Fix exception handling after Q*Application::exec()

Uncaught exceptions thrown after we call exec() are originating
from user code and we should not be catching those in our top-level
catch handler. This will just print "ERROR: <what()>" without any
context and make it look like the error is coming from the AM itself.

Instead we need to run the event loop without a try/catch handler, so
stray exception from user code go directly to our set_terminate handler
in the CrashHandler class, which preserves as much context as possible
and prints out a lot more useful meta data for debugging.

Change-Id: Icc0432d5a6c5db85de439cafab89d05aa88b5891
Pick-to: 6.7 6.6 6.5
Reviewed-by: Dominik Holland <dominik.holland@qt.io>

6 files changed, 51 insertions, 40 deletions

diff --git a/examples/applicationmanager/custom-appman/custom-appman.cpp b/examples/applicationmanager/custom-appman/custom-appman.cpp
index 28f7a1b9..3ec4c6e5 100644
--- a/examples/applicationmanager/custom-appman/custom-appman.cpp
+++ b/examples/applicationmanager/custom-appman/custom-appman.cpp
@@ -23,21 +23,24 @@ Q_DECL_EXPORT int main(int argc, char *argv[])
     QCoreApplication::setApplicationName(u"Custom Application Manager"_s);
     QCoreApplication::setApplicationVersion(u"0.1"_s);
 
-    try {
-        Main a(argc, argv, Main::InitFlag::ForkSudoServer | Main::InitFlag::InitializeLogging);
+    std::unique_ptr<Main> a;
+    std::unique_ptr<Configuration> cfg;
 
-        Configuration cfg;
-        cfg.parseWithArguments(QCoreApplication::arguments());
+    try {
+        a = std::make_unique<Main>(argc, argv, Main::InitFlag::ForkSudoServer
+                                                   | Main::InitFlag::InitializeLogging);
+        cfg = std::make_unique<Configuration>();
+        cfg->parseWithArguments(QCoreApplication::arguments());
 
-        a.setup(&cfg);
-        a.loadQml(cfg.loadDummyData());
-        a.showWindow(cfg.fullscreen() && !cfg.noFullscreen());
+        a->setup(cfg.get());
+        a->loadQml();
+        a->showWindow(cfg->fullscreen() && !cfg->noFullscreen());
 
-        return Main::exec();
     } catch (const std::exception &e) {
         qCritical() << "ERROR:" << e.what();
         return 2;
     }
+    return Main::exec();
 }
 
 #endif
diff --git a/examples/applicationmanager/custom-appman/doc/src/custom-appman.qdoc b/examples/applicationmanager/custom-appman/doc/src/custom-appman.qdoc
index ee6c1b82..55f9fc4f 100644
--- a/examples/applicationmanager/custom-appman/doc/src/custom-appman.qdoc
+++ b/examples/applicationmanager/custom-appman/doc/src/custom-appman.qdoc
@@ -36,7 +36,7 @@ them is both intended and required, so we need to set the define \c AM_COMPILING
 The following is a breakdown of the minimal code necessary:
 
 \quotefromfile applicationmanager/custom-appman/custom-appman.cpp
-\skipto #include
+\skipto #include <QtAppManMain/main.h>
 \printuntil QT_USE_NAMESPACE_AM
 
 The application manager is split into functional building blocks. These include statements
@@ -49,7 +49,7 @@ the application manager's symbols are namespaced - \c QT_USE_NAMESPACE_AM expand
 
 Generally, it's a good idea to set an application name and version.
 
-\printuntil Main a
+\printuntil a = std::make_unique<Main>
 
 This \c try block is the heart of the custom application manager. You need to create a \c Main
 object, which is a class derived from QGuiApplication (or QApplication, if widgets support is
diff --git a/src/main-lib/main.h b/src/main-lib/main.h
index fc2e2672..ddb6704e 100644
--- a/src/main-lib/main.h
+++ b/src/main-lib/main.h
@@ -72,7 +72,7 @@ public:
     bool isRunningOnEmbedded() const;
 
     void setup(const Configuration *cfg) noexcept(false);
-    void loadQml(bool loadDummyData) noexcept(false);
+    void loadQml(bool loadDummyData = false) noexcept(false);
     void showWindow(bool showFullscreen);
 
