Support undef statement (as nop)

lib/typeprof/core/ast.rb

@@ -40,6 +40,7 @@ def self.create_node(raw_node, lenv, use_result = true)
       when :singleton_class_node then SingletonClassNode.new(raw_node, lenv, use_result)
       when :def_node then DefNode.new(raw_node, lenv, use_result)
       when :alias_method_node then AliasNode.new(raw_node, lenv)
+      when :undef_node then UndefNode.new(raw_node, lenv)
 
       # control
       when :and_node then AndNode.new(raw_node, lenv)

lib/typeprof/core/ast/method.rb

@@ -304,5 +304,25 @@ def install0(genv)
         end
       end
     end
+
+    class UndefNode < Node
+      def initialize(raw_node, lenv)
+        super(raw_node, lenv)
+        @names = raw_node.names.map do |raw_name|
+          AST.create_node(raw_name, lenv)
+        end
+      end
+
+      attr_reader :names
+
+      def subnodes = { names: }
+
+      def install0(genv)
+        @names.each do |name|
+          name.install(genv)
+        end
+        Source.new(genv.nil_type)
+      end
+    end
   end
 end

scenario/method/undef.rb

@@ -0,0 +1,16 @@
+## update
+class Foo
+  def foo
+    42
+  end
+
+  # Currently, TypeProf just ignores undef statements
+  undef foo
+  undef :foo, :bar
+  undef :"foo#{ 42 }"
+end
+
+## assert
+class Foo
+  def foo: -> Integer
+end