Suppress "literal string will be frozen" warnings

lib/groonga/command/parser.rb

@@ -1,4 +1,4 @@
-# Copyright (C) 2011-2019  Kouhei Sutou <[email protected]>
+# Copyright (C) 2011-2024  Sutou Kouhei <[email protected]>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -345,7 +345,8 @@ def parse_command_line(command_line)
       def reset
         @command = nil
         @loading = false
-        @buffer = "".force_encoding("ASCII-8BIT")
+        @buffer = +""
+        @buffer.force_encoding("ASCII-8BIT")
         @load_values_parser = nil
       end
 
@@ -371,7 +372,8 @@ def initialize_load_values_parser
           if @loading
             @command.original_source << consumed if @need_original_source
             if @buffer.bytesize == consumed.bytesize
-              @buffer = "".force_encoding("ASCII-8BIT")
+              @buffer = +""
+              @buffer.force_encoding("ASCII-8BIT")
             else
               @buffer = @buffer[consumed.bytesize..-1]
             end

lib/groonga/command/parser/command-line-splitter.rb

@@ -1,4 +1,4 @@
-# Copyright (C) 2015  Kouhei Sutou <[email protected]>
+# Copyright (C) 2015-2024  Sutou Kouhei <[email protected]>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -32,7 +32,7 @@ def split
           start_quote = nil
           until scanner.eos?
             if start_quote
-              token = ""
+              token = +""
               loop do
                 chunk = scanner.scan_until(/#{Regexp.escape(start_quote)}/)
                 if chunk.nil?

lib/groonga/command/parser/error.rb

@@ -1,6 +1,4 @@
-# -*- coding: utf-8 -*-
-#
-# Copyright (C) 2011-2015  Kouhei Sutou <[email protected]>
+# Copyright (C) 2011-2024  Sutou Kouhei <[email protected]>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -31,7 +29,7 @@ def initialize(reason, before, after)
 
         private
         def compute_location(before, after)
-          location = ""
+          location = +""
           if before[-1] == ?\n
             location << before
             location << after