merge revision(s) 5c7af72304d0ad33cd3f21b24a4bc44e8acd5b2c,d650b17686d49c2ce8e6a87039861154e93d4621: [Backport #18497]

	Assuming EXIT_SUCCESS equals 0 is not portable

	---
	 test/ruby/test_fiber.rb | 6 +++---
	 1 file changed, 3 insertions(+), 3 deletions(-)

	`rb_fiber_terminate` must not return [Bug #18497]

	In a forked process from a fiber, the fiber becomes the only
	fiber, `fiber_switch` does nothing as there is no other fibers,
	`rb_fiber_terminate` does not terminate the fiber.  In that case,
	reaches the end of `fiber_entry` finaly, which is declared as
	"COROUTINE" and should never return.
	---
	 cont.c                     |  3 ++-
	 eval_intern.h              |  2 +-
	 test/fiber/test_process.rb | 15 +++++++++++++++
	 test/ruby/test_fiber.rb    |  5 +++++
	 4 files changed, 23 insertions(+), 2 deletions(-)

4 files changed, 26 insertions, 5 deletions

diff --git a/cont.c b/cont.c
index aad7612b25..a7103a087e 100644
--- a/cont.c
+++ b/cont.c
@@ -2008,7 +2008,7 @@ rb_fiber_set_scheduler(VALUE klass, VALUE scheduler)
     return rb_scheduler_set(scheduler);
 }
 
-static void rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt);
+NORETURN(static void rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt));
 
 void
 rb_fiber_start(void)
@@ -2384,6 +2384,7 @@ rb_fiber_terminate(rb_fiber_t *fiber, int need_interrupt)
     next_fiber = return_fiber(true);
     if (need_interrupt) RUBY_VM_SET_INTERRUPT(&next_fiber->cont.saved_ec);
     fiber_switch(next_fiber, 1, &value, RB_NO_KEYWORDS, Qfalse, false);
+    ruby_stop(0);
 }
 
 VALUE
diff --git a/test/fiber/test_process.rb b/test/fiber/test_process.rb
index c6583cac9b..a5990be204 100644
--- a/test/fiber/test_process.rb
+++ b/test/fiber/test_process.rb
@@ -33,4 +33,19 @@ class TestFiberProcess < Test::Unit::TestCase
       end
     end.join
   end
+
+  def test_fork
+    omit 'fork not supported' unless Process.respond_to?(:fork)
+    Thread.new do
+      scheduler = Scheduler.new
+      Fiber.set_scheduler scheduler
+
+      Fiber.schedule do
+        pid = Process.fork {}
+        Process.wait(pid)
+
+        assert_predicate $?, :success?
+      end
+    end.join
+  end
 end
diff --git a/test/ruby/test_fiber.rb b/test/ruby/test_fiber.rb
index e0cc59bd3c..9e994c7349 100644
--- a/test/ruby/test_fiber.rb
+++ b/test/ruby/test_fiber.rb
@@ -397,7 +397,7 @@ class TestFiber < Test::Unit::TestCase
                 Fiber.new {}.transfer
                 Fiber.new { Fiber.yield }
               end
-              exit!(0)
+              exit!(true)
             end
           }.transfer
           _, status = Process.waitpid2(xpid)
@@ -406,8 +406,13 @@ class TestFiber < Test::Unit::TestCase
       end.resume
     end
     pid, status = Process.waitpid2(pid)
-    assert_equal(0, status.exitstatus, bug5700)
-    assert_equal(false, status.signaled?, bug5700)
+    assert_not_predicate(status, :signaled?, bug5700)
+    assert_predicate(status, :success?, bug5700)
+
+    pid = Fiber.new {fork}.resume
+    pid, status = Process.waitpid2(pid)
+    assert_not_predicate(status, :signaled?)
+    assert_predicate(status, :success?)
   end
 
   def test_exit_in_fiber
diff --git a/version.h b/version.h
index ade88256a4..5de5de5fc7 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 4
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 190
+#define RUBY_PATCHLEVEL 191
 
 #define RUBY_RELEASE_YEAR 2022
 #define RUBY_RELEASE_MONTH 3