Client: Fail gracefully when wl_display_connect fails

[ChangeLog][QPA plugin] If we're unable to create a connection to the Wayland
display, fail gracefully so other platform integrations can be tried instead.

This also adds QWaylandIntegration::hasFailed() which can later be extended to
report that the platform plugin is unusable for other reasons. I.e. no
compatible shell extensions or similar.

Task-number: QTBUG-59762
Change-Id: I0f1ae73982e2860814235c1a189741d130e1db3e
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

5 files changed, 40 insertions, 5 deletions

diff --git a/src/plugins/platforms/qwayland-brcm-egl/main.cpp b/src/plugins/platforms/qwayland-brcm-egl/main.cpp
index 2640c8ea0..5fa40b8a7 100644
--- a/src/plugins/platforms/qwayland-brcm-egl/main.cpp
+++ b/src/plugins/platforms/qwayland-brcm-egl/main.cpp
@@ -56,7 +56,14 @@ QPlatformIntegration *QWaylandBrcmEglPlatformIntegrationPlugin::create(const QSt
 {
     Q_UNUSED(paramList);
     Q_UNUSED(system);
-    return new QWaylandBrcmEglPlatformIntegration();
+    auto *integration = new QWaylandBrcmEglPlatformIntegration();
+
+    if (integration->hasFailed()) {
+        delete integration;
+        integration = nullptr;
+    }
+
+    return integration;
 }
 
 }
diff --git a/src/plugins/platforms/qwayland-egl/main.cpp b/src/plugins/platforms/qwayland-egl/main.cpp
index ebeeff39f..76b82b3b2 100644
--- a/src/plugins/platforms/qwayland-egl/main.cpp
+++ b/src/plugins/platforms/qwayland-egl/main.cpp
@@ -56,7 +56,14 @@ QPlatformIntegration *QWaylandEglPlatformIntegrationPlugin::create(const QString
 {
     Q_UNUSED(paramList);
     Q_UNUSED(system);
-    return new QWaylandEglPlatformIntegration();
+    auto *integration = new QWaylandEglPlatformIntegration();
+
+    if (integration->hasFailed()) {
+        delete integration;
+        integration = nullptr;
+    }
+
+    return integration;
 }
 
 }
diff --git a/src/plugins/platforms/qwayland-generic/main.cpp b/src/plugins/platforms/qwayland-generic/main.cpp
index 08295c97c..e66a5d45c 100644
--- a/src/plugins/platforms/qwayland-generic/main.cpp
+++ b/src/plugins/platforms/qwayland-generic/main.cpp
@@ -56,7 +56,14 @@ QPlatformIntegration *QWaylandIntegrationPlugin::create(const QString& system, c
 {
     Q_UNUSED(paramList);
     Q_UNUSED(system);
-    return new QWaylandIntegration();
+    auto *integration =  new QWaylandIntegration();
+
+    if (integration->hasFailed()) {
+        delete integration;
+        integration = nullptr;
+    }
+
+    return integration;
 }
 
 }
diff --git a/src/plugins/platforms/qwayland-xcomposite-egl/main.cpp b/src/plugins/platforms/qwayland-xcomposite-egl/main.cpp
index 996f60848..d191bba92 100644
--- a/src/plugins/platforms/qwayland-xcomposite-egl/main.cpp
+++ b/src/plugins/platforms/qwayland-xcomposite-egl/main.cpp
@@ -56,7 +56,14 @@ QPlatformIntegration *QWaylandXCompositeEglPlatformIntegrationPlugin::create(con
 {
     Q_UNUSED(paramList);
     Q_UNUSED(system);
-    return new QWaylandXCompositeEglPlatformIntegration();
+    auto *integration = new QWaylandXCompositeEglPlatformIntegration();
+
+    if (integration->hasFailed()) {
+        delete integration;
+        integration = nullptr;
+    }
+
+    return integration;
 }
 
 }
diff --git a/src/plugins/platforms/qwayland-xcomposite-glx/main.cpp b/src/plugins/platforms/qwayland-xcomposite-glx/main.cpp
index 9f075ebb7..1dfbc0cf4 100644
--- a/src/plugins/platforms/qwayland-xcomposite-glx/main.cpp
+++ b/src/plugins/platforms/qwayland-xcomposite-glx/main.cpp
@@ -58,7 +58,14 @@ QPlatformIntegration *QWaylandXCompositeGlxPlatformIntegrationPlugin::create(con
 {
     Q_UNUSED(paramList);
     Q_UNUSED(system);
-    return new QWaylandXCompositeGlxPlatformIntegration();
+    auto *integration = new QWaylandXCompositeGlxPlatformIntegration();
+
+    if (integration->hasFailed()) {
+        delete integration;
+        integration = nullptr;
+    }
+
+    return integration;
 }
 
 }