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[derive] Unify handling of #[allow] attributes #2882

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Merged
joshlf merged 1 commit into from
Jan 12, 2026
Merged

[derive] Unify handling of #[allow] attributes #2882

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6 changes: 1 addition & 5 deletions zerocopy-derive/src/enum.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@ pub(crate) fn generate_tag_enum(repr: &EnumRepr, data: &DataEnum) -> TokenStream

quote! {
#repr
#[allow(dead_code, non_camel_case_types)]
#[allow(dead_code)]
enum ___ZerocopyTag {
#(#variants,)*
}
Expand Down Expand Up @@ -90,7 +90,6 @@ fn generate_tag_consts(data: &DataEnum) -> TokenStream {
//
// Casting between two integers of the same size (e.g. i32 -> u32)
// is a no-op.
#[allow(non_upper_case_globals)]
const #tag_ident: ___ZerocopyTagPrimitive =
___ZerocopyTag::#variant_ident as ___ZerocopyTagPrimitive;
}
Expand Down Expand Up @@ -143,7 +142,6 @@ fn generate_variant_structs(

let variant_struct = parse_quote! {
#[repr(C)]
#[allow(non_snake_case)]
struct #variant_struct_ident #impl_generics (
core_reexport::mem::MaybeUninit<___ZerocopyInnerTag>,
#(#field_types,)*
Expand Down Expand Up @@ -200,7 +198,6 @@ fn generate_variants_union(

let variants_union = parse_quote! {
#[repr(C)]
#[allow(non_snake_case)]
union ___ZerocopyVariants #generics {
#(#fields)*
// Enums can have variants with no fields, but unions must
Expand Down Expand Up @@ -446,7 +443,6 @@ pub(crate) fn derive_is_bit_valid(

let variants = raw_enum.project::<_, { #zerocopy_crate::ident_id!(variants) }>();

#[allow(non_upper_case_globals)]
match tag {
#(#match_arms,)*
_ => false,
Expand Down
89 changes: 35 additions & 54 deletions zerocopy-derive/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,11 @@ macro_rules! derive {
Ok(zerocopy_crate) => zerocopy_crate,
Err(e) => return e.into_compile_error().into(),
};
$inner(&ast, Trait::$trait, &zerocopy_crate).into_ts().into()
let ts = $inner(&ast, Trait::$trait, &zerocopy_crate).into_ts();
// We wrap in `const_block` as a backstop in case any derive fails
// to wrap its output in `const_block` (and thus fails to annotate)
// with the full set of `#[allow(...)]` attributes).
const_block([Some(ts)]).into()
}
};
}
Expand Down Expand Up @@ -337,7 +341,6 @@ fn derive_known_layout_inner(
// Define the collection of type-level field handles.
let field_defs = field_indices.iter().zip(&fields).map(|(idx, (vis, _, _))| {
quote! {
#[allow(non_camel_case_types)]
#vis struct #idx;
}
});
Expand All @@ -352,7 +355,6 @@ fn derive_known_layout_inner(
// would not respect `Self` hygiene, as `Self` would refer to
// the helper struct we are generating, not the derive target
// type.
#[allow(deprecated)]
unsafe impl #impl_generics #zerocopy_crate::util::macro_util::Field<#idx> for #ident #ty_generics
where
#predicates
Expand Down Expand Up @@ -393,11 +395,6 @@ fn derive_known_layout_inner(
// `#ty`, not `__ZerocopyKnownLayoutMaybeUninit` (see #2116).
#repr
#[doc(hidden)]
// Required on some rustc versions due to a lint that is only
// triggered when `derive(KnownLayout)` is applied to `repr(C)`
// structs that are generated by macros. See #2177 for details.
#[allow(private_bounds)]
#[allow(deprecated)]
#vis struct __ZerocopyKnownLayoutMaybeUninit<#params> (
#(#zerocopy_crate::util::macro_util::core_reexport::mem::MaybeUninit<
<#ident #ty_generics as
Expand All @@ -424,13 +421,11 @@ fn derive_known_layout_inner(
// sound, since `__ZerocopyKnownLayoutMaybeUninit` is guaranteed
// to have the same layout as the derive target type, except
// that `__ZerocopyKnownLayoutMaybeUninit` admits uninit bytes.
#[allow(deprecated)]
unsafe impl #impl_generics #zerocopy_crate::KnownLayout for __ZerocopyKnownLayoutMaybeUninit #ty_generics
where
#trailing_field_ty: #zerocopy_crate::KnownLayout,
#predicates
{
#[allow(clippy::missing_inline_in_public_items)]
fn only_derive_is_allowed_to_implement_this_trait() {}

