search_by_dependency

# File lib/bundler/index.rb, line 188
    def search_by_dependency(dependency, base = nil)
      @cache[base || false] ||= {}
      @cache[base || false][dependency] ||= begin
        specs = specs_by_name(dependency.name)
        specs += base if base
        found = specs.select do |spec|
          next true if spec.source.is_a?(Source::Gemspec)
          if base # allow all platforms when searching from a lockfile
            dependency.matches_spec?(spec)
          else
            dependency.matches_spec?(spec) && Gem::Platform.match(spec.platform)
          end
        end

        found
      end
    end