[3.8] bpo-37994: Fix silencing all errors if an attribute lookup fails. (GH-15630) (GH-15635)

Only AttributeError should be silenced.
(cherry picked from commit 41c57b335330ff48af098d47e379e0f9ba09d233)

6 files changed, 95 insertions, 90 deletions

diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 1bb19a9271..590b806056 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -2063,9 +2063,10 @@ _common_reduce(PyByteArrayObject *self, int proto)
     _Py_IDENTIFIER(__dict__);
     char *buf;
 
-    dict = _PyObject_GetAttrId((PyObject *)self, &PyId___dict__);
+    if (_PyObject_LookupAttrId((PyObject *)self, &PyId___dict__, &dict) < 0) {
+        return NULL;
+    }
     if (dict == NULL) {
-        PyErr_Clear();
         dict = Py_None;
         Py_INCREF(dict);
     }
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index dbb44de846..119be35db0 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -1622,29 +1622,25 @@ property_init_impl(propertyobject *self, PyObject *fget, PyObject *fset,
     /* if no docstring given and the getter has one, use that one */
     if ((doc == NULL || doc == Py_None) && fget != NULL) {
         _Py_IDENTIFIER(__doc__);
-        PyObject *get_doc = _PyObject_GetAttrId(fget, &PyId___doc__);
-        if (get_doc) {
-            if (Py_TYPE(self) == &PyProperty_Type) {
-                Py_XSETREF(self->prop_doc, get_doc);
-            }
-            else {
-                /* If this is a property subclass, put __doc__
-                in dict of the subclass instance instead,
-                otherwise it gets shadowed by __doc__ in the
-                class's dict. */
-                int err = _PyObject_SetAttrId((PyObject *)self, &PyId___doc__, get_doc);
-                Py_DECREF(get_doc);
-                if (err < 0)
-                    return -1;
-            }
-            self->getter_doc = 1;
+        PyObject *get_doc;
+        int rc = _PyObject_LookupAttrId(fget, &PyId___doc__, &get_doc);
+        if (rc <= 0) {
+            return rc;
         }
-        else if (PyErr_ExceptionMatches(PyExc_Exception)) {
-            PyErr_Clear();
+        if (Py_TYPE(self) == &PyProperty_Type) {
+            Py_XSETREF(self->prop_doc, get_doc);
         }
         else {
-            return -1;
+            /* If this is a property subclass, put __doc__
+               in dict of the subclass instance instead,
+               otherwise it gets shadowed by __doc__ in the
+               class's dict. */
+            int err = _PyObject_SetAttrId((PyObject *)self, &PyId___doc__, get_doc);
+            Py_DECREF(get_doc);
+            if (err < 0)
+                return -1;
         }
+        self->getter_doc = 1;
     }
 
     return 0;
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index 3791241e5c..dd42d51689 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -185,8 +185,10 @@ PyObject_AsFileDescriptor(PyObject *o)
     if (PyLong_Check(o)) {
         fd = _PyLong_AsInt(o);
     }
-    else if ((meth = _PyObject_GetAttrId(o, &PyId_fileno)) != NULL)
-    {
+    else if (_PyObject_LookupAttrId(o, &PyId_fileno, &meth) < 0) {
+        return -1;
+    }
+    else if (meth != NULL) {
         PyObject *fno = _PyObject_CallNoArg(meth);
         Py_DECREF(meth);
         if (fno == NULL)
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 8cd95ba890..f8ae0c05e2 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -1954,9 +1954,10 @@ set_reduce(PySetObject *so, PyObject *Py_UNUSED(ignored))
     args = PyTuple_Pack(1, keys);
     if (args == NULL)
         goto done;
-    dict = _PyObject_GetAttrId((PyObject *)so, &PyId___dict__);
+    if (_PyObject_LookupAttrId((PyObject *)so, &PyId___dict__, &dict) < 0) {
+        goto done;
+    }
     if (dict == NULL) {
-        PyErr_Clear();
         dict = Py_None;
         Py_INCREF(dict);
     }
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index bf0c3e0729..8ece218275 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -1547,17 +1547,10 @@ tail_contains(PyObject *tuple, int whence, PyObject *o)
 static PyObject *
 class_name(PyObject *cls)
 {
-    PyObject *name = _PyObject_GetAttrId(cls, &PyId___name__);
-    if (name == NULL) {
-        PyErr_Clear();
+    PyObject *name;
+    if (_PyObject_LookupAttrId(cls, &PyId___name__, &name) == 0) {
         name = PyObject_Repr(cls);
     }
-    if (name == NULL)
-        return NULL;
-    if (!PyUnicode_Check(name)) {
-        Py_DECREF(name);
-        return NULL;
-    }
     return name;
 }
 
