error: generic parameters may not be used in const operations --> $DIR/issue-46511.rs:5:35 | LL | _a: [u8; std::mem::size_of::<&'a mut u8>()] | ^^ cannot perform const operation using `'a` | = note: lifetime parameters may not be used in const expressions = help: add `#![feature(generic_const_exprs)]` to allow generic const expressions error[E0392]: parameter `'a` is never used --> $DIR/issue-46511.rs:3:12 | LL | struct Foo<'a> | ^^ unused parameter | = help: consider removing `'a`, referring to it in a field, or using a marker such as `PhantomData` error: aborting due to 2 previous errors For more information about this error, try `rustc --explain E0392`.