Issue #19235: Add new RecursionError exception. Patch by Georg Brandl.

1st1 · 1st1 · commit f488fb422a64 · 2015-07-03T01:04:23.000-04:00
diff --git a/Doc/c-api/exceptions.rst b/Doc/c-api/exceptions.rst
@@ -683,12 +683,12 @@ recursion depth automatically).
    sets a :exc:`MemoryError` and returns a nonzero value.
 
    The function then checks if the recursion limit is reached.  If this is the
-   case, a :exc:`RuntimeError` is set and a nonzero value is returned.
+   case, a :exc:`RecursionError` is set and a nonzero value is returned.
    Otherwise, zero is returned.
 
    *where* should be a string such as ``" in instance check"`` to be
-   concatenated to the :exc:`RuntimeError` message caused by the recursion depth
-   limit.
+   concatenated to the :exc:`RecursionError` message caused by the recursion
+   depth limit.
 
 .. c:function:: void Py_LeaveRecursiveCall()
 
@@ -800,6 +800,8 @@ the variables:
 +-----------------------------------------+---------------------------------+----------+
 | :c:data:`PyExc_ProcessLookupError`      | :exc:`ProcessLookupError`       |          |
 +-----------------------------------------+---------------------------------+----------+
+| :c:data:`PyExc_RecursionError`          | :exc:`RecursionError`           |          |
++-----------------------------------------+---------------------------------+----------+
 | :c:data:`PyExc_ReferenceError`          | :exc:`ReferenceError`           | \(2)     |
 +-----------------------------------------+---------------------------------+----------+
 | :c:data:`PyExc_RuntimeError`            | :exc:`RuntimeError`             |          |
@@ -829,6 +831,9 @@ the variables:
    :c:data:`PyExc_PermissionError`, :c:data:`PyExc_ProcessLookupError`
    and :c:data:`PyExc_TimeoutError` were introduced following :pep:`3151`.
 
+.. versionadded:: 3.5
+   :c:data:`PyExc_RecursionError`.
+
 
 These are compatibility aliases to :c:data:`PyExc_OSError`:
 
@@ -877,6 +882,7 @@ These are compatibility aliases to :c:data:`PyExc_OSError`:
    single: PyExc_OverflowError
    single: PyExc_PermissionError
    single: PyExc_ProcessLookupError
+   single: PyExc_RecursionError
    single: PyExc_ReferenceError
    single: PyExc_RuntimeError
    single: PyExc_SyntaxError
diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
@@ -282,6 +282,16 @@ The following exceptions are the exceptions that are usually raised.
    handling in C, most floating point operations are not checked.
 
 
+.. exception:: RecursionError
+
+   This exception is derived from :exc:`RuntimeError`.  It is raised when the
+   interpreter detects that the maximum recursion depth (see
+   :func:`sys.getrecursionlimit`) is exceeded.
+
+   .. versionadded:: 3.5
+      Previously, a plain :exc:`RuntimeError` was raised.
+
+
 .. exception:: ReferenceError
 
    This exception is raised when a weak reference proxy, created by the
diff --git a/Doc/library/pickle.rst b/Doc/library/pickle.rst
@@ -425,7 +425,7 @@ The following types can be pickled:
 Attempts to pickle unpicklable objects will raise the :exc:`PicklingError`
 exception; when this happens, an unspecified number of bytes may have already
 been written to the underlying file.  Trying to pickle a highly recursive data
-structure may exceed the maximum recursion depth, a :exc:`RuntimeError` will be
+structure may exceed the maximum recursion depth, a :exc:`RecursionError` will be
 raised in this case.  You can carefully raise this limit with
 :func:`sys.setrecursionlimit`.
 
diff --git a/Doc/whatsnew/3.5.rst b/Doc/whatsnew/3.5.rst
@@ -87,6 +87,8 @@ New built-in features:
 * Generators have new ``gi_yieldfrom`` attribute, which returns the
   object being iterated by ``yield from`` expressions. (Contributed
   by Benno Leslie and Yury Selivanov in :issue:`24450`.)
+* New :exc:`RecursionError` exception. (Contributed by Georg Brandl
+  in :issue:`19235`.)
 
 Implementation improvements:
 
diff --git a/Include/ceval.h b/Include/ceval.h
@@ -48,16 +48,16 @@ PyAPI_FUNC(int) Py_MakePendingCalls(void);
 
    In Python 3.0, this protection has two levels:
    * normal anti-recursion protection is triggered when the recursion level
-     exceeds the current recursion limit. It raises a RuntimeError, and sets
+     exceeds the current recursion limit. It raises a RecursionError, and sets
      the "overflowed" flag in the thread state structure. This flag
      temporarily *disables* the normal protection; this allows cleanup code
      to potentially outgrow the recursion limit while processing the
-     RuntimeError.
+     RecursionError.
    * "last chance" anti-recursion protection is triggered when the recursion
      level exceeds "current recursion limit + 50". By construction, this
      protection can only be triggered when the "overflowed" flag is set. It
      means the cleanup code has itself gone into an infinite loop, or the
-     RuntimeError has been mistakingly ignored. When this protection is
+     RecursionError has been mistakingly ignored. When this protection is
      triggered, the interpreter aborts with a Fatal Error.
 
