https://issues.dlang.org/show_bug.cgi?id=19279
--- Comment #1 from Manu <turkey...@gmail.com> --- Conversation: https://github.com/dlang/dmd/pull/8782 Reveals that `scope` is also necessary to guarantee that the promoted reference does not escape. Promotion is safe so long as no promoted-reference outlives the call where the instance was promoted. struct Bob { void setThing() shared scope; } void f(ref shared Bob a, ref Bob b) { a.setThing(); // I have a shared object, can call shared method b.setThing(); // this should work with `scope` } --