Ruby » Ruby master

• 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