Upgrade to C++20

.clang-format

@@ -1,7 +1,7 @@
 ---
 # Language
 Language:        Cpp
-Standard:        Cpp11  # Cpp14 and Cpp17 are not supported by clang 11
+Standard:        c++20
 
 # Indentation
 TabWidth:        4

.clang-tidy

@@ -20,7 +20,6 @@ Checks: >
   readability-simplify-boolean-expr
 WarningsAsErrors: ''
 HeaderFilterRegex: '' # don't show errors from headers
-AnalyzeTemporaryDtors: false
 FormatStyle:     none
 User:            user
 CheckOptions:    

cmake/modules/ErrorFlags.cmake

@@ -65,6 +65,10 @@ elseif(MSVC)
 			"/WX" # Treat warnings as errors
 		)
 	endif()
+
+	# Silence deprecation warnings for the std::atomic_...<std::shared_ptr> family of functions.
+	# TODO: Remove once C++20's std::atomic<std::shared_ptr> is fully supported.
+	add_compile_definitions("_SILENCE_CXX20_OLD_SHARED_PTR_ATOMIC_SUPPORT_DEPRECATION_WARNING")
 endif()
 
 # Add the flags to the whole directory tree. We use the third-party flags for

include/DeprecationHelper.h

@@ -27,7 +27,10 @@
 #ifndef LMMS_DEPRECATIONHELPER_H
 #define LMMS_DEPRECATIONHELPER_H
 
+#include <type_traits>
+
 #include <QFontMetrics>
+#include <QKeySequence>
 #include <QWheelEvent>
 
 namespace lmms
@@ -64,6 +67,30 @@ inline QPoint position(QWheelEvent *wheelEvent)
 #endif
 }
 
+
+namespace detail
+{
+
+template<typename T>
+inline constexpr bool IsKeyOrModifier = std::is_same_v<T, Qt::Key>
+	|| std::is_same_v<T, Qt::Modifier> || std::is_same_v<T, Qt::KeyboardModifier>;
+
+} // namespace detail
+
+
+/**
+ * @brief Combines Qt key and modifier arguments together,
+ * replacing A | B or A + B which was deprecated in C++20
+ * due to the enums being different types. (P1120R0)
+ * @param args Any number of Qt::Key, Qt::Modifier, or Qt::KeyboardModifier
+ * @return The combination of the given keys/modifiers as an int
+ */
+template<typename... Args, std::enable_if_t<(detail::IsKeyOrModifier<Args> && ...), bool> = true>
+constexpr int combine(Args... args)
+{
+	return (0 + ... + static_cast<int>(args));
+}
+
 } // namespace lmms
 
 #endif // LMMS_DEPRECATIONHELPER_H

plugins/CMakeLists.txt

@@ -2,8 +2,8 @@ SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
 SET(CMAKE_LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
 SET(CMAKE_DEBUG_POSTFIX "")
 
-# Enable C++17
-SET(CMAKE_CXX_STANDARD 17)
+# Enable C++20
+SET(CMAKE_CXX_STANDARD 20)
 
 IF(LMMS_BUILD_APPLE AND CMAKE_CXX_COMPILER_ID MATCHES "Clang")
 	SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")

plugins/SpectrumAnalyzer/SaControlsDialog.cpp

@@ -341,7 +341,6 @@ SaControlsDialog::SaControlsDialog(SaControls *controls, SaProcessor *processor)
 	m_waterfall = new SaWaterfallView(controls, processor, this);
 	display_splitter->addWidget(m_waterfall);
 	m_waterfall->setVisible(m_controls->m_waterfallModel.value());
-	connect(&controls->m_waterfallModel, &BoolModel::dataChanged, [=] {m_waterfall->updateVisibility();});
 }
 
 

plugins/SpectrumAnalyzer/SaWaterfallView.cpp

@@ -54,6 +54,7 @@ SaWaterfallView::SaWaterfallView(SaControls *controls, SaProcessor *processor, Q
 	setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
 
 	connect(getGUI()->mainWindow(), SIGNAL(periodicUpdate()), this, SLOT(periodicUpdate()));
+	connect(&controls->m_waterfallModel, &BoolModel::dataChanged, this, &SaWaterfallView::updateVisibility);
 
 	m_displayTop = 1;
 	m_displayBottom = height() -2;

plugins/Vibed/NineButtonSelector.cpp

@@ -47,7 +47,7 @@ NineButtonSelector::NineButtonSelector(std::array<QPixmap, 18> onOffIcons, int d
 		m_buttons[i]->setActiveGraphic(onOffIcons[i * 2]);
 		m_buttons[i]->setInactiveGraphic(onOffIcons[(i * 2) + 1]);
 		m_buttons[i]->setChecked(false);
-		connect(m_buttons[i].get(), &PixmapButton::clicked, this, [=](){ this->buttonClicked(i); });
+		connect(m_buttons[i].get(), &PixmapButton::clicked, this, [=, this](){ buttonClicked(i); });
 	}
 
