Merge pull request #2607 from scoder/gen_exc_py37_fix

Use exception stack in Py3.7

Cython/Compiler/Nodes.py

@@ -4256,7 +4256,10 @@ class GeneratorBodyDefNode(DefNode):
             code.put_xgiveref(Naming.retval_cname)
         else:
             code.put_xdecref_clear(Naming.retval_cname, py_object_type)
+        # For Py3.7, clearing is already done below.
+        code.putln("#if !CYTHON_USE_EXC_INFO_STACK")
         code.putln("__Pyx_Coroutine_ResetAndClearException(%s);" % Naming.generator_cname)
+        code.putln("#endif")
         code.putln('%s->resume_label = -1;' % Naming.generator_cname)
         # clean up as early as possible to help breaking any reference cycles
         code.putln('__Pyx_Coroutine_clear((PyObject*)%s);' % Naming.generator_cname)
@@ -7408,7 +7411,9 @@ class ExceptClauseNode(Node):
 
         if not self.body.is_terminator:
             for var in exc_vars:
-                code.put_decref_clear(var, py_object_type)
+                # FIXME: XDECREF() is needed to allow re-raising (which clears the exc_vars),
+                # but I don't think it's the right solution.
+                code.put_xdecref_clear(var, py_object_type)
             code.put_goto(end_label)
 
         for new_label, old_label in [(code.break_label, old_break_label),

Cython/Utility/Coroutine.c

@@ -364,13 +364,23 @@ static void __Pyx_Generator_Replace_StopIteration(CYTHON_UNUSED int in_async_gen
 
 typedef PyObject *(*__pyx_coroutine_body_t)(PyObject *, PyThreadState *, PyObject *);
 
+#if CYTHON_USE_EXC_INFO_STACK
+// See  https://bugs.python.org/issue25612
+#define __Pyx_ExcInfoStruct  _PyErr_StackItem
+#else
+// Minimal replacement struct for Py<3.7, without the Py3.7 exception state stack.
 typedef struct {
-    PyObject_HEAD
-    __pyx_coroutine_body_t body;
-    PyObject *closure;
     PyObject *exc_type;
     PyObject *exc_value;
     PyObject *exc_traceback;
+} __Pyx_ExcInfoStruct;
+#endif
+
+typedef struct {
+    PyObject_HEAD
+    __pyx_coroutine_body_t body;
+    PyObject *closure;
+    __Pyx_ExcInfoStruct gi_exc_state;
     PyObject *gi_weakreflist;
     PyObject *classobj;
     PyObject *yieldfrom;
@@ -391,20 +401,26 @@ static __pyx_CoroutineObject *__Pyx__Coroutine_NewInit(
             __pyx_CoroutineObject *gen, __pyx_coroutine_body_t body, PyObject *code, PyObject *closure,
             PyObject *name, PyObject *qualname, PyObject *module_name); /*proto*/
 
+static CYTHON_INLINE void __Pyx_Coroutine_ExceptionClear(__Pyx_ExcInfoStruct *self);
 static int __Pyx_Coroutine_clear(PyObject *self); /*proto*/
 static PyObject *__Pyx_Coroutine_Send(PyObject *self, PyObject *value); /*proto*/
 static PyObject *__Pyx_Coroutine_Close(PyObject *self); /*proto*/
 static PyObject *__Pyx_Coroutine_Throw(PyObject *gen, PyObject *args); /*proto*/
 
 // macros for exception state swapping instead of inline functions to make use of the local thread state context
+#if CYTHON_USE_EXC_INFO_STACK
+#define __Pyx_Coroutine_SwapException(self)
+#define __Pyx_Coroutine_ResetAndClearException(self)  __Pyx_Coroutine_ExceptionClear(&(self)->gi_exc_state)
+#else
 #define __Pyx_Coroutine_SwapException(self) { \
-    __Pyx_ExceptionSwap(&(self)->exc_type, &(self)->exc_value, &(self)->exc_traceback); \
-    __Pyx_Coroutine_ResetFrameBackpointer(self); \
+    __Pyx_ExceptionSwap(&(self)->gi_exc_state.exc_type, &(self)->gi_exc_state.exc_value, &(self)->gi_exc_state.exc_traceback); \
+    __Pyx_Coroutine_ResetFrameBackpointer(&(self)->gi_exc_state); \
     }
 #define __Pyx_Coroutine_ResetAndClearException(self) { \
-    __Pyx_ExceptionReset((self)->exc_type, (self)->exc_value, (self)->exc_traceback); \
-    (self)->exc_type = (self)->exc_value = (self)->exc_traceback = NULL; \
+    __Pyx_ExceptionReset((self)->gi_exc_state.exc_type, (self)->gi_exc_state.exc_value, (self)->gi_exc_state.exc_traceback); \
+    (self)->gi_exc_state.exc_type = (self)->gi_exc_state.exc_value = (self)->gi_exc_state.exc_traceback = NULL; \
     }
+#endif
 
 #if CYTHON_FAST_THREAD_STATE
 #define __Pyx_PyGen_FetchStopIterationValue(pvalue) \
@@ -414,7 +430,7 @@ static PyObject *__Pyx_Coroutine_Throw(PyObject *gen, PyObject *args); /*proto*/
     __Pyx_PyGen__FetchStopIterationValue(__Pyx_PyThreadState_Current, pvalue)
 #endif
 static int __Pyx_PyGen__FetchStopIterationValue(PyThreadState *tstate, PyObject **pvalue); /*proto*/
-static CYTHON_INLINE void __Pyx_Coroutine_ResetFrameBackpointer(__pyx_CoroutineObject *self); /*proto*/
+static CYTHON_INLINE void __Pyx_Coroutine_ResetFrameBackpointer(__Pyx_ExcInfoStruct *exc_state); /*proto*/
 
 
 //////////////////// Coroutine.proto ////////////////////
@@ -573,18 +589,19 @@ static int __Pyx_PyGen__FetchStopIterationValue(CYTHON_UNUSED PyThreadState *$lo
 }
 
 static CYTHON_INLINE
-void __Pyx_Coroutine_ExceptionClear(__pyx_CoroutineObject *self) {
-    PyObject *exc_type = self->exc_type;
-    PyObject *exc_value = self->exc_value;
-    PyObject *exc_traceback = self->exc_traceback;
-
-    self->exc_type = NULL;
-    self->exc_value = NULL;
-    self->exc_traceback = NULL;
-
-    Py_XDECREF(exc_type);
-    Py_XDECREF(exc_value);
-    Py_XDECREF(exc_traceback);
+void __Pyx_Coroutine_ExceptionClear(__Pyx_ExcInfoStruct *exc_state) {
+    PyObject *t, *v, *tb;
+    t = exc_state->exc_type;
+    v = exc_state->exc_value;
+    tb = exc_state->exc_traceback;
+
+    exc_state->exc_type = NULL;
+    exc_state->exc_value = NULL;
+    exc_state->exc_traceback = NULL;
+
+    Py_XDECREF(t);
+    Py_XDECREF(v);
+    Py_XDECREF(tb);
 }
 
 #define __Pyx_Coroutine_AlreadyRunningError(gen)  (__Pyx__Coroutine_AlreadyRunningError(gen), (PyObject*)NULL)
@@ -649,6 +666,7 @@ static
 PyObject *__Pyx_Coroutine_SendEx(__pyx_CoroutineObject *self, PyObject *value, int closing) {
     __Pyx_PyThreadState_declare
     PyThreadState *tstate;
+    __Pyx_ExcInfoStruct *exc_state;
     PyObject *retval;
 
     assert(!self->is_running);
@@ -670,55 +688,82 @@ PyObject *__Pyx_Coroutine_SendEx(__pyx_CoroutineObject *self, PyObject *value, i
     tstate = __Pyx_PyThreadState_Current;
 #endif
 
-    // Traceback/Frame rules:
-    // - on entry, save external exception state in self->exc_*, restore it on exit
-    // - on exit, keep internally generated exceptions in self->exc_*, clear everything else
+    // Traceback/Frame rules pre-Py3.7:
+    // - on entry, save external exception state in self->gi_exc_state, restore it on exit
+    // - on exit, keep internally generated exceptions in self->gi_exc_state, clear everything else
     // - on entry, set "f_back" pointer of internal exception traceback to (current) outer call frame
     // - on exit, clear "f_back" of internal exception traceback
     // - do not touch external frames and tracebacks
 
-    if (self->exc_type) {
-#if CYTHON_COMPILING_IN_PYPY || CYTHON_COMPILING_IN_PYSTON
+    // Traceback/Frame rules for Py3.7+ (CYTHON_USE_EXC_INFO_STACK):
+    // - on entry, push internal exception state in self->gi_exc_state on the exception stack
+    // - on exit, keep internally generated exceptions in self->gi_exc_state, clear everything else
+    // - on entry, set "f_back" pointer of internal exception traceback to (current) outer call frame
+    // - on exit, clear "f_back" of internal exception traceback
+    // - do not touch external frames and tracebacks
+
+    exc_state = &self->gi_exc_state;
+    if (exc_state->exc_type) {
+        #if CYTHON_COMPILING_IN_PYPY || CYTHON_COMPILING_IN_PYSTON
         // FIXME: what to do in PyPy?
-#else
+        #else
         // Generators always return to their most recent caller, not
         // necessarily their creator.
-        if (self->exc_traceback) {
-            PyTracebackObject *tb = (PyTracebackObject *) self->exc_traceback;
+        if (exc_state->exc_traceback) {
+            PyTracebackObject *tb = (PyTracebackObject *) exc_state->exc_traceback;
             PyFrameObject *f = tb->tb_frame;
 
