* 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, 3 insertions, 0 deletions

diff --git a/iseq.c b/iseq.c
index 9b32c0a20d..fa89f512d8 100644
--- a/iseq.c
+++ b/iseq.c
@@ -338,7 +338,9 @@ static rb_compile_option_t COMPILE_OPTION_DEFAULT = {
     OPT_INSTRUCTIONS_UNIFICATION, /* int instructions_unification; */
     OPT_STACK_CACHING, /* int stack_caching; */
     OPT_TRACE_INSTRUCTION, /* int trace_instruction */
+    OPT_FROZEN_STRING_LITERAL
 };
+
 static const rb_compile_option_t COMPILE_OPTION_FALSE = {0};
 
 static void
@@ -375,6 +377,7 @@ make_compile_option(rb_compile_option_t *option, VALUE opt)
 	SET_COMPILE_OPTION(option, opt, instructions_unification);
 	SET_COMPILE_OPTION(option, opt, stack_caching);
 	SET_COMPILE_OPTION(option, opt, trace_instruction);
+	SET_COMPILE_OPTION(option, opt, frozen_string_literal);
 	SET_COMPILE_OPTION_NUM(option, opt, debug_level);
 #undef SET_COMPILE_OPTION
 #undef SET_COMPILE_OPTION_NUM