Actually, provenance matters: "During the construction of an object, if the value of the object or any of its subobjects is accessed through a glvalue that is

Actually, provenance matters: "During the construction of an object, if the value of the object or any of its subobjects is accessed through a glvalue that is not obtained, directly or indirectly, from the constructor's this pointer, the value of the object or subobject thus obtained is unspecified." [0] Reading an unspecified value isn't UB, that's good, but I don't understand why the standard says 'unspecified' because it clearly can be indeterminate if a sub-object hasn't been initialized yet. [0] https://eel.is/c++draft/class.cdtor#2 https://eel.is/c++draft/class.cdtor#2