rubocops/no_fileutils_rmrf: Fix rmtree on a method returning Pathname

- Tidy up the node matchers. Either `FileUtils.rm_rf` or `rm_rf` on a
  `Pathname` instance or `self`.

Library/Homebrew/rubocops/no_fileutils_rmrf.rb

@@ -11,35 +11,38 @@ module RuboCop
 
         MSG = "Use `rm` or `rm_r` instead of `rm_rf`, `rm_f`, or `rmtree`."
 
-        def_node_matcher :fileutils_rm_r_f_tree?, <<~PATTERN
+        def_node_matcher :any_receiver_rm_r_f?, <<~PATTERN
-          (send (const {nil? cbase} :FileUtils) {:rm_rf :rm_f :rmtree} ...)
+          (send
+            {(const {nil? cbase} :FileUtils) (self)}
+            {:rm_rf :rm_f}
+            ...)
         PATTERN
 
-        def_node_matcher :instance_rmtree?, <<~PATTERN
+        def_node_matcher :no_receiver_rm_r_f?, <<~PATTERN
-          (send (lvar ...) :rmtree ...)
+          (send nil? {:rm_rf :rm_f} ...)
         PATTERN
 
-        def_node_matcher :self_rm_r_f_tree?, <<~PATTERN
+        def_node_matcher :no_receiver_rmtree?, <<~PATTERN
-          (send (self) {:rm_rf :rm_f :rmtree} ...)
+          (send nil? :rmtree ...)
         PATTERN
 
-        def_node_matcher :plain_rm_r_f_tree?, <<~PATTERN
+        def_node_matcher :any_receiver_rmtree?, <<~PATTERN
-          (send nil? {:rm_rf :rm_f :rmtree} ...)
+          (send !nil? :rmtree ...)
         PATTERN
 
         def on_send(node)
           return if neither_rm_rf_nor_rmtree?(node)
 
           add_offense(node) do |corrector|
-            class_name = "FileUtils." if fileutils_rm_r_f_tree?(node) || instance_rmtree?(node)
+            class_name = "FileUtils." if any_receiver_rm_r_f?(node) || any_receiver_rmtree?(node)
             new_method = if node.method?(:rm_rf) || node.method?(:rmtree)
               "rm_r"
             else
               "rm"
             end
 
-            args = if instance_rmtree?(node)
+            args = if any_receiver_rmtree?(node)
-              node.receiver.source
+              node.receiver&.source || node.arguments.first&.source
             else
               node.arguments.first.source
             end
@@ -49,8 +52,8 @@ module RuboCop
         end
 
         def neither_rm_rf_nor_rmtree?(node)
-          !self_rm_r_f_tree?(node) && !plain_rm_r_f_tree?(node) &&
+          !any_receiver_rm_r_f?(node) && !no_receiver_rm_r_f?(node) &&
-            !fileutils_rm_r_f_tree?(node) && !instance_rmtree?(node)
+            !any_receiver_rmtree?(node) && !no_receiver_rmtree?(node)
         end
       end
     end

Library/Homebrew/sorbet/rbi/dsl/rubo_cop/cop/homebrew/no_fileutils_rmrf.rbi

@@ -7,14 +7,14 @@
 
 class RuboCop::Cop::Homebrew::NoFileutilsRmrf
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
-  def fileutils_rm_r_f_tree?(node, **kwargs, &block); end
+  def any_receiver_rm_r_f?(node, **kwargs, &block); end
 
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
-  def instance_rmtree?(node, **kwargs, &block); end
+  def any_receiver_rmtree?(node, **kwargs, &block); end
 
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
-  def plain_rm_r_f_tree?(node, **kwargs, &block); end
+  def no_receiver_rm_r_f?(node, **kwargs, &block); end
 
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
-  def self_rm_r_f_tree?(node, **kwargs, &block); end
+  def no_receiver_rmtree?(node, **kwargs, &block); end
 end

Library/Homebrew/test/rubocops/no_fileutils_rmrf_spec.rb

@@ -59,6 +59,11 @@ RSpec.describe RuboCop::Cop::Homebrew::NoFileutilsRmrf do
         other_dir = Pathname("path/to/other/directory")
         other_dir.rmtree
         ^^^^^^^^^^^^^^^^ Homebrew/NoFileutilsRmrf: #{RuboCop::Cop::Homebrew::NoFileutilsRmrf::MSG}
+        def buildpath
+          Pathname("path/to/yet/another/directory")
+        end
+        buildpath.rmtree
+        ^^^^^^^^^^^^^^^^ Homebrew/NoFileutilsRmrf: #{RuboCop::Cop::Homebrew::NoFileutilsRmrf::MSG}
       RUBY
     end
 
@@ -67,12 +72,20 @@ RSpec.describe RuboCop::Cop::Homebrew::NoFileutilsRmrf do
         rmtree("path/to/directory")
         other_dir = Pathname("path/to/other/directory")
         other_dir.rmtree
+        def buildpath
+          Pathname("path/to/yet/another/directory")
+        end
+        buildpath.rmtree
       RUBY
 
       expect(corrected).to eq(<<~RUBY)
         rm_r("path/to/directory")
         other_dir = Pathname("path/to/other/directory")
         FileUtils.rm_r(other_dir)
+        def buildpath
+          Pathname("path/to/yet/another/directory")
+        end
+        FileUtils.rm_r(buildpath)
       RUBY
     end
   end