             Py_XINCREF(tstate->frame);
             assert(f->f_back == NULL);
             f->f_back = tstate->frame;
         }
-#endif
+        #endif
+    }
+
+#if CYTHON_USE_EXC_INFO_STACK
+    // See  https://bugs.python.org/issue25612
+    exc_state->previous_item = tstate->exc_info;
+    tstate->exc_info = exc_state;
+#else
+    if (exc_state->exc_type) {
         // We were in an except handler when we left,
         // restore the exception state which was put aside.
-        __Pyx_ExceptionSwap(&self->exc_type, &self->exc_value,
-                            &self->exc_traceback);
+        __Pyx_ExceptionSwap(&exc_state->exc_type, &exc_state->exc_value, &exc_state->exc_traceback);
         // self->exc_* now holds the exception state of the caller
     } else {
         // save away the exception state of the caller
-        __Pyx_Coroutine_ExceptionClear(self);
-        __Pyx_ExceptionSave(&self->exc_type, &self->exc_value, &self->exc_traceback);
+        __Pyx_Coroutine_ExceptionClear(exc_state);
+        __Pyx_ExceptionSave(&exc_state->exc_type, &exc_state->exc_value, &exc_state->exc_traceback);
     }
+#endif
 
     self->is_running = 1;
     retval = self->body((PyObject *) self, tstate, value);
     self->is_running = 0;
 
+#if CYTHON_USE_EXC_INFO_STACK
+    // See  https://bugs.python.org/issue25612
+    exc_state = &self->gi_exc_state;
+    tstate->exc_info = exc_state->previous_item;
+    exc_state->previous_item = NULL;
+    // Cut off the exception frame chain so that we can reconnect it on re-entry above.
+    __Pyx_Coroutine_ResetFrameBackpointer(exc_state);
+#endif
+
     return retval;
 }
 
-static CYTHON_INLINE void __Pyx_Coroutine_ResetFrameBackpointer(__pyx_CoroutineObject *self) {
+static CYTHON_INLINE void __Pyx_Coroutine_ResetFrameBackpointer(__Pyx_ExcInfoStruct *exc_state) {
     // Don't keep the reference to f_back any longer than necessary.  It
     // may keep a chain of frames alive or it could create a reference
     // cycle.
-    if (likely(self->exc_traceback)) {
+    PyObject *exc_tb = exc_state->exc_traceback;
+
+    if (likely(exc_tb)) {
 #if CYTHON_COMPILING_IN_PYPY || CYTHON_COMPILING_IN_PYSTON
     // FIXME: what to do in PyPy?
 #else
-        PyTracebackObject *tb = (PyTracebackObject *) self->exc_traceback;
+        PyTracebackObject *tb = (PyTracebackObject *) exc_tb;
         PyFrameObject *f = tb->tb_frame;
         Py_CLEAR(f->f_back);
 #endif
@@ -1039,14 +1084,18 @@ static PyObject *__Pyx_Coroutine_Throw(PyObject *self, PyObject *args) {
     return __Pyx__Coroutine_Throw(self, typ, val, tb, args, 1);
 }
 
+static CYTHON_INLINE int __Pyx_Coroutine_traverse_excstate(__Pyx_ExcInfoStruct *exc_state, visitproc visit, void *arg) {
+    Py_VISIT(exc_state->exc_type);
+    Py_VISIT(exc_state->exc_value);
+    Py_VISIT(exc_state->exc_traceback);
+    return 0;
+}
+
 static int __Pyx_Coroutine_traverse(__pyx_CoroutineObject *gen, visitproc visit, void *arg) {
     Py_VISIT(gen->closure);
     Py_VISIT(gen->classobj);
     Py_VISIT(gen->yieldfrom);
-    Py_VISIT(gen->exc_type);
-    Py_VISIT(gen->exc_value);
-    Py_VISIT(gen->exc_traceback);
-    return 0;
+    return __Pyx_Coroutine_traverse_excstate(&gen->gi_exc_state, visit, arg);
 }
 
 static int __Pyx_Coroutine_clear(PyObject *self) {
@@ -1055,9 +1104,7 @@ static int __Pyx_Coroutine_clear(PyObject *self) {
     Py_CLEAR(gen->closure);
     Py_CLEAR(gen->classobj);
     Py_CLEAR(gen->yieldfrom);
-    Py_CLEAR(gen->exc_type);
-    Py_CLEAR(gen->exc_value);
-    Py_CLEAR(gen->exc_traceback);
+    __Pyx_Coroutine_ExceptionClear(&gen->gi_exc_state);
 #ifdef __Pyx_AsyncGen_USED
     if (__Pyx_AsyncGen_CheckExact(self)) {
         Py_CLEAR(((__pyx_PyAsyncGenObject*)gen)->ag_finalizer);
@@ -1315,9 +1362,12 @@ static __pyx_CoroutineObject *__Pyx__Coroutine_NewInit(
     gen->resume_label = 0;
     gen->classobj = NULL;
     gen->yieldfrom = NULL;
-    gen->exc_type = NULL;
-    gen->exc_value = NULL;
-    gen->exc_traceback = NULL;
+    gen->gi_exc_state.exc_type = NULL;
+    gen->gi_exc_state.exc_value = NULL;
+    gen->gi_exc_state.exc_traceback = NULL;
+#if CYTHON_USE_EXC_INFO_STACK
+    gen->gi_exc_state.previous_item = NULL;
+#endif
     gen->gi_weakreflist = NULL;
     Py_XINCREF(qualname);
     gen->gi_qualname = qualname;
@@ -1862,8 +1912,8 @@ static void __Pyx__ReturnWithStopIteration(PyObject* value) {
     }
     #if CYTHON_FAST_THREAD_STATE
     __Pyx_PyThreadState_assign
-    #if PY_VERSION_HEX >= 0x030700A3
-    if (!$local_tstate_cname->exc_state.exc_type)
+    #if CYTHON_USE_EXC_INFO_STACK
+    if (!$local_tstate_cname->exc_info->exc_type)
     #else
     if (!$local_tstate_cname->exc_type)
     #endif

Cython/Utility/Exceptions.c

@@ -307,6 +307,31 @@ bad:
 }
 #endif
 
+
+/////////////// GetTopmostException.proto ///////////////
+
+#if CYTHON_USE_EXC_INFO_STACK
+static _PyErr_StackItem * __Pyx_PyErr_GetTopmostException(PyThreadState *tstate);
+#endif
+
+/////////////// GetTopmostException ///////////////
+
+#if CYTHON_USE_EXC_INFO_STACK
+// Copied from errors.c in CPython.
+static _PyErr_StackItem *
+__Pyx_PyErr_GetTopmostException(PyThreadState *tstate)
+{
+    _PyErr_StackItem *exc_info = tstate->exc_info;
+    while ((exc_info->exc_type == NULL || exc_info->exc_type == Py_None) &&
+           exc_info->previous_item != NULL)
+    {
+        exc_info = exc_info->previous_item;
+    }
+    return exc_info;
+}
+#endif
+
+
 /////////////// GetException.proto ///////////////
 //@substitute: naming
 //@requires: PyThreadStateGet
@@ -360,13 +385,16 @@ static int __Pyx_GetException(PyObject **type, PyObject **value, PyObject **tb)
     *value = local_value;
     *tb = local_tb;
 #if CYTHON_FAST_THREAD_STATE
-    #if PY_VERSION_HEX >= 0x030700A3
-    tmp_type = tstate->exc_state.exc_type;
-    tmp_value = tstate->exc_state.exc_value;
-    tmp_tb = tstate->exc_state.exc_traceback;
-    tstate->exc_state.exc_type = local_type;
-    tstate->exc_state.exc_value = local_value;
-    tstate->exc_state.exc_traceback = local_tb;
+    #if CYTHON_USE_EXC_INFO_STACK
+    {
+        _PyErr_StackItem *exc_info = tstate->exc_info;
+        tmp_type = exc_info->exc_type;
+        tmp_value = exc_info->exc_value;
+        tmp_tb = exc_info->exc_traceback;
+        exc_info->exc_type = local_type;
+        exc_info->exc_value = local_value;
+        exc_info->exc_traceback = local_tb;
+    }
     #else
     tmp_type = tstate->exc_type;
     tmp_value = tstate->exc_value;
@@ -398,16 +426,18 @@ bad:
 
 static CYTHON_INLINE void __Pyx_ReraiseException(void); /*proto*/
 
-/////////////// ReRaiseException.proto ///////////////
+/////////////// ReRaiseException ///////////////
+//@requires: GetTopmostException
 
 static CYTHON_INLINE void __Pyx_ReraiseException(void) {
     PyObject *type = NULL, *value = NULL, *tb = NULL;
 #if CYTHON_FAST_THREAD_STATE
     PyThreadState *tstate = PyThreadState_GET();
-    #if PY_VERSION_HEX >= 0x030700A3
-    type = tstate->exc_state.exc_type;
-    value = tstate->exc_state.exc_value;
-    tb = tstate->exc_state.exc_traceback;
+    #if CYTHON_USE_EXC_INFO_STACK
+    _PyErr_StackItem *exc_info = __Pyx_PyErr_GetTopmostException(tstate);
+    type = exc_info->exc_type;
+    value = exc_info->exc_value;
+    tb = exc_info->exc_traceback;
     #else
     type = tstate->exc_type;
     value = tstate->exc_value;
@@ -453,13 +483,15 @@ static CYTHON_INLINE void __Pyx__ExceptionReset(PyThreadState *tstate, PyObject
 #endif
 
