Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Make TryFromBytes a super-trait of FromZeros #952

Merged
merged 1 commit into from
Feb 29, 2024
Merged

Make TryFromBytes a super-trait of FromZeros #952

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
9 changes: 5 additions & 4 deletions src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1430,7 +1430,7 @@ pub unsafe trait TryFromBytes {
doc = concat!("[derive]: https://docs.rs/zerocopy/", env!("CARGO_PKG_VERSION"), "/zerocopy/derive.FromZeros.html"),
doc = concat!("[derive-analysis]: https://docs.rs/zerocopy/", env!("CARGO_PKG_VERSION"), "/zerocopy/derive.FromZeros.html#analysis"),
)]
pub unsafe trait FromZeros {
pub unsafe trait FromZeros: TryFromBytes {
// The `Self: Sized` bound makes it so that `FromZeros` is still object
// safe.
#[doc(hidden)]
Expand Down Expand Up @@ -3701,8 +3701,10 @@ safety_comment! {
///
/// `UnsafeCell<T>`` has the same in-memory representation as its inner
/// type `T`.
unsafe_impl!(T: ?Sized + FromZeros => FromZeros for UnsafeCell<T>);
unsafe_impl!(T: ?Sized + FromBytes => FromBytes for UnsafeCell<T>);
///
/// TODO(#5): Implement `FromZeros` and `FromBytes` when `T: ?Sized`.
unsafe_impl!(T: FromZeros => FromZeros for UnsafeCell<T>);
unsafe_impl!(T: FromBytes => FromBytes for UnsafeCell<T>);
unsafe_impl!(T: ?Sized + IntoBytes => IntoBytes for UnsafeCell<T>);
unsafe_impl!(T: ?Sized + Unaligned => Unaligned for UnsafeCell<T>);
assert_unaligned!(UnsafeCell<()>, UnsafeCell<u8>);
Expand Down Expand Up @@ -6928,7 +6930,6 @@ mod tests {
#[test]
fn test_object_safety() {
fn _takes_no_cell(_: &dyn NoCell) {}
fn _takes_from_zeros(_: &dyn FromZeros) {}
fn _takes_unaligned(_: &dyn Unaligned) {}
}

Expand Down
30 changes: 20 additions & 10 deletions zerocopy-derive/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -395,10 +395,12 @@ fn derive_try_from_bytes_struct(ast: &DeriveInput, strct: &DataStruct) -> proc_m
}

// A union is `TryFromBytes` if:
// - any of its fields are `TryFromBytes`
// - all of its fields are `TryFromBytes` and `NoCell`

fn derive_try_from_bytes_union(ast: &DeriveInput, unn: &DataUnion) -> proc_macro2::TokenStream {
let self_type_trait_bounds = SelfBounds::All(&[Trait::NoCell]);
// TODO(#5): Remove the `NoCell` bound.
let field_type_trait_bounds =
FieldBounds::All(&[TraitBound::Slf, TraitBound::Other(Trait::NoCell)]);
let extras = Some({
let fields = unn.fields();
let field_names = fields.iter().map(|(name, _ty)| name);
Expand Down Expand Up @@ -434,8 +436,8 @@ fn derive_try_from_bytes_union(ast: &DeriveInput, unn: &DataUnion) -> proc_macro
ast,
unn,
Trait::TryFromBytes,
FieldBounds::ALL_SELF,
self_type_trait_bounds,
field_type_trait_bounds,
SelfBounds::None,
None,
extras,
)
Expand Down Expand Up @@ -606,11 +608,15 @@ fn derive_from_zeros_enum(ast: &DeriveInput, enm: &DataEnum) -> proc_macro2::Tok
impl_block(ast, enm, Trait::FromZeros, FieldBounds::ALL_SELF, SelfBounds::None, None, None)
}

// Like structs, unions are `FromZeros` if
// - all fields are `FromZeros`
// Unions are `FromZeros` if
// - all fields are `FromZeros` and `NoCell`

fn derive_from_zeros_union(ast: &DeriveInput, unn: &DataUnion) -> proc_macro2::TokenStream {
impl_block(ast, unn, Trait::FromZeros, FieldBounds::ALL_SELF, SelfBounds::None, None, None)
// TODO(#5): Remove the `NoCell` bound. It's only necessary for
// compatibility with `derive(TryFromBytes)` on unions; not for soundness.
let field_type_trait_bounds =
FieldBounds::All(&[TraitBound::Slf, TraitBound::Other(Trait::NoCell)]);
impl_block(ast, unn, Trait::FromZeros, field_type_trait_bounds, SelfBounds::None, None, None)
}

// A struct is `FromBytes` if:
Expand Down Expand Up @@ -692,11 +698,15 @@ const ENUM_FROM_BYTES_CFG: Config<EnumRepr> = {
}
};

// Like structs, unions are `FromBytes` if
// - all fields are `FromBytes`
// Unions are `FromBytes` if
// - all fields are `FromBytes` and `NoCell`

fn derive_from_bytes_union(ast: &DeriveInput, unn: &DataUnion) -> proc_macro2::TokenStream {
impl_block(ast, unn, Trait::FromBytes, FieldBounds::ALL_SELF, SelfBounds::None, None, None)
// TODO(#5): Remove the `NoCell` bound. It's only necessary for
// compatibility with `derive(TryFromBytes)` on unions; not for soundness.
let field_type_trait_bounds =
FieldBounds::All(&[TraitBound::Slf, TraitBound::Other(Trait::NoCell)]);
impl_block(ast, unn, Trait::FromBytes, field_type_trait_bounds, SelfBounds::None, None, None)
}

fn derive_into_bytes_struct(ast: &DeriveInput, strct: &DataStruct) -> proc_macro2::TokenStream {
Expand Down