[tzs]

OT: speaking of Homebrew, I made an incorrect assumption about it that eventually led to some problems. It was me being stupid, but I bet others have made the same mistake but not yet hit problems. Hence this comment.

My mistake was when I upgraded from my 2017 iMac (Intel processor) to an Apple silicon Mac at the start of 2024 and migrated via Time Machine I did not do anything extra specifically for Homebrew. I just assumed that as things got updated via the normal periodic Homebrew updates I run it would start grabbing the Apple silicon binaries for binary things it installed.

It turn out that is wrong. They made Apple silicon Homebrew kind of independent of Intel Homebrew. Intel Homebrew uses /usr/local and Apple silicon Homebrew uses /opt/homebrew. This allows having both native and Intel Homebrew installed at the same time if you need both.

The correct way to migrate from an Intel Mac to an Apple silicon Mac is to install Apple silicon Homebrew on the new Mac, and then install all the packages you want. Intel Homebrew works fine on Apple silicon Macs so you can use the Intel Homebrew that migrated via Time Machine to make the package list to use with Apple silicon Homebrew (or you can make it on the old Mac).

I only noticed this because I was trying to build something from source using some libraries that were installed via Homebrew and running into problems. An LLM was helping figure this out and it was telling me I might have to manually symlink those libraries from where they were in /opt/homebrew to where the build process for the thing I was building expected to find them and I didn't have a /opt/homebrew. The libraries were somewhere in /usr/local. I then noticed those libraries were not for Apple silicon, checked other things installed view Homebrew and saw nothing was for Apple silicon, and realized I had the wrong Homebrew.