From: Kenta Murata <muraken@...>
Date: 2010-08-18T18:16:13+09:00
Subject: [ruby-dev:42068] Re: [Bug #3708] Array#permutation 	がおかしな結果を返す

むらたです。

On 2010/08/18, at 16:33, Shumpei Akai wrote:

> Array#permutationの結果に，配列に含まれていないはずの値が入っています
> 
> % ./ruby_head -e "p [0,1,2,3,4][1,4].permutation.to_a"
> [[0, 1, 2, 3], [0, 1, 3, 2], [0, 2, 1, 3], [0, 2, 3, 1], [0, 3, 1, 2], [0, 3, 2, 1], [1, 0, 2, 3], [1, 0, 3, 2], [1, 2, 0, 3], [1, 2, 3, 0], [1, 3, 0, 2], [1, 3, 2, 0], [2, 0, 1, 3], [2, 0, 3, 1], [2, 1, 0, 3], [2, 1, 3, 0], [2, 3, 0, 1], [2, 3, 1, 0], [3, 0, 1, 2], [3, 0, 2, 1], [3, 1, 0, 2], [3, 1, 2, 0], [3, 2, 0, 1], [3, 2, 1, 0]]
> 
> 
> [0,1,2,3,4][1,4] は [1, 2, 3, 4] なので0は含まれないはずです．
> 
> 
> % ./ruby_head -e "p [0,1,2,3][1,3].permutation.to_a"
> だと正しく動きます


ary_make_shared 関数を以下のように修正すると正常に動作します。

diff --git a/array.c b/array.c
index 51d3ad2..ea4fe43 100644
--- a/array.c
+++ b/array.c
@@ -409,10 +409,7 @@ static VALUE
 ary_make_shared(VALUE ary)
 {
     assert(!ARY_EMBED_P(ary));
-    if (ARY_SHARED_P(ary)) {
-       return ARY_SHARED(ary);
-    }
-    else if (ARY_SHARED_ROOT_P(ary)) {
+    if (ARY_SHARED_P(ary) || ARY_SHARED_ROOT_P(ary)) {
        return ary;
     }
     else if (OBJ_FROZEN(ary)) {
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index e8edcc2..f2d723f 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1549,6 +1549,9 @@ class TestArray < Test::Unit::TestCase
     a.permutation {|x| b << x; a.replace(@cls[9, 8, 7, 6]) }
     assert_equal(@cls[9, 8, 7, 6], a)
     assert_equal(@cls[1, 2, 3, 4].permutation.to_a, b)
+
+    bug3708 = '[ruby-dev:42067]'
+    assert_equal(b, @cls[0, 1, 2, 3, 4][1, 4].permutation.to_a, bug3708)
   end
 
   def test_repeated_permutation


--
Kenta Murata
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