* 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, 1 insertions, 0 deletions

diff --git a/iseq.h b/iseq.h
index 315a73f3c7..f796905470 100644
--- a/iseq.h
+++ b/iseq.h
@@ -61,6 +61,7 @@ struct rb_compile_option_struct {
     int instructions_unification;
     int stack_caching;
     int trace_instruction;
+    int frozen_string_literal;
     int debug_level;
 };