Fix [[nodiscard]] warnings coming from KDBindings

std::ignore used in cases where we don't need to store the connection.
I think it's more descriptive than (void).

Technically, using std::ignore is UB until Peppe's P2968 is ratified in
C++26 but every implementation we target does the right thing so I don't
care. Sue me.

examples/gui_window/gui_window.cpp

@@ -68,7 +68,7 @@ int main()
     w.title = "KDGui window example";
     w.visible = true;
 
-    w.visible.valueChanged().connect([&app](bool visible) {
+    KDBindings::ScopedConnection conn =  w.visible.valueChanged().connect([&app](bool visible) {
         if (!visible) {
             app.quit();
         }

src/KDFoundation/platform/linux/linux_platform_timer.cpp

@@ -23,21 +23,21 @@ using namespace KDFoundation;
 LinuxPlatformTimer::LinuxPlatformTimer(Timer *timer)
     : m_notifier(timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC), FileDescriptorNotifier::NotificationType::Read)
 {
-    m_notifier.triggered.connect([this, timer]() {
+    m_notifierConnection = m_notifier.triggered.connect([this, timer]() {
         char buf[8];
         const auto bytes = read(m_notifier.fileDescriptor(), buf, 8);
         KD_UNUSED(bytes);
         timer->timeout.emit();
     });
 
-    timer->running.valueChanged().connect([this, timer](bool running) {
+    m_timerRunningConnection = timer->running.valueChanged().connect([this, timer](bool running) {
         if (running) {
             arm(timer->interval.get());
         } else {
             disarm();
         }
     });
-    timer->interval.valueChanged().connect([this, timer]() {
+    m_timerIntervalConnection  = timer->interval.valueChanged().connect([this, timer]() {
         if (timer->running.get()) {
             arm(timer->interval.get());
         }

src/KDFoundation/platform/linux/linux_platform_timer.h

@@ -13,6 +13,8 @@
 
 #include <chrono>
 
+#include <kdbindings/signal.h>
+
 #include <KDFoundation/platform/abstract_platform_timer.h>
 #include <KDFoundation/file_descriptor_notifier.h>
 
@@ -35,6 +37,9 @@ class KDFOUNDATION_API LinuxPlatformTimer : public AbstractPlatformTimer
         int fd;
     } m_fdCloser;
     FileDescriptorNotifier m_notifier;
+    KDBindings::ScopedConnection m_notifierConnection;
+    KDBindings::ScopedConnection m_timerRunningConnection;
+    KDBindings::ScopedConnection m_timerIntervalConnection;
 };
 
 } // namespace KDFoundation

src/KDFoundation/platform/win32/win32_platform_timer.cpp

@@ -27,14 +27,14 @@ inline Win32PlatformEventLoop *eventLoop()
 Win32PlatformTimer::Win32PlatformTimer(Timer *timer)
     : m_timer(timer)
 {
-    timer->running.valueChanged().connect([this, timer](bool running) {
+    m_timerRunningConnection = timer->running.valueChanged().connect([this, timer](bool running) {
         if (running) {
             arm(timer->interval.get());
         } else {
             disarm();
         }
     });
-    timer->interval.valueChanged().connect([this, timer]() {
+    m_timerIntervalConnection = timer->interval.valueChanged().connect([this, timer]() {
         if (timer->running.get()) {
             arm(timer->interval.get());
         }

src/KDFoundation/platform/win32/win32_platform_timer.h

@@ -13,6 +13,7 @@
 
 #include <chrono>
 #include <windows.h>
+#include <kdbindings/signal.h>
 #undef max
 
 #include <KDFoundation/platform/abstract_platform_timer.h>
@@ -33,6 +34,8 @@ class KDFOUNDATION_API Win32PlatformTimer : public AbstractPlatformTimer
     static void callback(HWND hwnd, UINT uMsg, UINT_PTR timerId, DWORD dwTime);
 
