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Cleanup: use a macro for reprs, use syn errors & fix cfg-target-arch (#124)

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Daniel Henry-Mantilla 2022-08-12 14:50:51 +02:00 committed by GitHub
parent bbd6a927ad
commit 1ebf7c251d
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2 changed files with 238 additions and 278 deletions
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14
derive/src/lib.rs
View File

@ -5,8 +5,8 @@ extern crate proc_macro;
mod traits;
use proc_macro2::TokenStream;
use quote::{quote, quote_spanned};
use syn::{parse_macro_input, DeriveInput, spanned::Spanned};
use quote::quote;
use syn::{parse_macro_input, DeriveInput, Result};
use crate::traits::{
AnyBitPattern, Contiguous, Derivable, CheckedBitPattern, NoUninit, Pod, TransparentWrapper, Zeroable,
@ -223,17 +223,13 @@ pub fn derive_contiguous(
/// Basic wrapper for error handling
fn derive_marker_trait<Trait: Derivable>(input: DeriveInput) -> TokenStream {
let span = input.span();
derive_marker_trait_inner::<Trait>(input).unwrap_or_else(|err| {
quote_spanned! { span =>
compile_error!(#err);
}
})
derive_marker_trait_inner::<Trait>(input)
.unwrap_or_else(|err| err.into_compile_error())
}
fn derive_marker_trait_inner<Trait: Derivable>(
input: DeriveInput,
) -> Result<TokenStream, &'static str> {
) -> Result<TokenStream> {
let name = &input.ident;
let (impl_generics, ty_generics, where_clause) =

502
derive/src/traits.rs
View File

@ -1,30 +1,42 @@
#![allow(unused_imports)]
use proc_macro2::{Ident, Span, TokenStream, TokenTree};
use quote::{quote, quote_spanned, ToTokens};
use syn::{
spanned::Spanned, AttrStyle, Attribute, Data, DataEnum, DataStruct,
DataUnion, DeriveInput, Expr, ExprLit, ExprUnary, Fields, Lit, LitInt, Meta,
NestedMeta, Type, UnOp, Variant,
use syn::{*,
parse::{Parse, Parser, ParseStream},
punctuated::Punctuated,
spanned::Spanned,
Result,
};
macro_rules! bail {
($msg:expr $(,)?) => (
return Err(Error::new(Span::call_site(), &$msg[..]))
);
( $msg:expr => $span_to_blame:expr $(,)? ) => (
return Err(Error::new_spanned(&$span_to_blame, $msg))
);
}
pub trait Derivable {
fn ident() -> TokenStream;
fn implies_trait() -> Option<TokenStream> {
None
}
fn generic_params(_input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn generic_params(_input: &DeriveInput) -> Result<TokenStream> {
Ok(quote!())
}
fn asserts(_input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(_input: &DeriveInput) -> Result<TokenStream> {
Ok(quote!())
}
fn check_attributes(
_ty: &Data, _attributes: &[Attribute],
) -> Result<(), &'static str> {
) -> Result<()> {
Ok(())
}
fn trait_impl(
_input: &DeriveInput,
) -> Result<(TokenStream, TokenStream), &'static str> {
) -> Result<(TokenStream, TokenStream)> {
Ok((quote!(), quote!()))
}
}
@ -36,13 +48,17 @@ impl Derivable for Pod {
quote!(::bytemuck::Pod)
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
let repr = get_repr(&input.attrs);
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
let repr = get_repr(&input.attrs)?;
let completly_packed = repr.packed == Some(1);
if !completly_packed && !input.generics.params.is_empty() {
return Err("Pod requires cannot be derived for non-packed types containing generic parameters because the padding requirements can't be verified for generic non-packed structs");
bail!("\
Pod requires cannot be derived for non-packed types containing \
generic parameters because the padding requirements can't be verified \
for generic non-packed structs\