    In addition, the "overflowed" flag is automatically reset when the
diff --git a/Include/pyerrors.h b/Include/pyerrors.h
@@ -167,6 +167,7 @@ PyAPI_DATA(PyObject *) PyExc_MemoryError;
 PyAPI_DATA(PyObject *) PyExc_NameError;
 PyAPI_DATA(PyObject *) PyExc_OverflowError;
 PyAPI_DATA(PyObject *) PyExc_RuntimeError;
+PyAPI_DATA(PyObject *) PyExc_RecursionError;
 PyAPI_DATA(PyObject *) PyExc_NotImplementedError;
 PyAPI_DATA(PyObject *) PyExc_SyntaxError;
 PyAPI_DATA(PyObject *) PyExc_IndentationError;
diff --git a/Lib/ctypes/test/test_as_parameter.py b/Lib/ctypes/test/test_as_parameter.py
@@ -194,7 +194,7 @@ class A(object):
 
         a = A()
         a._as_parameter_ = a
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             c_int.from_param(a)
 
 
diff --git a/Lib/test/exception_hierarchy.txt b/Lib/test/exception_hierarchy.txt
@@ -39,6 +39,7 @@ BaseException
       +-- ReferenceError
       +-- RuntimeError
       |    +-- NotImplementedError
+      |    +-- RecursionError
       +-- SyntaxError
       |    +-- IndentationError
       |         +-- TabError
diff --git a/Lib/test/list_tests.py b/Lib/test/list_tests.py
@@ -56,7 +56,7 @@ def test_repr(self):
         l0 = []
         for i in range(sys.getrecursionlimit() + 100):
             l0 = [l0]
-        self.assertRaises(RuntimeError, repr, l0)
+        self.assertRaises(RecursionError, repr, l0)
 
     def test_print(self):
         d = self.type2test(range(200))
diff --git a/Lib/test/test_class.py b/Lib/test/test_class.py
@@ -500,10 +500,10 @@ class A:
 
         try:
             a() # This should not segfault
-        except RuntimeError:
+        except RecursionError:
             pass
         else:
-            self.fail("Failed to raise RuntimeError")
+            self.fail("Failed to raise RecursionError")
 
     def testForExceptionsRaisedInInstanceGetattr2(self):
         # Tests for exceptions raised in instance_getattr2().
diff --git a/Lib/test/test_compile.py b/Lib/test/test_compile.py
@@ -534,7 +534,7 @@ def check_limit(prefix, repeated):
             broken = prefix + repeated * fail_depth
             details = "Compiling ({!r} + {!r} * {})".format(
                          prefix, repeated, fail_depth)
-            with self.assertRaises(RuntimeError, msg=details):
+            with self.assertRaises(RecursionError, msg=details):
                 self.compile_single(broken)
 
         check_limit("a", "()")
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
@@ -327,7 +327,7 @@ def test_deepcopy_reflexive_list(self):
         x.append(x)
         y = copy.deepcopy(x)
         for op in comparisons:
-            self.assertRaises(RuntimeError, op, y, x)
+            self.assertRaises(RecursionError, op, y, x)
         self.assertIsNot(y, x)
         self.assertIs(y[0], y)
         self.assertEqual(len(y), 1)
@@ -354,7 +354,7 @@ def test_deepcopy_reflexive_tuple(self):
         x[0].append(x)
         y = copy.deepcopy(x)
         for op in comparisons:
-            self.assertRaises(RuntimeError, op, y, x)
+            self.assertRaises(RecursionError, op, y, x)
         self.assertIsNot(y, x)
         self.assertIsNot(y[0], x[0])
         self.assertIs(y[0][0], y)
@@ -373,7 +373,7 @@ def test_deepcopy_reflexive_dict(self):
         for op in order_comparisons:
             self.assertRaises(TypeError, op, y, x)
         for op in equality_comparisons:
-            self.assertRaises(RuntimeError, op, y, x)
+            self.assertRaises(RecursionError, op, y, x)
         self.assertIsNot(y, x)
         self.assertIs(y['foo'], y)
         self.assertEqual(len(y), 1)
diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py
@@ -3342,7 +3342,7 @@ class A(object):
         A.__call__ = A()
         try:
             A()()
-        except RuntimeError:
+        except RecursionError:
             pass
         else:
             self.fail("Recursion limit should have been reached for __call__()")
@@ -4317,8 +4317,8 @@ class Foo:
             pass
         Foo.__repr__ = Foo.__str__
         foo = Foo()
-        self.assertRaises(RuntimeError, str, foo)
-        self.assertRaises(RuntimeError, repr, foo)
+        self.assertRaises(RecursionError, str, foo)
+        self.assertRaises(RecursionError, repr, foo)
 
