[ruby/rubygems] Warn when require_relative is used to load compiled extensions during gem build

When a gem has native extensions and uses `require_relative` to load
a path without a corresponding .rb file in the gem, warn that this
will break in RubyGems 4.2, which will stop copying compiled
extensions into the gem's lib directory. Recommend using `require`
instead.

https://github.com/ruby/rubygems/commit/1198c24a08

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 55 insertions, 0 deletions

diff --git a/test/rubygems/test_gem_specification.rb b/test/rubygems/test_gem_specification.rb
index 7675ade415..cf01a40b8c 100644
--- a/test/rubygems/test_gem_specification.rb
+++ b/test/rubygems/test_gem_specification.rb
@@ -2887,6 +2887,61 @@ duplicate dependency on c (>= 1.2.3, development), (~> 1.2) use:
     end
   end
 
+  def test_validate_extension_require_relative_warning
+    util_setup_validate
+
+    Dir.chdir @tempdir do
+      @a1.extensions = ["ext/a/extconf.rb"]
+      @a1.files = %w[lib/code.rb lib/a.rb ext/a/extconf.rb]
+
+      File.write File.join("lib", "a.rb"), 'require_relative "a/a"'
+
+      use_ui @ui do
+        @a1.validate
+      end
+
+      assert_match(%r{require_relative "a/a"}, @ui.error)
+      assert_match(/will break in RubyGems 4\.2/, @ui.error)
+      assert_match(/Use `require` instead of `require_relative`/, @ui.error)
+    end
+  end
+
+  def test_validate_extension_require_relative_no_warning_when_rb_exists
+    util_setup_validate
+
+    Dir.chdir @tempdir do
+      @a1.extensions = ["ext/a/extconf.rb"]
+      @a1.files = %w[lib/code.rb lib/a.rb lib/a/a.rb ext/a/extconf.rb]
+
+      FileUtils.mkdir_p File.join("lib", "a")
+      File.write File.join("lib", "a.rb"), 'require_relative "a/a"'
+      File.write File.join("lib", "a", "a.rb"), ""
+
+      use_ui @ui do
+        @a1.validate
+      end
+
+      refute_match(/require_relative/, @ui.error)
+    end
+  end
+
+  def test_validate_extension_require_relative_no_warning_without_extensions
+    util_setup_validate
+
+    Dir.chdir @tempdir do
+      @a1.extensions = []
+      @a1.files = %w[lib/code.rb lib/a.rb]
+
+      File.write File.join("lib", "a.rb"), 'require_relative "a/a"'
+
+      use_ui @ui do
+        @a1.validate
+      end
+
+      refute_match(/require_relative/, @ui.error)
+    end
+  end
+
   def test_validate_description
     util_setup_validate