" => input.generics.params.first().unwrap());
}
match &input.data {
@ -60,20 +76,20 @@ impl Derivable for Pod {
#assert_fields_are_pod
))
}
Data::Enum(_) => Err("Deriving Pod is not supported for enums"),
Data::Union(_) => Err("Deriving Pod is not supported for unions"),
Data::Enum(_) => bail!("Deriving Pod is not supported for enums"),
Data::Union(_) => bail!("Deriving Pod is not supported for unions"),
}
}
fn check_attributes(
_ty: &Data, attributes: &[Attribute],
) -> Result<(), &'static str> {
let repr = get_repr(attributes);
) -> Result<()> {
let repr = get_repr(attributes)?;
match repr.repr {
Repr::C => Ok(()),
Repr::Transparent => Ok(()),
_ => {
Err("Pod requires the type to be #[repr(C)] or #[repr(transparent)]")
bail!("Pod requires the type to be #[repr(C)] or #[repr(transparent)]")
}
}
}
@ -90,11 +106,11 @@ impl Derivable for AnyBitPattern {
Some(quote!(::bytemuck::Zeroable))
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
match &input.data {
Data::Union(_) => Ok(quote!()), // unions are always `AnyBitPattern`
Data::Struct(_) => generate_fields_are_trait(input, Self::ident()),
Data::Enum(_) => Err("Deriving AnyBitPattern is not supported for enums"),
Data::Enum(_) => bail!("Deriving AnyBitPattern is not supported for enums"),
}
}
}
@ -106,11 +122,11 @@ impl Derivable for Zeroable {
quote!(::bytemuck::Zeroable)
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
match &input.data {
Data::Union(_) => Ok(quote!()), // unions are always `Zeroable`
Data::Struct(_) => generate_fields_are_trait(input, Self::ident()),
Data::Enum(_) => Err("Deriving Zeroable is not supported for enums"),
Data::Enum(_) => bail!("Deriving Zeroable is not supported for enums"),
}
}
}
@ -124,25 +140,25 @@ impl Derivable for NoUninit {
fn check_attributes(
ty: &Data, attributes: &[Attribute],
) -> Result<(), &'static str> {
let repr = get_repr(attributes);
) -> Result<()> {
let repr = get_repr(attributes)?;
match ty {
Data::Struct(_) => match repr.repr {
Repr::C | Repr::Transparent => Ok(()),
_ => Err("NoUninit requires the struct to be #[repr(C)] or #[repr(transparent)]"),
_ => bail!("NoUninit requires the struct to be #[repr(C)] or #[repr(transparent)]"),
},
Data::Enum(_) => if repr.repr.is_integer() {
Ok(())
} else {
Err("NoUninit requires the enum to be an explicit #[repr(Int)]")
bail!("NoUninit requires the enum to be an explicit #[repr(Int)]")
},
Data::Union(_) => Err("NoUninit can only be derived on enums and structs")
Data::Union(_) => bail!("NoUninit can only be derived on enums and structs")
}
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
if !input.generics.params.is_empty() {
return Err("NoUninit cannot be derived for structs containing generic parameters because the padding requirements can't be verified for generic structs");
bail!("NoUninit cannot be derived for structs containing generic parameters because the padding requirements can't be verified for generic structs");
}
match &input.data {
@ -158,18 +174,18 @@ impl Derivable for NoUninit {
}
Data::Enum(DataEnum { variants, .. }) => {
if variants.iter().any(|variant| !variant.fields.is_empty()) {
Err("Only fieldless enums are supported for NoUninit")
bail!("Only fieldless enums are supported for NoUninit")
} else {
Ok(quote!())
}
}
Data::Union(_) => Err("NoUninit cannot be derived for unions"), // shouldn't be possible since we already error in attribute check for this case
Data::Union(_) => bail!("NoUninit cannot be derived for unions"), // shouldn't be possible since we already error in attribute check for this case
}
}