@@ -1575,13 +1568,15 @@ check_duplicates(PyObject *tuple)
             if (PyTuple_GET_ITEM(tuple, j) == o) {
                 o = class_name(o);
                 if (o != NULL) {
-                    PyErr_Format(PyExc_TypeError,
-                                 "duplicate base class %U",
-                                 o);
+                    if (PyUnicode_Check(o)) {
+                        PyErr_Format(PyExc_TypeError,
+                                     "duplicate base class %U", o);
+                    }
+                    else {
+                        PyErr_SetString(PyExc_TypeError,
+                                        "duplicate base class");
+                    }
                     Py_DECREF(o);
-                } else {
-                    PyErr_SetString(PyExc_TypeError,
-                                 "duplicate base class");
                 }
                 return -1;
             }
@@ -1625,13 +1620,20 @@ consistent method resolution\norder (MRO) for bases");
     i = 0;
     while (PyDict_Next(set, &i, &k, &v) && (size_t)off < sizeof(buf)) {
         PyObject *name = class_name(k);
-        const char *name_str;
+        const char *name_str = NULL;
         if (name != NULL) {
-            name_str = PyUnicode_AsUTF8(name);
-            if (name_str == NULL)
+            if (PyUnicode_Check(name)) {
+                name_str = PyUnicode_AsUTF8(name);
+            }
+            else {
                 name_str = "?";
-        } else
-            name_str = "?";
+            }
+        }
+        if (name_str == NULL) {
+            Py_XDECREF(name);
+            Py_DECREF(set);
+            return;
+        }
         off += PyOS_snprintf(buf + off, sizeof(buf) - off, " %s", name_str);
         Py_XDECREF(name);
         if (--n && (size_t)(off+1) < sizeof(buf)) {
@@ -3418,10 +3420,10 @@ merge_class_dict(PyObject *dict, PyObject *aclass)
     assert(aclass);
 
     /* Merge in the type's dict (if any). */
-    classdict = _PyObject_GetAttrId(aclass, &PyId___dict__);
-    if (classdict == NULL)
-        PyErr_Clear();
-    else {
+    if (_PyObject_LookupAttrId(aclass, &PyId___dict__, &classdict) < 0) {
+        return -1;
+    }
+    if (classdict != NULL) {
         int status = PyDict_Update(dict, classdict);
         Py_DECREF(classdict);
         if (status < 0)
@@ -3429,15 +3431,17 @@ merge_class_dict(PyObject *dict, PyObject *aclass)
     }
 
     /* Recursively merge in the base types' (if any) dicts. */
-    bases = _PyObject_GetAttrId(aclass, &PyId___bases__);
-    if (bases == NULL)
-        PyErr_Clear();
-    else {
+    if (_PyObject_LookupAttrId(aclass, &PyId___bases__, &bases) < 0) {
+        return -1;
+    }
+    if (bases != NULL) {
         /* We have no guarantee that bases is a real tuple */
         Py_ssize_t i, n;
         n = PySequence_Size(bases); /* This better be right */
-        if (n < 0)
-            PyErr_Clear();
+        if (n < 0) {
+            Py_DECREF(bases);
+            return -1;
+        }
         else {
             for (i = 0; i < n; i++) {
                 int status;
@@ -4725,9 +4729,10 @@ object___dir___impl(PyObject *self)
     PyObject *itsclass = NULL;
 
     /* Get __dict__ (which may or may not be a real dict...) */
-    dict = _PyObject_GetAttrId(self, &PyId___dict__);
+    if (_PyObject_LookupAttrId(self, &PyId___dict__, &dict) < 0) {
+        return NULL;
+    }
     if (dict == NULL) {
-        PyErr_Clear();
         dict = PyDict_New();
     }
     else if (!PyDict_Check(dict)) {
@@ -4745,12 +4750,12 @@ object___dir___impl(PyObject *self)
         goto error;
 
     /* Merge in attrs reachable from its class. */
-    itsclass = _PyObject_GetAttrId(self, &PyId___class__);
-    if (itsclass == NULL)
-        /* XXX(tomer): Perhaps fall back to obj->ob_type if no
-                       __class__ exists? */
-        PyErr_Clear();
-    else if (merge_class_dict(dict, itsclass) != 0)
+    if (_PyObject_LookupAttrId(self, &PyId___class__, &itsclass) < 0) {
+        goto error;
+    }
+    /* XXX(tomer): Perhaps fall back to obj->ob_type if no
+                   __class__ exists? */
+    if (itsclass != NULL && merge_class_dict(dict, itsclass) < 0)
         goto error;
 
     result = PyDict_Keys(dict);
@@ -6105,16 +6110,19 @@ method_is_overloaded(PyObject *left, PyObject *right, struct _Py_Identifier *nam
     PyObject *a, *b;
     int ok;
 
