From e15fc35df11c27e59140231f52c8a0859c661bf9 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 20:12:33 +0900
Subject: [PATCH 01/12] Move identifiers to function local

---
 Modules/_abc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index 504e23d9a74d3e1..2702bb80a3b250f 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -12,13 +12,7 @@ module _abc
 PyDoc_STRVAR(_abc__doc__,
 "Module contains faster C implementation of abc.ABCMeta");
 
-_Py_IDENTIFIER(__abstractmethods__);
-_Py_IDENTIFIER(__class__);
-_Py_IDENTIFIER(__dict__);
-_Py_IDENTIFIER(__bases__);
 _Py_IDENTIFIER(_abc_impl);
-_Py_IDENTIFIER(__subclasscheck__);
-_Py_IDENTIFIER(__subclasshook__);
 
 /* A global counter that is incremented each time a class is
    registered as a virtual subclass of anything.  It forces the
@@ -258,6 +252,7 @@ _abc__get_dump(PyObject *module, PyObject *self)
 static int
 compute_abstract_methods(PyObject *self)
 {
+    _Py_IDENTIFIER(__abstractmethods__);
     int ret = -1;
     PyObject *abstracts = PyFrozenSet_New(NULL);
     if (abstracts == NULL) {
@@ -267,6 +262,7 @@ compute_abstract_methods(PyObject *self)
     PyObject *ns = NULL, *items = NULL, *bases = NULL;  // Py_XDECREF()ed on error.
 
     /* Stage 1: direct abstract methods. */
+    _Py_IDENTIFIER(__dict__);
     ns = _PyObject_GetAttrId(self, &PyId___dict__);
     if (!ns) {
         goto error;
@@ -311,6 +307,7 @@ compute_abstract_methods(PyObject *self)
     }
 
     /* Stage 2: inherited abstract methods. */
+    _Py_IDENTIFIER(__bases__);
     bases = _PyObject_GetAttrId(self, &PyId___bases__);
     if (!bases) {
         goto error;
@@ -479,12 +476,14 @@ _abc__abc_instancecheck_impl(PyObject *module, PyObject *self,
                              PyObject *instance)
 /*[clinic end generated code: output=b8b5148f63b6b56f input=a4f4525679261084]*/
 {
+    _Py_IDENTIFIER(__subclasscheck__);
     PyObject *subtype, *result = NULL, *subclass = NULL;
     _abc_data *impl = _get_impl(self);
     if (impl == NULL) {
         return NULL;
     }
 
+    _Py_IDENTIFIER(__class__);
     subclass = _PyObject_GetAttrId(instance, &PyId___class__);
     if (subclass == NULL) {
         Py_DECREF(impl);
@@ -608,6 +607,7 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     }
 
     /* 3. Check the subclass hook. */
+    _Py_IDENTIFIER(__subclasshook__);
     ok = _PyObject_CallMethodIdObjArgs((PyObject *)self, &PyId___subclasshook__,
                                        subclass, NULL);
     if (ok == NULL) {

From 868fa3a8b544c52840f17ef2def349a250a2e9e5 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 20:12:56 +0900
Subject: [PATCH 02/12] add test

---
 Lib/test/test_abc.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index af26c1d6b8c5ea6..ff1c93e0c3402c4 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -392,6 +392,13 @@ class MyInt(int):
             self.assertIsInstance(42, A)
             self.assertIsInstance(42, (A,))
 
+        def test_issubclass(self):
+            class A(metaclass=abc_ABCMeta):
+                pass
+            with self.assertRaises(TypeError):
+                issubclass(42, A)
+
+
         def test_all_new_methods_are_called(self):
             class A(metaclass=abc_ABCMeta):
                 pass

From 97ec4e7a11e4a79cba6f4ac3f179501f39c5ab06 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 20:24:24 +0900
Subject: [PATCH 03/12] fix the bug

---
 Modules/_abc.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index 2702bb80a3b250f..e0d89eec1894618 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -637,20 +637,29 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     }
     Py_DECREF(ok);
 