fn trait_impl(
_input: &DeriveInput,
) -> Result<(TokenStream, TokenStream), &'static str> {
) -> Result<(TokenStream, TokenStream)> {
Ok((quote!(), quote!()))
}
}
@ -183,25 +199,25 @@ impl Derivable for CheckedBitPattern {
fn check_attributes(
ty: &Data, attributes: &[Attribute],
) -> Result<(), &'static str> {
let repr = get_repr(attributes);
) -> Result<()> {
let repr = get_repr(attributes)?;
match ty {
Data::Struct(_) => match repr.repr {
Repr::C | Repr::Transparent => Ok(()),
_ => Err("CheckedBitPattern derive requires the struct to be #[repr(C)] or #[repr(transparent)]"),
_ => bail!("CheckedBitPattern derive requires the struct to be #[repr(C)] or #[repr(transparent)]"),
},
Data::Enum(_) => if repr.repr.is_integer() {
Ok(())
} else {
Err("CheckedBitPattern requires the enum to be an explicit #[repr(Int)]")
bail!("CheckedBitPattern requires the enum to be an explicit #[repr(Int)]")
},
Data::Union(_) => Err("CheckedBitPattern can only be derived on enums and structs")
Data::Union(_) => bail!("CheckedBitPattern can only be derived on enums and structs")
}
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
if !input.generics.params.is_empty() {
return Err("CheckedBitPattern cannot be derived for structs containing generic parameters");
bail!("CheckedBitPattern cannot be derived for structs containing generic parameters");
}
match &input.data {
@ -212,19 +228,19 @@ impl Derivable for CheckedBitPattern {
Ok(assert_fields_are_maybe_pod)
}
Data::Enum(_) => Ok(quote!()), // nothing needed, already guaranteed OK by NoUninit
Data::Union(_) => Err("Internal error in CheckedBitPattern derive"), // shouldn't be possible since we already error in attribute check for this case
Data::Union(_) => bail!("Internal error in CheckedBitPattern derive"), // shouldn't be possible since we already error in attribute check for this case
}
}
fn trait_impl(
input: &DeriveInput,
) -> Result<(TokenStream, TokenStream), &'static str> {
) -> Result<(TokenStream, TokenStream)> {
match &input.data {
Data::Struct(DataStruct { fields, .. }) => Ok(
generate_checked_bit_pattern_struct(&input.ident, fields, &input.attrs),
),
Data::Struct(DataStruct { fields, .. }) => {
generate_checked_bit_pattern_struct(&input.ident, fields, &input.attrs)
},
Data::Enum(_) => generate_checked_bit_pattern_enum(input),
Data::Union(_) => Err("Internal error in CheckedBitPattern derive"), // shouldn't be possible since we already error in attribute check for this case
Data::Union(_) => bail!("Internal error in CheckedBitPattern derive"), // shouldn't be possible since we already error in attribute check for this case
}
}
}
@ -254,14 +270,19 @@ impl Derivable for TransparentWrapper {
quote!(::bytemuck::TransparentWrapper)
}
fn generic_params(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn generic_params(input: &DeriveInput) -> Result<TokenStream> {
let fields = get_struct_fields(input)?;
Self::get_wrapper_type(&input.attrs, &fields).map(|ty| quote!(<#ty>))
.ok_or("when deriving TransparentWrapper for a struct with more than one field you need to specify the transparent field using #[transparent(T)]")
match Self::get_wrapper_type(&input.attrs, &fields) {
| Some(ty) => Ok(quote!(<#ty>)),
| None => bail!("\
when deriving TransparentWrapper for a struct with more than one field \
you need to specify the transparent field using #[transparent(T)]\
"),
}
}
fn asserts(input: &DeriveInput) -> Result<TokenStream, &'static str> {
fn asserts(input: &DeriveInput) -> Result<TokenStream> {
let fields = get_struct_fields(input)?;
