Re: [PATCH v2 1/2] rust: pin-init: internal: init: remove `#[disable_initialized_field_access]`

[Miguel Ojeda]

On Mon, Mar 2, 2026 at 3:04 PM Benno Lossin <lossin@xxxxxxxxxx> wrote:
>
> Gary noticed [1] that the initializer macros as well as the `[Pin]Init`
> traits cannot support unaligned fields, since they use operations that
> require aligned pointers. This means that any code using structs with
> unaligned fields in pin-init is unsound.
>
> By default, the `init!` macro generates references to initialized
> fields, which makes the compiler check that those fields are aligned.
> However, we added the `#[disable_initialized_field_access]` attribute to
> avoid this behavior in ceca298c53f9 ("rust: pin-init: internal: init:
> add escape hatch for referencing initialized fields"). Thus remove the
> `#[disable_initialized_field_access]` attribute from `init!`, which is
> the only safe way to create an initializer handling unaligned fields.
>
> If support for in-place initializing structs with unaligned fields is
> required in the future, we could figure out a solution. This is tracked
> in [2].
>
> Reported-by: Gary Guo <gary@xxxxxxxxxxx>
> Link: https://rust-for-linux.zulipchat.com/#narrow/channel/561532-pin-init/topic/initialized.20field.20accessor.20detection/with/576210658 [1]
> Link: https://github.com/Rust-for-Linux/pin-init/issues/112 [2]
> Fixes: ceca298c53f9 ("rust: pin-init: internal: init: add escape hatch for referencing initialized fields")
> Signed-off-by: Benno Lossin <lossin@xxxxxxxxxx>

Applied to `rust-fixes` -- thanks everyone!

    [ Adjusted tags and reworded as discussed. - Miguel ]

    [ Updated Cc: stable@ tags as discussed. - Miguel ]

Cheers,
Miguel