-    /* 4. Check if it's a direct subclass. */
-    mro = ((PyTypeObject *)subclass)->tp_mro;
-    assert(PyTuple_Check(mro));
-    for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
-        PyObject *mro_item = PyTuple_GET_ITEM(mro, pos);
-        if (mro_item == NULL) {
-            goto end;
-        }
-        if ((PyObject *)self == mro_item) {
-            if (_add_to_weak_set(&impl->_abc_cache, subclass) < 0) {
+    /* 4. Check if it's a direct subclass.
+     *
+     * if cls in getattr(subclass, '__mro__', ()):
+     *     cls._abc_cache.add(subclass)
+     *     return True
+     */
+    _Py_IDENTIFIER(__mro__);
+    if (_PyObject_LookupAttrId(subclass, &PyId___mro__, &mro) < 0) {
+        return NULL;
+    }
+    if (mro != NULL && PyTuple_Check(mro)) {
+        for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
+            PyObject *mro_item = PyTuple_GET_ITEM(mro, pos);
+            if (mro_item == NULL) {
+                goto end;
+            }
+            if ((PyObject *)self == mro_item) {
+                if (_add_to_weak_set(&impl->_abc_cache, subclass) < 0) {
+                    goto end;
+                }
+                result = Py_True;
                 goto end;
             }
-            result = Py_True;
-            goto end;
         }
     }
 

From 59998e7e569dbe2ae2906a9fef5f8480a6c7bbcb Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 20:30:23 +0900
Subject: [PATCH 04/12] Add NEWS

---
 .../next/Library/2018-03-06-20-30-20.bpo-32999.lgFXWl.rst       | 2 ++
 1 file changed, 2 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2018-03-06-20-30-20.bpo-32999.lgFXWl.rst

diff --git a/Misc/NEWS.d/next/Library/2018-03-06-20-30-20.bpo-32999.lgFXWl.rst b/Misc/NEWS.d/next/Library/2018-03-06-20-30-20.bpo-32999.lgFXWl.rst
new file mode 100644
index 000000000000000..45e75f939310c6b
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-03-06-20-30-20.bpo-32999.lgFXWl.rst
@@ -0,0 +1,2 @@
+Fix C implemetation of ``ABC.__subclasscheck__(cls, subclass)`` crashed when
+``subclass`` is not a type object.

From b901e1e6315a90a82d4e22e8ced2c279acc58643 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 21:31:48 +0900
Subject: [PATCH 05/12] Fix leak

---
 Modules/_abc.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index e0d89eec1894618..1162758adc8210f 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -567,7 +567,7 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
                              PyObject *subclass)
 /*[clinic end generated code: output=b56c9e4a530e3894 input=1d947243409d10b8]*/
 {
-    PyObject *ok, *mro, *subclasses = NULL, *result = NULL;
+    PyObject *ok, *mro = NULL, *subclasses = NULL, *result = NULL;
     Py_ssize_t pos;
     int incache;
     _abc_data *impl = _get_impl(self);
@@ -645,7 +645,7 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
      */
     _Py_IDENTIFIER(__mro__);
     if (_PyObject_LookupAttrId(subclass, &PyId___mro__, &mro) < 0) {
-        return NULL;
+        goto end;
     }
     if (mro != NULL && PyTuple_Check(mro)) {
         for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
@@ -699,6 +699,7 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     result = Py_False;
 
 end:
+    Py_XDECREF(mro);
     Py_XDECREF(impl);
     Py_XDECREF(subclasses);
     Py_XINCREF(result);

From c06fcaea1c1947b8a3841dd7d86d363d9f5ac62c Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 21:52:24 +0900
Subject: [PATCH 06/12] More corner cases

---
 Lib/test/test_abc.py | 13 ++++++++++++-
 Modules/_abc.c       |  8 +++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index ff1c93e0c3402c4..21c7459360b93fb 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -395,9 +395,20 @@ class MyInt(int):
         def test_issubclass(self):
             class A(metaclass=abc_ABCMeta):
                 pass
+
+            with self.assertRaises(TypeError):
+                issubclass({}, A)  # unhashable
+
             with self.assertRaises(TypeError):
-                issubclass(42, A)
+                issubclass(42, A)  # No __mro__
 