let wrapped_type = match Self::get_wrapper_type(&input.attrs, &fields) {
Some(wrapped_type) => wrapped_type.to_string(),
@ -271,10 +292,10 @@ impl Derivable for TransparentWrapper {
.iter()
.filter(|field| field.ty.to_token_stream().to_string() == wrapped_type);
if let None = wrapped_fields.next() {
return Err("TransparentWrapper must have one field of the wrapped type");
bail!("TransparentWrapper must have one field of the wrapped type");
};
if let Some(_) = wrapped_fields.next() {
Err("TransparentWrapper can only have one field of the wrapped type")
bail!("TransparentWrapper can only have one field of the wrapped type")
} else {
Ok(quote!())
}
@ -282,13 +303,13 @@ impl Derivable for TransparentWrapper {
fn check_attributes(
_ty: &Data, attributes: &[Attribute],
) -> Result<(), &'static str> {
let repr = get_repr(attributes);
) -> Result<()> {
let repr = get_repr(attributes)?;
match repr.repr {
Repr::Transparent => Ok(()),
_ => {
Err("TransparentWrapper requires the struct to be #[repr(transparent)]")
bail!("TransparentWrapper requires the struct to be #[repr(transparent)]")
}
}
}
@ -303,13 +324,13 @@ impl Derivable for Contiguous {
fn trait_impl(
input: &DeriveInput,
) -> Result<(TokenStream, TokenStream), &'static str> {
let repr = get_repr(&input.attrs);
) -> Result<(TokenStream, TokenStream)> {
let repr = get_repr(&input.attrs)?;
let integer_ty = if let Some(integer_ty) = repr.repr.as_integer_type() {
integer_ty
} else {
return Err("Contiguous requires the enum to be #[repr(Int)]");
bail!("Contiguous requires the enum to be #[repr(Int)]");
};
let variants = get_enum_variants(input)?;
@ -320,7 +341,7 @@ impl Derivable for Contiguous {
(i64::max_value(), i64::min_value(), 0),
|(min, max, count), res| {
let discriminator = res?;
Ok((
Ok::<_, Error>((
i64::min(min, discriminator),
i64::max(max, discriminator),
count + 1,
@ -329,9 +350,9 @@ impl Derivable for Contiguous {
)?;
if max - min != count - 1 {
return Err(
bail! {
"Contiguous requires the enum discriminants to be contiguous",
);
}
}
let min_lit = LitInt::new(&format!("{}", min), input.span());
@ -348,29 +369,29 @@ impl Derivable for Contiguous {
}
}
fn get_struct_fields(input: &DeriveInput) -> Result<&Fields, &'static str> {
fn get_struct_fields(input: &DeriveInput) -> Result<&Fields> {
if let Data::Struct(DataStruct { fields, .. }) = &input.data {
Ok(fields)
} else {
Err("deriving this trait is only supported for structs")
bail!("deriving this trait is only supported for structs")
}
}
fn get_fields(input: &DeriveInput) -> Result<Fields, &'static str> {
fn get_fields(input: &DeriveInput) -> Result<Fields> {
match &input.data {
Data::Struct(DataStruct { fields, .. }) => Ok(fields.clone()),
Data::Union(DataUnion { fields, .. }) => Ok(Fields::Named(fields.clone())),
Data::Enum(_) => Err("deriving this trait is not supported for enums"),
Data::Enum(_) => bail!("deriving this trait is not supported for enums"),
}
}
fn get_enum_variants<'a>(
input: &'a DeriveInput,
) -> Result<impl Iterator<Item = &'a Variant> + 'a, &'static str> {
) -> Result<impl Iterator<Item = &'a Variant> + 'a> {
if let Data::Enum(DataEnum { variants, .. }) = &input.data {
Ok(variants.iter())
} else {
Err("deriving this trait is only supported for enums")
bail!("deriving this trait is only supported for enums")
}
}
@ -382,10 +403,10 @@ fn get_field_types<'a>(
fn generate_checked_bit_pattern_struct(
input_ident: &Ident, fields: &Fields, attrs: &[Attribute],
) -> (TokenStream, TokenStream) {
) -> Result<(TokenStream, TokenStream)> {
