Merge bitcoin/bitcoin#29845: rpc: return warnings as an array instead of just a single one

42fb5311b19582361409d65c6fddeadbee14bb97 rpc: return warnings as an array instead of just a single one (stickies-v)

Pull request description:

  The RPC documentation for `getblockchaininfo`, `getmininginfo` and `getnetworkinfo` states that "warnings" returns "any network and blockchain warnings". In practice, only a single warning (i.e. the latest one that is set) is returned, the other ones are ignored.

  Fix that by returning all warnings as an array.

  As a side benefit, clean up the GetWarnings() logic.

  Since this PR changes the RPC result schema, I've added release notes. Users can temporarily revert to the old results by using `-deprecatedrpc=warnings`, until it's removed in a future version.

  ---

  Some historical context from git log:

  - when `GetWarnings` was introduced in 401926283a200994ecd7df8eae8ced8e0b067c46, it was used in the `getinfo` RPC, where only a [single error/warning was returned](https://github.com/bitcoin/bitcoin/commit/401926283a200994ecd7df8eae8ced8e0b067c46#diff-7442c48d42cd5455a79915a0f00cce5e13359db46437a32b812876edb0a5ccddR250) (similar to how it is now).
  - later on, "warnings" RPC response fields were introduced, e.g. in ef2a3de25c882396e1776b554878d2784b6b7391, with the description [stating](https://github.com/bitcoin/bitcoin/commit/ef2a3de25c882396e1776b554878d2784b6b7391#diff-1021bd3c74415ad9719bd764ad6ca35af5dfb33b1cd863c0be49bdf52518af54R411) that it returned "any network warnings" but in practice still only a single warning was returned

ACKs for top commit:
  achow101:
    re-ACK 42fb5311b19582361409d65c6fddeadbee14bb97
  tdb3:
    Re ACK for 42fb5311b19582361409d65c6fddeadbee14bb97
  TheCharlatan:
    ACK 42fb5311b19582361409d65c6fddeadbee14bb97
  maflcko:
    ACK 42fb5311b19582361409d65c6fddeadbee14bb97 🔺

Tree-SHA512: 4225ed8979cd5f030dec785a80e7452a041ad5703445da79d2906ada983ed0bbe7b15889d663d75aae4a77d92e302c93e93eca185c7bd47c9cce29e12f752bd3

5 files changed, 46 insertions, 9 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index eed004806a..c9997ae063 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -47,7 +47,6 @@
 #include <validation.h>
 #include <validationinterface.h>
 #include <versionbits.h>
-#include <warnings.h>
 
 #include <stdint.h>
 
@@ -1260,7 +1259,14 @@ RPCHelpMan getblockchaininfo()
                 {RPCResult::Type::NUM, "pruneheight", /*optional=*/true, "height of the last block pruned, plus one (only present if pruning is enabled)"},
                 {RPCResult::Type::BOOL, "automatic_pruning", /*optional=*/true, "whether automatic pruning is enabled (only present if pruning is enabled)"},
                 {RPCResult::Type::NUM, "prune_target_size", /*optional=*/true, "the target size used by pruning (only present if automatic pruning is enabled)"},
-                {RPCResult::Type::STR, "warnings", "any network and blockchain warnings"},
+                (IsDeprecatedRPCEnabled("warnings") ?
+                    RPCResult{RPCResult::Type::STR, "warnings", "any network and blockchain warnings (DEPRECATED)"} :
+                    RPCResult{RPCResult::Type::ARR, "warnings", "any network and blockchain warnings (run with `-deprecatedrpc=warnings` to return the latest warning as a single string)",
+                    {
+                        {RPCResult::Type::STR, "", "warning"},
+                    }
+                    }
+                ),
             }},
         RPCExamples{
             HelpExampleCli("getblockchaininfo", "")
@@ -1298,7 +1304,7 @@ RPCHelpMan getblockchaininfo()
         }
     }
 
-    obj.pushKV("warnings", GetWarnings(false).original);
+    obj.pushKV("warnings", GetNodeWarnings(IsDeprecatedRPCEnabled("warnings")));
     return obj;
 },
     };
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 454c262803..f36665a819 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -39,7 +39,6 @@
 #include <util/translation.h>
 #include <validation.h>
 #include <validationinterface.h>
-#include <warnings.h>
 