     Timer *m_timer;
+    KDBindings::ScopedConnection m_timerRunningConnection;
+    KDBindings::ScopedConnection m_timerIntervalConnection;
     uintptr_t m_id{ 0 };
 };
 

src/KDGui/abstract_platform_window.cpp

@@ -21,7 +21,7 @@ AbstractPlatformWindow::AbstractPlatformWindow(Window *window, AbstractPlatformW
     , m_type(type)
 {
     assert(window);
-    window->title.valueChanged().connect(&AbstractPlatformWindow::setTitle, this);
+    m_titleChangedConnection = window->title.valueChanged().connect(&AbstractPlatformWindow::setTitle, this);
 }
 
 AbstractPlatformWindow::Type AbstractPlatformWindow::type() const

src/KDGui/abstract_platform_window.h

@@ -15,6 +15,8 @@
 #include <KDGui/kdgui_keys.h>
 #include <KDGui/gui_events.h>
 
+#include <kdbindings/signal.h>
+
 #include <string>
 
 namespace KDGui {
@@ -86,6 +88,7 @@ class KDGUI_API AbstractPlatformWindow
 
 protected:
     Window *m_window;
+    KDBindings::ScopedConnection m_titleChangedConnection;
     AbstractPlatformWindow::Type m_type;
 };
 

src/KDGui/platform/linux/wayland/linux_wayland_platform_input.cpp

@@ -26,6 +26,8 @@
 #include <wayland-zwp-relative-pointer-unstable-v1-client-protocol.h>
 #include <wayland-zwp-pointer-constraints-v1-client-protocol.h>
 
+#include <tuple>
+
 using namespace KDGui;
 
 LinuxWaylandPlatformInput::LinuxWaylandPlatformInput(LinuxWaylandPlatformIntegration *integration,
@@ -41,7 +43,7 @@ LinuxWaylandPlatformInput::LinuxWaylandPlatformInput(LinuxWaylandPlatformIntegra
     };
     wl_seat_add_listener(seat, &listener, this);
 
-    m_keyboard.repeat.timer.timeout.connect(&LinuxWaylandPlatformInput::keyboardRepeatKey, this);
+    std::ignore = m_keyboard.repeat.timer.timeout.connect(&LinuxWaylandPlatformInput::keyboardRepeatKey, this);
 }
 
 LinuxWaylandPlatformInput::~LinuxWaylandPlatformInput()
@@ -223,7 +225,7 @@ void LinuxWaylandPlatformInput::pointerEnter(wl_pointer *pointer, uint32_t seria
         m_pointer.accumulatedEvent.focusChange = true;
     } else {
         m_pointer.focus = LinuxWaylandPlatformWindow::fromSurface(surface);
-        m_pointer.focus->cursorChanged.connect(&LinuxWaylandPlatformInput::setCursor, this);
+        std::ignore = m_pointer.focus->cursorChanged.connect(&LinuxWaylandPlatformInput::setCursor, this);
         setCursor();
     }
 }
@@ -333,7 +335,7 @@ void LinuxWaylandPlatformInput::pointerFrame(wl_pointer *pointer)
     auto &ev = m_pointer.accumulatedEvent;
     if (ev.focusChange && ev.focus) {
         m_pointer.focus = ev.focus;
-        m_pointer.focus->cursorChanged.connect(&LinuxWaylandPlatformInput::setCursor, this);
+        std::ignore = m_pointer.focus->cursorChanged.connect(&LinuxWaylandPlatformInput::setCursor, this);
         setCursor();
     }
 

src/KDGui/platform/linux/wayland/linux_wayland_platform_window.cpp

@@ -24,6 +24,7 @@
 
 #include <array>
 #include <cassert>
+#include <tuple>
 
 using namespace KDFoundation;
 using namespace KDGui;
@@ -34,12 +35,12 @@ LinuxWaylandPlatformWindow::LinuxWaylandPlatformWindow(
     : AbstractPlatformWindow(window, AbstractPlatformWindow::Type::Wayland)
     , m_platformIntegration{ platformIntegration }
 {
-    CoreApplication::instance()->applicationName.valueChanged().connect([this]() {
+    std::ignore = CoreApplication::instance()->applicationName.valueChanged().connect([this]() {
         if (m_toplevel) {
             setAppId();
         }
     });
-    window->scaleFactor.valueChanged().connect([this](float value) {
+    m_scaleChangedConnection = window->scaleFactor.valueChanged().connect([this](float value) {
         if (m_surface) {
             wl_surface_set_buffer_scale(m_surface, int32_t(value));
         }

