* enum.c (enum_inject): Consider redefinition of Fixnum#+.

  [ruby-dev:49510] [Bug#12178] Reported by usa.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@54122 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 19 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index f526654ce0..cbf7794614 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Mar 15 21:38:28 2016  Tanaka Akira  <akr@fsij.org>
+
+	* enum.c (enum_inject): Consider redefinition of Fixnum#+.
+	  [ruby-dev:49510] [Bug#12178] Reported by usa.
+
 Tue Mar 15 20:32:57 2016  Tanaka Akira  <akr@fsij.org>
 
 	* enum.c (enum_inject): Implement the specialized code for :+ operator
diff --git a/enum.c b/enum.c
index ba444e33c6..951e30ab32 100644
--- a/enum.c
+++ b/enum.c
@@ -719,7 +719,8 @@ enum_inject(int argc, VALUE *argv, VALUE obj)
             i = 0;
         }
         id = SYM2ID(op);
-        if (id == idPLUS && FIXNUM_P(v)) {
+        if (id == idPLUS && FIXNUM_P(v) &&
+            rb_method_basic_definition_p(rb_cFixnum, idPLUS)) {
             long n = FIX2LONG(v);
             while (i < RARRAY_LEN(obj)) {
                 VALUE e = RARRAY_AREF(obj, i);
diff --git a/test/ruby/test_enum.rb b/test/ruby/test_enum.rb
index 6162830b69..3dfbd26929 100644
--- a/test/ruby/test_enum.rb
+++ b/test/ruby/test_enum.rb
@@ -184,6 +184,18 @@ class TestEnumerable < Test::Unit::TestCase
     assert_equal(nil, @empty.inject() {9})
   end
 
+  def test_inject_array_plus
+    assert_separately([], <<-"end;")
+      class Fixnum
+        undef :+
+        def +(x)
+          0
+        end
+      end
+      assert_equal(0, [1,2,3].inject(:+), "[ruby-dev:49510] [Bug#12178]")
+    end;
+  end
+
   def test_partition
     assert_equal([[1, 3, 1], [2, 2]], @obj.partition {|x| x % 2 == 1 })
     cond = ->(x, i) { x % 2 == 1 }