Comparing Date object with nil sets global $! variable to NoMethodError

[amitsuryavanshi]

Date.today.compare_with_coercion nil or Date.today <=> nil sets the ruby global variable $! to #<NoMethodError: undefined method coerce for nil:NilClass>. It does not throw the exception but sets the global $! variable. Now when I raise the exception in my app code the raised exception's cause is set to #<NoMethodError: undefined method coerce' for nil:NilClass>`.

Environment Information

• JRuby version - jruby-9.2.13.0
• Operating system - MaC OS Catalina
• Rails - 6.0.3.2

Expected Behavior

• Raise the exception #<NoMethodError: undefined method coerce for nil:NilClass> rather than just setting it in $!

Actual Behavior

• Sets the ruby's $! variable to #<NoMethodError: undefined method coerce for nil:NilClass> but does not raises it.

Script

require 'rubygems'
require 'active_support'
require "date"

puts 'Before $! => '
puts  $!
Date.today <=> nil
puts 'After $! => '
puts  $!

Script Output :

Before $! => 

After $! => 
undefined method `coerce' for nil:NilClass

[klobuczek]

Another way to illustrate the problem:

require "date"
require 'active_support'
begin
  Date.today <=> nil
  raise Exception
rescue Exception => e
  puts e.cause
end

The comparison does not raise any non rescued exceptions but it wrongfully sets the next Exception's cause. This does not happen on any MRI >= 2.5.0.

Unfortunately, I was not able to reproduce this behavior with plain exceptions without the Date comparison. There is something special about Date implementation.

[headius]

Thanks @ahorek for the fix!