* vm_opts.h, iseq.c, iseq.h: add compile option to force frozen

  string literals.
  [Feature #11473]
  This addition is not specification change, but to try frozen
  string literal world discussed on [Feature #11473].
  You can try frozen string literal world using this magical line:
    RubyVM::InstructionSequence.compile_option =
      {frozen_string_literal: true}
  Note that this is a global compilation option, so that you need to
  compile another script like that:
    p 'foo'.frozen? #=> false
    RubyVM::InstructionSequence.compile_option =
      {frozen_string_literal: true}
    p 'foo'.frozen? #=> false, because this line is already compiled.
    p eval("'foo'.frozen?") #=> true
  Details:
    * String literals are deduped by rb_fstring().
    * Dynamic string literals ("...#{xyz}...") is now only frozen,
      not deduped. Maybe you have other ideas.
  Now, please do not use this option on your productions :)
  Of course, current specification can be changed.
* compile.c: ditto.
* test/ruby/test_iseq.rb: add a test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51659 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 0 deletions

diff --git a/test/ruby/test_iseq.rb b/test/ruby/test_iseq.rb
index 686646ddd8..3938fb3d48 100644
--- a/test/ruby/test_iseq.rb
+++ b/test/ruby/test_iseq.rb
@@ -141,4 +141,17 @@ class TestISeq < Test::Unit::TestCase
     assert_raise(TypeError, bug11159) {ISeq.compile(:foo)}
     assert_raise(TypeError, bug11159) {ISeq.compile(1)}
   end
+
+  def test_frozen_string_literal_compile_option
+    $f = 'f'
+    line = __LINE__ + 2
+    code = <<-'EOS'
+    ['foo', 'foo', "#{$f}foo"]
+    EOS
+    s1, s2, s3 = RubyVM::InstructionSequence.compile(code, __FILE__, __FILE__, line, {frozen_string_literal: true}).eval
+    assert(s1.frozen?)
+    assert(s2.frozen?)
+    assert(s3.frozen?)
+    assert(s1.object_id == s2.object_id)
+  end
 end