[GR-20446] Make complex and rational frozen when initializing.

PullRequest: truffleruby/1243

Author: eregon

CHANGELOG.md

@@ -59,6 +59,7 @@ Bug fixes:
 * Fixed `String#{upcase!,downcase!,swapcase!}(:ascii)` for non-ASCII-compatible encodings like UTF-16.
 * Fixed `String#capitalize!` for strings that weren't full ASCII.
 * Fixed enumeration issue in `ENV.{select, filter}`.
+* Fixed `Complex` and `Rational` should be frozen after initializing.
 
 Compatibility:
 

spec/tags/core/kernel/freeze_tags.txt

@@ -110,6 +110,7 @@ def Complex.check_real?(obj)
   def initialize(a, b = 0)
     @real = a
     @imag = b
+    freeze
   end
 
   def -@

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

@@ -386,6 +386,7 @@ def self.reduce(num, den)
   def initialize(num, den)
     @numerator = num
     @denominator = den
+    freeze
   end
   private :initialize