From 2382ae09e2514b218c0797fe82d4218d05383225 Mon Sep 17 00:00:00 2001
From: Yuya Nishihara <yuya@tcha.org>
Date: Thu, 27 Jul 2023 04:30:11 +0900
Subject: [PATCH] gen-protos: make old protoc accept optional fields

The version installed by ubuntu "latest" doesn't seem to support optional
fields yet. This is copied from the prost documentation.

https://docs.rs/prost-build/latest/prost_build/struct.Config.html#method.protoc_arg
---
 lib/gen-protos/src/main.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/lib/gen-protos/src/main.rs b/lib/gen-protos/src/main.rs
index d9c6b9632..c9b8d4f01 100644
--- a/lib/gen-protos/src/main.rs
+++ b/lib/gen-protos/src/main.rs
@@ -29,6 +29,8 @@ fn main() -> Result<()> {
     prost_build::Config::new()
         .out_dir(&protos_dir)
         .include_file("mod.rs")
+        // For old protoc versions. 3.12.4 needs this, but 3.21.12 doesn't.
+        .protoc_arg("--experimental_allow_proto3_optional")
         .compile_protos(
             &input
                 .into_iter()