Merge pull request puppetlabs#5229 from thallgren/issue/pup-6647/zero-parameters-dispatch

(PUP-6647) Fix problem with dispatch that declares zero parameters

Author: hlindberg

lib/puppet/functions.rb

@@ -521,7 +521,7 @@ def create_callable(types, block_type, from, to)
         @type_parser.parse(t, loader)
       end
 
-      if from != to
+      if from == 0 || from != to
         # :optional and/or :repeated parameters are present.
         mapped_types << from
         mapped_types << to

spec/unit/functions4_spec.rb

@@ -113,6 +113,13 @@ def test(x)
     end.to raise_error(ArgumentError, "'min' expects 2 arguments, got 3")
   end
 
+  it 'correct dispatch is chosen when zero parameter dispatch exists' do
+    f = create_function_with_no_parameter_dispatch
+    func = f.new(:closure_scope, :loader)
+    expect(func.is_a?(Puppet::Functions::Function)).to be_truthy
+    expect(func.call({}, 1)).to eql(1)
+  end
+
   it 'an error is raised if simple function-name and method are not matched' do
     expect do
       f = create_badly_named_method_function_class()
@@ -917,6 +924,22 @@ def test(x)
     end
   end
 
+  def create_function_with_no_parameter_dispatch
+    f = Puppet::Functions.create_function('test') do
+      dispatch :test_no_args do
+      end
+      dispatch :test_one_arg do
+        param 'Integer', :x
+      end
+      def test_no_args
+        0
+      end
+      def test_one_arg(x)
+        x
+      end
+    end
+  end
+
   def type_alias_t(name, type_string)
     type_expr = Puppet::Pops::Parser::EvaluatingParser.new.parse_string(type_string).current
     Puppet::Pops::Types::TypeFactory.type_alias(name, type_expr)