[GR-18163] Process#spawn should call #to_io on non-IO file descriptor…

… objects (#2809)

PullRequest: truffleruby/3589

CHANGELOG.md

@@ -48,6 +48,7 @@ Compatibility:
 * Warn about unknown directive passed to `Array#pack` in verbose mode (#2791, @andrykonchin).
 * Added constants `IO::SEEK_DATE` and `IO::SEEK_HOLE` (#2792, @andrykonchin).
 * Fix `StringIO.new` to accept keyword arguments (#2793, @andrykonchin).
+* `Process#spawn` should call `#to_io` on non-IO file descriptor objects (#2809, @jcouball).
 
 Performance:
 

spec/ruby/core/process/spawn_spec.rb

@@ -477,6 +477,16 @@ def child_pids(pid)
 
   # redirection
 
+  it 'redirects to the wrapped IO using wrapped_io.to_io if out: wrapped_io' do
+    File.open(@name, 'w') do |file|
+      -> do
+        wrapped_io = mock('wrapped IO')
+        wrapped_io.should_receive(:to_io).and_return(file)
+        Process.wait Process.spawn('echo "Hello World"', out: wrapped_io)
+      end.should output_to_fd("Hello World\n", file)
+    end
+  end
+
   it "redirects STDOUT to the given file descriptor if out: Integer" do
     File.open(@name, 'w') do |file|
       -> do

src/main/ruby/truffleruby/core/truffle/process_operations.rb

@@ -377,7 +377,11 @@ def convert_to_fd(obj, target)
             open_file_for_child(obj[0], convert_file_mode(obj[1]), obj[2])
           end
         else
-          raise ArgumentError, "wrong exec redirect: #{obj.inspect}"
+          if obj.respond_to?(:to_io)
+            obj.to_io.fileno
+          else
+            raise ArgumentError, "wrong exec redirect: #{obj.inspect}"
+          end
         end
       end