🔧 Use client config for debug mode

In Net::IMAP, the `@@debug` cvar is replaced by `config.debug?`.  And in
ResponseParser, references to the global `Net::IMAP.debug` is replaced
by `config.debug?`.

By default, the client's own config won't have a value set for `debug`,
so it will still inherit from the global `Net::IMAP.config.debug?`.
Since the parser "belongs" to a client, it uses the client's
configuration rather than simply following the global debug mode.

Author: nevans

lib/net/imap.rb

@@ -2609,8 +2609,6 @@ def remove_response_handler(handler)
     PORT = 143         # :nodoc:
     SSL_PORT = 993   # :nodoc:
 
-    @@debug = false
-
     def start_imap_connection
       @greeting        = get_server_greeting
       @capabilities    = capabilities_from_resp_code @greeting
@@ -2755,7 +2753,7 @@ def get_response
         end
       end
       return nil if buff.length == 0
-      if @@debug
+      if config.debug?
         $stderr.print(buff.gsub(/^/n, "S: "))
       end
       return @parser.parse(buff)
@@ -2834,7 +2832,7 @@ def generate_tag
 
     def put_string(str)
       @sock.print(str)
-      if @@debug
+      if config.debug?
         if @debug_output_bol
           $stderr.print("C: ")
         end

lib/net/imap/response_parser/parser_utils.rb

@@ -154,7 +154,7 @@ def accept(*args)
         end
 
         # To be used conditionally:
-        #   assert_no_lookahead if Net::IMAP.debug
+        #   assert_no_lookahead if config.debug?
         def assert_no_lookahead
           @token.nil? or
             parse_error("assertion failed: expected @token.nil?, actual %s: %p",
@@ -181,23 +181,23 @@ def lookahead!(*args)
         end
 
         def peek_str?(str)
-          assert_no_lookahead if Net::IMAP.debug
+          assert_no_lookahead if config.debug?
           @str[@pos, str.length] == str
         end
 
         def peek_re(re)
-          assert_no_lookahead if Net::IMAP.debug
+          assert_no_lookahead if config.debug?
           re.match(@str, @pos)
         end
 
         def accept_re(re)
-          assert_no_lookahead if Net::IMAP.debug
+          assert_no_lookahead if config.debug?
           re.match(@str, @pos) and @pos = $~.end(0)
           $~
         end
 
         def match_re(re, name)
-          assert_no_lookahead if Net::IMAP.debug
+          assert_no_lookahead if config.debug?
           if re.match(@str, @pos)
             @pos = $~.end(0)
             $~
@@ -212,7 +212,7 @@ def shift_token
 
         def parse_error(fmt, *args)
           msg = format(fmt, *args)
-          if IMAP.debug
+          if config.debug?
             local_path = File.dirname(__dir__)
             tok = @token ? "%s: %p" % [@token.symbol, @token.value] : "nil"
             warn "%s %s: %s"        % [self.class, __method__, msg]