Fix calling .arity on Proc with undefined `initialize`

Fix segfault on remove_method with invalid argument

Fix segfault when defining class inside instance_exec on primitive

Remove constant when a struct is redefined.

Get String length after args in String#chomp!

Read length after args in String#setbyte

Fix unsafe peephole optimization

Reported by https://hackerone.com/dkasak

Prevents RCE
Reported by https://hackerone.com/raydot

Fixes RCE issue
Reported by @bouk

Reported by @bouk

Reported by https://hackerone.com/jpenalbae

Reported by https://hackerone.com/haquaman

Reported by https://hackerone.com/jpenalbae

Reported by https://hackerone.com/dkasak

As reported by https://hackerone.com/jpenalbae

Fixed float tolerance in tests when MRB_USE_FLOAT is set

Update AUTHORS

To prevent crash from nasty code like:

  class Time
    def initialize
    end
  end

  a = Time.new
  b = Time.new
  a.initialize_copy b