[ruby/irb] Change default completor from regexp to auto, try

TypeCompletor and fallback to RegexpCompletor.
(https://github.com/ruby/irb/pull/1010)

https://github.com/ruby/irb/commit/bb6a99d815

lib/irb/context.rb

@@ -176,11 +176,17 @@ module IRB
 
     private def build_completor
       completor_type = IRB.conf[:COMPLETOR]
+
+      # Gem repl_type_completor is added to bundled gems in Ruby 3.4.
+      # Use :type as default completor only in Ruby 3.4 or later.
+      verbose = !!completor_type
+      completor_type ||= RUBY_VERSION >= '3.4' ? :type : :regexp
+
       case completor_type
       when :regexp
         return RegexpCompletor.new
       when :type
-        completor = build_type_completor
+        completor = build_type_completor(verbose: verbose)
         return completor if completor
       else
         warn "Invalid value for IRB.conf[:COMPLETOR]: #{completor_type}"
@@ -189,17 +195,17 @@ module IRB
       RegexpCompletor.new
     end
 
-    private def build_type_completor
+    private def build_type_completor(verbose:)
       if RUBY_ENGINE == 'truffleruby'
         # Avoid SyntaxError. truffleruby does not support endless method definition yet.
-        warn 'TypeCompletor is not supported on TruffleRuby yet'
+        warn 'TypeCompletor is not supported on TruffleRuby yet' if verbose
         return
       end
 
       begin
         require 'repl_type_completor'
       rescue LoadError => e
-        warn "TypeCompletor requires `gem repl_type_completor`: #{e.message}"
+        warn "TypeCompletor requires `gem repl_type_completor`: #{e.message}" if verbose
         return
       end
 

lib/irb/init.rb

@@ -80,7 +80,7 @@ module IRB # :nodoc:
     @CONF[:USE_SINGLELINE] = false unless defined?(ReadlineInputMethod)
     @CONF[:USE_COLORIZE] = (nc = ENV['NO_COLOR']).nil? || nc.empty?
     @CONF[:USE_AUTOCOMPLETE] = ENV.fetch("IRB_USE_AUTOCOMPLETE", "true") != "false"
-    @CONF[:COMPLETOR] = ENV.fetch("IRB_COMPLETOR", "regexp").to_sym
+    @CONF[:COMPLETOR] = ENV["IRB_COMPLETOR"]&.to_sym
     @CONF[:INSPECT_MODE] = true
     @CONF[:USE_TRACER] = false
     @CONF[:USE_LOADER] = false

test/irb/test_context.rb

@@ -705,6 +705,8 @@ module TestIRB
     def test_build_completor
       verbose, $VERBOSE = $VERBOSE, nil
       original_completor = IRB.conf[:COMPLETOR]
+      IRB.conf[:COMPLETOR] = nil
+      assert_match /IRB::(Regexp|Type)Completor/, @context.send(:build_completor).class.name
       IRB.conf[:COMPLETOR] = :regexp
       assert_equal 'IRB::RegexpCompletor', @context.send(:build_completor).class.name
       IRB.conf[:COMPLETOR] = :unknown

test/irb/test_init.rb

@@ -167,9 +167,10 @@ module TestIRB
       orig_use_autocomplete_env = ENV['IRB_COMPLETOR']
       orig_use_autocomplete_conf = IRB.conf[:COMPLETOR]
 
+      # Default value is nil: auto-detect
       ENV['IRB_COMPLETOR'] = nil
       IRB.setup(__FILE__)
-      assert_equal(:regexp, IRB.conf[:COMPLETOR])
+      assert_equal(nil, IRB.conf[:COMPLETOR])
 
       ENV['IRB_COMPLETOR'] = 'regexp'
       IRB.setup(__FILE__)
@@ -193,10 +194,12 @@ module TestIRB
 
     def test_completor_setup_with_argv
       orig_completor_conf = IRB.conf[:COMPLETOR]
+      orig_completor_env = ENV['IRB_COMPLETOR']
+      ENV['IRB_COMPLETOR'] = nil
 
-      # Default is :regexp
+      # Default value is nil: auto-detect
       IRB.setup(__FILE__, argv: [])
-      assert_equal :regexp, IRB.conf[:COMPLETOR]
+      assert_equal nil, IRB.conf[:COMPLETOR]
 
       IRB.setup(__FILE__, argv: ['--type-completor'])
       assert_equal :type, IRB.conf[:COMPLETOR]
@@ -205,6 +208,7 @@ module TestIRB
       assert_equal :regexp, IRB.conf[:COMPLETOR]
     ensure
       IRB.conf[:COMPLETOR] = orig_completor_conf
+      ENV['IRB_COMPLETOR'] = orig_completor_env
     end
 
     def test_noscript

test/irb/test_type_completor.rb

@@ -27,6 +27,22 @@ module TestIRB
       binding
     end
 
+    def test_build_completor
+      IRB.init_config(nil)
+      verbose, $VERBOSE = $VERBOSE, nil
+      original_completor = IRB.conf[:COMPLETOR]
+      workspace = IRB::WorkSpace.new(Object.new)
+      @context = IRB::Context.new(nil, workspace, TestInputMethod.new)
+      IRB.conf[:COMPLETOR] = nil
+      expected_default_completor = RUBY_VERSION >= '3.4' ? 'IRB::TypeCompletor' : 'IRB::RegexpCompletor'
+      assert_equal expected_default_completor, @context.send(:build_completor).class.name
+      IRB.conf[:COMPLETOR] = :type
+      assert_equal 'IRB::TypeCompletor', @context.send(:build_completor).class.name
+    ensure
+      $VERBOSE = verbose
+      IRB.conf[:COMPLETOR] = original_completor
+    end
+
     def assert_completion(preposing, target, binding: empty_binding, include: nil, exclude: nil)
       raise ArgumentError if include.nil? && exclude.nil?
       candidates = @completor.completion_candidates(preposing, target, '', bind: binding)