     def test_mixing_slot_wrappers(self):
         class X(dict):
diff --git a/Lib/test/test_dictviews.py b/Lib/test/test_dictviews.py
@@ -195,7 +195,7 @@ def test_items_set_operations(self):
     def test_recursive_repr(self):
         d = {}
         d[42] = d.values()
-        self.assertRaises(RuntimeError, repr, d)
+        self.assertRaises(RecursionError, repr, d)
 
 
 if __name__ == "__main__":
diff --git a/Lib/test/test_exceptions.py b/Lib/test/test_exceptions.py
@@ -84,6 +84,7 @@ def testRaising(self):
             x += x  # this simply shouldn't blow up
 
         self.raise_catch(RuntimeError, "RuntimeError")
+        self.raise_catch(RecursionError, "RecursionError")
 
         self.raise_catch(SyntaxError, "SyntaxError")
         try: exec('/\n')
@@ -474,14 +475,14 @@ def __init__(self, fancy_arg):
     def testInfiniteRecursion(self):
         def f():
             return f()
-        self.assertRaises(RuntimeError, f)
+        self.assertRaises(RecursionError, f)
 
         def g():
             try:
                 return g()
             except ValueError:
                 return -1
-        self.assertRaises(RuntimeError, g)
+        self.assertRaises(RecursionError, g)
 
     def test_str(self):
         # Make sure both instances and classes have a str representation.
@@ -887,10 +888,10 @@ class MyException(Exception, metaclass=Meta):
         def g():
             try:
                 return g()
-            except RuntimeError:
+            except RecursionError:
                 return sys.exc_info()
         e, v, tb = g()
-        self.assertTrue(isinstance(v, RuntimeError), type(v))
+        self.assertTrue(isinstance(v, RecursionError), type(v))
         self.assertIn("maximum recursion depth exceeded", str(v))
 
 
@@ -989,10 +990,10 @@ def inner():
         # We cannot use assertRaises since it manually deletes the traceback
         try:
             inner()
-        except RuntimeError as e:
+        except RecursionError as e:
             self.assertNotEqual(wr(), None)
         else:
-            self.fail("RuntimeError not raised")
+            self.fail("RecursionError not raised")
         self.assertEqual(wr(), None)
 
     def test_errno_ENOTDIR(self):
diff --git a/Lib/test/test_isinstance.py b/Lib/test/test_isinstance.py
@@ -258,18 +258,18 @@ def test_subclass_tuple(self):
         self.assertEqual(True, issubclass(str, (str, (Child, NewChild, str))))
 
     def test_subclass_recursion_limit(self):
-        # make sure that issubclass raises RuntimeError before the C stack is
+        # make sure that issubclass raises RecursionError before the C stack is
         # blown
-        self.assertRaises(RuntimeError, blowstack, issubclass, str, str)
+        self.assertRaises(RecursionError, blowstack, issubclass, str, str)
 
     def test_isinstance_recursion_limit(self):
-        # make sure that issubclass raises RuntimeError before the C stack is
+        # make sure that issubclass raises RecursionError before the C stack is
         # blown
-        self.assertRaises(RuntimeError, blowstack, isinstance, '', str)
+        self.assertRaises(RecursionError, blowstack, isinstance, '', str)
 
 def blowstack(fxn, arg, compare_to):
     # Make sure that calling isinstance with a deeply nested tuple for its
-    # argument will raise RuntimeError eventually.
+    # argument will raise RecursionError eventually.
     tuple_arg = (compare_to,)
     for cnt in range(sys.getrecursionlimit()+5):
         tuple_arg = (tuple_arg,)
diff --git a/Lib/test/test_json/test_recursion.py b/Lib/test/test_json/test_recursion.py
@@ -68,21 +68,21 @@ def default(self, o):
     def test_highly_nested_objects_decoding(self):
         # test that loading highly-nested objects doesn't segfault when C
         # accelerations are used. See #12017
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             self.loads('{"a":' * 100000 + '1' + '}' * 100000)
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             self.loads('{"a":' * 100000 + '[1]' + '}' * 100000)
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             self.loads('[' * 100000 + '1' + ']' * 100000)
 
     def test_highly_nested_objects_encoding(self):
         # See #12051
         l, d = [], {}
         for x in range(100000):
             l, d = [l], {'k':d}
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             self.dumps(l)
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             self.dumps(d)
 
     def test_endless_recursion(self):
@@ -92,7 +92,7 @@ def default(self, o):
                 """If check_circular is False, this will keep adding another list."""
                 return [o]
 
