brew/Library/Homebrew/dev-cmd/linkage.rb

#:  * `linkage` [`--test`] [`--reverse`] [`--cached`] <formula>:
#:    Checks the library links of an installed formula.
#:
#:    Only works on installed formulae. An error is raised if it is run on
#:    uninstalled formulae.
#:
#:    If `--test` is passed, only display missing libraries and exit with a
#:    non-zero exit code if any missing libraries were found.
#:
#:    If `--reverse` is passed, print the dylib followed by the binaries
#:    which link to it for each library the keg references.
#:
#:    If `--cached` is passed, print the cached linkage values stored in
#:    HOMEBREW_CACHE, set from a previous `brew linkage` run

require "cache_store"
require "linkage_checker"

module Homebrew
  module_function

  def linkage
    DatabaseCache.use(:linkage) do |database_cache|
      ARGV.kegs.each do |keg|
        ohai "Checking #{keg.name} linkage" if ARGV.kegs.size > 1

        use_cache = ARGV.include?("--cached") || ENV["HOMEBREW_LINKAGE_CACHE"]
        result = LinkageChecker.new(keg, database_cache, use_cache)

        if ARGV.include?("--test")
          result.display_test_output
          Homebrew.failed = true if result.broken_library_linkage?
        elsif ARGV.include?("--reverse")
          result.display_reverse_output
        else
          result.display_normal_output
        end
      end
    end
  end
end