[tsl] Implement tsl::NullTerminatedMessage() in terms of `absl::Sta…

…tusMessageAsCStr()`

* This allows TF to outsource correct acquisition of a null-terminated C-string of the status message to the Abseil library itself
* The previous implementation happened to work currently, but depended on internal implementation details of `absl::Status::message()` (namely, that when the message isn't empty, the returned `absl::string_view` is backed by a null-terminated `std::string`)
* Unfortunately we currently have to duplicate the definition depending on the platform due to linker-issues in the Windows build

PiperOrigin-RevId: 625785085

third_party/xla/third_party/tsl/tsl/platform/status.cc

@@ -155,16 +155,13 @@ std::vector<StackFrame> GetStackTrace(const ::tsl::Status& status) {
 
 }  // namespace errors
 
-const absl::string_view kEmptyString = "";
-
-const char* NullTerminatedMessage(const Status& status) {
-  auto message = status.message();
-  if (message.empty()) {
-    return kEmptyString.data();
-  }
-  return message.data();
+// NB: This Windows-only implementation is exists only to avoid a linker error.
+// Remove if this is resolved.
+#ifdef _WIN32
+const char* NullTerminatedMessage(const absl::Status& status) {
+  return absl::StatusMessageAsCStr(status);
 }
-
+#endif
 
 std::string* TfCheckOpHelperOutOfLine(const ::tsl::Status& v, const char* msg) {
   std::string r("Non-OK-status: ");

third_party/xla/third_party/tsl/tsl/platform/status.h

@@ -119,7 +119,15 @@ inline absl::Status ToAbslStatus(const ::absl::Status& s) { return s; }
 // the Tensorflow C-API.
 // A more robust API would be to get both a `char*` of the beginning of the
 // string, plus the size (see e.g. `XlaCustomCallStatusSetFailure`).
-const char* NullTerminatedMessage(const Status& status);
+// NB: This Windows-only implementation is exists only to avoid a linker error.
+// Remove if this is resolved.
+#ifdef _WIN32
+const char* NullTerminatedMessage(const absl::Status& status);
+#else
+inline const char* NullTerminatedMessage(const absl::Status& status) {
+  return absl::StatusMessageAsCStr(status);
+}
+#endif
 
 // TODO(b/197552541) Move this namespace to errors.h.
 namespace errors {