[Ruby 3.0 support] Remove TRUE, FALSE, and NIL constants

CHANGELOG.md

@@ -19,6 +19,7 @@ Compatibility:
 * `Module#attr_*` methods now return an array of method names (#2498, @gogainda).
 * Fixed `Socket#(local|remote)_address` to retrieve family and type from the file descriptor (#2444, @larskanis).
 * Add `Thread.ignore_deadlock` accessor (#2453).
+* Remove `TRUE`, `FALSE`, and `NIL` constants like CRuby 3.0 (#2505, @andrykonchin).
 
 Performance:
 

spec/tags/language/predefined_tags.txt

@@ -6,6 +6,3 @@ slow:The predefined global constant ARGV contains Strings encoded in locale Enco
 slow:Global variable $0 is the path given as the main script and the same as __FILE__
 slow:Global variable $? is thread-local
 slow:Global variable $0 actually sets the program name
-fails:The predefined global constants TRUE is no longer defined
-fails:The predefined global constants FALSE is no longer defined
-fails:The predefined global constants NIL is no longer defined

src/main/ruby/truffleruby/core/false.rb

@@ -48,6 +48,3 @@ def self.__allocate__
     raise TypeError, "allocator undefined for #{self}"
   end
 end
-
-FALSE = false
-Object.deprecate_constant :FALSE

src/main/ruby/truffleruby/core/nil.rb

@@ -87,6 +87,3 @@ def self.__allocate__
     raise TypeError, "allocator undefined for #{self}"
   end
 end
-
-NIL = nil
-Object.deprecate_constant :NIL

src/main/ruby/truffleruby/core/true.rb

@@ -48,6 +48,3 @@ def self.__allocate__
     raise TypeError, "allocator undefined for #{self}"
   end
 end
-
-TRUE = true
-Object.deprecate_constant :TRUE