error[E0793]: reference to packed field is unaligned --> $DIR/unaligned_references_external_macro.rs:5:1 | LL | / unaligned_references_external_crate::mac! { LL | | #[repr(packed)] LL | | pub struct X { LL | | pub field: u16 LL | | } LL | | } | |_^ | = note: packed structs are only aligned by one byte, and many modern architectures penalize unaligned field accesses = note: creating a misaligned reference is undefined behavior (even if that reference is never dereferenced) = help: copy the field contents to a local variable, or replace the reference with a raw pointer and use `read_unaligned`/`write_unaligned` (loads and stores via `*p` must be properly aligned even when using raw pointers) = note: this error originates in the macro `unaligned_references_external_crate::mac` (in Nightly builds, run with -Z macro-backtrace for more info) error: aborting due to previous error For more information about this error, try `rustc --explain E0793`.