 	m_lastBtn = m_buttons[defaultButton].get();

plugins/VstBase/RemoteVstPlugin/CMakeLists.txt

@@ -6,7 +6,7 @@ endif()
 
 project(RemoteVstPlugin 
 	LANGUAGES CXX)
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 
 include(CheckCXXPreprocessor)
 include(CheckCXXSourceCompiles)
@@ -73,7 +73,7 @@ if(MSVC)
 endif()
 
 if(IS_MINGW)
-	SET(CMAKE_REQUIRED_FLAGS "-std=c++17")
+	SET(CMAKE_REQUIRED_FLAGS "-std=c++20")
 endif()
 
 if(LMMS_BUILD_WIN32)

src/3rdparty/CMakeLists.txt

@@ -15,7 +15,7 @@ ADD_SUBDIRECTORY(weakjack)
 add_library(ringbuffer OBJECT
 	ringbuffer/src/lib/ringbuffer.cpp
 )
-target_compile_features(ringbuffer PUBLIC cxx_std_17)
+target_compile_features(ringbuffer PUBLIC cxx_std_20)
 target_include_directories(ringbuffer PUBLIC
 	ringbuffer/include
 	"${CMAKE_CURRENT_BINARY_DIR}"

src/3rdparty/hiir/CMakeLists.txt

@@ -1,3 +1,3 @@
 add_library(hiir INTERFACE)
 target_include_directories(hiir INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
-target_compile_features(hiir INTERFACE cxx_std_17)
+target_compile_features(hiir INTERFACE cxx_std_20)

src/CMakeLists.txt

@@ -9,8 +9,8 @@ SET(CMAKE_AUTOMOC ON)
 SET(CMAKE_AUTOUIC ON)
 SET(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR})
 
-# Enable C++17
-SET(CMAKE_CXX_STANDARD 17)
+# Enable C++20
+SET(CMAKE_CXX_STANDARD 20)
 
 IF(LMMS_BUILD_APPLE AND CMAKE_CXX_COMPILER_ID MATCHES "Clang")
 	SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++")

src/gui/ControllerRackView.cpp

@@ -23,20 +23,22 @@
  *
  */
 
+#include "ControllerRackView.h"
+
 #include <QApplication>
 #include <QAction>
 #include <QPushButton>
 #include <QScrollArea>
 #include <QMessageBox>
 #include <QVBoxLayout>
 
-#include "Song.h"
+#include "ControllerView.h"
+#include "DeprecationHelper.h"
 #include "embed.h"
 #include "GuiApplication.h"
-#include "MainWindow.h"
-#include "ControllerRackView.h"
-#include "ControllerView.h"
 #include "LfoController.h"
+#include "MainWindow.h"
+#include "Song.h"
 #include "SubWindow.h"
 
 namespace lmms::gui
@@ -167,13 +169,13 @@ void ControllerRackView::addController(Controller* controller)
 	connect(controllerView, &ControllerView::removedController, this, &ControllerRackView::deleteController, Qt::QueuedConnection);
 
 	auto moveUpAction = new QAction(controllerView);
-	moveUpAction->setShortcut(Qt::Key_Up | Qt::AltModifier);
+	moveUpAction->setShortcut(combine(Qt::Key_Up, Qt::AltModifier));
 	moveUpAction->setShortcutContext(Qt::WidgetShortcut);
 	connect(moveUpAction, &QAction::triggered, controllerView, &ControllerView::moveUp);
 	controllerView->addAction(moveUpAction);
 
 	auto moveDownAction = new QAction(controllerView);
-	moveDownAction->setShortcut(Qt::Key_Down | Qt::AltModifier);
+	moveDownAction->setShortcut(combine(Qt::Key_Down, Qt::AltModifier));
 	moveDownAction->setShortcutContext(Qt::WidgetShortcut);
 	connect(moveDownAction, &QAction::triggered, controllerView, &ControllerView::moveDown);
 	controllerView->addAction(moveDownAction);

src/gui/EffectRackView.cpp

@@ -23,13 +23,15 @@
  *
  */
 
+#include "EffectRackView.h"
+
 #include <QApplication>
 #include <QAction>
 #include <QPushButton>
 #include <QScrollArea>
 #include <QVBoxLayout>
 
-#include "EffectRackView.h"
+#include "DeprecationHelper.h"
 #include "EffectSelectDialog.h"
 #include "EffectView.h"
 #include "GroupBox.h"
@@ -176,13 +178,13 @@ void EffectRackView::update()
 			connect(view, &EffectView::deletedPlugin, this, &EffectRackView::deletePlugin, Qt::QueuedConnection);
 
