From 409a95ddc2f1b8aac54612da3658b1f36a734469 Mon Sep 17 00:00:00 2001
From: Weston Pace <weston.pace@gmail.com>
Date: Sat, 26 Nov 2022 22:45:11 -0800
Subject: [PATCH] ARROW-18406: [C++] Can't build Arrow with Substrait on Ubuntu
 20.04 (#14735)

Authored-by: Weston Pace <weston.pace@gmail.com>
Signed-off-by: Weston Pace <weston.pace@gmail.com>
---
 cpp/src/arrow/engine/substrait/expression_internal.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/cpp/src/arrow/engine/substrait/expression_internal.cc b/cpp/src/arrow/engine/substrait/expression_internal.cc
index 8b33b6729a302..b8b545febc7c5 100644
--- a/cpp/src/arrow/engine/substrait/expression_internal.cc
+++ b/cpp/src/arrow/engine/substrait/expression_internal.cc
@@ -57,7 +57,7 @@ Id NormalizeFunctionName(Id id) {
 Status DecodeArg(const substrait::FunctionArgument& arg, int idx, SubstraitCall* call,
                  const ExtensionSet& ext_set,
                  const ConversionOptions& conversion_options) {
-  if (arg.has_enum_()) {
+  if (!arg.enum_().empty()) {
     call->SetEnumArg(idx, arg.enum_());
   } else if (arg.has_value()) {
     ARROW_ASSIGN_OR_RAISE(compute::Expression expr,