bpo-32571: Avoid raising unneeded AttributeError and silencing it in C code (GH-5222)

Add two new private APIs: _PyObject_LookupAttr() and _PyObject_LookupAttrId()

1 files changed, 10 insertions, 12 deletions

diff --git a/Python/ceval.c b/Python/ceval.c
index 2b7c0c8..3d7bed0 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4813,13 +4813,12 @@ import_from(PyObject *v, PyObject *name)
     _Py_IDENTIFIER(__name__);
     PyObject *fullmodname, *pkgname, *pkgpath, *pkgname_or_unknown, *errmsg;
 
-    x = PyObject_GetAttr(v, name);
-    if (x != NULL || !PyErr_ExceptionMatches(PyExc_AttributeError))
+    if (_PyObject_LookupAttr(v, name, &x) != 0) {
         return x;
+    }
     /* Issue #17636: in case this failed because of a circular relative
        import, try to fallback on reading the module directly from
        sys.modules. */
-    PyErr_Clear();
     pkgname = _PyObject_GetAttrId(v, &PyId___name__);
     if (pkgname == NULL) {
         goto error;
@@ -4881,21 +4880,20 @@ import_all_from(PyObject *locals, PyObject *v)
 {
     _Py_IDENTIFIER(__all__);
     _Py_IDENTIFIER(__dict__);
-    PyObject *all = _PyObject_GetAttrId(v, &PyId___all__);
-    PyObject *dict, *name, *value;
+    PyObject *all, *dict, *name, *value;
     int skip_leading_underscores = 0;
     int pos, err;
 
+    if (_PyObject_LookupAttrId(v, &PyId___all__, &all) < 0) {
+        return -1; /* Unexpected error */
+    }
     if (all == NULL) {
-        if (!PyErr_ExceptionMatches(PyExc_AttributeError))
-            return -1; /* Unexpected error */
-        PyErr_Clear();
-        dict = _PyObject_GetAttrId(v, &PyId___dict__);
+        if (_PyObject_LookupAttrId(v, &PyId___dict__, &dict) < 0) {
+            return -1;
+        }
         if (dict == NULL) {
-            if (!PyErr_ExceptionMatches(PyExc_AttributeError))
-                return -1;
             PyErr_SetString(PyExc_ImportError,
-            "from-import-* object has no __dict__ and no __all__");
+                    "from-import-* object has no __dict__ and no __all__");
             return -1;
         }
         all = PyMapping_Keys(dict);