fixed ref-count bug in try-except handling

Cython/Compiler/Nodes.py

@@ -3960,6 +3960,8 @@ class TryExceptStatNode(StatNode):
             self.else_clause.generate_execution_code(code)
             code.putln(
                 "}")
+        for var in Naming.exc_save_vars:
+            code.put_xdecref_clear(var, py_object_type)
         code.put_goto(try_end_label)
         code.put_label(our_error_label)
         code.put_var_xdecrefs_clear(self.cleanup_list)

tests/run/exceptionrefcount.pyx

+__doc__ = u"""
+>>> class SampleException(Exception): pass
+>>> import sys
+
+>>> def assert_refcount(rc1, rc2, func):
+...     # test ref-counts, but allow a bit of freedom
+...     assert rc2 <= rc1 + 4, "%s, before: %d, after %d" % (
+...         func.__name__, rc1, rc2)
+
+>>> def run_test(repeat, test_func):
+...     initial_refcount = sys.getrefcount(SampleException)
+...     for i in range(repeat):
+...         try: raise SampleException
+...         except:
+...             refcount1 = sys.getrefcount(SampleException)
+...             test_func()
+...             refcount2 = sys.getrefcount(SampleException)
+...             
+...             assert_refcount(refcount1, refcount2, test_func)
+...             assert_refcount(initial_refcount, refcount2, test_func)
+...         refcount3 = sys.getrefcount(SampleException)
+...         assert_refcount(refcount1, refcount3, test_func)
+...         assert_refcount(initial_refcount, refcount3, test_func)
+
+>>> run_test(50, test_no_exception_else)
+>>> run_test(50, test_no_exception)
+>>> run_test(50, test_exception)
+>>> run_test(50, test_finally)
+"""
+
+def test_no_exception():
+    try:
+        a = 1+1
+    except:
+        pass
+
+def test_no_exception_else():
+    try:
+        a = 1+1
+    except:
+        pass
+    else:
+        b = 1+1
+
+def test_exception():
+    try:
+        raise TypeError
+    except:
+        pass
+
+def test_finally():
+    try:
+        a = 1+1
+    finally:
+        b = 1+1