#![feature(offset_of_enum)] use std::mem::offset_of; struct S { a: u8, b: (u8, u8), c: T, } struct T { t: &'static str, } enum Alpha { One(u8), Two(u8), } fn main() { offset_of!(Alpha, Two.0); //~ ERROR only a single ident or integer is stable as the field in offset_of offset_of!(S, a); offset_of!((u8, S), 1); offset_of!((u32, (S, T)), 1.1); //~ ERROR only a single ident or integer is stable as the field in offset_of offset_of!(S, b.0); //~ ERROR only a single ident or integer is stable as the field in offset_of offset_of!((S, ()), 0.c); //~ ERROR only a single ident or integer is stable as the field in offset_of offset_of!(S, c.t); //~ ERROR only a single ident or integer is stable as the field in offset_of }