Merge bitcoin/bitcoin#30058: Encapsulate warnings in generalized node::Warnings and remove globals

260f8da71a35232d859d7705861fc1a88bfbbe81 refactor: remove warnings globals (stickies-v)
9c4b0b7ce459765fa1a63b410c3423b90f0d2a5f node: update uiInterface whenever warnings updated (stickies-v)
b071ad9770b7ae7fc718dcbfdc8f62dffbf6cfee introduce and use the generalized `node::Warnings` interface (stickies-v)
20e616f86444d00712ac7eb840666e2b0378af4a move-only: move warnings from common to node (stickies-v)
bed29c481aebeb2b0160450c63c03cc68fb89bc6 refactor: remove unnecessary AppendWarning helper function (stickies-v)

Pull request description:

  This PR:
  - moves warnings from common to the node library and into the node namespace (as suggested in https://github.com/bitcoin/bitcoin/pull/29845#discussion_r1570069541)
  - generalizes the warnings interface to `Warnings::Set()` and `Warnings::Unset()` methods, instead of having a separate function and globals for each warning. As a result, this simplifies the `kernel::Notifications` interface.
  - removes warnings.cpp from the kernel library
  - removes warning globals
  - adds testing for the warning logic

  Behaviour change introduced:
  - the `-alertnotify` command is executed for all `KernelNotifications::warningSet` calls, which now also covers the `LARGE_WORK_INVALID_CHAIN` warning
  - the GUI is updated automatically whenever a warning is (un)set, covering some code paths where it previously wouldn't be, e.g. when `node::AbortNode()` is called, or for the `LARGE_WORK_INVALID_CHAIN` warning

  Some discussion points:
  - ~is `const std::string& id` the best way to refer to warnings? Enums are an obvious alternative, but since we need to define warnings across libraries, strings seem like a straightforward solution.~ _edit: updated approach to use `node::Warning` and `kernel::Warning` enums._

ACKs for top commit:
  achow101:
    ACK 260f8da71a35232d859d7705861fc1a88bfbbe81
  ryanofsky:
    Code review ACK 260f8da71a35232d859d7705861fc1a88bfbbe81. Only change since last review was rebasing
  TheCharlatan:
    Re-ACK 260f8da71a35232d859d7705861fc1a88bfbbe81

Tree-SHA512: a3fcedaee0d3ad64e9c111aeb30665162f98e0e72acd6a70b76ff2ddf4f0a34da4f97ce353c322a1668ca6ee4d8a81cc6e6d170c5bbeb7a43cffdaf66646b588

1 files changed, 68 insertions, 0 deletions

diff --git a/src/node/warnings.cpp b/src/node/warnings.cpp
new file mode 100644
index 0000000000..b99c845900
--- /dev/null
+++ b/src/node/warnings.cpp
@@ -0,0 +1,68 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2022 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <config/bitcoin-config.h> // IWYU pragma: keep
+
+#include <node/warnings.h>
+
+#include <common/system.h>
+#include <node/interface_ui.h>
+#include <sync.h>
+#include <univalue.h>
+#include <util/translation.h>
+
+#include <utility>
+#include <vector>
+
+namespace node {
+Warnings::Warnings()
+{
+    // Pre-release build warning
+    if (!CLIENT_VERSION_IS_RELEASE) {
+        m_warnings.insert(
+            {Warning::PRE_RELEASE_TEST_BUILD,
+             _("This is a pre-release test build - use at your own risk - do not use for mining or merchant applications")});
+    }
+}
+bool Warnings::Set(warning_type id, bilingual_str message)
+{
+    LOCK(m_mutex);
+    const auto& [_, inserted]{m_warnings.insert({id, std::move(message)})};
+    if (inserted) uiInterface.NotifyAlertChanged();
+    return inserted;
+}
+
+bool Warnings::Unset(warning_type id)
+{
+    auto success{WITH_LOCK(m_mutex, return m_warnings.erase(id))};
+    if (success) uiInterface.NotifyAlertChanged();
+    return success;
+}
+
+std::vector<bilingual_str> Warnings::GetMessages() const
+{
+    LOCK(m_mutex);
+    std::vector<bilingual_str> messages;
+    messages.reserve(m_warnings.size());
+    for (const auto& [id, msg] : m_warnings) {
+        messages.push_back(msg);
+    }
+    return messages;
+}
+
+UniValue GetWarningsForRpc(const Warnings& warnings, bool use_deprecated)
+{
+    if (use_deprecated) {
+        const auto all_messages{warnings.GetMessages()};
+        return all_messages.empty() ? "" : all_messages.back().original;
+    }
+
+    UniValue messages{UniValue::VARR};
+    for (auto&& message : warnings.GetMessages()) {
+        messages.push_back(std::move(message.original));
+    }
+    return messages;
+}
+} // namespace node