-        with self.assertRaises(RuntimeError):
+        with self.assertRaises(RecursionError):
             EndlessJSONEncoder(check_circular=False).encode(5j)
 
 
diff --git a/Lib/test/test_pickle.py b/Lib/test/test_pickle.py
@@ -353,7 +353,8 @@ def test_exceptions(self):
             with self.subTest(name):
                 if exc in (BlockingIOError,
                            ResourceWarning,
-                           StopAsyncIteration):
+                           StopAsyncIteration,
+                           RecursionError):
                     continue
                 if exc is not OSError and issubclass(exc, OSError):
                     self.assertEqual(reverse_mapping('builtins', name),
diff --git a/Lib/test/test_richcmp.py b/Lib/test/test_richcmp.py
@@ -228,25 +228,25 @@ def test_recursion(self):
         b = UserList()
         a.append(b)
         b.append(a)
-        self.assertRaises(RuntimeError, operator.eq, a, b)
-        self.assertRaises(RuntimeError, operator.ne, a, b)
-        self.assertRaises(RuntimeError, operator.lt, a, b)
-        self.assertRaises(RuntimeError, operator.le, a, b)
-        self.assertRaises(RuntimeError, operator.gt, a, b)
-        self.assertRaises(RuntimeError, operator.ge, a, b)
+        self.assertRaises(RecursionError, operator.eq, a, b)
+        self.assertRaises(RecursionError, operator.ne, a, b)
+        self.assertRaises(RecursionError, operator.lt, a, b)
+        self.assertRaises(RecursionError, operator.le, a, b)
+        self.assertRaises(RecursionError, operator.gt, a, b)
+        self.assertRaises(RecursionError, operator.ge, a, b)
 
         b.append(17)
         # Even recursive lists of different lengths are different,
         # but they cannot be ordered
         self.assertTrue(not (a == b))
         self.assertTrue(a != b)
-        self.assertRaises(RuntimeError, operator.lt, a, b)
-        self.assertRaises(RuntimeError, operator.le, a, b)
-        self.assertRaises(RuntimeError, operator.gt, a, b)
-        self.assertRaises(RuntimeError, operator.ge, a, b)
+        self.assertRaises(RecursionError, operator.lt, a, b)
+        self.assertRaises(RecursionError, operator.le, a, b)
+        self.assertRaises(RecursionError, operator.gt, a, b)
+        self.assertRaises(RecursionError, operator.ge, a, b)
         a.append(17)
-        self.assertRaises(RuntimeError, operator.eq, a, b)
-        self.assertRaises(RuntimeError, operator.ne, a, b)
+        self.assertRaises(RecursionError, operator.eq, a, b)
+        self.assertRaises(RecursionError, operator.ne, a, b)
         a.insert(0, 11)
         b.insert(0, 12)
         self.assertTrue(not (a == b))
diff --git a/Lib/test/test_runpy.py b/Lib/test/test_runpy.py
@@ -673,7 +673,7 @@ def test_main_recursion_error(self):
             script_name = self._make_test_script(script_dir, mod_name, source)
             zip_name, fname = make_zip_script(script_dir, 'test_zip', script_name)
             msg = "recursion depth exceeded"
-            self.assertRaisesRegex(RuntimeError, msg, run_path, zip_name)
+            self.assertRaisesRegex(RecursionError, msg, run_path, zip_name)
 
     def test_encoding(self):
         with temp_dir() as script_dir:
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
@@ -211,8 +211,8 @@ def f():
             for i in (50, 1000):
                 # Issue #5392: stack overflow after hitting recursion limit twice
                 sys.setrecursionlimit(i)
-                self.assertRaises(RuntimeError, f)
-                self.assertRaises(RuntimeError, f)
+                self.assertRaises(RecursionError, f)
+                self.assertRaises(RecursionError, f)
         finally:
             sys.setrecursionlimit(oldlimit)
 
@@ -225,7 +225,7 @@ def test_recursionlimit_fatalerror(self):
             def f():
                 try:
                     f()
-                except RuntimeError:
+                except RecursionError:
                     f()
 
             sys.setrecursionlimit(%d)
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
diff --git a/Misc/NEWS b/Misc/NEWS
diff --git a/Modules/_pickle.c b/Modules/_pickle.c
diff --git a/Modules/_sre.c b/Modules/_sre.c
diff --git a/Objects/exceptions.c b/Objects/exceptions.c
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
diff --git a/Python/ceval.c b/Python/ceval.c
diff --git a/Python/errors.c b/Python/errors.c
diff --git a/Python/symtable.c b/Python/symtable.c
diff --git a/Tools/scripts/find_recursionlimit.py b/Tools/scripts/find_recursionlimit.py
