[3.12] gh-105375: Improve error handling in `zoneinfo` module (GH-105586) (#105612)

Fix bugs where exceptions could end up being overwritten
because of deferred error handling.

(cherry picked from commit 33c92c4f15539806c8aff8574ff30a8b307e3e4d)

Co-authored-by: Nikita Sobolev <mail@sobolevn.me>
Co-authored-by: Erlend E. Aasland <erlend.aasland@protonmail.com>

2 files changed, 12 insertions, 6 deletions

diff --git a/Misc/NEWS.d/next/Library/2023-06-09-21-11-28.gh-issue-105375.4Mxn7t.rst b/Misc/NEWS.d/next/Library/2023-06-09-21-11-28.gh-issue-105375.4Mxn7t.rst
new file mode 100644
index 0000000..4202b75
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2023-06-09-21-11-28.gh-issue-105375.4Mxn7t.rst
@@ -0,0 +1 @@
+Fix bugs in :mod:`zoneinfo` where exceptions could be overwritten.
diff --git a/Modules/_zoneinfo.c b/Modules/_zoneinfo.c
index c8c791b..38b806c 100644
--- a/Modules/_zoneinfo.c
+++ b/Modules/_zoneinfo.c
@@ -694,14 +694,19 @@ zoneinfo_fromutc(PyObject *obj_self, PyObject *dt)
         }
         else {
             PyObject *replace = PyObject_GetAttrString(tmp, "replace");
+            Py_DECREF(tmp);
+            if (replace == NULL) {
+                return NULL;
+            }
             PyObject *args = PyTuple_New(0);
+            if (args == NULL) {
+                Py_DECREF(replace);
+                return NULL;
+            }
             PyObject *kwargs = PyDict_New();
-
-            Py_DECREF(tmp);
-            if (args == NULL || kwargs == NULL || replace == NULL) {
-                Py_XDECREF(args);
-                Py_XDECREF(kwargs);
-                Py_XDECREF(replace);
+            if (kwargs == NULL) {
+                Py_DECREF(replace);
+                Py_DECREF(args);
                 return NULL;
             }