Introduce RuboCop::Ast::MethodDispatchNode#selector

If you need to manipulate the call-site of a method dispatch, you have
to use node.loc.selector for regular methods and node.loc.keyword for
syntax nodes that behave like method invocations, but are not. Super and
yield nodes are an example of that.

This forces us to check if node.loc responds to #keyword in a few places
in rubocop proper and we can make it easier if we expose a method, here
I have called it #selector, to all method dispatch nodes and work with
it.

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master (unreleased)
 
+* [#262](https://github.com/rubocop/rubocop-ast/pull/267): Introduce RuboCop::Ast::MethodDispatchNode#selector. ([@gsamokovarov][])
+
 ## 1.28.1 (2023-05-01)
 
 ### Bug fixes
@@ -416,4 +418,4 @@
 [@gsamokovarov]: https://github.com/gsamokovarov
 [@nobuyo]: https://github.com/nobuyo
 [@tdeo]: https://github.com/tdeo
-[@ydah]: https://github.com/ydah
+[@ydah]: https://github.com/ydah

lib/rubocop/ast/node/mixin/method_dispatch_node.rb

@@ -5,7 +5,7 @@ module AST
     # Common functionality for nodes that are a kind of method dispatch:
     # `send`, `csend`, `super`, `zsuper`, `yield`, `defined?`,
     # and (modern only): `index`, `indexasgn`, `lambda`
-    module MethodDispatchNode
+    module MethodDispatchNode # rubocop:disable Metrics/ModuleLength
       extend NodePattern::Macros
       include MethodIdentifierPredicates
 
@@ -28,6 +28,17 @@ def method_name
         node_parts[1]
       end
 
+      # The source range for the method name or keyword that dispatches this call.
+      #
+      # @return [Parser::Source::Range] the source range for the method name or keyword
+      def selector
+        if loc.respond_to? :keyword
+          loc.keyword
+        else
+          loc.selector
+        end
+      end
+
       # The `block` or `numblock` node associated with this method dispatch, if any.
       #
       # @return [BlockNode, nil] the `block` or `numblock` node associated with this method
@@ -147,7 +158,7 @@ def const_receiver?
       #
       # @return [Boolean] whether the method is the implicit form of `#call`
       def implicit_call?
-        method?(:call) && !loc.selector
+        method?(:call) && !selector
       end
 
       # Whether this method dispatch has an explicit block.
@@ -222,9 +233,9 @@ def lambda_literal?
       #
       # @return [Boolean] whether this method is a unary operation
       def unary_operation?
-        return false unless loc.selector
+        return false unless selector
 
-        operator_method? && loc.expression.begin_pos == loc.selector.begin_pos
+        operator_method? && loc.expression.begin_pos == selector.begin_pos
       end
 
       # Checks whether this is a binary operation.
@@ -235,9 +246,9 @@ def unary_operation?
       #
       # @return [Boolean] whether this method is a binary operation
       def binary_operation?
-        return false unless loc.selector
+        return false unless selector
 
-        operator_method? && loc.expression.begin_pos != loc.selector.begin_pos
+        operator_method? && loc.expression.begin_pos != selector.begin_pos
       end
 
       private

spec/rubocop/ast/super_node_spec.rb

@@ -31,6 +31,12 @@
     it { expect(super_node.method_name).to eq(:super) }
   end
 
+  describe '#selector' do
+    let(:source) { 'super(foo)' }
+
+    it { expect(super_node.selector.source).to eq('super') }
+  end
+
   describe '#method?' do
     context 'when message matches' do
       context 'when argument is a symbol' do

spec/rubocop/ast/yield_node_spec.rb

@@ -23,6 +23,12 @@
     it { expect(yield_node.method_name).to eq(:yield) }
   end
 
+  describe '#selector' do
+    let(:source) { 'yield :foo, :bar' }
+
+    it { expect(yield_node.selector.source).to eq('yield') }
+  end
+
   describe '#method?' do
     context 'when message matches' do
       context 'when argument is a symbol' do