Ruby » Ruby master

Feature #19780

Updated by k0kubun (Takashi Kokubun) 10 months ago

## Proposal 
 Remove `tailcall_optimization` flag from `RubyVM::InstructionSequence` 

 ## Motivation 
 The consensus at [Feature #6602] seems to be that we're not going to enable tailcall optimization by default until we introduce syntax for it. Until this syntax is introduced, this feature is useless. Can we remove this flag until we do support that future syntax? 

 ## Background 
 This script crashes doesn't work with `--yjit-call-threshold=1` on any YJIT-enabled build. 

 ```rb 
 src = <<-EOS 
   def apply_one_and_two(&block) 
     [1, p(1)] 
   end 
 ​ 
   def add_one_and_two 
     apply_one_and_two(&:+) 
   end 
 EOS 
 ​ 
 RubyVM::InstructionSequence.new( 
   "proc {|_|_.class_eval {#{src}}}", 
   __FILE__, __FILE__, 1, 
   tailcall_optimization: true, 
   trace_instruction: false, 
 ).eval[self.singleton_class] 
 ​ 
 def entry 
   add_one_and_two 
 end 
 ​ 
 entry 
 ``` 

 I already wasted a lot of time just for noticing it's already broken. I don't want to waste time for users that do not exist yet.

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