From 814f52a9ebd035ec6e20641c602fa42f64b5dbe0 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Mon, 1 May 2023 01:13:57 +0900
Subject: [Bug #19624] Hide internal IO for backquote

---
 io.c                     |  1 +
 test/ruby/test_system.rb | 13 +++++++++++++
 2 files changed, 14 insertions(+)

diff --git a/io.c b/io.c
index fb822f0f58..17a2d30c71 100644
--- a/io.c
+++ b/io.c
@@ -10497,6 +10497,7 @@ rb_f_backquote(VALUE obj, VALUE str)
     if (NIL_P(port)) return rb_str_new(0,0);
 
     GetOpenFile(port, fptr);
+    rb_obj_hide(port);
     result = read_all(fptr, remain_size(fptr), Qnil);
     rb_io_close(port);
     RFILE(port)->fptr = NULL;
diff --git a/test/ruby/test_system.rb b/test/ruby/test_system.rb
index 31c9cd7654..3fcdaa6aad 100644
--- a/test/ruby/test_system.rb
+++ b/test/ruby/test_system.rb
@@ -146,6 +146,19 @@ class TestSystem < Test::Unit::TestCase
     end
   end
 
+  def test_system_closed
+    assert_separately([], "#{<<~"begin;"}\n#{<<~'end;'}")
+    begin;
+      ios = []
+      ObjectSpace.each_object(IO) {|io| ios << io}
+      `echo`
+      ObjectSpace.each_object(IO) do |io|
+        next if ios.include?(io)
+        assert_nothing_raised {io.close}
+      end
+    end;
+  end
+
   def test_empty_evstr
     assert_equal("", eval('"#{}"', nil, __FILE__, __LINE__), "[ruby-dev:25113]")
   end
-- 
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