bpo-41991: Remove _PyObject_HasAttrId

It can silence arbitrary exceptions.

Author: serhiy-storchaka

Include/cpython/object.h

@@ -306,7 +306,6 @@ PyAPI_FUNC(int) _PyObject_IsFreed(PyObject *);
 PyAPI_FUNC(int) _PyObject_IsAbstract(PyObject *);
 PyAPI_FUNC(PyObject *) _PyObject_GetAttrId(PyObject *, struct _Py_Identifier *);
 PyAPI_FUNC(int) _PyObject_SetAttrId(PyObject *, struct _Py_Identifier *, PyObject *);
-PyAPI_FUNC(int) _PyObject_HasAttrId(PyObject *, struct _Py_Identifier *);
 /* Replacements of PyObject_GetAttr() and _PyObject_GetAttrId() which
    don't raise AttributeError.
 

Objects/object.c

@@ -854,17 +854,6 @@ _PyObject_GetAttrId(PyObject *v, _Py_Identifier *name)
     return result;
 }
 
-int
-_PyObject_HasAttrId(PyObject *v, _Py_Identifier *name)
-{
-    int result;
-    PyObject *oname = _PyUnicode_FromId(name); /* borrowed */
-    if (!oname)
-        return -1;
-    result = PyObject_HasAttr(v, oname);
-    return result;
-}
-
 int
 _PyObject_SetAttrId(PyObject *v, _Py_Identifier *name, PyObject *w)
 {

Objects/unionobject.c

@@ -311,21 +311,22 @@ union_repr_item(_PyUnicodeWriter *writer, PyObject *p)
     _Py_IDENTIFIER(__args__);
     PyObject *qualname = NULL;
     PyObject *module = NULL;
+    PyObject *tmp;
     PyObject *r = NULL;
     int err;
 
-    int has_origin = _PyObject_HasAttrId(p, &PyId___origin__);
-    if (has_origin < 0) {
+    if (_PyObject_LookupAttrId(p, &PyId___origin__, &tmp) < 0) {
         goto exit;
     }
 
-    if (has_origin) {
-        int has_args = _PyObject_HasAttrId(p, &PyId___args__);
-        if (has_args < 0) {
+    if (tmp) {
+        Py_DECREF(tmp);
+        if (_PyObject_LookupAttrId(p, &PyId___args__, &tmp) < 0) {
             goto exit;
         }
-        if (has_args) {
+        if (tmp) {
             // It looks like a GenericAlias
+            Py_DECREF(tmp);
             goto use_repr;
         }
     }

Python/errors.c

@@ -1593,9 +1593,18 @@ PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)
             }
             Py_DECREF(tmp);
         }
+        else {
+            _PyErr_Clear(tstate);
+        }
     }
     if (exc != PyExc_SyntaxError) {
-        if (!_PyObject_HasAttrId(v, &PyId_msg)) {
+        if (_PyObject_LookupAttrId(v, &PyId_msg, &tmp) < 0) {
+            _PyErr_Clear(tstate);
+        }
+        else if (tmp) {
+            Py_DECREF(tmp);
+        }
+        else {
             tmp = PyObject_Str(v);
             if (tmp) {
                 if (_PyObject_SetAttrId(v, &PyId_msg, tmp)) {
@@ -1607,7 +1616,13 @@ PyErr_SyntaxLocationObject(PyObject *filename, int lineno, int col_offset)
                 _PyErr_Clear(tstate);
             }
         }
-        if (!_PyObject_HasAttrId(v, &PyId_print_file_and_line)) {
+        if (_PyObject_LookupAttrId(v, &PyId_print_file_and_line, &tmp) < 0) {
+            _PyErr_Clear(tstate);
+        }
+        else if (tmp) {
+            Py_DECREF(tmp);
+        }
+        else {
             if (_PyObject_SetAttrId(v, &PyId_print_file_and_line,
                                     Py_None)) {
                 _PyErr_Clear(tstate);

Python/pythonrun.c

@@ -770,7 +770,7 @@ static void
 print_exception(PyObject *f, PyObject *value)
 {
     int err = 0;
-    PyObject *type, *tb;
+    PyObject *type, *tb, *tmp;
     _Py_IDENTIFIER(print_file_and_line);
 
     if (!PyExceptionInstance_Check(value)) {
@@ -789,10 +789,12 @@ print_exception(PyObject *f, PyObject *value)
     if (tb && tb != Py_None)
         err = PyTraceBack_Print(tb, f);
     if (err == 0 &&
-        _PyObject_HasAttrId(value, &PyId_print_file_and_line))
+        (err = _PyObject_LookupAttrId(value, &PyId_print_file_and_line, &tmp)) > 0)
     {
         PyObject *message, *filename, *text;
         Py_ssize_t lineno, offset;
+        err = 0;
+        Py_DECREF(tmp);
         if (!parse_syntax_error(value, &message, &filename,
                                 &lineno, &offset, &text))
             PyErr_Clear();