* vm_eval.c (rb_f_caller): return [] instead of nil when the function

  is called on toplevel.  [ruby-dev:41348]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27895 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 13 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 4a0b034d96..82cff7e61f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed May 19 20:09:38 2010  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* vm_eval.c (rb_f_caller): return [] instead of nil when the function
+	  is called on toplevel.  [ruby-dev:41348]
+
 Wed May 19 19:58:01 2010  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* ext/socket/extconf.rb: mswin/mingw ruby has socketpair(), but it's
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index ddeb6d6c87..86ab64feb1 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -228,6 +228,10 @@ class TestMethod < Test::Unit::TestCase
     assert_in_out_err([], "p __callee__", %w(nil), [])
   end
 
+  def test_caller_top_level
+    assert_in_out_err([], "p caller", %w([]), [])
+  end
+
   def test_caller_negative_level
     assert_raise(ArgumentError) { caller(-1) }
   end
diff --git a/vm_eval.c b/vm_eval.c
index 2bf640d978..d1e6352e03 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1562,7 +1562,7 @@ rb_catch_obj(VALUE tag, VALUE (*func)(), VALUE data)
 static VALUE
 rb_f_caller(int argc, VALUE *argv)
 {
-    VALUE level;
+    VALUE level, ary;
     int lev;
 
     rb_scan_args(argc, argv, "01", &level);
@@ -1574,7 +1574,9 @@ rb_f_caller(int argc, VALUE *argv)
     if (lev < 0)
 	rb_raise(rb_eArgError, "negative level (%d)", lev);
 
-    return vm_backtrace(GET_THREAD(), lev);
+    ary = vm_backtrace(GET_THREAD(), lev);
+    if (NIL_P(ary)) ary = rb_ary_new();
+    return ary;
 }
 
 static int