let bits_ty = Ident::new(&format!("{}Bits", input_ident), input_ident.span());
let repr = get_repr(attrs);
let repr = get_repr(attrs)?;
let field_names = fields
.iter()
@ -401,12 +422,9 @@ fn generate_checked_bit_pattern_struct(
let field_name = &field_names[..];
let field_ty = &field_tys[..];
#[cfg(not(target_arch = "spirv"))]
let derive_dbg = quote!(#[derive(Debug)]);
#[cfg(target_arch = "spirv")]
let derive_dbg = quote!();
let derive_dbg = quote!(#[cfg_attr(not(target_arch = "spirv"), derive(Debug))]);
(
Ok((
quote! {
#repr
#[derive(Clone, Copy, ::bytemuck::AnyBitPattern)]
@ -424,12 +442,12 @@ fn generate_checked_bit_pattern_struct(
#(<#field_ty as ::bytemuck::CheckedBitPattern>::is_valid_bit_pattern(&bits.#field_name) && )* true
}
},
)
))
}
fn generate_checked_bit_pattern_enum(
input: &DeriveInput,
) -> Result<(TokenStream, TokenStream), &'static str> {
) -> Result<(TokenStream, TokenStream)> {
let span = input.span();
let mut variants_with_discriminant =
VariantDiscriminantIterator::new(get_enum_variants(input)?);
@ -438,7 +456,7 @@ fn generate_checked_bit_pattern_enum(
(i64::max_value(), i64::min_value(), 0),
|(min, max, count), res| {
let discriminant = res?;
Ok((i64::min(min, discriminant), i64::max(max, discriminant), count + 1))
Ok::<_, Error>((i64::min(min, discriminant), i64::max(max, discriminant), count + 1))
},
)?;
@ -458,7 +476,7 @@ fn generate_checked_bit_pattern_enum(
let variant = res?;
Ok(LitInt::new(&format!("{}", variant), span))
})
.collect::<Result<Vec<_>, _>>()?;
.collect::<Result<Vec<_>>>()?;
// count is at least 1
let first = &variant_lits[0];
@ -467,7 +485,7 @@ fn generate_checked_bit_pattern_enum(
quote!(matches!(*bits, #first #(| #rest )*))
};
let repr = get_repr(&input.attrs);
let repr = get_repr(&input.attrs)?;
let integer_ty = repr.repr.as_integer_type().unwrap(); // should be checked in attr check already
Ok((
quote!(),
@ -487,7 +505,7 @@ fn generate_checked_bit_pattern_enum(
/// is equal to the sum of the size of it's fields
fn generate_assert_no_padding(
input: &DeriveInput,
) -> Result<TokenStream, &'static str> {
) -> Result<TokenStream> {
let struct_type = &input.ident;
let span = input.ident.span();
let fields = get_fields(input)?;
@ -512,7 +530,7 @@ fn generate_assert_no_padding(
/// Check that all fields implement a given trait
fn generate_fields_are_trait(
input: &DeriveInput, trait_: TokenStream,
) -> Result<TokenStream, &'static str> {
) -> Result<TokenStream> {
let (impl_generics, _ty_generics, where_clause) =
input.generics.split_for_impl();
let fields = get_fields(input)?;
@ -553,200 +571,143 @@ fn get_simple_attr(attributes: &[Attribute], attr_name: &str) -> Option<Ident> {
None
}
#[derive(Clone, Copy)]
struct Representation {
packed: Option<u32>,
repr: Repr,
}
impl ToTokens for Representation {
fn to_tokens(&self, tokens: &mut TokenStream) {
let repr = match self.repr {
Repr::Rust => None,
Repr::C => Some("C"),
Repr::Transparent => Some("transparent"),
Repr::U8 => Some("u8"),
Repr::I8 => Some("i8"),
Repr::U16 => Some("u16"),
Repr::I16 => Some("i16"),
Repr::U32 => Some("u32"),
Repr::I32 => Some("i32"),
Repr::U64 => Some("u64"),
Repr::I64 => Some("i64"),
Repr::I128 => Some("i128"),
Repr::U128 => Some("u128"),
};
if let Some(repr) = repr {
let ident = Ident::new(repr, Span::call_site());
tokens.extend(quote! {
#[repr(#ident)]
});
}
if let Some(packed) = self.packed {
let lit = LitInt::new(&packed.to_string(), Span::call_site());
tokens.extend(quote! {
#[repr(packed(#lit))]
});
}
}
}
#[derive(Clone, Copy)]
enum Repr {
Rust,
C,
Transparent,
U8,
I8,