 /////////////// SaveResetException ///////////////
+//@requires: GetTopmostException
 
 #if CYTHON_FAST_THREAD_STATE
 static CYTHON_INLINE void __Pyx__ExceptionSave(PyThreadState *tstate, PyObject **type, PyObject **value, PyObject **tb) {
-    #if PY_VERSION_HEX >= 0x030700A3
-    *type = tstate->exc_state.exc_type;
-    *value = tstate->exc_state.exc_value;
-    *tb = tstate->exc_state.exc_traceback;
+    #if CYTHON_USE_EXC_INFO_STACK
+    _PyErr_StackItem *exc_info = __Pyx_PyErr_GetTopmostException(tstate);
+    *type = exc_info->exc_type;
+    *value = exc_info->exc_value;
+    *tb = exc_info->exc_traceback;
     #else
     *type = tstate->exc_type;
     *value = tstate->exc_value;
@@ -473,13 +505,14 @@ static CYTHON_INLINE void __Pyx__ExceptionSave(PyThreadState *tstate, PyObject *
 static CYTHON_INLINE void __Pyx__ExceptionReset(PyThreadState *tstate, PyObject *type, PyObject *value, PyObject *tb) {
     PyObject *tmp_type, *tmp_value, *tmp_tb;
 
-    #if PY_VERSION_HEX >= 0x030700A3
-    tmp_type = tstate->exc_state.exc_type;
-    tmp_value = tstate->exc_state.exc_value;
-    tmp_tb = tstate->exc_state.exc_traceback;
-    tstate->exc_state.exc_type = type;
-    tstate->exc_state.exc_value = value;
-    tstate->exc_state.exc_traceback = tb;
+    #if CYTHON_USE_EXC_INFO_STACK
+    _PyErr_StackItem *exc_info = tstate->exc_info;
+    tmp_type = exc_info->exc_type;
+    tmp_value = exc_info->exc_value;
+    tmp_tb = exc_info->exc_traceback;
+    exc_info->exc_type = type;
+    exc_info->exc_value = value;
+    exc_info->exc_traceback = tb;
     #else
     tmp_type = tstate->exc_type;
     tmp_value = tstate->exc_value;
@@ -511,14 +544,15 @@ static CYTHON_INLINE void __Pyx_ExceptionSwap(PyObject **type, PyObject **value,
 static CYTHON_INLINE void __Pyx__ExceptionSwap(PyThreadState *tstate, PyObject **type, PyObject **value, PyObject **tb) {
     PyObject *tmp_type, *tmp_value, *tmp_tb;
 
-    #if PY_VERSION_HEX >= 0x030700A3
-    tmp_type = tstate->exc_state.exc_type;
-    tmp_value = tstate->exc_state.exc_value;
-    tmp_tb = tstate->exc_state.exc_traceback;
+    #if CYTHON_USE_EXC_INFO_STACK
+    _PyErr_StackItem *exc_info = tstate->exc_info;
+    tmp_type = exc_info->exc_type;
+    tmp_value = exc_info->exc_value;
+    tmp_tb = exc_info->exc_traceback;
 
-    tstate->exc_state.exc_type = *type;
-    tstate->exc_state.exc_value = *value;
-    tstate->exc_state.exc_traceback = *tb;
+    exc_info->exc_type = *type;
+    exc_info->exc_value = *value;
+    exc_info->exc_traceback = *tb;
     #else
     tmp_type = tstate->exc_type;
     tmp_value = tstate->exc_value;

Cython/Utility/ModuleSetupCode.c

@@ -81,6 +81,8 @@
   #define CYTHON_USE_TP_FINALIZE 0
   #undef CYTHON_USE_DICT_VERSIONS
   #define CYTHON_USE_DICT_VERSIONS 0
+  #undef CYTHON_USE_EXC_INFO_STACK
+  #define CYTHON_USE_EXC_INFO_STACK 0
 
 #elif defined(PYSTON_VERSION)
   #define CYTHON_COMPILING_IN_PYPY 0
@@ -122,6 +124,8 @@
   #define CYTHON_USE_TP_FINALIZE 0
   #undef CYTHON_USE_DICT_VERSIONS
   #define CYTHON_USE_DICT_VERSIONS 0
+  #undef CYTHON_USE_EXC_INFO_STACK
+  #define CYTHON_USE_EXC_INFO_STACK 0
 
 #else
   #define CYTHON_COMPILING_IN_PYPY 0
@@ -186,6 +190,9 @@
   #ifndef CYTHON_USE_DICT_VERSIONS
     #define CYTHON_USE_DICT_VERSIONS (PY_VERSION_HEX >= 0x030600B1)
   #endif
+  #ifndef CYTHON_USE_EXC_INFO_STACK
+    #define CYTHON_USE_EXC_INFO_STACK (PY_VERSION_HEX >= 0x030700A3)
+  #endif
 #endif
 
 #if !defined(CYTHON_FAST_PYCCALL)

runtests.py

@@ -145,6 +145,7 @@ EXT_DEP_MODULES = {
     'Coverage':     'Cython.Coverage',
     'tag:ipython':  'IPython.testing.globalipapp',
     'tag:jedi':     'jedi_BROKEN_AND_DISABLED',
+    'tag:test.support': 'test.support',  # support module for CPython unit tests
 }
 
 def patch_inspect_isfunction():
@@ -433,6 +434,7 @@ VER_DEP_MODULES = {
                                          'run.py35_asyncio_async_def',
                                          'run.mod__spec__',
                                          'run.pep526_variable_annotations',  # typing module
+                                         'run.test_exceptions',  # copied from Py3.7+
                                          ]),
 }
 

