open conifg

*Deprecate* `open_frontend` and add `open` configuration. It is
consistent with `rdbg --open` option.

`RUBY_DEBUG_OPEN` is also introduced.
For example,

```
$ RUBY_DEBUG_OPEN=true ruby -r debug script.rb
```

opens the debug port remotely.

Author: ko1

README.md

@@ -494,14 +494,14 @@ config set no_color true
   * `RUBY_DEBUG_SAVE_HISTORY` (`save_history`): maximum save history lines (default: 10000)
 
 * REMOTE
+  * `RUBY_DEBUG_OPEN` (`open`): Open remote port (same as `rdbg --open` option)
   * `RUBY_DEBUG_PORT` (`port`): TCP/IP remote debugging: port
   * `RUBY_DEBUG_HOST` (`host`): TCP/IP remote debugging: host (default: 127.0.0.1)
   * `RUBY_DEBUG_SOCK_PATH` (`sock_path`): UNIX Domain Socket remote debugging: socket path
   * `RUBY_DEBUG_SOCK_DIR` (`sock_dir`): UNIX Domain Socket remote debugging: socket directory
   * `RUBY_DEBUG_LOCAL_FS_MAP` (`local_fs_map`): Specify local fs map
   * `RUBY_DEBUG_SKIP_BP` (`skip_bp`): Skip breakpoints if no clients are attached (default: false)
   * `RUBY_DEBUG_COOKIE` (`cookie`): Cookie for negotiation
-  * `RUBY_DEBUG_OPEN_FRONTEND` (`open_frontend`): frontend used by open command (vscode, chrome, default: rdbg).
   * `RUBY_DEBUG_CHROME_PATH` (`chrome_path`): Platform dependent path of Chrome (For more information, See [here](https://github.com/ruby/debug/pull/334/files#diff-5fc3d0a901379a95bc111b86cf0090b03f857edfd0b99a0c1537e26735698453R55-R64))
 
 * OBSOLETE

exe/rdbg

@@ -10,7 +10,7 @@ when :start
   require 'rbconfig'
 
   libpath = File.join(File.expand_path(File.dirname(__dir__)), 'lib/debug')
-  start_mode = config[:remote] ? "open" : 'start'
+  start_mode = config[:open] ? "open" : 'start'
   cmd = config[:command] ? ARGV.shift : (ENV['RUBY'] || RbConfig.ruby)
 
   if defined?($:.resolve_feature_path)

lib/debug/config.rb

@@ -39,14 +39,14 @@ module DEBUGGER__
     save_history:   ['RUBY_DEBUG_SAVE_HISTORY',"BOOT: maximum save history lines", :int, "10000"],
 
     # remote setting
+    open:           ['RUBY_DEBUG_OPEN',         "REMOTE: Open remote port (same as `rdbg --open` option)"],
     port:           ['RUBY_DEBUG_PORT',         "REMOTE: TCP/IP remote debugging: port"],
     host:           ['RUBY_DEBUG_HOST',         "REMOTE: TCP/IP remote debugging: host", :string, "127.0.0.1"],
     sock_path:      ['RUBY_DEBUG_SOCK_PATH',    "REMOTE: UNIX Domain Socket remote debugging: socket path"],
     sock_dir:       ['RUBY_DEBUG_SOCK_DIR',     "REMOTE: UNIX Domain Socket remote debugging: socket directory"],
     local_fs_map:   ['RUBY_DEBUG_LOCAL_FS_MAP', "REMOTE: Specify local fs map", :path_map],
     skip_bp:        ['RUBY_DEBUG_SKIP_BP',      "REMOTE: Skip breakpoints if no clients are attached", :bool, 'false'],
     cookie:         ['RUBY_DEBUG_COOKIE',       "REMOTE: Cookie for negotiation"],
-    open_frontend:  ['RUBY_DEBUG_OPEN_FRONTEND',"REMOTE: frontend used by open command (vscode, chrome, default: rdbg)."],
     chrome_path:    ['RUBY_DEBUG_CHROME_PATH',  "REMOTE: Platform dependent path of Chrome (For more information, See [here](https://github.com/ruby/debug/pull/334/files#diff-5fc3d0a901379a95bc111b86cf0090b03f857edfd0b99a0c1537e26735698453R55-R64))"],
 