+            # Python version supports any iterable as __mro__.
+            # But it's implementation detail and don't emulate it in C version.
+            class C:
+                __mro__ = 42  # __mro__ is not tuple
+
+            with self.assertRaises(TypeError):
+                self.assertTrue(issubclass(C(), A))
 
         def test_all_new_methods_are_called(self):
             class A(metaclass=abc_ABCMeta):
diff --git a/Modules/_abc.c b/Modules/_abc.c
index 1162758adc8210f..26636db61c53689 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -647,7 +647,13 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     if (_PyObject_LookupAttrId(subclass, &PyId___mro__, &mro) < 0) {
         goto end;
     }
-    if (mro != NULL && PyTuple_Check(mro)) {
+    if (mro != NULL) {
+        if (!PyTuple_Check(mro)) {
+            // Python version supports non-tuple iterable.  Keep it as
+            // implementation detail.
+            PyErr_SetString(PyExc_TypeError, "__mro__ is not a tuple");
+            goto end;
+        }
         for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
             PyObject *mro_item = PyTuple_GET_ITEM(mro, pos);
             if (mro_item == NULL) {

From 7767ef775f7ea9dc781c0545972ef34333efa7ac Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 21:54:12 +0900
Subject: [PATCH 07/12] impl must not be NULL

---
 Modules/_abc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index 26636db61c53689..cea4582db28470d 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -705,8 +705,8 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     result = Py_False;
 
 end:
+    Py_DECREF(impl);
     Py_XDECREF(mro);
-    Py_XDECREF(impl);
     Py_XDECREF(subclasses);
     Py_XINCREF(result);
     return result;

From e2aa5cad681f08fd50009eea3c4cfe69b4ed61d6 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Tue, 6 Mar 2018 22:15:35 +0900
Subject: [PATCH 08/12] oops

---
 Lib/test/test_abc.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index 21c7459360b93fb..a65d44d2645a638 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -408,7 +408,7 @@ class C:
                 __mro__ = 42  # __mro__ is not tuple
 
             with self.assertRaises(TypeError):
-                self.assertTrue(issubclass(C(), A))
+                issubclass(C(), A)
 
         def test_all_new_methods_are_called(self):
             class A(metaclass=abc_ABCMeta):

From 23f555f072443df42e592ab61e9e10e6b249b57c Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Wed, 7 Mar 2018 01:26:38 +0900
Subject: [PATCH 09/12] Remove redundant NULL check

---
 Modules/_abc.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index cea4582db28470d..104267e37991baf 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -656,9 +656,6 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
         }
         for (pos = 0; pos < PyTuple_GET_SIZE(mro); pos++) {
             PyObject *mro_item = PyTuple_GET_ITEM(mro, pos);
-            if (mro_item == NULL) {
-                goto end;
-            }
             if ((PyObject *)self == mro_item) {
                 if (_add_to_weak_set(&impl->_abc_cache, subclass) < 0) {
                     goto end;

From 8bcb74c18e390d253c2721ada1014558a7fe5ca6 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Wed, 7 Mar 2018 02:09:38 +0900
Subject: [PATCH 10/12] Revert "Move identifiers to function local"

This reverts commit e15fc35df11c27e59140231f52c8a0859c661bf9.
---
 Modules/_abc.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index 104267e37991baf..e136280856fda2f 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -12,7 +12,13 @@ module _abc
 PyDoc_STRVAR(_abc__doc__,
 "Module contains faster C implementation of abc.ABCMeta");
 
+_Py_IDENTIFIER(__abstractmethods__);
+_Py_IDENTIFIER(__class__);
+_Py_IDENTIFIER(__dict__);
+_Py_IDENTIFIER(__bases__);
 _Py_IDENTIFIER(_abc_impl);
+_Py_IDENTIFIER(__subclasscheck__);
+_Py_IDENTIFIER(__subclasshook__);
 
 /* A global counter that is incremented each time a class is
    registered as a virtual subclass of anything.  It forces the
@@ -252,7 +258,6 @@ _abc__get_dump(PyObject *module, PyObject *self)
 static int
 compute_abstract_methods(PyObject *self)
 {
-    _Py_IDENTIFIER(__abstractmethods__);
     int ret = -1;
     PyObject *abstracts = PyFrozenSet_New(NULL);
     if (abstracts == NULL) {
@@ -262,7 +267,6 @@ compute_abstract_methods(PyObject *self)
     PyObject *ns = NULL, *items = NULL, *bases = NULL;  // Py_XDECREF()ed on error.
 