tests/run/test_exceptions.pyx

+# Python test set -- part 5, built-in exceptions
+# Copied from CPython 3.7.
+
+# cython: language_level=3
+# mode: run
+# tag: generator, exception, tryfinally, tryexcept, test.support
+
+import copy
+import os
+import sys
+import unittest
+import pickle
+import weakref
+import errno
+
+from test.support import (TESTFN, captured_stderr, check_impl_detail,
+                          check_warnings, gc_collect,
+                          # no_tracing, cpython_only,
+                          unlink, import_module, script_helper,
+                          SuppressCrashReport)
+
+no_tracing = unittest.skip("For nested functions, Cython generates a C call without recursion checks.")
+
+cpython_only = unittest.skip("Tests for _testcapi make no sense here.")
+
+
+class NaiveException(Exception):
+    def __init__(self, x):
+        self.x = x
+
+class SlottedNaiveException(Exception):
+    __slots__ = ('x',)
+    def __init__(self, x):
+        self.x = x
+
+class BrokenStrException(Exception):
+    def __str__(self):
+        raise Exception("str() is broken")
+
+# XXX This is not really enough, each *operation* should be tested!
+
+class ExceptionTests(unittest.TestCase):
+
+    def raise_catch(self, exc, excname):
+        try:
+            raise exc("spam")
+        except exc as err:
+            buf1 = str(err)
+        try:
+            raise exc("spam")
+        except exc as err:
+            buf2 = str(err)
+        self.assertEqual(buf1, buf2)
+        self.assertEqual(exc.__name__, excname)
+
+    def testRaising(self):
+        self.raise_catch(AttributeError, "AttributeError")
+        self.assertRaises(AttributeError, getattr, sys, "undefined_attribute")
+
+        self.raise_catch(EOFError, "EOFError")
+        fp = open(TESTFN, 'w')
+        fp.close()
+        fp = open(TESTFN, 'r')
+        savestdin = sys.stdin
+        try:
+            try:
+                import marshal
+                marshal.loads(b'')
+            except EOFError:
+                pass
+        finally:
+            sys.stdin = savestdin
+            fp.close()
+            unlink(TESTFN)
+
+        self.raise_catch(OSError, "OSError")
+        self.assertRaises(OSError, open, 'this file does not exist', 'r')
+
+        self.raise_catch(ImportError, "ImportError")
+        self.assertRaises(ImportError, __import__, "undefined_module")
+
+        self.raise_catch(IndexError, "IndexError")
+        x = []
+        self.assertRaises(IndexError, x.__getitem__, 10)
+
+        self.raise_catch(KeyError, "KeyError")
+        x = {}
+        self.assertRaises(KeyError, x.__getitem__, 'key')
+
+        self.raise_catch(KeyboardInterrupt, "KeyboardInterrupt")
+
+        self.raise_catch(MemoryError, "MemoryError")
+
+        self.raise_catch(NameError, "NameError")
+        #try: x = undefined_variable
+        #except NameError: pass
+
+        self.raise_catch(OverflowError, "OverflowError")
+        x = 1
+        for dummy in range(128):
+            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')
+        except SyntaxError: pass
+
+        self.raise_catch(IndentationError, "IndentationError")
+
+        self.raise_catch(TabError, "TabError")
+        try: compile("try:\n\t1/0\n    \t1/0\nfinally:\n pass\n",
+                     '<string>', 'exec')
+        except TabError: pass
+        else: self.fail("TabError not raised")
+
+        self.raise_catch(SystemError, "SystemError")
+
+        self.raise_catch(SystemExit, "SystemExit")
+        self.assertRaises(SystemExit, sys.exit, 0)
+
+        self.raise_catch(TypeError, "TypeError")
+        try: [] + ()
+        except TypeError: pass
+
+        self.raise_catch(ValueError, "ValueError")
+        self.assertRaises(ValueError, chr, 17<<16)
+
+        self.raise_catch(ZeroDivisionError, "ZeroDivisionError")
+        try: x = 1/0
+        except ZeroDivisionError: pass
+
+        self.raise_catch(Exception, "Exception")
+        try: x = 1/0
+        except Exception as e: pass
+
+        self.raise_catch(StopAsyncIteration, "StopAsyncIteration")
+
+    def testSyntaxErrorMessage(self):
+        # make sure the right exception message is raised for each of
+        # these code fragments
+
+        def ckmsg(src, msg):
+            try:
+                compile(src, '<fragment>', 'exec')
+            except SyntaxError as e:
+                if e.msg != msg:
+                    self.fail("expected %s, got %s" % (msg, e.msg))
+            else:
+                self.fail("failed to get expected SyntaxError")
+
+        s = '''if 1:
+        try:
+            continue
+        except:
+            pass'''
+
+        ckmsg(s, "'continue' not properly in loop")
+        ckmsg("continue\n", "'continue' not properly in loop")
+
+    def testSyntaxErrorMissingParens(self):
+        def ckmsg(src, msg, exception=SyntaxError):
+            try:
+                compile(src, '<fragment>', 'exec')
+            except exception as e:
+                if e.msg != msg and sys.version_info >= (3, 6):
+                    self.fail("expected %s, got %s" % (msg, e.msg))
+            else:
+                self.fail("failed to get expected SyntaxError")
+
+        s = '''print "old style"'''
+        ckmsg(s, "Missing parentheses in call to 'print'. "
+                 "Did you mean print(\"old style\")?")
+
+        s = '''print "old style",'''
+        ckmsg(s, "Missing parentheses in call to 'print'. "
+                 "Did you mean print(\"old style\", end=\" \")?")
+
+        s = '''exec "old style"'''
+        ckmsg(s, "Missing parentheses in call to 'exec'")
+
+        # should not apply to subclasses, see issue #31161
+        s = '''if True:\nprint "No indent"'''
+        ckmsg(s, "expected an indented block", IndentationError)
+
+        s = '''if True:\n        print()\n\texec "mixed tabs and spaces"'''
+        ckmsg(s, "inconsistent use of tabs and spaces in indentation", TabError)
+
+    def testSyntaxErrorOffset(self):
+        def check(src, lineno, offset):
+            with self.assertRaises(SyntaxError) as cm:
+                compile(src, '<fragment>', 'exec')
+            self.assertEqual(cm.exception.lineno, lineno)
+            self.assertEqual(cm.exception.offset, offset)
+
+        check('def fact(x):\n\treturn x!\n', 2, 10)
+        check('1 +\n', 1, 4)
+        check('def spam():\n  print(1)\n print(2)', 3, 10)
+        check('Python = "Python" +', 1, 20)
+        check('Python = "\u1e54\xfd\u0163\u0125\xf2\xf1" +', 1, 20)
+
+    @cpython_only
+    def testSettingException(self):
+        # test that setting an exception at the C level works even if the
+        # exception object can't be constructed.
+
+        class BadException(Exception):
+            def __init__(self_):
+                raise RuntimeError("can't instantiate BadException")
+
+        class InvalidException:
+            pass
+
+        def test_capi1():
+            import _testcapi
+            try:
+                _testcapi.raise_exception(BadException, 1)
+            except TypeError as err:
+                exc, err, tb = sys.exc_info()
+                co = tb.tb_frame.f_code
+                self.assertEqual(co.co_name, "test_capi1")
+                self.assertTrue(co.co_filename.endswith('test_exceptions.py'))
+            else:
+                self.fail("Expected exception")
+
+        def test_capi2():
+            import _testcapi
+            try:
+                _testcapi.raise_exception(BadException, 0)
+            except RuntimeError as err:
+                exc, err, tb = sys.exc_info()
+                co = tb.tb_frame.f_code
+                self.assertEqual(co.co_name, "__init__")
+                self.assertTrue(co.co_filename.endswith('test_exceptions.py'))
+                co2 = tb.tb_frame.f_back.f_code
+                self.assertEqual(co2.co_name, "test_capi2")
+            else:
+                self.fail("Expected exception")
+
+        def test_capi3():
+            import _testcapi
+            self.assertRaises(SystemError, _testcapi.raise_exception,
+                              InvalidException, 1)
+
+        if not sys.platform.startswith('java'):
+            test_capi1()
+            test_capi2()
+            test_capi3()
+
+    def test_WindowsError(self):
+        try:
+            WindowsError
+        except NameError:
+            pass
+        else:
+            self.assertIs(WindowsError, OSError)
+            self.assertEqual(str(OSError(1001)), "1001")
+            self.assertEqual(str(OSError(1001, "message")),
+                             "[Errno 1001] message")
+            # POSIX errno (9 aka EBADF) is untranslated
+            w = OSError(9, 'foo', 'bar')
+            self.assertEqual(w.errno, 9)
+            self.assertEqual(w.winerror, None)
+            self.assertEqual(str(w), "[Errno 9] foo: 'bar'")
+            # ERROR_PATH_NOT_FOUND (win error 3) becomes ENOENT (2)
+            w = OSError(0, 'foo', 'bar', 3)
+            self.assertEqual(w.errno, 2)
+            self.assertEqual(w.winerror, 3)
+            self.assertEqual(w.strerror, 'foo')
+            self.assertEqual(w.filename, 'bar')
+            self.assertEqual(w.filename2, None)
+            self.assertEqual(str(w), "[WinError 3] foo: 'bar'")
+            # Unknown win error becomes EINVAL (22)
+            w = OSError(0, 'foo', None, 1001)
+            self.assertEqual(w.errno, 22)
+            self.assertEqual(w.winerror, 1001)
+            self.assertEqual(w.strerror, 'foo')
+            self.assertEqual(w.filename, None)
+            self.assertEqual(w.filename2, None)
+            self.assertEqual(str(w), "[WinError 1001] foo")
+            # Non-numeric "errno"
+            w = OSError('bar', 'foo')
+            self.assertEqual(w.errno, 'bar')
+            self.assertEqual(w.winerror, None)
+            self.assertEqual(w.strerror, 'foo')
+            self.assertEqual(w.filename, None)
+            self.assertEqual(w.filename2, None)
+
+    @unittest.skipUnless(sys.platform == 'win32',
+                         'test specific to Windows')
+    def test_windows_message(self):