     # obsolete
@@ -298,8 +298,25 @@ def self.parse_argv argv
                                         'If TCP/IP options are not given, a UNIX domain socket will be used.',
                                         'If FRONTEND is given, prepare for the FRONTEND.',
                                         'Now rdbg, vscode and chrome is supported.') do |f|
-          config[:remote] = true
-          config[:open_frontend] = f.downcase if f
+
+          case f # some format patterns are not documented yet
+          when nil
+            config[:open] = true
+          when /\A\d\z/
+            config[:open] = true
+            config[:port] = f.to_i
+          when /\A(\S+):(\d+)\z/
+            config[:open] = true
+            config[:host] = $1
+            config[:port] = $2.to_i
+          when 'tcp'
+            config[:open] = true
+            config[:port] ||= 0
+          when 'vscode', 'chrome', 'cdp'
+            config[:open] = f&.downcase
+          else
+            raise "Unknown option for --open: #{f}"
+          end
         end
         o.on('--sock-path=SOCK_PATH', 'UNIX Domain socket path') do |path|
           config[:sock_path] = path

lib/debug/server.rb

@@ -437,7 +437,7 @@ def accept
           #
           EOS
 
-          case CONFIG[:open_frontend]
+          case CONFIG[:open]
           when 'chrome'
             chrome_setup
           when 'vscode'
@@ -494,7 +494,7 @@ def accept
       end
 
       ::DEBUGGER__.warn "Debugger can attach via UNIX domain socket (#{@sock_path})"
-      vscode_setup @sock_path if CONFIG[:open_frontend] == 'vscode'
+      vscode_setup @sock_path if CONFIG[:open] == 'vscode'
 
       begin
         Socket.unix_server_loop @sock_path do |sock, client|

lib/debug/session.rb

@@ -1042,10 +1042,10 @@ def register_default_command
         when 'tcp'
           ::DEBUGGER__.open_tcp host: CONFIG[:host], port: (CONFIG[:port] || 0), nonstop: true
         when 'vscode'
-          CONFIG[:open_frontend] = 'vscode'
+          CONFIG[:open] = 'vscode'
           ::DEBUGGER__.open nonstop: true
         when 'chrome', 'cdp'
-          CONFIG[:open_frontend] = 'chrome'
+          CONFIG[:open] = 'chrome'
           ::DEBUGGER__.open_tcp host: CONFIG[:host], port: (CONFIG[:port] || 0), nonstop: true
         else
           raise "Unknown arg: #{arg}"
@@ -2105,19 +2105,22 @@ def self.require_location
   def self.start nonstop: false, **kw
     CONFIG.set_config(**kw)
 
-    unless defined? SESSION
-      require_relative 'local'
-      initialize_session{ UI_LocalConsole.new }
+    if CONFIG[:open]
+      open nonstop: nonstop, **kw
+    else
+      unless defined? SESSION
+        require_relative 'local'
+        initialize_session{ UI_LocalConsole.new }
+      end
+      setup_initial_suspend unless nonstop
     end
-
-    setup_initial_suspend unless nonstop
   end
 
   def self.open host: nil, port: CONFIG[:port], sock_path: nil, sock_dir: nil, nonstop: false, **kw
     CONFIG.set_config(**kw)
     require_relative 'server'
 
-    if port || CONFIG[:open_frontend] == 'chrome' || (!::Addrinfo.respond_to?(:unix))
+    if port || CONFIG[:open] == 'chrome' || (!::Addrinfo.respond_to?(:unix))
       open_tcp host: host, port: (port || 0), nonstop: nonstop
     else
       open_unix sock_path: sock_path, sock_dir: sock_dir, nonstop: nonstop