Make `type_caster<absl::StatusOr<T>>` supports loading Python instance as `absl::Status`.

PiperOrigin-RevId: 520478536

pybind11_abseil/statusor_caster.h

@@ -45,9 +45,20 @@ struct type_caster<absl::StatusOr<PayloadType>> {
   PYBIND11_TYPE_CASTER(absl::StatusOr<PayloadType>, PayloadCaster::name);
   PYBIND11_TYPE_CASTER(absl::StatusOr<PayloadType>, PayloadCaster::name);
 
 
   bool load(handle src, bool convert) {
   bool load(handle src, bool convert) {
-    PayloadCaster base_caster;
-    if (base_caster.load(src, convert)) {
-      value = cast_op<PayloadType>(std::move(base_caster));
+    PayloadCaster payload_caster;
+    if (payload_caster.load(src, convert)) {
+      value = cast_op<PayloadType>(std::move(payload_caster));
+      return true;
+    }
+    StatusCaster status_caster;
+    if (status_caster.load(src, convert)) {
+      absl::Status status = cast_op<absl::Status>(std::move(status_caster));
+      if (status.ok()) {
+        throw cast_error(
+            "An OK status is not a valid constructor argument to StatusOr<T>.");
+      } else {
+        value = status;
+      }
       return true;
       return true;
     }
     }
     return false;
     return false;

pybind11_abseil/tests/status_example.cc

@@ -34,6 +34,13 @@ bool CheckStatus(const absl::Status& status, absl::StatusCode code) {
   return status.code() == code;
   return status.code() == code;
 }
 }
 
 
+bool CheckStatusOr(const absl::StatusOr<int>& statusor, absl::StatusCode code) {
+  if (statusor.ok()) {
+    return true;
+  }
+  return statusor.status().code() == code;
+}
+
 absl::Status ReturnStatus(absl::StatusCode code, const std::string& text = "") {
 absl::Status ReturnStatus(absl::StatusCode code, const std::string& text = "") {
   return absl::Status(code, text);
   return absl::Status(code, text);
 }
 }
@@ -151,6 +158,7 @@ PYBIND11_MODULE(status_example, m) {
 
 
   // absl::Status bindings
   // absl::Status bindings
   m.def("check_status", &CheckStatus, arg("status"), arg("code"));
   m.def("check_status", &CheckStatus, arg("status"), arg("code"));
+  m.def("check_statusor", &CheckStatusOr, arg("statusor"), arg("code"));
   m.def("return_status", &ReturnStatus, "Raise an error if code is not OK.",
   m.def("return_status", &ReturnStatus, "Raise an error if code is not OK.",
         arg("code"), arg("text") = "");
         arg("code"), arg("text") = "");
   m.def("make_status", google::DoNotThrowStatus(&ReturnStatus),
   m.def("make_status", google::DoNotThrowStatus(&ReturnStatus),

pybind11_abseil/tests/status_example_test.py

@@ -43,6 +43,22 @@ class StatusTest(parameterized.TestCase):
     self.assertTrue(
     self.assertTrue(
         status_example.check_status(test_status, status.StatusCode.CANCELLED))
         status_example.check_status(test_status, status.StatusCode.CANCELLED))
 
 
+  def test_pass_statusor(self):
+    test_status = status.Status(status.StatusCode.CANCELLED, 'test')
+    self.assertTrue(
+        status_example.check_statusor(test_status, status.StatusCode.CANCELLED))
+    test_status = status.Status(status.StatusCode.OK, 'test')
+    with self.assertRaises(RuntimeError) as ctx:
+      status_example.check_statusor(test_status, status.StatusCode.CANCELLED)
+    self.assertEqual(
+        str(ctx.exception),
+        'An OK status is not a valid constructor argument to StatusOr<T>.')
+    with self.assertRaises(RuntimeError) as ctx:
+      status_example.check_statusor(None, status.StatusCode.CANCELLED)
+    self.assertEqual(
+        str(ctx.exception),
+        'An OK status is not a valid constructor argument to StatusOr<T>.')
+
   def test_return_status_return_type_from_doc(self):
   def test_return_status_return_type_from_doc(self):
     self.assertEndsWith(
     self.assertEndsWith(
         docstring_signature(status_example.return_status), ' -> None')
         docstring_signature(status_example.return_status), ' -> None')