Set#merge does not take keyword arguments as a Hash

Author: knu

lib/set.rb

@@ -598,7 +598,7 @@ def select!(&block)
 
   # Merges the elements of the given enumerable objects to the set and
   # returns self.
-  def merge(*enums)
+  def merge(*enums, **nil)
     enums.each do |enum|
       if enum.instance_of?(self.class)
         @hash.update(enum.instance_variable_get(:@hash))

set.gemspec

@@ -8,7 +8,7 @@ Gem::Specification.new do |spec|
   spec.description   = %q{Provides a class to deal with collections of unordered, unique values}
   spec.homepage      = "https://github.com/ruby/set"
   spec.licenses      = ["Ruby", "BSD-2-Clause"]
-  spec.required_ruby_version = Gem::Requirement.new(">= 2.3.0")
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.7.0")
 
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["source_code_uri"] = spec.homepage

test/test_set.rb

@@ -600,6 +600,10 @@ def test_merge
     ret = set.merge([2,4,6], Set[4,5,6])
     assert_same(set, ret)
     assert_equal(Set[1,2,3,4,5,6], set)
+
+    assert_raise(ArgumentError) {
+      Set[].merge(a: 1)
+    }
   end
 
   def test_subtract