src/KDGui/platform/linux/wayland/linux_wayland_platform_window.h

@@ -115,6 +115,7 @@ class KDGUI_API LinuxWaylandPlatformWindow : public AbstractPlatformWindow
     CursorMode m_cursorMode{ CursorMode::Normal };
     MouseButtons m_mouseButtons{ MouseButton::NoButton };
     std::vector<LinuxWaylandPlatformOutput *> m_enteredOutputs;
+    KDBindings::ScopedConnection m_scaleChangedConnection;
 };
 
 } // namespace KDGui

src/KDGui/platform/linux/xcb/linux_xcb_platform_event_loop.cpp

@@ -21,6 +21,8 @@
 
 #include <xcb/xcb.h>
 
+#include <tuple>
+
 using namespace KDFoundation;
 using namespace KDGui;
 
@@ -39,7 +41,7 @@ LinuxXcbPlatformEventLoop::LinuxXcbPlatformEventLoop(LinuxXcbPlatformIntegration
     auto xcbfd = xcb_get_file_descriptor(connection);
     SPDLOG_LOGGER_DEBUG(m_logger, "Registering xcb fd {} with event loop", xcbfd);
     m_xcbNotifier = std::make_unique<FileDescriptorNotifier>(xcbfd, FileDescriptorNotifier::NotificationType::Read);
-    m_xcbNotifier->triggered.connect([this](const int &) {
+    std::ignore = m_xcbNotifier->triggered.connect([this](const int &) {
         this->m_xcbEventsPending = true;
     });
 

src/KDGui/window.cpp

@@ -16,6 +16,8 @@
 #include <KDFoundation/platform/abstract_platform_integration.h>
 #include <KDFoundation/event.h>
 
+#include <tuple>
+
 using namespace KDFoundation;
 using namespace KDGui;
 
@@ -24,13 +26,13 @@ Window::Window()
     , m_logger{ KDUtils::Logger::logger("window", spdlog::level::info) }
 {
 
-    visible.valueChanged().connect(&Window::onVisibleChanged, this);
+    std::ignore = visible.valueChanged().connect(&Window::onVisibleChanged, this);
     m_resizeConnectionIds = {
         width.valueChanged().connect(&Window::onSizeChanged, this),
         height.valueChanged().connect(&Window::onSizeChanged, this)
     };
-    cursorEnabled.valueChanged().connect(&Window::onCursorEnabledChanged, this);
-    rawMouseInputEnabled.valueChanged().connect(&Window::onRawMouseInputEnabledChanged, this);
+    std::ignore = cursorEnabled.valueChanged().connect(&Window::onCursorEnabledChanged, this);
+    std::ignore = rawMouseInputEnabled.valueChanged().connect(&Window::onRawMouseInputEnabledChanged, this);
 }
 
 Window::~Window()

tests/auto/foundation/common/signal_spy.h

@@ -23,7 +23,7 @@ class SignalSpy
     template<typename Signal>
     explicit SignalSpy(Signal &s)
     {
-        s.connect([this](Args... args) {
+        m_connection = s.connect([this](Args... args) {
             callback(args...);
         });
     }
@@ -74,4 +74,5 @@ class SignalSpy
 
     uint32_t m_count = 0;
     std::tuple<Args...> m_args;
+    KDBindings::ScopedConnection m_connection;
 };

tests/auto/foundation/core_application/tst_core_application.cpp

@@ -18,6 +18,7 @@
 #include <condition_variable>
 #include <mutex>
 #include <thread>
+#include <tuple>
 
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
 #include <doctest.h>
@@ -203,7 +204,7 @@ TEST_CASE("Timer handling")
         int timeout = 0;
         auto startTime = std::chrono::steady_clock::now();
         auto time = startTime;
-        timer.timeout.connect([&]() {
+        std::ignore = timer.timeout.connect([&]() {
             const auto endTime = std::chrono::steady_clock::now();
             REQUIRE(endTime - time > 50ms);
             REQUIRE(endTime - time < 150ms);
@@ -240,7 +241,7 @@ TEST_CASE("Timer handling")
 
         bool fired = false;
 
