Enum From Integer is UB Problem

[Michael-F-Bryan]

Problem 4 (link) shows how it is UB to cast a random integer as an enum when there isn't a corresponding variant. This was originally mentioned by @bluss on the user forums.

The solutions section should mention how this is UB, as well as ways you can prevent this sort of behaviour.

[bluss]

See also

• Match on repr(C) enum returned from C library with unknown value leads to UB rust-lang/rust#36927