 #include <memory>
 #include <stdint.h>
@@ -426,7 +425,14 @@ static RPCHelpMan getmininginfo()
                         {RPCResult::Type::NUM, "networkhashps", "The network hashes per second"},
                         {RPCResult::Type::NUM, "pooledtx", "The size of the mempool"},
                         {RPCResult::Type::STR, "chain", "current network name (main, test, signet, regtest)"},
-                        {RPCResult::Type::STR, "warnings", "any network and blockchain warnings"},
+                        (IsDeprecatedRPCEnabled("warnings") ?
+                            RPCResult{RPCResult::Type::STR, "warnings", "any network and blockchain warnings (DEPRECATED)"} :
+                            RPCResult{RPCResult::Type::ARR, "warnings", "any network and blockchain warnings (run with `-deprecatedrpc=warnings` to return the latest warning as a single string)",
+                            {
+                                {RPCResult::Type::STR, "", "warning"},
+                            }
+                            }
+                        ),
                     }},
                 RPCExamples{
                     HelpExampleCli("getmininginfo", "")
@@ -448,7 +454,7 @@ static RPCHelpMan getmininginfo()
     obj.pushKV("networkhashps",    getnetworkhashps().HandleRequest(request));
     obj.pushKV("pooledtx",         (uint64_t)mempool.size());
     obj.pushKV("chain", chainman.GetParams().GetChainTypeString());
-    obj.pushKV("warnings",         GetWarnings(false).original);
+    obj.pushKV("warnings", GetNodeWarnings(IsDeprecatedRPCEnabled("warnings")));
     return obj;
 },
     };
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index 739ff1a48e..04f9410b32 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -29,7 +29,6 @@
 #include <util/time.h>
 #include <util/translation.h>
 #include <validation.h>
-#include <warnings.h>
 
 #include <optional>
 
@@ -657,7 +656,14 @@ static RPCHelpMan getnetworkinfo()
                                 {RPCResult::Type::NUM, "score", "relative score"},
                             }},
                         }},
-                        {RPCResult::Type::STR, "warnings", "any network and blockchain warnings"},
+                        (IsDeprecatedRPCEnabled("warnings") ?
+                            RPCResult{RPCResult::Type::STR, "warnings", "any network and blockchain warnings (DEPRECATED)"} :
+                            RPCResult{RPCResult::Type::ARR, "warnings", "any network and blockchain warnings (run with `-deprecatedrpc=warnings` to return the latest warning as a single string)",
+                            {
+                                {RPCResult::Type::STR, "", "warning"},
+                            }
+                            }
+                        ),
                     }
                 },
                 RPCExamples{
@@ -707,7 +713,7 @@ static RPCHelpMan getnetworkinfo()
         }
     }
     obj.pushKV("localaddresses", localAddresses);
-    obj.pushKV("warnings",       GetWarnings(false).original);
+    obj.pushKV("warnings", GetNodeWarnings(IsDeprecatedRPCEnabled("warnings")));
     return obj;
 },
     };
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index f683878054..0ac2c4e7b0 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -18,16 +18,19 @@
 #include <script/signingprovider.h>
 #include <script/solver.h>
 #include <tinyformat.h>
+#include <univalue.h>
 #include <util/check.h>
 #include <util/result.h>
 #include <util/strencodings.h>
 #include <util/string.h>
 #include <util/translation.h>
+#include <warnings.h>
 
 #include <algorithm>
 #include <iterator>
 #include <string_view>
 #include <tuple>
+#include <utility>
 
 const std::string UNIX_EPOCH_TIME = "UNIX epoch time";
 const std::string EXAMPLE_ADDRESS[2] = {"bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl", "bc1q02ad21edsxd23d32dfgqqsz4vv4nmtfzuklhy3"};
@@ -1357,3 +1360,17 @@ void PushWarnings(const std::vector<bilingual_str>& warnings, UniValue& obj)
     if (warnings.empty()) return;
     obj.pushKV("warnings", BilingualStringsToUniValue(warnings));
 }
+
+UniValue GetNodeWarnings(bool use_deprecated)
+{
+    if (use_deprecated) {
+        const auto all_warnings{GetWarnings()};
+        return all_warnings.empty() ? "" : all_warnings.back().original;
+    }
+
+    UniValue warnings{UniValue::VARR};
+    for (auto&& warning : GetWarnings()) {
+        warnings.push_back(std::move(warning.original));
+    }
+    return warnings;
+}
diff --git a/src/rpc/util.h b/src/rpc/util.h
index 177af90c05..0e4dcc27b5 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -513,4 +513,6 @@ private:
 void PushWarnings(const UniValue& warnings, UniValue& obj);
 void PushWarnings(const std::vector<bilingual_str>& warnings, UniValue& obj);
 
+UniValue GetNodeWarnings(bool use_deprecated);
+
 #endif // BITCOIN_RPC_UTIL_H