-        timer.timeout.connect([&] {
+        std::ignore = timer.timeout.connect([&] {
             fired = true;
         });
 

tests/auto/foundation/object/tst_object.cpp

@@ -19,6 +19,7 @@
 
 #include <numeric>
 #include <string>
+#include <tuple>
 
 #define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
 #include <doctest.h>
@@ -288,7 +289,7 @@ TEST_CASE("Object destruction")
 
         for (int i = 0; i < 10; ++i) {
             auto child = parent->createChild<IntObject>(i);
-            child->aboutToBeDestroyed.connect(onAboutToBeDestroyed);
+            std::ignore = child->aboutToBeDestroyed.connect(onAboutToBeDestroyed);
         }
         // THEN
         REQUIRE(childRemovedSpy.count() == 0);

tests/auto/foundation/win32_platform_event_loop/tst_win32_platform_event_loop.cpp

@@ -25,6 +25,7 @@
 #include <numeric>
 #include <string>
 #include <thread>
+#include <tuple>
 
 #include <WinSock2.h>
 #include <WS2tcpip.h>
@@ -185,15 +186,15 @@ TEST_CASE("Wait for events")
         // A notifier for testing deregistration
         int unregisteredCalls = 0;
         FileDescriptorNotifier unregistered(clientSock, FileDescriptorNotifier::NotificationType::Read);
-        unregistered.triggered.connect([&unregisteredCalls] {
+        std::ignore = unregistered.triggered.connect([&unregisteredCalls] {
             unregisteredCalls++;
         });
         loop.registerNotifier(&unregistered);
         loop.unregisterNotifier(&unregistered);
 
         // Set up read notifier to receive the data
         FileDescriptorNotifier readNotifier(clientSock, FileDescriptorNotifier::NotificationType::Read);
-        readNotifier.triggered.connect([&dataReceived](int fd) {
+        std::ignore = readNotifier.triggered.connect([&dataReceived](int fd) {
             char buf[128] = {};
             recv(fd, buf, 128, 0);
             const int recvSize = recv(fd, buf, 128, 0);
@@ -205,7 +206,7 @@ TEST_CASE("Wait for events")
         // A notifier for testing Write notification type
         FileDescriptorNotifier writeNotifier(clientSock, FileDescriptorNotifier::NotificationType::Write);
         int writeTriggered = 0;
-        writeNotifier.triggered.connect([&writeTriggered]() {
+        std::ignore = writeNotifier.triggered.connect([&writeTriggered]() {
             writeTriggered++;
         });
         loop.registerNotifier(&writeNotifier);

tests/auto/utils/signal/tst_signal.cpp

@@ -14,6 +14,7 @@
 #include <kdbindings/signal.h>
 
 #include <thread>
+#include <tuple>
 
 using namespace KDUtils;
 
@@ -31,13 +32,13 @@ TEST_SUITE("Signal")
         KDBindings::Signal<int> signal2;
 
         std::thread thread1([&] {
-            signal1.connectDeferred(app.connectionEvaluator(), [&val](int value) {
+            std::ignore = signal1.connectDeferred(app.connectionEvaluator(), [&val](int value) {
                 val += value;
             });
         });
 
         std::thread thread2([&] {
-            signal2.connectDeferred(app.connectionEvaluator(), [&val](int value) {
+            std::ignore = signal2.connectDeferred(app.connectionEvaluator(), [&val](int value) {
                 val += value;
             });
         });
@@ -91,11 +92,11 @@ TEST_SUITE("Signal")
         int val1 = 4;
         int val2 = 4;
 
-        signal1.connectDeferred(app.connectionEvaluator(), [&val1](int value) {
+        std::ignore = signal1.connectDeferred(app.connectionEvaluator(), [&val1](int value) {
             val1 += value;
         });
 
-        signal2.connectDeferred(app.connectionEvaluator(), [&val2](int value) {
+        std::ignore = signal2.connectDeferred(app.connectionEvaluator(), [&val2](int value) {
             val2 += value;
         });