+        """Should fill in unknown error code in Windows error message"""
+        ctypes = import_module('ctypes')
+        # this error code has no message, Python formats it as hexadecimal
+        code = 3765269347
+        with self.assertRaisesRegex(OSError, 'Windows Error 0x%x' % code):
+            ctypes.pythonapi.PyErr_SetFromWindowsErr(code)
+
+    def testAttributes(self):
+        # test that exception attributes are happy
+
+        exceptionList = [
+            (BaseException, (), {'args' : ()}),
+            (BaseException, (1, ), {'args' : (1,)}),
+            (BaseException, ('foo',),
+                {'args' : ('foo',)}),
+            (BaseException, ('foo', 1),
+                {'args' : ('foo', 1)}),
+            (SystemExit, ('foo',),
+                {'args' : ('foo',), 'code' : 'foo'}),
+            (OSError, ('foo',),
+                {'args' : ('foo',), 'filename' : None, 'filename2' : None,
+                 'errno' : None, 'strerror' : None}),
+            (OSError, ('foo', 'bar'),
+                {'args' : ('foo', 'bar'),
+                 'filename' : None, 'filename2' : None,
+                 'errno' : 'foo', 'strerror' : 'bar'}),
+            (OSError, ('foo', 'bar', 'baz'),
+                {'args' : ('foo', 'bar'),
+                 'filename' : 'baz', 'filename2' : None,
+                 'errno' : 'foo', 'strerror' : 'bar'}),
+            (OSError, ('foo', 'bar', 'baz', None, 'quux'),
+                {'args' : ('foo', 'bar'), 'filename' : 'baz', 'filename2': 'quux'}),
+            (OSError, ('errnoStr', 'strErrorStr', 'filenameStr'),
+                {'args' : ('errnoStr', 'strErrorStr'),
+                 'strerror' : 'strErrorStr', 'errno' : 'errnoStr',
+                 'filename' : 'filenameStr'}),
+            (OSError, (1, 'strErrorStr', 'filenameStr'),
+                {'args' : (1, 'strErrorStr'), 'errno' : 1,
+                 'strerror' : 'strErrorStr',
+                 'filename' : 'filenameStr', 'filename2' : None}),
+            (SyntaxError, (), {'msg' : None, 'text' : None,
+                'filename' : None, 'lineno' : None, 'offset' : None,
+                'print_file_and_line' : None}),
+            (SyntaxError, ('msgStr',),
+                {'args' : ('msgStr',), 'text' : None,
+                 'print_file_and_line' : None, 'msg' : 'msgStr',
+                 'filename' : None, 'lineno' : None, 'offset' : None}),
+            (SyntaxError, ('msgStr', ('filenameStr', 'linenoStr', 'offsetStr',
+                           'textStr')),
+                {'offset' : 'offsetStr', 'text' : 'textStr',
+                 'args' : ('msgStr', ('filenameStr', 'linenoStr',
+                                      'offsetStr', 'textStr')),
+                 'print_file_and_line' : None, 'msg' : 'msgStr',
+                 'filename' : 'filenameStr', 'lineno' : 'linenoStr'}),
+            (SyntaxError, ('msgStr', 'filenameStr', 'linenoStr', 'offsetStr',
+                           'textStr', 'print_file_and_lineStr'),
+                {'text' : None,
+                 'args' : ('msgStr', 'filenameStr', 'linenoStr', 'offsetStr',
+                           'textStr', 'print_file_and_lineStr'),
+                 'print_file_and_line' : None, 'msg' : 'msgStr',
+                 'filename' : None, 'lineno' : None, 'offset' : None}),
+            (UnicodeError, (), {'args' : (),}),
+            (UnicodeEncodeError, ('ascii', 'a', 0, 1,
+                                  'ordinal not in range'),
+                {'args' : ('ascii', 'a', 0, 1,
+                                           'ordinal not in range'),
+                 'encoding' : 'ascii', 'object' : 'a',
+                 'start' : 0, 'reason' : 'ordinal not in range'}),
+            (UnicodeDecodeError, ('ascii', bytearray(b'\xff'), 0, 1,
+                                  'ordinal not in range'),
+                {'args' : ('ascii', bytearray(b'\xff'), 0, 1,
+                                           'ordinal not in range'),
+                 'encoding' : 'ascii', 'object' : b'\xff',
+                 'start' : 0, 'reason' : 'ordinal not in range'}),
+            (UnicodeDecodeError, ('ascii', b'\xff', 0, 1,
+                                  'ordinal not in range'),
+                {'args' : ('ascii', b'\xff', 0, 1,
+                                           'ordinal not in range'),
+                 'encoding' : 'ascii', 'object' : b'\xff',
+                 'start' : 0, 'reason' : 'ordinal not in range'}),
+            (UnicodeTranslateError, ("\u3042", 0, 1, "ouch"),
+                {'args' : ('\u3042', 0, 1, 'ouch'),
+                 'object' : '\u3042', 'reason' : 'ouch',
+                 'start' : 0, 'end' : 1}),
+            (NaiveException, ('foo',),
+                {'args': ('foo',), 'x': 'foo'}),
+            (SlottedNaiveException, ('foo',),
+                {'args': ('foo',), 'x': 'foo'}),
+        ]
+        try:
+            # More tests are in test_WindowsError
+            exceptionList.append(
+                (WindowsError, (1, 'strErrorStr', 'filenameStr'),
+                    {'args' : (1, 'strErrorStr'),
+                     'strerror' : 'strErrorStr', 'winerror' : None,
+                     'errno' : 1,
+                     'filename' : 'filenameStr', 'filename2' : None})
+            )
+        except NameError:
+            pass
+
+        for exc, args, expected in exceptionList:
+            try:
+                e = exc(*args)
+            except:
+                print("\nexc=%r, args=%r" % (exc, args), file=sys.stderr)
+                raise
+            else:
+                # Verify module name
+                if not type(e).__name__.endswith('NaiveException'):
+                    self.assertEqual(type(e).__module__, 'builtins')
+                # Verify no ref leaks in Exc_str()
+                s = str(e)
+                for checkArgName in expected:
+                    value = getattr(e, checkArgName)
+                    self.assertEqual(repr(value),
+                                     repr(expected[checkArgName]),
+                                     '%r.%s == %r, expected %r' % (
+                                     e, checkArgName,
+                                     value, expected[checkArgName]))
+
+                # test for pickling support
+                for p in [pickle]:
+                    for protocol in range(p.HIGHEST_PROTOCOL + 1):
+                        s = p.dumps(e, protocol)
+                        new = p.loads(s)
+                        for checkArgName in expected:
+                            got = repr(getattr(new, checkArgName))
+                            want = repr(expected[checkArgName])
+                            self.assertEqual(got, want,
+                                             'pickled "%r", attribute "%s' %
+                                             (e, checkArgName))
+
+    def testWithTraceback(self):
+        try:
+            raise IndexError(4)
+        except:
+            tb = sys.exc_info()[2]
+
+        e = BaseException().with_traceback(tb)
+        self.assertIsInstance(e, BaseException)
+        self.assertEqual(e.__traceback__, tb)
+
+        e = IndexError(5).with_traceback(tb)
+        self.assertIsInstance(e, IndexError)
+        self.assertEqual(e.__traceback__, tb)
+
+        class MyException(Exception):
+            pass
+
+        e = MyException().with_traceback(tb)
+        self.assertIsInstance(e, MyException)
+        self.assertEqual(e.__traceback__, tb)
+
+    def testInvalidTraceback(self):
+        try:
+            Exception().__traceback__ = 5
+        except TypeError as e:
+            self.assertIn("__traceback__ must be a traceback", str(e))
+        else:
+            self.fail("No exception raised")
+
+    def testInvalidAttrs(self):
+        self.assertRaises(TypeError, setattr, Exception(), '__cause__', 1)
+        self.assertRaises(TypeError, delattr, Exception(), '__cause__')
+        self.assertRaises(TypeError, setattr, Exception(), '__context__', 1)
+        self.assertRaises(TypeError, delattr, Exception(), '__context__')
+
+    def testNoneClearsTracebackAttr(self):
+        try:
+            raise IndexError(4)
+        except:
+            tb = sys.exc_info()[2]
+
+        e = Exception()
+        e.__traceback__ = tb
+        e.__traceback__ = None
+        self.assertEqual(e.__traceback__, None)
+
+    def testChainingAttrs(self):
+        e = Exception()
+        self.assertIsNone(e.__context__)
+        self.assertIsNone(e.__cause__)
+
+        e = TypeError()
+        self.assertIsNone(e.__context__)
+        self.assertIsNone(e.__cause__)
+
+        class MyException(OSError):
+            pass
+
+        e = MyException()
+        self.assertIsNone(e.__context__)
+        self.assertIsNone(e.__cause__)
+
+    def testChainingDescriptors(self):
+        try:
+            raise Exception()
+        except Exception as exc:
+            e = exc
+
+        self.assertIsNone(e.__context__)
+        self.assertIsNone(e.__cause__)
+        self.assertFalse(e.__suppress_context__)
+
+        e.__context__ = NameError()
+        e.__cause__ = None
+        self.assertIsInstance(e.__context__, NameError)
+        self.assertIsNone(e.__cause__)
+        self.assertTrue(e.__suppress_context__)
+        e.__suppress_context__ = False
+        self.assertFalse(e.__suppress_context__)
+
+    def testKeywordArgs(self):
+        # test that builtin exception don't take keyword args,
+        # but user-defined subclasses can if they want
+        self.assertRaises(TypeError, BaseException, a=1)
+
+        class DerivedException(BaseException):
+            def __init__(self, fancy_arg):
+                BaseException.__init__(self)
+                self.fancy_arg = fancy_arg
+
+        x = DerivedException(fancy_arg=42)
+        self.assertEqual(x.fancy_arg, 42)
+
+    @no_tracing
+    def testInfiniteRecursion(self):
+        def f():
+            return f()
+        self.assertRaises(RecursionError, f)
+
+        def g():
+            try:
+                return g()
+            except ValueError:
+                return -1
+        self.assertRaises(RecursionError, g)
+
+    def test_str(self):
+        # Make sure both instances and classes have a str representation.
+        self.assertTrue(str(Exception))
+        self.assertTrue(str(Exception('a')))
+        self.assertTrue(str(Exception('a', 'b')))
+
+    def testExceptionCleanupNames(self):
+        # Make sure the local variable bound to the exception instance by
+        # an "except" statement is only visible inside the except block.
+        try:
+            raise Exception()
+        except Exception as e:
+            self.assertTrue(e)
+            del e
+        self.assertNotIn('e', locals())
+
+    def testExceptionCleanupState(self):
+        # Make sure exception state is cleaned up as soon as the except
+        # block is left. See #2507
+
+        class MyException(Exception):
+            def __init__(self, obj):
+                self.obj = obj
+        class MyObj:
+            pass
+
+        def inner_raising_func():
+            # Create some references in exception value and traceback
+            local_ref = obj
+            raise MyException(obj)
+
+        # Qualified "except" with "as"
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        try:
+            inner_raising_func()
+        except MyException as e:
+            pass
+        obj = None
+        obj = wr()
+        self.assertIsNone(obj)
+
+        # Qualified "except" without "as"
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        try:
+            inner_raising_func()
+        except MyException:
+            pass
+        obj = None
+        obj = wr()
+        self.assertIsNone(obj)
+
+        # Bare "except"
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        try:
+            inner_raising_func()
+        except:
+            pass
+        obj = None
+        obj = wr()
+        self.assertIsNone(obj)
+
+        # "except" with premature block leave
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        for i in [0]:
+            try:
+                inner_raising_func()
+            except:
+                break
+        obj = None
+        obj = wr()
+        self.assertIsNone(obj)
+
+        # "except" block raising another exception
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        try:
+            try:
+                inner_raising_func()
+            except:
+                raise KeyError
+        except KeyError as e:
+            # We want to test that the except block above got rid of
+            # the exception raised in inner_raising_func(), but it
+            # also ends up in the __context__ of the KeyError, so we
+            # must clear the latter manually for our test to succeed.
+            e.__context__ = None
+            obj = None
+            obj = wr()
+            # guarantee no ref cycles on CPython (don't gc_collect)
+            if check_impl_detail(cpython=False):
+                gc_collect()
+            self.assertIsNone(obj)
+
+        # Some complicated construct
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        try:
+            inner_raising_func()
+        except MyException:
+            try:
+                try:
+                    raise
+                finally:
+                    raise
+            except MyException:
+                pass
+        obj = None
+        if check_impl_detail(cpython=False):
+            gc_collect()
+        obj = wr()
+        self.assertIsNone(obj)
+
+        # Inside an exception-silencing "with" block
+        class Context:
+            def __enter__(self):
+                return self
+            def __exit__ (self, exc_type, exc_value, exc_tb):
+                return True
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        with Context():
+            inner_raising_func()
+        obj = None
+        if check_impl_detail(cpython=False):
+            gc_collect()
+        obj = wr()
+        self.assertIsNone(obj)
+
+    '''
+    # This is currently a compile error in Cython-3, although it works in Cython-2 => could also work in Cy-3.
+    def test_exception_target_in_nested_scope(self):
+        # issue 4617: This used to raise a SyntaxError
+        # "can not delete variable 'e' referenced in nested scope"
+        def print_error():
+            e
+        try:
+            1/0
+        except Exception as e:
+            print_error()
+            # implicit "del e" here
+    '''
+
+    def test_generator_leaking(self):
+        # Test that generator exception state doesn't leak into the calling
+        # frame
+        def yield_raise():
+            try:
+                raise KeyError("caught")
+            except KeyError:
+                yield sys.exc_info()[0]
+                yield sys.exc_info()[0]
+            yield sys.exc_info()[0]
+        g = yield_raise()
+        self.assertEqual(next(g), KeyError)
+        self.assertEqual(sys.exc_info()[0], None)
+        self.assertEqual(next(g), KeyError)
+        self.assertEqual(sys.exc_info()[0], None)
+        self.assertEqual(next(g), None)
+
+        # Same test, but inside an exception handler
+        try:
+            raise TypeError("foo")
+        except TypeError:
+            g = yield_raise()
+            self.assertEqual(next(g), KeyError)
+            self.assertEqual(sys.exc_info()[0], TypeError)
+            self.assertEqual(next(g), KeyError)
+            self.assertEqual(sys.exc_info()[0], TypeError)
+            self.assertEqual(next(g), TypeError)
+            del g
+            self.assertEqual(sys.exc_info()[0], TypeError)
+
+    def test_generator_leaking2(self):
+        # See issue 12475.
+        def g():
+            yield
+        try:
+            raise RuntimeError
+        except RuntimeError:
+            it = g()
+            next(it)
+        try:
+            next(it)
+        except StopIteration:
+            pass
+        self.assertEqual(sys.exc_info(), (None, None, None))
+
+    def test_generator_leaking3(self):
+        # See issue #23353.  When gen.throw() is called, the caller's
+        # exception state should be save and restored.
+        def g():
+            try:
+                yield
+            except ZeroDivisionError:
+                yield sys.exc_info()[1]
+        it = g()
+        next(it)
+        try:
+            1/0
+        except ZeroDivisionError as e:
+            self.assertIs(sys.exc_info()[1], e)
+            gen_exc = it.throw(e)
+            self.assertIs(sys.exc_info()[1], e)
+            self.assertIs(gen_exc, e)
+        self.assertEqual(sys.exc_info(), (None, None, None))
+
+    def test_generator_leaking4(self):
+        # See issue #23353.  When an exception is raised by a generator,
+        # the caller's exception state should still be restored.
+        def g():
+            try:
+                1/0
+            except ZeroDivisionError:
+                yield sys.exc_info()[0]
+                raise
+        it = g()
+        try:
+            raise TypeError
+        except TypeError:
+            # The caller's exception state (TypeError) is temporarily
+            # saved in the generator.
+            tp = next(it)
+        self.assertIs(tp, ZeroDivisionError)
+        try:
+            next(it)
+            # We can't check it immediately, but while next() returns
+            # with an exception, it shouldn't have restored the old
+            # exception state (TypeError).
+        except ZeroDivisionError as e:
+            self.assertIs(sys.exc_info()[1], e)
+        # We used to find TypeError here.
+        self.assertEqual(sys.exc_info(), (None, None, None))
+
+    def test_generator_doesnt_retain_old_exc(self):
+        def g():
+            self.assertIsInstance(sys.exc_info()[1], RuntimeError)
+            yield
+            self.assertEqual(sys.exc_info(), (None, None, None))
+        it = g()
+        try:
+            raise RuntimeError
+        except RuntimeError:
+            next(it)
+        self.assertRaises(StopIteration, next, it)
+
+    def test_generator_finalizing_and_exc_info(self):
+        # See #7173
+        def simple_gen():
+            yield 1
+        def run_gen():
+            gen = simple_gen()
+            try:
+                raise RuntimeError
+            except RuntimeError:
+                return next(gen)
+        run_gen()
+        gc_collect()
+        self.assertEqual(sys.exc_info(), (None, None, None))
+
+    def _check_generator_cleanup_exc_state(self, testfunc):
+        # Issue #12791: exception state is cleaned up as soon as a generator
+        # is closed (reference cycles are broken).
+        class MyException(Exception):
+            def __init__(self, obj):
+                self.obj = obj
+        class MyObj:
+            pass
+
+        def raising_gen():
+            try:
+                raise MyException(obj)
+            except MyException:
+                yield
+
+        obj = MyObj()
+        wr = weakref.ref(obj)
+        g = raising_gen()
+        next(g)
+        testfunc(g)
+        g = obj = None
+        obj = wr()
+        self.assertIsNone(obj)
+
+    def test_generator_throw_cleanup_exc_state(self):
+        def do_throw(g):
+            try:
+                g.throw(RuntimeError())
+            except RuntimeError:
+                pass
+        self._check_generator_cleanup_exc_state(do_throw)
+
+    def test_generator_close_cleanup_exc_state(self):
+        def do_close(g):
+            g.close()
+        self._check_generator_cleanup_exc_state(do_close)
+
+    def test_generator_del_cleanup_exc_state(self):
+        def do_del(g):
+            g = None
+        self._check_generator_cleanup_exc_state(do_del)
+
+    def test_generator_next_cleanup_exc_state(self):
+        def do_next(g):
+            try:
+                next(g)
+            except StopIteration:
+                pass
+            else:
+                self.fail("should have raised StopIteration")
+        self._check_generator_cleanup_exc_state(do_next)
+
+    def test_generator_send_cleanup_exc_state(self):
+        def do_send(g):
