From 971bae9174293b79f1f29822d662b31a2ba62234 Mon Sep 17 00:00:00 2001
From: Anthony Towns <aj@erisian.com.au>
Date: Mon, 11 Sep 2023 15:43:40 +1000
Subject: [PATCH] rpc: Deprecate rpcserialversion=0

---
 doc/release-notes-28448.md        | 6 ++++++
 src/init.cpp                      | 6 +++++-
 test/functional/feature_segwit.py | 1 +
 3 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 doc/release-notes-28448.md

diff --git a/doc/release-notes-28448.md b/doc/release-notes-28448.md
new file mode 100644
index 00000000000..d3ef8cf65ba
--- /dev/null
+++ b/doc/release-notes-28448.md
@@ -0,0 +1,6 @@
+RPC
+---
+
+- Setting `-rpcserialversion=0` is deprecated and will be removed in
+  a future release. It can currently still be used by also adding
+  the `-deprecatedrpc=serialversion` option. (#28448)
diff --git a/src/init.cpp b/src/init.cpp
index f0847bd4f75..c025fb8ed88 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -618,7 +618,7 @@ void SetupServerArgs(ArgsManager& argsman)
     argsman.AddArg("-rpccookiefile=<loc>", "Location of the auth cookie. Relative paths will be prefixed by a net-specific datadir location. (default: data dir)", ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     argsman.AddArg("-rpcpassword=<pw>", "Password for JSON-RPC connections", ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE, OptionsCategory::RPC);
     argsman.AddArg("-rpcport=<port>", strprintf("Listen for JSON-RPC connections on <port> (default: %u, testnet: %u, signet: %u, regtest: %u)", defaultBaseParams->RPCPort(), testnetBaseParams->RPCPort(), signetBaseParams->RPCPort(), regtestBaseParams->RPCPort()), ArgsManager::ALLOW_ANY | ArgsManager::NETWORK_ONLY, OptionsCategory::RPC);
-    argsman.AddArg("-rpcserialversion", strprintf("Sets the serialization of raw transaction or block hex returned in non-verbose mode, non-segwit(0) or segwit(1) (default: %d)", DEFAULT_RPC_SERIALIZE_VERSION), ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
+    argsman.AddArg("-rpcserialversion", strprintf("Sets the serialization of raw transaction or block hex returned in non-verbose mode, non-segwit(0) (DEPRECATED) or segwit(1) (default: %d)", DEFAULT_RPC_SERIALIZE_VERSION), ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     argsman.AddArg("-rpcservertimeout=<n>", strprintf("Timeout during HTTP requests (default: %d)", DEFAULT_HTTP_SERVER_TIMEOUT), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::RPC);
     argsman.AddArg("-rpcthreads=<n>", strprintf("Set the number of threads to service RPC calls (default: %d)", DEFAULT_HTTP_THREADS), ArgsManager::ALLOW_ANY, OptionsCategory::RPC);
     argsman.AddArg("-rpcuser=<user>", "Username for JSON-RPC connections", ArgsManager::ALLOW_ANY | ArgsManager::SENSITIVE, OptionsCategory::RPC);
@@ -988,6 +988,10 @@ bool AppInitParameterInteraction(const ArgsManager& args)
     if (args.GetIntArg("-rpcserialversion", DEFAULT_RPC_SERIALIZE_VERSION) > 1)
         return InitError(Untranslated("Unknown rpcserialversion requested."));
 
+    if (args.GetIntArg("-rpcserialversion", DEFAULT_RPC_SERIALIZE_VERSION) == 0 && !IsDeprecatedRPCEnabled("serialversion")) {
+        return InitError(Untranslated("-rpcserialversion=0 is deprecated and will be removed in the future. Specify -deprecatedrpc=serialversion to allow anyway."));
+    }
+
     // Also report errors from parsing before daemonization
     {
         kernel::Notifications notifications{};
diff --git a/test/functional/feature_segwit.py b/test/functional/feature_segwit.py
index 3ddf21ee5de..6c467fa6135 100755
--- a/test/functional/feature_segwit.py
+++ b/test/functional/feature_segwit.py
@@ -89,6 +89,7 @@ class SegWitTest(BitcoinTestFramework):
             [
                 "-acceptnonstdtxn=1",
                 "-rpcserialversion=0",
+                "-deprecatedrpc=serialversion",
                 "-testactivationheight=segwit@165",
                 "-addresstype=legacy",
             ],