type PointerMetadata = <#ident #ty_generics as #zerocopy_crate::KnownLayout>::PointerMetadata;
Expand Down Expand Up @@ -631,10 +626,6 @@ fn derive_hash_inner(
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let where_predicates = where_clause.map(|clause| &clause.predicates);
Ok(quote! {
#[allow(deprecated)]
// While there are not currently any warnings that this suppresses (that
// we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
impl #impl_generics #zerocopy_crate::util::macro_util::core_reexport::hash::Hash for #type_ident #ty_generics
where
Self: #zerocopy_crate::IntoBytes + #zerocopy_crate::Immutable,
Expand Down Expand Up @@ -677,12 +668,6 @@ fn derive_eq_inner(
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let where_predicates = where_clause.map(|clause| &clause.predicates);
Ok(quote! {
// FIXME(#553): Add a test that generates a warning when
// `#[allow(deprecated)]` isn't present.
#[allow(deprecated)]
// While there are not currently any warnings that this suppresses (that
// we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
impl #impl_generics #zerocopy_crate::util::macro_util::core_reexport::cmp::PartialEq for #type_ident #ty_generics
where
Self: #zerocopy_crate::IntoBytes + #zerocopy_crate::Immutable,
Expand All @@ -696,12 +681,6 @@ fn derive_eq_inner(
}
}

// FIXME(#553): Add a test that generates a warning when
// `#[allow(deprecated)]` isn't present.
#[allow(deprecated)]
// While there are not currently any warnings that this suppresses (that
// we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
impl #impl_generics #zerocopy_crate::util::macro_util::core_reexport::cmp::Eq for #type_ident #ty_generics
where
Self: #zerocopy_crate::IntoBytes + #zerocopy_crate::Immutable,
Expand Down Expand Up @@ -867,13 +846,7 @@ fn derive_has_field_struct_union(
.build()
});

quote! {
#[allow(non_camel_case_types)]
const _: () = {
#(#field_tokens)*
#(#has_fields)*
};
}
const_block(field_tokens.into_iter().chain(has_fields).map(Some))
}

/// A struct is `TryFromBytes` if:
Expand Down Expand Up @@ -1945,10 +1918,6 @@ impl<'a> ImplBlockBuilder<'a> {

let inner_extras = self.inner_extras;
let impl_tokens = quote! {
#[allow(deprecated, non_local_definitions)]
// While there are not currently any warnings that this suppresses
// (that we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
unsafe impl < #(#params),* > #trait_path for #type_ident < #(#param_idents),* >
where
#(#bounds,)*
Expand All @@ -1959,23 +1928,8 @@ impl<'a> ImplBlockBuilder<'a> {
}
};

if let Some(outer_extras) = self.outer_extras.filter(|e| !e.is_empty()) {
// So that any items defined in `#outer_extras` don't conflict with
// existing names defined in this scope.
quote! {
#[allow(deprecated, non_local_definitions)]
// While there are not currently any warnings that this suppresses
// (that we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
const _: () = {
#impl_tokens

#outer_extras
};
}
} else {
impl_tokens
}
let outer_extras = self.outer_extras.filter(|e| !e.is_empty());
const_block([Some(impl_tokens), outer_extras])
}
}

Expand All @@ -2000,3 +1954,30 @@ impl BoolExt for bool {
}
}
}

fn const_block(items: impl IntoIterator<Item = Option<TokenStream>>) -> TokenStream {
let items = items.into_iter().flatten();
quote! {
#[allow(
// FIXME(#553): Add a test that generates a warning when
// `#[allow(deprecated)]` isn't present.
deprecated,
// Required on some rustc versions due to a lint that is only
// triggered when `derive(KnownLayout)` is applied to `repr(C)`
// structs that are generated by macros. See #2177 for details.
private_bounds,
non_local_definitions,
non_camel_case_types,
non_upper_case_globals,
non_snake_case,
non_ascii_idents,
clippy::missing_inline_in_public_items,
)]
// While there are not currently any warnings that this suppresses
// (that we're aware of), it's good future-proofing hygiene.
#[automatically_derived]
const _: () = {
#(#items)*
};
}
}
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