U16,
I16,
U32,
I32,
U64,
I64,
I128,
U128,
}
impl Repr {
fn is_integer(&self) -> bool {
match *self {
Repr::Rust | Repr::C | Repr::Transparent => false,
Repr::U8
| Repr::I8
| Repr::U16
| Repr::I16
| Repr::U32
| Repr::I32
| Repr::U64
| Repr::I64
| Repr::I128
| Repr::U128 => true,
}
}
fn as_integer_type(&self) -> Option<TokenStream> {
match self {
Repr::Rust | Repr::C | Repr::Transparent => None,
Repr::U8 => Some(quote! { ::core::primitive::u8 }),
Repr::I8 => Some(quote! { ::core::primitive::i8 }),
Repr::U16 => Some(quote! { ::core::primitive::u16 }),
Repr::I16 => Some(quote! { ::core::primitive::i16 }),
Repr::U32 => Some(quote! { ::core::primitive::u32 }),
Repr::I32 => Some(quote! { ::core::primitive::i32 }),
Repr::U64 => Some(quote! { ::core::primitive::u64 }),
Repr::I64 => Some(quote! { ::core::primitive::i64 }),
Repr::I128 => Some(quote! { ::core::primitive::u128 }),
Repr::U128 => Some(quote! { ::core::primitive::i128 }),
}
}
}
fn get_repr(attributes: &[Attribute]) -> Representation {
let mut repr = Representation { packed: None, repr: Repr::Rust };
for attr in attributes {
let meta = if let Ok(meta) = attr.parse_meta() { meta } else { continue };
if !meta.path().is_ident("repr") {
continue;
}
let list = if let Meta::List(list) = meta {
list
fn get_repr(attributes: &[Attribute]) -> Result<Representation> {
attributes
.iter()
.filter_map(|attr| if attr.path.is_ident("repr") {
Some(attr.parse_args::<Representation>())
} else {
// The other `Meta` variants are illegal for `repr`.
continue;
};
None
})
.try_fold(Representation::default(), |a, b| {
let b = b?;
Ok(Representation {
repr: match (a.repr, b.repr) {
| (a, Repr::Rust) => a,
| (Repr::Rust, b) => b,
| _ => bail!("conflicting representation hints"),
},
packed: match (a.packed, b.packed) {
| (a, None) => a,
| (None, b) => b,
| _ => bail!("conflicting representation hints"),
},
})
})
}
for item in list.nested {
let meta = if let NestedMeta::Meta(meta) = item {
meta
} else {
// Other nested items are illegal for `repr`.
continue;
};
mk_repr! {
U8 => u8,
I8 => i8,
U16 => u16,
I16 => i16,
U32 => u32,
I32 => i32,
U64 => u64,
I64 => i64,
I128 => i128,
U128 => u128,
}
// where
macro_rules! mk_repr {(
$(
$Xn:ident => $xn:ident
),* $(,)?
) => (
#[derive(Clone, Copy, PartialEq)]
enum Repr {
Rust,
C,
Transparent,
$($Xn),*
}
match meta.path() {
path if path.is_ident("C") => {
repr.repr = Repr::C;
}
path if path.is_ident("transparent") => {
repr.repr = Repr::Transparent;
}
path if path.is_ident("u8") => {
repr.repr = Repr::U8;
}
path if path.is_ident("i8") => {
repr.repr = Repr::I8;
}
path if path.is_ident("u16") => {
repr.repr = Repr::U16;
}
path if path.is_ident("i16") => {
repr.repr = Repr::I16;
}
path if path.is_ident("u32") => {
repr.repr = Repr::U32;
}
path if path.is_ident("i32") => {
repr.repr = Repr::I32;
}
path if path.is_ident("u64") => {
repr.repr = Repr::U64;
}
path if path.is_ident("i64") => {
repr.repr = Repr::I64;
}
path if path.is_ident("u128") => {
repr.repr = Repr::U128;
}
path if path.is_ident("i128") => {
repr.repr = Repr::I128;
}
path if path.is_ident("packed") => {
let packed_alignment = match meta {
Meta::Path(_) => 1,
Meta::List(list) => {
if list.nested.len() != 1 {
// `repr(packed(n))` must have exactly one nested item.
continue;
}
impl Repr {
fn is_integer(self) -> bool {
match self {
Repr::Rust | Repr::C | Repr::Transparent => false,
_ => true,
}
}
let nested = &list.nested[0];
let int_lit = if let NestedMeta::Lit(Lit::Int(int_lit)) = nested {
int_lit
} else {
// The nested item must be an integer literal.
