[Fix rubocop#9636] Resolve symlinks when excluding directories

CHANGELOG.md

@@ -5555,3 +5555,4 @@
 [@kachick]: https://github.com/kachick
 [@corroded]: https://github.com/corroded
 [@osyo-manga]: https://github.com/osyo-manga
+[@ob-stripe]: https://github.com/ob-stripe

changelog/fix_resolve_symlinks_when_excluding_directories.md

@@ -0,0 +1 @@
+* [#9636](https://github.com/rubocop/rubocop/issues/9636): Resolve symlinks when excluding directories. ([@ob-stripe][])

lib/rubocop/target_finder.rb

@@ -97,7 +97,11 @@ def wanted_dir_patterns(base_dir, exclude_pattern, flags)
       base_dir = base_dir.gsub('/{}/', '/\{}/')
       dirs = Dir.glob(File.join(base_dir.gsub('/**/', '/\**/'), '*/'), flags)
                 .reject do |dir|
-                  dir.end_with?('/./', '/../') || File.fnmatch?(exclude_pattern, dir, flags)
+                  next true if dir.end_with?('/./', '/../')
+                  next true if File.fnmatch?(exclude_pattern, dir, flags)
+
+                  File.symlink?(dir.chomp('/')) && File.fnmatch?(exclude_pattern,
+                                                                 "#{File.realpath(dir)}/", flags)
                 end
       dirs.flat_map { |dir| wanted_dir_patterns(dir, exclude_pattern, flags) }.unshift(base_dir)
     end

spec/rubocop/target_finder_spec.rb

@@ -447,6 +447,33 @@
         expect(found_basenames).to include('ruby5.rb')
       end
     end
+
+    it 'resolves symlinks when looking for excluded directories' do
+      create_link('link', 'dir1')
+
+      config = instance_double(RuboCop::Config)
+      exclude_property = { 'Exclude' => [File.expand_path('dir1/**/*')] }
+      allow(config).to receive(:for_all_cops).and_return(exclude_property)
+      allow(config_store).to receive(:for).and_return(config)
+
+      expect(found_basenames).not_to include('ruby1.rb')
+      expect(found_basenames).to include('ruby3.rb')
+    end
+
+    it 'can exclude symlinks as well as directories' do
+      Dir.mktmpdir do |tmpdir|
+        create_empty_file(File.join(tmpdir, 'ruby5.rb'))
+        create_link('link', tmpdir)
+
+        config = instance_double(RuboCop::Config)
+        exclude_property = { 'Exclude' => [File.expand_path('link/**/*')] }
+        allow(config).to receive(:for_all_cops).and_return(exclude_property)
+        allow(config_store).to receive(:for).and_return(config)
+
+        expect(found_basenames).not_to include('ruby5.rb')
+        expect(found_basenames).to include('ruby3.rb')
+      end
+    end
   end
 
   describe '#target_files_in_dir' do

spec/support/file_helper.rb

@@ -24,4 +24,13 @@ def create_file(file_path, content)
   def create_empty_file(file_path)
     create_file(file_path, '')
   end
+
+  def create_link(link_path, target_path)
+    link_path = File.expand_path(link_path)
+
+    dir_path = File.dirname(link_path)
+    FileUtils.makedirs dir_path unless File.exist?(dir_path)
+
+    FileUtils.symlink(target_path, link_path)
+  end
 end