nixpkgs/pkgs/development/libraries/qt-5/5.9/qtbase/dlopen-gl.patch

Index: qtbase-opensource-src-5.9.0/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
===================================================================
--- qtbase-opensource-src-5.9.0.orig/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
+++ qtbase-opensource-src-5.9.0/src/plugins/platforms/xcb/gl_integrations/xcb_glx/qglxintegration.cpp
@@ -580,7 +580,14 @@ QFunctionPointer QGLXContext::getProcAdd
 #if QT_CONFIG(library)
                 extern const QString qt_gl_library_name();
 //                QLibrary lib(qt_gl_library_name());
+                // Check system library paths first
                 QLibrary lib(QLatin1String("GL"));
+#ifdef NIXPKGS_MESA_GL
+                if (!lib.load()) {
+                    // Fallback to Mesa driver
+                    lib.setFileName(QLatin1String(NIXPKGS_MESA_GL));
+                }
+#endif // NIXPKGS_MESA_GL
                 glXGetProcAddressARB = (qt_glXGetProcAddressARB) lib.resolve("glXGetProcAddressARB");
 #endif
             }