compat/mutex: drop const when casting mutex

Fixes const correctness in spline-widget

1 files changed, 2 insertions, 2 deletions

diff --git a/opentrack-compat/qcopyable-mutex.hpp b/opentrack-compat/qcopyable-mutex.hpp
index f7f36f93..57b0030d 100644
--- a/opentrack-compat/qcopyable-mutex.hpp
+++ b/opentrack-compat/qcopyable-mutex.hpp
@@ -30,8 +30,8 @@ public:
     {
     }
 
-    QMutex* operator&()
+    QMutex* operator&() const
     {
-        return &inner;
+        return const_cast<QMutex*>(&inner);
     }
 };