4 files changed, 44 insertions, 0 deletions
diff --git a/spec/ruby/core/method/parameters_spec.rb b/spec/ruby/core/method/parameters_spec.rb
index f1c2523cf0..41b9cd8d12 100644
--- a/spec/ruby/core/method/parameters_spec.rb
+++ b/spec/ruby/core/method/parameters_spec.rb
@@ -22,6 +22,12 @@ describe "Method#parameters" do
       local_is_not_parameter = {}
     end
 
+    ruby_version_is "4.1" do
+      eval <<-RUBY
+        def one_noblock(&nil); end
+      RUBY
+    end
+
     def forward_parameters(...) end
 
     def underscore_parameters(_, _, _ = 1, *_, _:, _: 2, **_, &_); end
@@ -187,6 +193,13 @@ describe "Method#parameters" do
     m.parameters.should == [[:nokey]]
   end
 
+  ruby_version_is "4.1" do
+    it "returns [[:noblock]] for a method with a single &nil parameter" do
+      m = MethodSpecs::Methods.instance_method(:one_noblock)
+      m.parameters.should == [[:noblock]]
+    end
+  end
+
   it "works with ->(){} as the value of an optional argument" do
     m = MethodSpecs::Methods.instance_method(:one_opt_with_stabby)
     m.parameters.should == [[:opt,:a]]
diff --git a/spec/ruby/core/proc/parameters_spec.rb b/spec/ruby/core/proc/parameters_spec.rb
index cf8a8f5b12..0876ad0daf 100644
--- a/spec/ruby/core/proc/parameters_spec.rb
+++ b/spec/ruby/core/proc/parameters_spec.rb
@@ -172,4 +172,12 @@ describe "Proc#parameters" do
       eval("lambda { it }").parameters.should == [[:req]]
     end
   end
+
+  ruby_version_is "4.1" do
+    it "returns :noblock for &nil parameter" do
+      eval <<~RUBY
+        proc { |&nil| }.parameters.should == [[:noblock]]
+      RUBY
+    end
+  end
 end
diff --git a/spec/ruby/language/block_spec.rb b/spec/ruby/language/block_spec.rb
index 67aad76c57..ad6f7190b4 100644
--- a/spec/ruby/language/block_spec.rb
+++ b/spec/ruby/language/block_spec.rb
@@ -1110,6 +1110,17 @@ describe "`it` calls without arguments in a block" do
       end
     end
   end
+
+  ruby_version_is "4.1" do
+    it "works alongside disallowed block argument" do
+      no_block = eval <<-EOF
+        proc {|arg1, &nil| arg1}
+      EOF
+
+      no_block.call(:a).should == :a
+      -> { no_block.call(:a) {} }.should raise_error(ArgumentError, 'no block accepted')
+    end
+  end
 end
 
 # Duplicates specs in language/it_parameter_spec.rb
diff --git a/spec/ruby/language/method_spec.rb b/spec/ruby/language/method_spec.rb
index 8f9f094fd8..dd93703d9f 100644
--- a/spec/ruby/language/method_spec.rb
+++ b/spec/ruby/language/method_spec.rb
@@ -1127,6 +1127,18 @@ describe "A method" do
       result = m(1, {foo: :bar})
       result.should == [1, nil, nil, {foo: :bar}, nil, {}]
     end
+
+    ruby_version_is "4.1" do
+      evaluate <<-ruby do
+        def m(a, &nil); a end;
+        ruby
+
+        m(1).should == 1
+
+        -> { m(1) {} }.should raise_error(ArgumentError, 'no block accepted')
+        -> { m(1, &proc {}) }.should raise_error(ArgumentError, 'no block accepted')
+      end
+    end
   end
 
   context 'when passing an empty keyword splat to a method that does not accept keywords' do