-    b = _PyObject_GetAttrId((PyObject *)(Py_TYPE(right)), name);
+    if (_PyObject_LookupAttrId((PyObject *)(Py_TYPE(right)), name, &b) < 0) {
+        return -1;
+    }
     if (b == NULL) {
-        PyErr_Clear();
         /* If right doesn't have it, it's not overloaded */
         return 0;
     }
 
-    a = _PyObject_GetAttrId((PyObject *)(Py_TYPE(left)), name);
+    if (_PyObject_LookupAttrId((PyObject *)(Py_TYPE(left)), name, &a) < 0) {
+        Py_DECREF(b);
+        return -1;
+    }
     if (a == NULL) {
-        PyErr_Clear();
         Py_DECREF(b);
         /* If right has it but left doesn't, it's overloaded */
         return 1;
@@ -6123,11 +6131,6 @@ method_is_overloaded(PyObject *left, PyObject *right, struct _Py_Identifier *nam
     ok = PyObject_RichCompareBool(a, b, Py_NE);
     Py_DECREF(a);
     Py_DECREF(b);
-    if (ok < 0) {
-        PyErr_Clear();
-        return 0;
-    }
-
     return ok;
 }
 
@@ -6145,15 +6148,19 @@ FUNCNAME(PyObject *self, PyObject *other) \
     if (Py_TYPE(self)->tp_as_number != NULL && \
         Py_TYPE(self)->tp_as_number->SLOTNAME == TESTFUNC) { \
         PyObject *r; \
-        if (do_other && \
-            PyType_IsSubtype(Py_TYPE(other), Py_TYPE(self)) && \
-            method_is_overloaded(self, other, &rop_id)) { \
-            stack[0] = self; \
-            r = call_maybe(other, &rop_id, stack, 1); \
-            if (r != Py_NotImplemented) \
-                return r; \
-            Py_DECREF(r); \
-            do_other = 0; \
+        if (do_other && PyType_IsSubtype(Py_TYPE(other), Py_TYPE(self))) { \
+            int ok = method_is_overloaded(self, other, &rop_id); \
+            if (ok < 0) { \
+                return NULL; \
+            } \
+            if (ok) { \
+                stack[0] = self; \
+                r = call_maybe(other, &rop_id, stack, 1); \
+                if (r != Py_NotImplemented) \
+                    return r; \
+                Py_DECREF(r); \
+                do_other = 0; \
+            } \
         } \
         stack[0] = other; \
         r = call_maybe(self, &op_id, stack, 1); \
@@ -7739,7 +7746,9 @@ supercheck(PyTypeObject *type, PyObject *obj)
         /* Try the slow way */
         PyObject *class_attr;
 
-        class_attr = _PyObject_GetAttrId(obj, &PyId___class__);
+        if (_PyObject_LookupAttrId(obj, &PyId___class__, &class_attr) < 0) {
+            return NULL;
+        }
         if (class_attr != NULL &&
             PyType_Check(class_attr) &&
             (PyTypeObject *)class_attr != Py_TYPE(obj))
@@ -7749,11 +7758,7 @@ supercheck(PyTypeObject *type, PyObject *obj)
             if (ok)
                 return (PyTypeObject *)class_attr;
         }
-
-        if (class_attr == NULL)
-            PyErr_Clear();
-        else
-            Py_DECREF(class_attr);
+        Py_XDECREF(class_attr);
     }
 
     PyErr_SetString(PyExc_TypeError,
diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index 8b8e71031a..4b81450de8 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -163,10 +163,10 @@ weakref_repr(PyWeakReference *self)
     if (PyWeakref_GET_OBJECT(self) == Py_None)
         return PyUnicode_FromFormat("<weakref at %p; dead>", self);
 
-    name = _PyObject_GetAttrId(PyWeakref_GET_OBJECT(self), &PyId___name__);
+    if (_PyObject_LookupAttrId(PyWeakref_GET_OBJECT(self), &PyId___name__, &name) < 0) {
+        return NULL;
+    }
     if (name == NULL || !PyUnicode_Check(name)) {
-        if (name == NULL)
-            PyErr_Clear();
         repr = PyUnicode_FromFormat(
             "<weakref at %p; to '%s' at %p>",
             self,