Inside a macro expresion, next and break cannot be used inside while and until, simply because these loops also aren't supported yet (see #10959). But there are also next and break inside blocks:

{%
  (0..10).each do |i|
    p i
    break if i >= 5 # Error: can't execute Break in a macro
  end
%}

It would allow us to rewrite this:

into one of the following:

{%
  # normal refactor
  ssl_version = nil
  Crystal::LIBRARY_PATH.split(';').each do |dir|
    config_path = "#{dir.id}\\openssl_VERSION"
    if config_version = read_file?(config_path)
      ssl_version = config_version.chomp
      break
    end
  end

  # `break` with value
  ssl_version = Crystal::LIBRARY_PATH.split(';').each do |dir|
    config_path = "#{dir.id}\\openssl_VERSION"
    if config_version = read_file?(config_path)
      break config_version.chomp
    end
  end
%}

It is always unambiguous whether a given next or break is associated with a block or a while, and these keywords inside blocks cannot introduce any more macro infinite loops than we already have right now, unlike #10959. There is also the macro for, which one might argue should also support next and break, but for isn't impacted since it cannot appear inside a macro block. So I believe there are no blockers here and we could implement those keywords straight away.