From 1ef5911d28bcbbcb1f4dff63889b80fa24a6cf4e Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Mon, 17 Jun 2024 16:22:07 -0700
Subject: [PATCH] QPluginLoader: set an errorString if resolving
 qt_plugin_instance fails

We're getting load() == false but errorString() == "Unknown error".

Not backporting past 6.8 because of a new translatable string.

Change-Id: Ic0adfa808d28487a8303fffd17d9ee19ce074e4b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
(cherry picked from commit 2be44b57da951007ecab4d6c9e4bc2f3b5cd067a)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/plugin/qlibrary.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/corelib/plugin/qlibrary.cpp b/src/corelib/plugin/qlibrary.cpp
index a3ef8e3c525..094fb941fff 100644
--- a/src/corelib/plugin/qlibrary.cpp
+++ b/src/corelib/plugin/qlibrary.cpp
@@ -589,7 +589,9 @@ QtPluginInstanceFunction QLibraryPrivate::loadPlugin()
     if (load()) {
         auto ptr = reinterpret_cast<QtPluginInstanceFunction>(resolve("qt_plugin_instance"));
         instanceFactory.storeRelease(ptr); // two threads may store the same value
-        return ptr;
+        if (Q_LIKELY(ptr))
+            return ptr;
+        errorString = QLibrary::tr("Could not resolve 'qt_plugin_instance' function");
     }
     qCDebug(qt_lcDebugPlugins) << "QLibraryPrivate::loadPlugin failed on" << fileName << ":" << errorString;
     pluginState = IsNotAPlugin;