crash: print warning messages for run/buildtime Qt version mismatch

README.md

@@ -67,6 +67,11 @@ It is not managed by us and should be looked over before use.
 
 [AUR package]: https://aur.archlinux.org/packages/quickshell
 
+> [!CAUTION]
+> The AUR provides no way to force the quickshell package to rebuild when the Qt version changes.
+> If you experience crashes after updating Qt, please try rebuilding Quickshell against the
+> current Qt version before opening an issue.
+
 ## Fedora (COPR)
 Quickshell has a third party [Fedora COPR package] available under the same name.
 It is not managed by us and should be looked over before use.

src/core/main.cpp

@@ -4,6 +4,7 @@
 #include <cerrno>
 #include <cstdio>
 #include <cstdlib>
+#include <cstring>
 #include <limits>
 #include <string>
 #include <vector>
@@ -176,6 +177,7 @@ struct CommandState {
 	} subcommand;
 
 	struct {
+		bool checkCompat = false;
 		bool printVersion = false;
 		bool killAll = false;
 		bool noDuplicate = false;
@@ -290,6 +292,8 @@ int runCommand(int argc, char** argv, QCoreApplication* coreApplication) {
 	addDebugOptions(&cli);
 
 	{
+		cli.add_option_group("")->add_flag("--private-check-compat", state.misc.checkCompat);
+
 		cli.add_flag("-V,--version", state.misc.printVersion)
 		    ->description("Print quickshell's version and exit.");
 
@@ -378,6 +382,18 @@ int runCommand(int argc, char** argv, QCoreApplication* coreApplication) {
 
 	CLI11_PARSE(cli, argc, argv);
 
+	if (state.misc.checkCompat) {
+		if (strcmp(qVersion(), QT_VERSION_STR) != 0) {
+			QTextStream(stdout) << "\033[31mCOMPATIBILITY WARNING: Quickshell was built against Qt "
+			                    << QT_VERSION_STR << " but the system has updated to Qt " << qVersion()
+			                    << " without rebuilding the package. This is likely to cause crashes, so "
+			                       "you must rebuild the quickshell package.\n";
+			return 1;
+		}
+
+		return 0;
+	}
+
 	// Has to happen before extra threads are spawned.
 	if (state.misc.daemonize) {
 		auto closepipes = std::array<int, 2>();
@@ -451,6 +467,13 @@ int runCommand(int argc, char** argv, QCoreApplication* coreApplication) {
 	} else if (*state.subcommand.msg) {
 		return msgInstance(state);
 	} else {
+		if (strcmp(qVersion(), QT_VERSION_STR) != 0) {
+			qWarning() << "\033[31mQuickshell was built against Qt" << QT_VERSION_STR
+			           << "but the system has updated to Qt" << qVersion()
+			           << "without rebuilding the package. This is likely to cause crashes, so "
+			              "the quickshell package must be rebuilt.\n";
+		}
+
 		return launchFromCommand(state, coreApplication);
 	}
 

src/crash/interface.cpp

@@ -1,8 +1,10 @@
 #include "interface.hpp"
+#include <cstring>
 #include <utility>
 
 #include <qapplication.h>
 #include <qboxlayout.h>
+#include <qconfig.h>
 #include <qdesktopservices.h>
 #include <qfont.h>
 #include <qfontinfo.h>
@@ -10,6 +12,7 @@
 #include <qnamespace.h>
 #include <qobject.h>
 #include <qpushbutton.h>
+#include <qtversion.h>
 #include <qwidget.h>
 
 #include "build.hpp"
@@ -37,20 +40,40 @@ CrashReporterGui::CrashReporterGui(QString reportFolder, int pid)
 
 	auto* mainLayout = new QVBoxLayout(this);
 
-	mainLayout->addWidget(new QLabel(
-	    "<u>Quickshell has crashed. Please submit a bug report to help us fix it.</u>",
-	    this
-	));
+	auto qtVersionMatches = strcmp(qVersion(), QT_VERSION_STR) == 0;
+	if (qtVersionMatches) {
+		mainLayout->addWidget(new QLabel(
+		    "<u>Quickshell has crashed. Please submit a bug report to help us fix it.</u>",
+		    this
+		));
+	} else {
+		mainLayout->addWidget(
+		    new QLabel("<u>Quickshell has crashed, likely due to a Qt version mismatch.</u>", this)
+		);
+	}
 
 	mainLayout->addSpacing(textHeight);
 
 	mainLayout->addWidget(new QLabel("General information", this));
 	mainLayout->addWidget(new ReportLabel("Git Revision:", GIT_REVISION, this));
+	mainLayout->addWidget(new QLabel(
+	    QString::fromLatin1("Runtime Qt version: ") % qVersion() % ", Buildtime Qt version: "
+	        % QT_VERSION_STR,
+	    this
+	));
 	mainLayout->addWidget(new ReportLabel("Crashed process ID:", QString::number(pid), this));
 	mainLayout->addWidget(new ReportLabel("Crash report folder:", this->reportFolder, this));
 	mainLayout->addSpacing(textHeight);
 
-	mainLayout->addWidget(new QLabel("Please open a bug report for this issue via github or email."));
+	if (qtVersionMatches) {
+		mainLayout->addWidget(new QLabel("Please open a bug report for this issue via github or email.")
+		);
+	} else {
+		mainLayout->addWidget(new QLabel(
+		    "Please rebuild Quickshell against the current Qt version.\n"
+		    "If this does not solve the problem, please open a bug report via github or email."
+		));
+	}
 
 	mainLayout->addWidget(new ReportLabel(
 	    "Github:",

src/crash/main.cpp

@@ -4,6 +4,7 @@
 
 #include <qapplication.h>
 #include <qconfig.h>
+#include <qcoreapplication.h>
 #include <qdatastream.h>
 #include <qdir.h>
 #include <qfile.h>
@@ -12,7 +13,6 @@
 #include <qtenvironmentvariables.h>
 #include <qtextstream.h>
 #include <qtversion.h>
-#include <qversiontagging.h>
 #include <sys/sendfile.h>
 #include <sys/types.h>