+            try:
+                g.send(None)
+            except StopIteration:
+                pass
+            else:
+                self.fail("should have raised StopIteration")
+        self._check_generator_cleanup_exc_state(do_send)
+
+    def test_3114(self):
+        # Bug #3114: in its destructor, MyObject retrieves a pointer to
+        # obsolete and/or deallocated objects.
+        class MyObject:
+            def __del__(self):
+                nonlocal e
+                e = sys.exc_info()
+        e = ()
+        try:
+            raise Exception(MyObject())
+        except:
+            pass
+        self.assertEqual(e, (None, None, None))
+
+    def test_unicode_change_attributes(self):
+        # See issue 7309. This was a crasher.
+
+        u = UnicodeEncodeError('baz', 'xxxxx', 1, 5, 'foo')
+        self.assertEqual(str(u), "'baz' codec can't encode characters in position 1-4: foo")
+        u.end = 2
+        self.assertEqual(str(u), "'baz' codec can't encode character '\\x78' in position 1: foo")
+        u.end = 5
+        u.reason = 0x345345345345345345
+        self.assertEqual(str(u), "'baz' codec can't encode characters in position 1-4: 965230951443685724997")
+        u.encoding = 4000
+        self.assertEqual(str(u), "'4000' codec can't encode characters in position 1-4: 965230951443685724997")
+        u.start = 1000
+        self.assertEqual(str(u), "'4000' codec can't encode characters in position 1000-4: 965230951443685724997")
+
+        u = UnicodeDecodeError('baz', b'xxxxx', 1, 5, 'foo')
+        self.assertEqual(str(u), "'baz' codec can't decode bytes in position 1-4: foo")
+        u.end = 2
+        self.assertEqual(str(u), "'baz' codec can't decode byte 0x78 in position 1: foo")
+        u.end = 5
+        u.reason = 0x345345345345345345
+        self.assertEqual(str(u), "'baz' codec can't decode bytes in position 1-4: 965230951443685724997")
+        u.encoding = 4000
+        self.assertEqual(str(u), "'4000' codec can't decode bytes in position 1-4: 965230951443685724997")
+        u.start = 1000
+        self.assertEqual(str(u), "'4000' codec can't decode bytes in position 1000-4: 965230951443685724997")
+
+        u = UnicodeTranslateError('xxxx', 1, 5, 'foo')
+        self.assertEqual(str(u), "can't translate characters in position 1-4: foo")
+        u.end = 2
+        self.assertEqual(str(u), "can't translate character '\\x78' in position 1: foo")
+        u.end = 5
+        u.reason = 0x345345345345345345
+        self.assertEqual(str(u), "can't translate characters in position 1-4: 965230951443685724997")
+        u.start = 1000
+        self.assertEqual(str(u), "can't translate characters in position 1000-4: 965230951443685724997")
+
+    def test_unicode_errors_no_object(self):
+        # See issue #21134.
+        klasses = UnicodeEncodeError, UnicodeDecodeError, UnicodeTranslateError
+        for klass in klasses:
+            self.assertEqual(str(klass.__new__(klass)), "")
+
+    @no_tracing
+    def test_badisinstance(self):
+        # Bug #2542: if issubclass(e, MyException) raises an exception,
+        # it should be ignored
+        class Meta(type):
+            def __subclasscheck__(cls, subclass):
+                raise ValueError()
+        class MyException(Exception, metaclass=Meta):
+            pass
+
+        with captured_stderr() as stderr:
+            try:
+                raise KeyError()
+            except MyException as e:
+                self.fail("exception should not be a MyException")
+            except KeyError:
+                pass
+            except:
+                self.fail("Should have raised KeyError")
+            else:
+                self.fail("Should have raised KeyError")
+
+        def g():
+            try:
+                return g()
+            except RecursionError:
+                return sys.exc_info()
+        e, v, tb = g()
+        self.assertIsInstance(v, RecursionError, type(v))
+        self.assertIn("maximum recursion depth exceeded", str(v))
+
+    @cpython_only
+    def test_recursion_normalizing_exception(self):
+        # Issue #22898.
+        # Test that a RecursionError is raised when tstate->recursion_depth is
+        # equal to recursion_limit in PyErr_NormalizeException() and check
+        # that a ResourceWarning is printed.
+        # Prior to #22898, the recursivity of PyErr_NormalizeException() was
+        # controlled by tstate->recursion_depth and a PyExc_RecursionErrorInst
+        # singleton was being used in that case, that held traceback data and
+        # locals indefinitely and would cause a segfault in _PyExc_Fini() upon
+        # finalization of these locals.
+        code = """if 1:
+            import sys
+            from _testcapi import get_recursion_depth
+
+            class MyException(Exception): pass
+
+            def setrecursionlimit(depth):
+                while 1:
+                    try:
+                        sys.setrecursionlimit(depth)
+                        return depth
+                    except RecursionError:
+                        # sys.setrecursionlimit() raises a RecursionError if
+                        # the new recursion limit is too low (issue #25274).
+                        depth += 1
+
+            def recurse(cnt):
+                cnt -= 1
+                if cnt:
+                    recurse(cnt)
+                else:
+                    generator.throw(MyException)
+
+            def gen():
+                f = open(%a, mode='rb', buffering=0)
+                yield
+
+            generator = gen()
+            next(generator)
+            recursionlimit = sys.getrecursionlimit()
+            depth = get_recursion_depth()
+            try:
+                # Upon the last recursive invocation of recurse(),
+                # tstate->recursion_depth is equal to (recursion_limit - 1)
+                # and is equal to recursion_limit when _gen_throw() calls
+                # PyErr_NormalizeException().
+                recurse(setrecursionlimit(depth + 2) - depth - 1)
+            finally:
+                sys.setrecursionlimit(recursionlimit)
+                print('Done.')
+        """ % __file__
+        rc, out, err = script_helper.assert_python_failure("-Wd", "-c", code)
+        # Check that the program does not fail with SIGABRT.
+        self.assertEqual(rc, 1)
+        self.assertIn(b'RecursionError', err)
+        self.assertIn(b'ResourceWarning', err)
+        self.assertIn(b'Done.', out)
+
+    @cpython_only
+    def test_recursion_normalizing_infinite_exception(self):
+        # Issue #30697. Test that a RecursionError is raised when
+        # PyErr_NormalizeException() maximum recursion depth has been
+        # exceeded.
+        code = """if 1:
+            import _testcapi
+            try:
+                raise _testcapi.RecursingInfinitelyError
+            finally:
+                print('Done.')
+        """
+        rc, out, err = script_helper.assert_python_failure("-c", code)
+        self.assertEqual(rc, 1)
+        self.assertIn(b'RecursionError: maximum recursion depth exceeded '
+                      b'while normalizing an exception', err)
+        self.assertIn(b'Done.', out)
+
+    @cpython_only
+    def test_recursion_normalizing_with_no_memory(self):
+        # Issue #30697. Test that in the abort that occurs when there is no
+        # memory left and the size of the Python frames stack is greater than
+        # the size of the list of preallocated MemoryError instances, the
+        # Fatal Python error message mentions MemoryError.
+        code = """if 1:
+            import _testcapi
+            class C(): pass
+            def recurse(cnt):
+                cnt -= 1
+                if cnt:
+                    recurse(cnt)
+                else:
+                    _testcapi.set_nomemory(0)
+                    C()
+            recurse(16)
+        """
+        with SuppressCrashReport():
+            rc, out, err = script_helper.assert_python_failure("-c", code)
+            self.assertIn(b'Fatal Python error: Cannot recover from '
+                          b'MemoryErrors while normalizing exceptions.', err)
+
+    @cpython_only
+    def test_MemoryError(self):
+        # PyErr_NoMemory always raises the same exception instance.
+        # Check that the traceback is not doubled.
+        import traceback
+        from _testcapi import raise_memoryerror
+        def raiseMemError():
+            try:
+                raise_memoryerror()
+            except MemoryError as e:
+                tb = e.__traceback__
+            else:
+                self.fail("Should have raises a MemoryError")
+            return traceback.format_tb(tb)
+
+        tb1 = raiseMemError()
+        tb2 = raiseMemError()
+        self.assertEqual(tb1, tb2)
+
+    @cpython_only
+    def test_exception_with_doc(self):
+        import _testcapi
+        doc2 = "This is a test docstring."
+        doc4 = "This is another test docstring."
+
+        self.assertRaises(SystemError, _testcapi.make_exception_with_doc,
+                          "error1")
+
+        # test basic usage of PyErr_NewException
+        error1 = _testcapi.make_exception_with_doc("_testcapi.error1")
+        self.assertIs(type(error1), type)
+        self.assertTrue(issubclass(error1, Exception))
+        self.assertIsNone(error1.__doc__)
+
+        # test with given docstring
+        error2 = _testcapi.make_exception_with_doc("_testcapi.error2", doc2)
+        self.assertEqual(error2.__doc__, doc2)
+
+        # test with explicit base (without docstring)
+        error3 = _testcapi.make_exception_with_doc("_testcapi.error3",
+                                                   base=error2)
+        self.assertTrue(issubclass(error3, error2))
+
+        # test with explicit base tuple
+        class C(object):
+            pass
+        error4 = _testcapi.make_exception_with_doc("_testcapi.error4", doc4,
+                                                   (error3, C))
+        self.assertTrue(issubclass(error4, error3))
+        self.assertTrue(issubclass(error4, C))
