Fix Fiber#transfer

Fiber#transfer previously made it impossible to resume the fiber
if it was transferred to (no resuming the target of Fiber#transfer).
However, the documentation specifies that you cannot resume a fiber
that has transferred to another fiber (no resuming the source of
Fiber#transfer), unless control is transferred back.

Fix the code by setting the transferred flag on the current/source
fiber, and unsetting the transferred flag on the target fiber.

Fixes [Bug #9664]
Fixes [Bug #12555]

1 files changed, 4 insertions, 6 deletions

diff --git a/test/ruby/test_fiber.rb b/test/ruby/test_fiber.rb
index 2d7cbc8a9e..aa47aaf9be 100644
--- a/test/ruby/test_fiber.rb
+++ b/test/ruby/test_fiber.rb
@@ -222,8 +222,8 @@ class TestFiber < Test::Unit::TestCase
   end
 
   def test_resume_self
-    f = Fiber.new {f.resume}
-    assert_raise(FiberError, '[ruby-core:23651]') {f.transfer}
+    f = Fiber.new {f.resume 1}
+    assert_equal(1, f.transfer)
   end
 
   def test_fiber_transfer_segv
@@ -289,14 +289,12 @@ class TestFiber < Test::Unit::TestCase
     assert_raise(FiberError){
       g=nil
       f=Fiber.new{
-        g.resume
-        g.resume
+        g.transfer
       }
       g=Fiber.new{
         f.resume
-        f.resume
       }
-      f.transfer
+      f.resume
     }
   end