message: add size assertions for some core types
diff: @@ -12,6 +12,8 @@ use rand::SeedableRng;
  use rustc_ast::ast::Mutability;
  use rustc_data_structures::fx::FxHashMap;
  +#[allow(unused)]
  +use rustc_data_structures::static_assert_size;
  use rustc_middle::{
  mir,
  ty::{
  @@ -128,6 +130,13 @@ pub struct Tag {
  pub sb: SbTag,
  }
  +#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
  +static_assert_size!(Pointer<Tag>, 24);
  +#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
  +static_assert_size!(Pointer<Option<Tag>>, 24);
  +#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
  +static_assert_size!(ScalarMaybeUninit<Tag>, 32);
  +
  impl Provenance for Tag {
  /// We use absolute addresses in the `offset` of a `Pointer<Tag>`.
  const OFFSET_IS_ADDR: bool = true;
  