Re:Fun with C++26 reflection: Keyword Arguments
by drysine on Thursday February 20, 2025 @03:34PM
(#43119808)
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.
"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