Migrate to C++ 20 & switch to websocketpp develop branch (#4252)

* feat: c++ 20

* fix: c++ 20 deprecations

* fix(msvc): warnings

* chore: add changelog entry

* fix: formatting

* Update websocketpp to the `develop` branch

* Specify other template type in FlagsEnum != operator

* Remove the user of simple template ids in our websocketpp template class

Also standardizes the file a bit by using nested namespaces, using
pragma once

* fix: turn `MAGIC_MESSAGE_SUFFIX` into a `QString`

* hacky unhacky hacky const char hack

Co-authored-by: Rasmus Karlsson <[email protected]>

CHANGELOG.md

@@ -16,6 +16,7 @@
 - Bugfix: Fixed crash that could occur when changing Tab layout and utilizing multiple windows. (#4248)
 - Dev: Remove protocol from QApplication's Organization Domain (so changed from `https://www.chatterino.com` to `chatterino.com`). (#4256)
 - Dev: Ignore `WM_SHOWWINDOW` hide events, causing fewer attempted rescales. (#4198)
+- Dev: Migrated to C++ 20 (#4252)
 
 ## 2.4.0
 

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.8)
+cmake_minimum_required(VERSION 3.12)
 cmake_policy(SET CMP0087 NEW)
 include(FeatureSummary)
 
@@ -143,7 +143,7 @@ else()
     add_subdirectory("${CMAKE_SOURCE_DIR}/lib/settings" EXCLUDE_FROM_ALL)
 endif()
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
 if (BUILD_TESTS OR BUILD_BENCHMARKS)

src/Application.cpp

@@ -551,7 +551,7 @@ void Application::initPubSub()
 
     this->twitch->pubsub->start();
 
-    auto RequestModerationActions = [=]() {
+    auto RequestModerationActions = [this]() {
         this->twitch->pubsub->setAccount(
             getApp()->accounts->twitch.getCurrent());
         // TODO(pajlada): Unlisten to all authed topics instead of only
@@ -561,7 +561,7 @@ void Application::initPubSub()
     };
 
     this->accounts->twitch.currentUserChanged.connect(
-        [=] {
+        [this] {
             this->twitch->pubsub->unlistenAllModerationActions();
             this->twitch->pubsub->unlistenAutomod();
             this->twitch->pubsub->unlistenWhispers();

src/CMakeLists.txt

@@ -789,28 +789,32 @@ if (MSVC)
     # Someone adds /W3 before we add /W4.
     # This makes sure, only /W4 is specified.
     string(REPLACE "/W3" "/W4" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-    # 4714 - function marked as __forceinline not inlined
-    # 4996 - occurs when the compiler encounters a function or variable that is marked as deprecated.
-    #        These functions may have a different preferred name, may be insecure or have
-    #        a more secure variant, or may be obsolete.
-    # 4505 - unreferenced local version has been removed
-    # 4127 - conditional expression is constant
-    # 4503 - decorated name length exceeded, name was truncated
-    # 4100 - unreferences formal parameter
-    # 4305 - possible truncation of data
-    # 4267 - possible loss of data in return
+    # 4505 - "unreferenced local version has been removed"
+    #        Although this might give hints on dead code,
+    #        there are some cases where it's distracting.
+    #
+    # 4100 - "unreferenced formal parameter"
+    #        There are a lot of functions and methods where
+    #        an argument was given a name but never used.
+    #        There's a clang-tidy rule that will catch this
+    #        for new/updated functions/methods.
+    #
+    # 4267 - "possible loss of data in return"
+    #        These are implicit conversions from size_t to int/qsizetype.
+    #        We don't use size_t in a lot of cases, since
+    #        Qt doesn't use it - it uses int (or qsizetype in Qt6).
     target_compile_options(${LIBRARY_PROJECT} PUBLIC
         /W4
-        # Disable the following warnings
-        /wd4714
-        /wd4996
+        # 5038 - warnings about initialization order
+        /w15038
+        # 4855 - implicit capture of 'this' via '[=]' is deprecated
+        /w14855
+        # Disable the following warnings (see reasoning above)
         /wd4505
-        /wd4127
-        /wd4503
         /wd4100
-        /wd4305
         /wd4267
     )
+    target_compile_definitions(${LIBRARY_PROJECT} PUBLIC NOMINMAX)
 else ()
     target_compile_options(${LIBRARY_PROJECT} PUBLIC
         -Wall

src/common/CompletionModel.cpp

@@ -94,7 +94,7 @@ void CompletionModel::refresh(const QString &prefix, bool isFirstWord)
     // Twitch channel
     auto *tc = dynamic_cast<TwitchChannel *>(&this->channel_);
 
-    auto addString = [=](const QString &str, TaggedString::Type type) {
+    auto addString = [=, this](const QString &str, TaggedString::Type type) {
         // Special case for handling default Twitch commands
         if (type == TaggedString::TwitchCommand)
         {

src/common/FlagsEnum.hpp

@@ -32,7 +32,7 @@ class FlagsEnum
         return this->value_ == other.value_;
     }
 
-    bool operator!=(const FlagsEnum &other)
+    bool operator!=(const FlagsEnum<T> &other)
     {
         return this->value_ != other.value_;
     }

src/controllers/notifications/NotificationController.cpp

@@ -42,7 +42,7 @@ void NotificationController::initialize(Settings &settings, Paths &paths)
 
     this->fetchFakeChannels();
 
-    QObject::connect(this->liveStatusTimer_, &QTimer::timeout, [=] {
+    QObject::connect(this->liveStatusTimer_, &QTimer::timeout, [this] {
         this->fetchFakeChannels();
     });
     this->liveStatusTimer_->start(60 * 1000);

src/messages/layouts/MessageLayout.cpp

@@ -273,7 +273,7 @@ void MessageLayout::paint(QPainter &painter, int width, int y, int messageIndex,
     if (isLastReadMessage)
     {
         QColor color;
-        if (getSettings()->lastMessageColor != "")
+        if (getSettings()->lastMessageColor != QStringLiteral(""))
         {
             color = QColor(getSettings()->lastMessageColor.getValue());
         }

src/providers/liveupdates/BasicPubSubManager.hpp

@@ -204,8 +204,8 @@ class BasicPubSubManager
 
         this->clients_.emplace(hdl, client);
 
-        auto pendingSubsToTake = (std::min)(this->pendingSubscriptions_.size(),
-                                            client->maxSubscriptions);
+        auto pendingSubsToTake = std::min(this->pendingSubscriptions_.size(),
+                                          client->maxSubscriptions);
 
         qCDebug(chatterinoLiveupdates)
             << "LiveUpdate connection opened, subscribing to"