 			QAction* moveUpAction = new QAction(view);
-			moveUpAction->setShortcut(Qt::Key_Up | Qt::AltModifier);
+			moveUpAction->setShortcut(combine(Qt::Key_Up, Qt::AltModifier));
 			moveUpAction->setShortcutContext(Qt::WidgetShortcut);
 			connect(moveUpAction, &QAction::triggered, view, &EffectView::moveUp);
 			view->addAction(moveUpAction);
 
 			QAction* moveDownAction = new QAction(view);
-			moveDownAction->setShortcut(Qt::Key_Down | Qt::AltModifier);
+			moveDownAction->setShortcut(combine(Qt::Key_Down, Qt::AltModifier));
 			moveDownAction->setShortcutContext(Qt::WidgetShortcut);
 			connect(moveDownAction, &QAction::triggered, view, &EffectView::moveDown);
 			view->addAction(moveDownAction);

src/gui/FileBrowser.cpp

@@ -635,15 +635,15 @@ void FileBrowserTreeWidget::contextMenuEvent(QContextMenuEvent * e )
 
 		contextMenu.addAction(
 			tr( "Send to active instrument-track" ),
-			[=]{ sendToActiveInstrumentTrack(file); }
+			[=, this]{ sendToActiveInstrumentTrack(file); }
 		);
 
 		contextMenu.addSeparator();
 
 		contextMenu.addAction(
 			QIcon(embed::getIconPixmap("folder")),
 			tr("Open containing folder"),
-			[=]{ openContainingFolder(file); }
+			[=, this]{ openContainingFolder(file); }
 		);
 
 		auto songEditorHeader = new QAction(tr("Song Editor"), nullptr);
@@ -676,14 +676,14 @@ QList<QAction*> FileBrowserTreeWidget::getContextActions(FileItem* file, bool so
 
 	auto toInstrument = new QAction(instrumentAction + tr(" (%2Enter)").arg(shortcutMod), nullptr);
 	connect(toInstrument, &QAction::triggered,
-		[=]{ openInNewInstrumentTrack(file, songEditor); });
+		[=, this]{ openInNewInstrumentTrack(file, songEditor); });
 	result.append(toInstrument);
 
 	if (songEditor && fileIsSample)
 	{
 		auto toSampleTrack = new QAction(tr("Send to new sample track (Shift + Enter)"), nullptr);
 		connect(toSampleTrack, &QAction::triggered,
-			[=]{ openInNewSampleTrack(file); });
+			[=, this]{ openInNewSampleTrack(file); });
 		result.append(toSampleTrack);
 	}
 

src/gui/MainWindow.cpp

@@ -38,6 +38,7 @@
 #include "AboutDialog.h"
 #include "AutomationEditor.h"
 #include "ControllerRackView.h"
+#include "DeprecationHelper.h"
 #include "embed.h"
 #include "Engine.h"
 #include "ExportProjectDialog.h"
@@ -293,11 +294,11 @@ void MainWindow::finalize()
 	project_menu->addAction( embed::getIconPixmap( "project_save" ),
 					tr( "Save &As..." ),
 					this, SLOT(saveProjectAs()),
-					Qt::CTRL + Qt::SHIFT + Qt::Key_S );
+					combine(Qt::CTRL, Qt::SHIFT, Qt::Key_S));
 	project_menu->addAction( embed::getIconPixmap( "project_save" ),
 					tr( "Save as New &Version" ),
 					this, SLOT(saveProjectAsNewVersion()),
-					Qt::CTRL + Qt::ALT + Qt::Key_S );
+					combine(Qt::CTRL, Qt::ALT, Qt::Key_S));
 
 	project_menu->addAction( embed::getIconPixmap( "project_save" ),
 					tr( "Save as default template" ),
@@ -312,23 +313,23 @@ void MainWindow::finalize()
 					tr( "E&xport..." ),
 					this,
 					SLOT(onExportProject()),
-					Qt::CTRL + Qt::Key_E );
+					combine(Qt::CTRL, Qt::Key_E));
 	project_menu->addAction( embed::getIconPixmap( "project_export" ),
 					tr( "E&xport Tracks..." ),
 					this,
 					SLOT(onExportProjectTracks()),
-					Qt::CTRL + Qt::SHIFT + Qt::Key_E );
+					combine(Qt::CTRL, Qt::SHIFT, Qt::Key_E));
 
 	project_menu->addAction( embed::getIconPixmap( "midi_file" ),
 					tr( "Export &MIDI..." ),
 					this,
 					SLOT(onExportProjectMidi()),
-					Qt::CTRL + Qt::Key_M );
+					combine(Qt::CTRL, Qt::Key_M));
 
 	project_menu->addSeparator();
 	project_menu->addAction( embed::getIconPixmap( "exit" ), tr( "&Quit" ),
 					qApp, SLOT(closeAllWindows()),
-					Qt::CTRL + Qt::Key_Q );
+					combine(Qt::CTRL, Qt::Key_Q));
 
