory to your PATH
PATH=/tmp:$PATH

# Run it as an external command, with and without the flags
brew cask example
brew cask example --flag
brew cask example -a

# You’ll get (in order)
no flag given # correct
long flag given # correct
Error: There is more than one possible option that starts with '-a' # incorrect

That last option is being “stolen” by Homebrew itself. Try something like brew cask example --help and you’ll get their help, not even ours.

HB flags shouldn’t interfere with HBC commands. That --help example would be particularly confusing to a user.

Pinging @reitermarkus @claui @jawshooah @mwean.

[MikeMcQuaid]

Try something like brew cask example --help and you’ll get their help, not even ours.

If you use #: before your comments at the top of a file they will be output by brew --help.

[vitorgalvao]

If you use #: before your comments at the top of a file they will be output by brew --help.

It only works for brew external commands, not brew cask ones.

And this looks like a bug, but I just tried brew services --help and my terminal is filled with the (correct) instructions. I then cannot leave/do anything until I ctrlC.

[MikeMcQuaid]

It only works for brew external commands, not brew cask ones.

It could be made to work on brew cask external commands fairly easily.

And this looks like a bug, but I just tried brew services --help and my terminal is filled with the (correct) instructions. I then cannot leave/do anything until I ctrlC.

I cannot reproduce this. It could be related to pager (e.g. less) settings.

[vitorgalvao]

I cannot reproduce this. It could be related to pager (e.g. less) settings.

I have no custom settings for less. I can reproduce in both zsh inside iTerm2 (my setup) and bash inside Terminal (pristine and unchanged, that I keep for tests such as this).

In both terminals the title bar (where the current running command is shown) goes crazy, switching between bash and ruby, suggesting there‘s an infinite loop. When you brew services --help, does it fit all at once on your Terminal? In mine it does not (not tall enough).

[MikeMcQuaid]

@vitorgalvao No idea then, sorry.

[amyspark]

@MikeMcQuaid, I can confirm and reproduce the two bugs described by @vitorgalvao.

The first one:

That last option is being “stolen” by Homebrew itself. Try something like brew cask example --help and you’ll get their help, not even ours.

It's a bug in Cask's cli.rb:
https://github.com/Homebrew/brew/blob/56458f03fcc68ef6d8ee3ee4a7c1d16021aa5800/Library/Homebrew/cask/lib/hbc/cli.rb#L227-L235
Line 234 specifies that it should print the first argument if available, which the example script does (instead of example, which doesn't exist as a command!)

The second one:

And this looks like a bug, but I just tried brew services --help and my terminal is filled with the (correct) instructions. I then cannot leave/do anything until I ctrlC.

This one only happens if homebrew/services has not been previously tapped, because in this case the help request is redirected to the tap command, which always returns the help text without actually tapping the cask 🤦‍♀️ .
The execution flow is roughly like this:

brew services --help

• help.rb does not find the command and so returns
• now brew.rb tests whether it belongs to a Tap
• it does, so brew tap homebrew/services is triggered
• because the HOMEBREW_HELP environment variable is still set, help.rb sets the help_flag, and attempts to print tap help instead
• now, puts(command_help(path)) does the job, but after doing so exit 0 returns from the "tap"
• we execute brew services --help again, and since the tap didn't clone the repo but merely printed the help text, this triggers the loop.

The bug lies in the remarked step: if a tap is required, it should not obey the HOMEBREW_HELP environment variable.

A pull request in Homebrew is forthcoming.