     Q_INVOKABLE void shutDown(int exitCode = 0);
diff --git a/src/main-lib/mainmacro.h b/src/main-lib/mainmacro.h
index 2b99fcba..f27af6a6 100644
--- a/src/main-lib/mainmacro.h
+++ b/src/main-lib/mainmacro.h
@@ -14,21 +14,24 @@ QT_END_NAMESPACE_AM
 #define QT_AM_MAIN() \
 Q_DECL_EXPORT int main(int argc, char *argv[]) \
 { \
+    std::unique_ptr<QtAM::Main> a; \
+    std::unique_ptr<QtAM::Configuration> cfg; \
+\
     try { \
-        QtAM::Main a(argc, argv, QtAM::Main::InitFlag::ForkSudoServer | QtAM::Main::InitFlag::InitializeLogging); \
- \
-        QtAM::Configuration cfg; \
-        cfg.parseWithArguments(QCoreApplication::arguments()); \
- \
-        a.setup(&cfg); \
-        a.loadQml(cfg.loadDummyData()); \
-        a.showWindow(cfg.fullscreen() && !cfg.noFullscreen()); \
- \
-        return QtAM::MainBase::exec(); \
+        a = std::make_unique<QtAM::Main>(argc, argv, QtAM::Main::InitFlag::ForkSudoServer \
+                                                         | QtAM::Main::InitFlag::InitializeLogging); \
+        cfg = std::make_unique<QtAM::Configuration>(); \
+        cfg->parseWithArguments(QCoreApplication::arguments()); \
+\
+        a->setup(cfg.get()); \
+        a->loadQml(); \
+        a->showWindow(cfg->fullscreen() && !cfg->noFullscreen()); \
     } catch (const std::exception &e) { \
         qCritical() << "ERROR:" << e.what(); \
         return 2; \
     } \
+\
+    return QtAM::Main::exec(); \
 }
 
 #endif // MAINMACRO_H
diff --git a/src/tools/appman/appman.cpp b/src/tools/appman/appman.cpp
index 06cc3ce6..02f32424 100644
--- a/src/tools/appman/appman.cpp
+++ b/src/tools/appman/appman.cpp
@@ -46,26 +46,31 @@ Q_DECL_EXPORT int main(int argc, char *argv[])
     QCoreApplication::setOrganizationDomain(u"qt-project.org"_s);
     QCoreApplication::setApplicationVersion(QString::fromLatin1(QT_AM_VERSION_STR));
 
-    try {
-        Main a(argc, argv, Main::InitFlag::ForkSudoServer | Main::InitFlag::InitializeLogging);
-
-        Configuration cfg(additionalDescription, onlyOnePositionalArgument);
-        cfg.parseWithArguments(QCoreApplication::arguments());
+    std::unique_ptr<Main> a;
+    std::unique_ptr<Configuration> cfg;
 
-#if defined(AM_TESTRUNNER)
-        TestRunner::setup(&cfg);
-#endif
-        a.setup(&cfg);
-        a.loadQml(cfg.loadDummyData());
-        a.showWindow(cfg.fullscreen() && !cfg.noFullscreen());
+    try {
+        a = std::make_unique<Main>(argc, argv, Main::InitFlag::ForkSudoServer
+                                                   | Main::InitFlag::InitializeLogging);
+        cfg = std::make_unique<Configuration>(additionalDescription, onlyOnePositionalArgument);
+        cfg->parseWithArguments(QCoreApplication::arguments());
 
 #if defined(AM_TESTRUNNER)
-        return TestRunner::exec(a.qmlEngine());
-#else
-        return Main::exec();
+        TestRunner::setup(cfg.get());
 #endif
+        a->setup(cfg.get());
+        a->loadQml(cfg->loadDummyData());
+        a->showWindow(cfg->fullscreen() && !cfg->noFullscreen());
     } catch (const Exception &e) {
         qCCritical(LogSystem).noquote() << "ERROR:" << e.errorString();
         return 2;
     }
+
+    // we want the exec() outside of the try/catch block, so stray user exceptions trigger the
+    // CrashHandler's set_terminate callback.
+#if defined(AM_TESTRUNNER)
+    return TestRunner::exec(a->qmlEngine());
+#else
+    return Main::exec();
+#endif
 }
diff --git a/src/tools/launcher-qml/launcher-qml.cpp b/src/tools/launcher-qml/launcher-qml.cpp
index c0953385..55b2a945 100644
--- a/src/tools/launcher-qml/launcher-qml.cpp
+++ b/src/tools/launcher-qml/launcher-qml.cpp
@@ -82,6 +82,7 @@ int main(int argc, char *argv[])
     Logging::initialize();
 
     std::unique_ptr<ApplicationMain> am;
+    std::unique_ptr<Controller> controller; // this needs to die BEFORE qApp does
 
     try {
         const QString socket = QDir(qEnvironmentVariable("XDG_RUNTIME_DIR"))
@@ -116,8 +117,6 @@ int main(int argc, char *argv[])
 
         StartupTimer::instance()->checkpoint("after basic initialization");
 
-        std::unique_ptr<Controller> controller; // this needs to die BEFORE qApp does
-
         if (!directLoadManifest.isEmpty()) {
             QString directLoadAppId;
             qsizetype appPos = directLoadManifest.indexOf(u"@"_s);
@@ -136,13 +135,14 @@ int main(int argc, char *argv[])
             StartupTimer::instance()->checkpoint("after dbus initialization");
             controller.reset(new Controller(am.get(), quicklaunched));
         }
-
-        return am->exec();
-
     } catch (const std::exception &e) {
         qCCritical(LogQmlRuntime) << "ERROR:" << e.what();
         return 2;
     }
+
+    // we want the exec() outside of the try/catch block, so stray user exceptions trigger the
+    // CrashHandler's set_terminate callback.
+    return ApplicationMainBase::exec();
 }
 
 Controller::Controller(ApplicationMain *am, bool quickLaunched)