2 files changed, 50 insertions, 3 deletions
diff --git a/src/array.c b/src/array.c
index 9b8a49584..df953832b 100644
--- a/src/array.c
+++ b/src/array.c
@@ -891,15 +891,32 @@ mrb_ary_rindex_m(mrb_state *mrb, mrb_value self)
 MRB_API mrb_value
 mrb_ary_splat(mrb_state *mrb, mrb_value v)
 {
+  mrb_value a, recv_class;
+
   if (mrb_array_p(v)) {
     return v;
   }
-  if (mrb_respond_to(mrb, v, mrb_intern_lit(mrb, "to_a"))) {
-    return mrb_funcall(mrb, v, "to_a", 0);
+
+  if (!mrb_respond_to(mrb, v, mrb_intern_lit(mrb, "to_a"))) {
+    return mrb_ary_new_from_values(mrb, 1, &v);
   }
-  else {
+
+  a = mrb_funcall(mrb, v, "to_a", 0);
+  if (mrb_array_p(a)) {
+    return a;
+  }
+  else if (mrb_nil_p(a)) {
     return mrb_ary_new_from_values(mrb, 1, &v);
   }
+  else {
+    recv_class = mrb_obj_value(mrb_obj_class(mrb, v));
+    mrb_raisef(mrb, E_TYPE_ERROR, "can't convert %S to Array (%S#to_a gives %S)",
+      recv_class,
+      recv_class,
+      mrb_obj_value(mrb_obj_class(mrb, a))
+    );
+    return mrb_undef_value();
+  }
 }
 
 static mrb_value
diff --git a/test/t/syntax.rb b/test/t/syntax.rb
index 25ae09828..3bc68484b 100644
--- a/test/t/syntax.rb
+++ b/test/t/syntax.rb
@@ -307,6 +307,36 @@ assert('Return values of no expression case statement') do
   assert_equal 1, when_value
 end
 
+assert('splat object in assignment') do
+  o = Object.new
+  def o.to_a
+    nil
+  end
+  assert_equal [o], (a = *o)
+
+  def o.to_a
+    1
+  end
+  assert_raise(TypeError) { a = *o }
+
+  def o.to_a
+    [2]
+  end
+  assert_equal [2], (a = *o)
+end
+
+assert('splat object in case statement') do
+  o = Object.new
+  def o.to_a
+    nil
+  end
+  a = case o
+  when *o
+    1
+  end
+  assert_equal 1, a
+end
+
 assert('splat in case statement') do
   values = [3,5,1,7,8]
   testa = [1,2,7]