Make Module#prepend affect ancestor chain even if argument already included in receiver

Previously, if a class included a module and then prepended the
same module, the prepend had no effect.  This changes the behavior
so that the prepend has an effect unless the module is already
prepended the receiver.

While here, rename the origin_seen variable in include_modules_at,
since it is misleading. The variable tracks whether c has been seen,
not whether the origin of klass has been.

Fixes [Bug #17423]

1 files changed, 36 insertions, 1 deletions

diff --git a/test/ruby/test_module.rb b/test/ruby/test_module.rb
index fac3131f42..6b53b7d5f4 100644
--- a/test/ruby/test_module.rb
+++ b/test/ruby/test_module.rb
@@ -641,6 +641,41 @@ class TestModule < Test::Unit::TestCase
     assert_equal([:p, :a, :s, :q, :r, :c], a.new.m)
   end
 
+  def test_prepend_after_include
+    c = Class.new{def m; [:c] end}
+    sc = Class.new(c){def m; [:sc] + super end}
+    m = Module.new{def m; [:m] + super end}
+    sc.include m
+    sc.prepend m
+    sc.prepend m
+    assert_equal([:m, :sc, :m, :c], sc.new.m)
+
+    c = Class.new{def m; [:c] end}
+    sc = Class.new(c){def m; [:sc] + super end}
+    m0 = Module.new{def m; [:m0] + super end}
+    m1 = Module.new{def m; [:m1] + super end}
+    m1.prepend m0
+    sc.include m1
+    sc.prepend m1
+    assert_equal([:m0, :m1, :sc, :m0, :m1, :c], sc.new.m)
+    sc.prepend m
+    assert_equal([:m, :m0, :m1, :sc, :m0, :m1, :c], sc.new.m)
+    sc.prepend m1
+    assert_equal([:m, :m0, :m1, :sc, :m0, :m1, :c], sc.new.m)
+
+
+    c = Class.new{def m; [:c] end}
+    sc = Class.new(c){def m; [:sc] + super end}
+    m0 = Module.new{def m; [:m0] + super end}
+    m1 = Module.new{def m; [:m1] + super end}
+    m1.include m0
+    sc.include m1
+    sc.prepend m
+    sc.prepend m1
+    sc.prepend m1
+    assert_equal([:m1, :m0, :m, :sc, :m1, :m0, :c], sc.new.m)
+  end
+
   def test_instance_methods
     assert_equal([:user, :user2], User.instance_methods(false).sort)
     assert_equal([:user, :user2, :mixin].sort, User.instance_methods(true).sort)
@@ -2158,7 +2193,7 @@ class TestModule < Test::Unit::TestCase
     assert_equal([:c2, :m0, :m1, :m2, :c0], c2.new.x)
 
     m3 = labeled_module("m3") {include m1; prepend m1}
-    assert_equal([m3, m0, m1], m3.ancestors)
+    assert_equal([m0, m1, m3, m0, m1], m3.ancestors)
     m3 = labeled_module("m3") {prepend m1; include m1}
     assert_equal([m0, m1, m3], m3.ancestors)
     m3 = labeled_module("m3") {prepend m1; prepend m1}