Add Apple Silicon support

[lunij]

This is an addition to the PR #12 by @nemoDreamer.

Newer installations of Homebrew use /opt/homebrew/ instead of /usr/local/.

The difference is the if type -q brew condition that didn't work for me on my M1. type can only find brew when it is already part of the $PATH variable, but to be part of the $PATH variable this fish script needs to run first.

In other words: This fish script adds necessary paths used by brew to $PATH to make brew accessible. Only after this script did its job, commands like type brew and which brew can finally work.

[scorphus]

Hey, @lunij, thanks for contributing!

How about reporting the absence of brew at the end, after all existing paths are appended to $PATH? This may not only maintain the behavior in that regard but also help troubleshooting issues.

[lunij]

How about reporting the absence of brew at the end [...]

Yes, I did it.

In addition I changed the algorithm to one for loop only. Now, a path is added to $PATH only if it is not already part of $PATH and contains a file called brew. Also, the path is added in the beginning of $PATH to ensure it has precedence over system paths, otherwise system apps like ruby and python would be preferred over the Homebrew variants. It should be the other way around.

[scorphus]

How about reporting the absence of brew at the end [...]

Yes, I did it.

Thank you!

In addition I changed the algorithm to one for loop only. Now, a path is added to $PATH only if it is not already part of $PATH and contains a file called brew. [...]

Nice! We need to make sure contains is supported in older Fish releases.

[...] Also, the path is added in the beginning of $PATH to ensure it has precedence over system paths, otherwise system apps like ruby and python would be preferred over the Homebrew variants. It should be the other way around.

It's usually a good idea to give system apps preference. Perhaps not when it's the user's shell (whereas in bash and scripts not child of the user's shell process, system's apps would still be preferred — which could also cause confusion other than failures).

I don't really know all implications as I always append (instead of prepend) brew path to PATH — and use virtual environments for pretty much everything (ruby, python, etc.)

Still, this is a radical change that might affect many users who have it the other way around. Maybe that should still be the default behavior and a the plugin could support some sort of a flag to indicate that brew paths should be prepended.

What are your thoughts, @bobthecow?

[isinyaaa]

Hi, folks. I've been trying to set this up on my machine and was having issues until I noticed that if for some reason, the user is already appending to PATH somewhere else, this script will yell needlessly.

[isinyaaa]

My suggestion would be:

Suggested change

	if not set -q brew_found
	if not set -q brew_found; and not command -q brew

[misimpso]

I was having the problem of brew not being available on the path, and fish complaining with the "type -q" conditional check failing. This fix, along with the first fix from this issue, fixed my problem.

[scorphus]

Thanks, @lunij!