4 files changed, 56 insertions, 20 deletions

diff --git a/ChangeLog b/ChangeLog
index 7aacfb4cb0..01e9aafcb6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Apr 23 11:35:55 2015  Nobuyoshi Nakada  <[email protected]>
+
+	* vm_eval.c (rb_obj_instance_eval, rb_obj_instance_exec): allow
+	  symbols to just instance_eval/exec, execept for definition of
+	  singletons.  [ruby-core:68961] [Bug #11086]
+
 Thu Apr 23 10:01:36 2015  SHIBATA Hiroshi  <[email protected]>
 
 	* lib/delegate.rb: fix a typo.
diff --git a/class.c b/class.c
index 11210682fe..37ad4b542b 100644
--- a/class.c
+++ b/class.c
@@ -1539,7 +1539,8 @@ singleton_class_of(VALUE obj)
 {
     VALUE klass;
 
-    if (FIXNUM_P(obj) || FLONUM_P(obj) || SYMBOL_P(obj)) {
+    if (FIXNUM_P(obj) || FLONUM_P(obj) || STATIC_SYM_P(obj)) {
+      no_singleton:
 	rb_raise(rb_eTypeError, "can't define singleton");
     }
     if (SPECIAL_CONST_P(obj)) {
@@ -1549,9 +1550,9 @@ singleton_class_of(VALUE obj)
 	return klass;
     }
     else {
-	enum ruby_value_type type = BUILTIN_TYPE(obj);
-	if (type == T_FLOAT || type == T_BIGNUM) {
-	    rb_raise(rb_eTypeError, "can't define singleton");
+	switch (BUILTIN_TYPE(obj)) {
+	  case T_FLOAT: case T_BIGNUM: case T_SYMBOL:
+	    goto no_singleton;
 	}
     }
 
diff --git a/test/ruby/test_symbol.rb b/test/ruby/test_symbol.rb
index 66c62cb298..0a055db2c9 100644
--- a/test/ruby/test_symbol.rb
+++ b/test/ruby/test_symbol.rb
@@ -199,6 +199,35 @@ class TestSymbol < Test::Unit::TestCase
     assert_raise(TypeError) { a = :foo; def a.foo; end }
   end
 
+  SymbolsForEval = [
+    :foo,
+    "dynsym_#{Random.rand(10000)}_#{Time.now}".to_sym
+  ]
+
+  def test_instance_eval
+    bug11086 = '[ruby-core:68961] [Bug #11086]'
+    SymbolsForEval.each do |sym|
+      assert_nothing_raised(TypeError, sym, bug11086) {
+        sym.instance_eval {}
+      }
+      assert_raise(TypeError, sym, bug11086) {
+        sym.instance_eval {def foo; end}
+      }
+    end
+  end
+
+  def test_instance_exec
+    bug11086 = '[ruby-core:68961] [Bug #11086]'
+    SymbolsForEval.each do |sym|
+      assert_nothing_raised(TypeError, sym, bug11086) {
+        sym.instance_exec {}
+      }
+      assert_raise(TypeError, sym, bug11086) {
+        sym.instance_exec {def foo; end}
+      }
+    end
+  end
+
   def test_frozen_symbol
     assert_equal(true, :foo.frozen?)
     assert_equal(true, :each.frozen?)
diff --git a/vm_eval.c b/vm_eval.c
index b63eec262e..281dbe77cc 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1627,6 +1627,20 @@ specific_eval(int argc, const VALUE *argv, VALUE klass, VALUE self)
     }
 }
 
+static VALUE
+singleton_class_for_eval(VALUE self)
+{
+    if (SPECIAL_CONST_P(self)) {
+	return rb_special_singleton_class(self);
+    }
+    switch (BUILTIN_TYPE(self)) {
+      case T_FLOAT: case T_BIGNUM: case T_SYMBOL:
+	return Qnil;
+      default:
+	return rb_singleton_class(self);
+    }
+}
+
 /*
  *  call-seq:
  *     obj.instance_eval(string [, filename [, lineno]] )   -> obj
@@ -1663,14 +1677,7 @@ specific_eval(int argc, const VALUE *argv, VALUE klass, VALUE self)
 VALUE
 rb_obj_instance_eval(int argc, const VALUE *argv, VALUE self)
 {
-    VALUE klass;
-
-    if (SPECIAL_CONST_P(self)) {
-	klass = rb_special_singleton_class(self);
-    }
-    else {
-	klass = rb_singleton_class(self);
-    }
+    VALUE klass = singleton_class_for_eval(self);
     return specific_eval(argc, argv, klass, self);
 }
 
@@ -1695,14 +1702,7 @@ rb_obj_instance_eval(int argc, const VALUE *argv, VALUE self)
 VALUE
 rb_obj_instance_exec(int argc, const VALUE *argv, VALUE self)
 {
-    VALUE klass;
-
-    if (SPECIAL_CONST_P(self)) {
-	klass = rb_special_singleton_class(self);
-    }
-    else {
-	klass = rb_singleton_class(self);
-    }
+    VALUE klass = singleton_class_for_eval(self);
     return yield_under(klass, self, rb_ary_new4(argc, argv));
 }