Default to printing a help message when bundle is run without arguments on 2.0

lib/bundler/cli.rb

@@ -55,7 +55,14 @@ def initialize(*args)
     check_unknown_options!(:except => [:config, :exec])
     stop_on_unknown_option! :exec
 
-    default_task :install
+    desc "cli_help", "Prints a summary of bundler commands", :hide => true
+    def cli_help
+      version
+      Bundler.ui.info "\n"
+      self.class.help(shell)
+    end
+    default_task(Bundler.feature_flag.default_cli_command)
+
     class_option "no-color", :type => :boolean, :desc => "Disable colorization in output"
     class_option "retry",    :type => :numeric, :aliases => "-r", :banner => "NUM",
                              :desc => "Specify the number of times you wish to attempt network commands"

lib/bundler/feature_flag.rb

@@ -5,12 +5,24 @@ def self.settings_flag(flag, &default)
       unless Bundler::Settings::BOOL_KEYS.include?(flag.to_s)
         raise "Cannot use `#{flag}` as a settings feature flag since it isn't a bool key"
       end
-      define_method("#{flag}?") do
-        value = Bundler.settings[flag]
+
+      settings_method("#{flag}?", flag, &default)
+    end
+    private_class_method :settings_flag
+
+    def self.settings_option(key, &default)
+      settings_method(key, key, &default)
+    end
+    private_class_method :settings_option
+
+    def self.settings_method(name, key, &default)
+      define_method(name) do
+        value = Bundler.settings[key]
         value = instance_eval(&default) if value.nil? && !default.nil?
         value
       end
     end
+    private_class_method :settings_method
 
     (1..10).each {|v| define_method("bundler_#{v}_mode?") { major_version >= v } }
 
@@ -20,6 +32,8 @@ def self.settings_flag(flag, &default)
     settings_flag(:error_on_stderr) { bundler_2_mode? }
     settings_flag(:init_gems_rb) { bundler_2_mode? }
 
+    settings_option(:default_cli_command) { bundler_2_mode? ? :cli_help : :install }
+
     def initialize(bundler_version)
       @bundler_version = Gem::Version.create(bundler_version)
     end
@@ -28,7 +42,5 @@ def major_version
       @bundler_version.segments.first
     end
     private :major_version
-
-    class << self; private :settings_flag; end
   end
 end

spec/quality_spec.rb

@@ -169,6 +169,7 @@ def check_for_specific_pronouns(filename)
 
   it "documents all used settings" do
     exemptions = %w[
+      default_cli_command
       gem.coc
       gem.mit
       warned_version