+        self.assertEqual(error4.__doc__, doc4)
+
+        # test with explicit dictionary
+        error5 = _testcapi.make_exception_with_doc("_testcapi.error5", "",
+                                                   error4, {'a': 1})
+        self.assertTrue(issubclass(error5, error4))
+        self.assertEqual(error5.a, 1)
+        self.assertEqual(error5.__doc__, "")
+
+    @cpython_only
+    def test_memory_error_cleanup(self):
+        # Issue #5437: preallocated MemoryError instances should not keep
+        # traceback objects alive.
+        from _testcapi import raise_memoryerror
+        class C:
+            pass
+        wr = None
+        def inner():
+            nonlocal wr
+            c = C()
+            wr = weakref.ref(c)
+            raise_memoryerror()
+        # We cannot use assertRaises since it manually deletes the traceback
+        try:
+            inner()
+        except MemoryError as e:
+            self.assertNotEqual(wr(), None)
+        else:
+            self.fail("MemoryError not raised")
+        self.assertEqual(wr(), None)
+
+    @no_tracing
+    def test_recursion_error_cleanup(self):
+        # Same test as above, but with "recursion exceeded" errors
+        class C:
+            pass
+        wr = None
+        def inner():
+            nonlocal wr
+            c = C()
+            wr = weakref.ref(c)
+            inner()
+        # We cannot use assertRaises since it manually deletes the traceback
+        try:
+            inner()
+        except RecursionError as e:
+            self.assertNotEqual(wr(), None)
+        else:
+            self.fail("RecursionError not raised")
+        self.assertEqual(wr(), None)
+
+    def test_errno_ENOTDIR(self):
+        # Issue #12802: "not a directory" errors are ENOTDIR even on Windows
+        with self.assertRaises(OSError) as cm:
+            os.listdir(__file__)
+        self.assertEqual(cm.exception.errno, errno.ENOTDIR, cm.exception)
+
+    def test_unraisable(self):
+        # Issue #22836: PyErr_WriteUnraisable() should give sensible reports
+        class BrokenDel:
+            def __del__(self):
+                exc = ValueError("del is broken")
+                # The following line is included in the traceback report:
+                raise exc
+
+        class BrokenExceptionDel:
+            def __del__(self):
+                exc = BrokenStrException()
+                # The following line is included in the traceback report:
+                raise exc
+
+        for test_class in (BrokenDel, BrokenExceptionDel):
+            with self.subTest(test_class):
+                obj = test_class()
+                with captured_stderr() as stderr:
+                    del obj
+                report = stderr.getvalue()
+                self.assertIn("Exception ignored", report)
+                self.assertIn(test_class.__del__.__qualname__, report)
+                self.assertIn("test_exceptions.py", report)
+                self.assertIn("raise exc", report)
+                if test_class is BrokenExceptionDel:
+                    self.assertIn("BrokenStrException", report)
+                    if sys.version_info >= (3, 6):
+                        self.assertIn("<exception str() failed>", report)
+                else:
+                    self.assertIn("ValueError", report)
+                    self.assertIn("del is broken", report)
+                if sys.version_info >= (3, 6):
+                    self.assertTrue(report.endswith("\n"))
+
+    def test_unhandled(self):
+        # Check for sensible reporting of unhandled exceptions
+        for exc_type in (ValueError, BrokenStrException):
+            with self.subTest(exc_type):
+                try:
+                    exc = exc_type("test message")
+                    # The following line is included in the traceback report:
+                    raise exc
+                except exc_type:
+                    with captured_stderr() as stderr:
+                        sys.__excepthook__(*sys.exc_info())
+                report = stderr.getvalue()
+                self.assertIn("test_exceptions.py", report)
+                self.assertIn("raise exc", report)
+                self.assertIn(exc_type.__name__, report)
+                if exc_type is BrokenStrException:
+                    if sys.version_info >= (3, 6):
+                        self.assertIn("<exception str() failed>", report)
+                else:
+                    self.assertIn("test message", report)
+                if sys.version_info >= (3, 6):
+                    self.assertTrue(report.endswith("\n"))
+
+    @cpython_only
+    def test_memory_error_in_PyErr_PrintEx(self):
+        code = """if 1:
+            import _testcapi
+            class C(): pass
+            _testcapi.set_nomemory(0, %d)
+            C()
+        """
+
+        # Issue #30817: Abort in PyErr_PrintEx() when no memory.
+        # Span a large range of tests as the CPython code always evolves with
+        # changes that add or remove memory allocations.
+        for i in range(1, 20):
+            rc, out, err = script_helper.assert_python_failure("-c", code % i)
+            self.assertIn(rc, (1, 120))
+            self.assertIn(b'MemoryError', err)
+
+    def test_yield_in_nested_try_excepts(self):
+        #Issue #25612
+        class MainError(Exception):
+            pass
+
+        class SubError(Exception):
+            pass
+
+        def main():
+            try:
+                raise MainError()
+            except MainError:
+                try:
+                    yield
+                except SubError:
+                    pass
+                raise
+
+        coro = main()
+        coro.send(None)
+        with self.assertRaises(MainError):
+            coro.throw(SubError())
+
+    @unittest.skip('currently fails')  #  FIXME: fails in the "inside" assertion but not "outside"
+    def test_generator_doesnt_retain_old_exc2(self):
+        #Issue 28884#msg282532
+        def g():
+            try:
+                raise ValueError
+            except ValueError:
+                yield 1
+            self.assertEqual(sys.exc_info(), (None, None, None))  # inside
+            yield 2
+
+        gen = g()
+
+        try:
+            raise IndexError
+        except IndexError:
+            self.assertEqual(next(gen), 1)
+        self.assertEqual(sys.exc_info(), (None, None, None))  # outside
+        self.assertEqual(next(gen), 2)
+
+    def test_raise_in_generator(self):
+        #Issue 25612#msg304117
+        def g():
+            yield 1
+            raise
+            yield 2
+
+        with self.assertRaises(ZeroDivisionError):
+            i = g()
+            try:
+                1/0
+            except:
+                next(i)
+                next(i)
+
+
+class ImportErrorTests(unittest.TestCase):
+
+    @unittest.skipIf(sys.version_info < (3, 6), "Requires Py3.6+")
+    def test_attributes(self):
+        # Setting 'name' and 'path' should not be a problem.
+        exc = ImportError('test')
+        self.assertIsNone(exc.name)
+        self.assertIsNone(exc.path)
+
+        exc = ImportError('test', name='somemodule')
+        self.assertEqual(exc.name, 'somemodule')
+        self.assertIsNone(exc.path)
+
+        exc = ImportError('test', path='somepath')
+        self.assertEqual(exc.path, 'somepath')
+        self.assertIsNone(exc.name)
+
+        exc = ImportError('test', path='somepath', name='somename')
+        self.assertEqual(exc.name, 'somename')
+        self.assertEqual(exc.path, 'somepath')
+
+        msg = ("'invalid' is an invalid keyword argument for ImportError"
+               if sys.version_info >= (3, 7) else ".*keyword argument.*")
+        with self.assertRaisesRegex(TypeError, msg):
+            ImportError('test', invalid='keyword')
+
+        with self.assertRaisesRegex(TypeError, msg):
+            ImportError('test', name='name', invalid='keyword')
+
+        with self.assertRaisesRegex(TypeError, msg):
+            ImportError('test', path='path', invalid='keyword')
+
+        with self.assertRaisesRegex(TypeError, msg):
+            ImportError(invalid='keyword')
+
+        with self.assertRaisesRegex(TypeError, msg):
+            ImportError('test', invalid='keyword', another=True)
+
+    @unittest.skipIf(sys.version_info < (3, 7), "requires Py3.7+")
+    def test_reset_attributes(self):
+        exc = ImportError('test', name='name', path='path')
+        self.assertEqual(exc.args, ('test',))
+        self.assertEqual(exc.msg, 'test')
+        self.assertEqual(exc.name, 'name')
+        self.assertEqual(exc.path, 'path')
+
+        # Reset not specified attributes
+        exc.__init__()
+        self.assertEqual(exc.args, ())
+        self.assertEqual(exc.msg, None)
+        self.assertEqual(exc.name, None)
+        self.assertEqual(exc.path, None)
+
+    def test_non_str_argument(self):
+        # Issue #15778
+        with check_warnings(('', BytesWarning), quiet=True):
+            arg = b'abc'
+            exc = ImportError(arg)
+            self.assertEqual(str(arg), str(exc))
+
+    @unittest.skipIf(sys.version_info < (3, 6), "Requires Py3.6+")
+    def test_copy_pickle(self):
+        for kwargs in (dict(),
+                       dict(name='somename'),
+                       dict(path='somepath'),
+                       dict(name='somename', path='somepath')):
+            orig = ImportError('test', **kwargs)
+            for proto in range(pickle.HIGHEST_PROTOCOL + 1):
+                exc = pickle.loads(pickle.dumps(orig, proto))
+                self.assertEqual(exc.args, ('test',))
+                self.assertEqual(exc.msg, 'test')
+                self.assertEqual(exc.name, orig.name)
+                self.assertEqual(exc.path, orig.path)
+            for c in copy.copy, copy.deepcopy:
+                exc = c(orig)
+                self.assertEqual(exc.args, ('test',))
+                self.assertEqual(exc.msg, 'test')
+                self.assertEqual(exc.name, orig.name)
+                self.assertEqual(exc.path, orig.path)
+
+
+if __name__ == '__main__':
+    unittest.main()