Start handling &nil in method parameters

Similar to `:nokey` for `**nil` declaring methods/procs, a method/proc with a `&nil` declaration will return a `:noblock` entry in the parameters array.

Author: paracycle

core/method/parameters_spec.rb

@@ -22,6 +22,12 @@ def one_splat_one_block(*args, &block)
       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 @@ def underscore_parameters(_, _, _ = 1, *_, _:, _: 2, **_, &_); end
     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]]

core/proc/parameters_spec.rb

@@ -172,4 +172,12 @@
       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

language/block_spec.rb

@@ -1111,7 +1111,7 @@ def o.it
     end
   end
 
-  ruby_version_is "3.4" do
+  ruby_version_is "4.1" do
     it "works alongside disallowed block argument" do
       no_block = eval <<-EOF
         proc {|arg1, &nil| arg1}

language/method_spec.rb

@@ -1128,7 +1128,7 @@ def m(a, b = nil, c = nil, d, e: nil, **f)
       result.should == [1, nil, nil, {foo: :bar}, nil, {}]
     end
 
-    ruby_version_is "3.4" do
+    ruby_version_is "4.1" do
       evaluate <<-ruby do
         def m(a, &nil); a end;
         ruby