 	auto edit_menu = new QMenu(this);
 	menuBar()->addMenu( edit_menu )->setText( tr( "&Edit" ) );
@@ -341,13 +342,13 @@ void MainWindow::finalize()
 					this, SLOT(redo()),
 					QKeySequence::Redo );
 	// Ensure that both (Ctrl+Y) and (Ctrl+Shift+Z) activate redo shortcut regardless of OS defaults
-	if (QKeySequence(QKeySequence::Redo) != QKeySequence(Qt::CTRL + Qt::Key_Y))
+	if (QKeySequence(QKeySequence::Redo) != QKeySequence(combine(Qt::CTRL, Qt::Key_Y)))
 	{
-		new QShortcut( QKeySequence( Qt::CTRL + Qt::Key_Y ), this, SLOT(redo()));
+		new QShortcut(QKeySequence(combine(Qt::CTRL, Qt::Key_Y)), this, SLOT(redo()));
 	}
-	if (QKeySequence(QKeySequence::Redo) != QKeySequence(Qt::CTRL + Qt::SHIFT + Qt::Key_Z ))
+	if (QKeySequence(QKeySequence::Redo) != QKeySequence(combine(Qt::CTRL, Qt::SHIFT, Qt::Key_Z)))
 	{
-		new QShortcut( QKeySequence( Qt::CTRL + Qt::SHIFT + Qt::Key_Z ), this, SLOT(redo()));
+		new QShortcut(QKeySequence(combine(Qt::CTRL, Qt::SHIFT, Qt::Key_Z)), this, SLOT(redo()));
 	}
 
 	edit_menu->addSeparator();
@@ -446,31 +447,31 @@ void MainWindow::finalize()
 	// window-toolbar
 	auto song_editor_window = new ToolButton(embed::getIconPixmap("songeditor"), tr("Song Editor") + " (Ctrl+1)", this,
 		SLOT(toggleSongEditorWin()), m_toolBar);
-	song_editor_window->setShortcut( Qt::CTRL + Qt::Key_1 );
+	song_editor_window->setShortcut(combine(Qt::CTRL, Qt::Key_1));
 
 	auto pattern_editor_window = new ToolButton(embed::getIconPixmap("pattern_track_btn"),
 		tr("Pattern Editor") + " (Ctrl+2)", this, SLOT(togglePatternEditorWin()), m_toolBar);
-	pattern_editor_window->setShortcut(Qt::CTRL + Qt::Key_2);
+	pattern_editor_window->setShortcut(combine(Qt::CTRL, Qt::Key_2));
 
 	auto piano_roll_window = new ToolButton(
 		embed::getIconPixmap("piano"), tr("Piano Roll") + " (Ctrl+3)", this, SLOT(togglePianoRollWin()), m_toolBar);
-	piano_roll_window->setShortcut( Qt::CTRL + Qt::Key_3 );
+	piano_roll_window->setShortcut(combine(Qt::CTRL, Qt::Key_3));
 
 	auto automation_editor_window = new ToolButton(embed::getIconPixmap("automation"),
 		tr("Automation Editor") + " (Ctrl+4)", this, SLOT(toggleAutomationEditorWin()), m_toolBar);
-	automation_editor_window->setShortcut( Qt::CTRL + Qt::Key_4 );
+	automation_editor_window->setShortcut(combine(Qt::CTRL, Qt::Key_4));
 
 	auto mixer_window = new ToolButton(
 		embed::getIconPixmap("mixer"), tr("Mixer") + " (Ctrl+5)", this, SLOT(toggleMixerWin()), m_toolBar);
-	mixer_window->setShortcut( Qt::CTRL + Qt::Key_5 );
+	mixer_window->setShortcut(combine(Qt::CTRL, Qt::Key_5));
 
 	auto controllers_window = new ToolButton(embed::getIconPixmap("controller"),
 		tr("Show/hide controller rack") + " (Ctrl+6)", this, SLOT(toggleControllerRack()), m_toolBar);
-	controllers_window->setShortcut( Qt::CTRL + Qt::Key_6 );
+	controllers_window->setShortcut(combine(Qt::CTRL, Qt::Key_6));
 
 	auto project_notes_window = new ToolButton(embed::getIconPixmap("project_notes"),
 		tr("Show/hide project notes") + " (Ctrl+7)", this, SLOT(toggleProjectNotesWin()), m_toolBar);
-	project_notes_window->setShortcut( Qt::CTRL + Qt::Key_7 );
+	project_notes_window->setShortcut(combine(Qt::CTRL, Qt::Key_7));
 
 	m_toolBarLayout->addWidget( song_editor_window, 1, 1 );
 	m_toolBarLayout->addWidget( pattern_editor_window, 1, 2 );