continue;
};
let value = if let Ok(value) = int_lit.base10_parse::<u32>() {
value
} else {
// The literal must be positive and less than 2^29.
continue;
};
value
}
Meta::NameValue(_) => {
// `repr(packed)` doesn't support name value syntax.
continue;
}
};
let new_packed_alignment = match repr.packed {
Some(prev) => u32::min(prev, packed_alignment),
None => packed_alignment,
};
repr.packed = Some(new_packed_alignment);
}
_ => {}
fn as_integer_type(self) -> Option<TokenStream> {
match self {
Repr::Rust | Repr::C | Repr::Transparent => None,
$(
Repr::$Xn => Some(quote! { ::core::primitive::$xn }),
)*
}
}
}
repr
}
#[derive(Clone, Copy)]
struct Representation {
packed: Option<u32>,
repr: Repr,
}
impl Default for Representation {
fn default() -> Self {
Self { packed: None, repr: Repr::Rust }
}
}
impl Parse for Representation {
fn parse(input: ParseStream<'_>) -> Result<Representation> {
let mut ret = Representation::default();
while !input.is_empty() {
let keyword = input.parse::<Ident>()?;
// preëmptively call `.to_string()` *once* (rather than on `is_ident()`)
let keyword_str = keyword.to_string();
let new_repr = match keyword_str.as_str() {
"C" => Repr::C,
"transparent" => Repr::Transparent,
"packed" => {
ret.packed = Some(if input.peek(token::Paren) {
let contents; parenthesized!(contents in input);
LitInt::base10_parse::<u32>(&contents.parse()?)?
} else {
1
});
let _: Option<Token![,]> = input.parse()?;
continue;
},
$(
stringify!($xn) => Repr::$Xn,
)*
_ => return Err(input.error("unrecognized representation hint"))
};
if ::core::mem::replace(&mut ret.repr, new_repr) != Repr::Rust {
input.error("duplicate representation hint");
}
let _: Option<Token![,]> = input.parse()?;
}
Ok(ret)
}
}
impl ToTokens for Representation {
fn to_tokens(&self, tokens: &mut TokenStream) {
let repr = match self.repr {
Repr::Rust => None,
Repr::C => Some(quote!(C)),
Repr::Transparent => Some(quote!(transparent)),
$(
Repr::$Xn => Some(quote!($xn)),
)*
};
let packed = self.packed.map(|p| quote!(packed(#p)));
let comma = if packed.is_some() && repr.is_some() {
Some(quote!(,))
} else {
None
};
tokens.extend(quote!(
#[repr( #repr #comma #packed )]
));
}
}
)} use mk_repr;
struct VariantDiscriminantIterator<'a, I: Iterator<Item = &'a Variant> + 'a> {
inner: I,
@ -764,12 +725,15 @@ impl<'a, I: Iterator<Item = &'a Variant> + 'a>
impl<'a, I: Iterator<Item = &'a Variant> + 'a> Iterator
for VariantDiscriminantIterator<'a, I>
{
type Item = Result<i64, &'static str>;
type Item = Result<i64>;
fn next(&mut self) -> Option<Self::Item> {
let variant = self.inner.next()?;
if !variant.fields.is_empty() {
return Some(Err("Only fieldless enums are supported"));
return Some(Err(Error::new_spanned(
&variant.fields,
"Only fieldless enums are supported",
)));
}
if let Some((_, discriminant)) = &variant.discriminant {
@ -786,14 +750,14 @@ impl<'a, I: Iterator<Item = &'a Variant> + 'a> Iterator
}
}
fn parse_int_expr(expr: &Expr) -> Result<i64, &'static str> {
fn parse_int_expr(expr: &Expr) -> Result<i64> {
match expr {
Expr::Unary(ExprUnary { op: UnOp::Neg(_), expr, .. }) => {
parse_int_expr(expr).map(|int| -int)
}
Expr::Lit(ExprLit { lit: Lit::Int(int), .. }) => {
int.base10_parse().map_err(|_| "Invalid integer expression")
int.base10_parse()
}
_ => Err("Not an integer expression"),
_ => bail!("Not an integer expression"),
}
}