One Weird Trick to Fix Linker Errors on Apple Silicon After Restore

This post might be useful for maybe like 10 people who are running into issues when compiling software on Apple M* machines.

If you run into error like this:

ld: warning: ignoring file '/usr/local/lib/libpng.dylib': found architecture 'x86_64', required architecture 'arm64'
ld: warning: ignoring file '/usr/local/lib/libavformat.dylib': found architecture 'x86_64', required architecture 'arm64'

And you have installed these packages using brew. I verified that these dylibs are definitely for x86_64 and the linker was not going crazy. (use lipo -archs /usr/local/lib/libavformat.dylib)

Well, that was caused because  I had installed the new M3 macbook from backup (Timemachine) and the backup was created from an x86_64.  

The fix is described here

brew bundle dump --global
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/uninstall.sh)"
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
brew bundle install --global

This first creates a ~/.Brewfile and then installs back those packages.