Updating Linuxbrew xorg packages

This (quick) guide is for current and future maintainers of Linuxbrew/xorg.

1. Get homebrew-livecheck that works with Linuxbrew/xorg:

   brew tap homebrew/livecheck
   cd $(brew --repo homebrew/livecheck)
   git fetch https://github.com/maxim-belkin/homebrew-livecheck.git livecheck-xorg:livecheck-xorg
   git checkout livecheck-xorg

2. Find formulae that can be updated & determine the order in which the formulae can be safely updated (for that purpose you can check out Linuxbrew/xorg updater).

   cd $(brew --repo linuxbrew/xorg)/Formula
   echo -n "" > ../TODO.txt
   for file in *.rb
   do 
     echo Processing $file
     brew livecheck -n linuxbrew/xorg/${file%.rb} 2>/dev/null 1>>../TODO.txt
   done
   
   # The above code creates a file `TODO.txt` with the output of `brew livecheck` that looks like this:
   # 
   # encodings (guessed) : 1.0.4 ==> 1.0.5
   # libdrm (guessed) : 2.4.97 ==> 2.4.98
   # libevdev (guessed) : 1.6.0 ==> 1.7.0
   # libfs (guessed) : 1.0.7 ==> 1.0.8
   # libglvnd (guessed) : 1.1.0 ==> 1.1.1

3. Create a new "Update packages" issue in this repository documenting the packages that have to be updated. You may use the following code snippet to generate a list with check-boxes:

   sed 's|^| - [ ] |; s| (guessed) :||;' ../TODO.txt > ../TODO.issue.txt

4. Figure out the order in which to update the packages: start with those that have fewer dependencies on packages in Linuxbrew/xorg:

   for file in $(cut -d' ' -f1 ../TODO.txt);
   do
     echo -n "$file "
     brew deps --include-build --include-test linuxbrew/xorg/$file | grep linuxbrew/xorg | wc -l
   done | sort -nk2 > ../TODO.order.txt

   Alternative solution that does not use brew deps:

    for file in $(cut -d' ' -f1 ../TODO.txt);
    do
      grep -Hc "depends_on.*linuxbrew/xorg" $file.rb | sed 's|:| |'
    done | sort -nk2 > ../TODO.order.txt

   This alternative solution might produce incorrect results if dependencies are in conditional blocks, as in:

   unless OS.mac?
       depends_on "linuxbrew/xorg/mesa"
   end
   

5. Proceed with updating formulae!