     /* Stage 1: direct abstract methods. */
-    _Py_IDENTIFIER(__dict__);
     ns = _PyObject_GetAttrId(self, &PyId___dict__);
     if (!ns) {
         goto error;
@@ -307,7 +311,6 @@ compute_abstract_methods(PyObject *self)
     }
 
     /* Stage 2: inherited abstract methods. */
-    _Py_IDENTIFIER(__bases__);
     bases = _PyObject_GetAttrId(self, &PyId___bases__);
     if (!bases) {
         goto error;
@@ -476,14 +479,12 @@ _abc__abc_instancecheck_impl(PyObject *module, PyObject *self,
                              PyObject *instance)
 /*[clinic end generated code: output=b8b5148f63b6b56f input=a4f4525679261084]*/
 {
-    _Py_IDENTIFIER(__subclasscheck__);
     PyObject *subtype, *result = NULL, *subclass = NULL;
     _abc_data *impl = _get_impl(self);
     if (impl == NULL) {
         return NULL;
     }
 
-    _Py_IDENTIFIER(__class__);
     subclass = _PyObject_GetAttrId(instance, &PyId___class__);
     if (subclass == NULL) {
         Py_DECREF(impl);
@@ -607,7 +608,6 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
     }
 
     /* 3. Check the subclass hook. */
-    _Py_IDENTIFIER(__subclasshook__);
     ok = _PyObject_CallMethodIdObjArgs((PyObject *)self, &PyId___subclasshook__,
                                        subclass, NULL);
     if (ok == NULL) {

From 697abd2094538efa443286d74d84f218212c8cfc Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Wed, 7 Mar 2018 02:10:51 +0900
Subject: [PATCH 11/12] Move __mro__ identifier to top of the file

---
 Modules/_abc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Modules/_abc.c b/Modules/_abc.c
index e136280856fda2f..862883987fb7f8c 100644
--- a/Modules/_abc.c
+++ b/Modules/_abc.c
@@ -16,6 +16,7 @@ _Py_IDENTIFIER(__abstractmethods__);
 _Py_IDENTIFIER(__class__);
 _Py_IDENTIFIER(__dict__);
 _Py_IDENTIFIER(__bases__);
+_Py_IDENTIFIER(__mro__);
 _Py_IDENTIFIER(_abc_impl);
 _Py_IDENTIFIER(__subclasscheck__);
 _Py_IDENTIFIER(__subclasshook__);
@@ -643,7 +644,6 @@ _abc__abc_subclasscheck_impl(PyObject *module, PyObject *self,
      *     cls._abc_cache.add(subclass)
      *     return True
      */
-    _Py_IDENTIFIER(__mro__);
     if (_PyObject_LookupAttrId(subclass, &PyId___mro__, &mro) < 0) {
         goto end;
     }

From fa4af5fbc92c840418c5a572148c9b6c8c0f6d41 Mon Sep 17 00:00:00 2001
From: INADA Naoki <songofacandy@gmail.com>
Date: Wed, 7 Mar 2018 15:01:20 +0900
Subject: [PATCH 12/12] rename test func

---
 Lib/test/test_abc.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index a65d44d2645a638..6fc3c95e4a645ef 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -392,7 +392,7 @@ class MyInt(int):
             self.assertIsInstance(42, A)
             self.assertIsInstance(42, (A,))
 
-        def test_issubclass(self):
+        def test_issubclass_bad_arguments(self):
             class A(metaclass=abc_ABCMeta):
                 pass