bytemuck_derive-1.10.2/.cargo_vcs_info.json0000644000000001440000000000100142750ustar { "git": { "sha1": "abbebe597e02ac0828bb987c73a3f037cd8d62b5" }, "path_in_vcs": "derive" }bytemuck_derive-1.10.2/Cargo.lock0000644000000021400000000000100122460ustar # This file is automatically @generated by Cargo. # It is not intended for manual editing. version = 4 [[package]] name = "bytemuck_derive" version = "1.10.2" dependencies = [ "proc-macro2", "quote", "syn", ] [[package]] name = "proc-macro2" version = "1.0.92" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "37d3544b3f2748c54e147655edb5025752e2303145b5aefb3c3ea2c78b973bb0" dependencies = [ "unicode-ident", ] [[package]] name = "quote" version = "1.0.38" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "0e4dccaaaf89514f546c693ddc140f729f958c247918a13380cccc6078391acc" dependencies = [ "proc-macro2", ] [[package]] name = "syn" version = "2.0.95" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "46f71c0377baf4ef1cc3e3402ded576dccc315800fbc62dfc7fe04b009773b4a" dependencies = [ "proc-macro2", "quote", "unicode-ident", ] [[package]] name = "unicode-ident" version = "1.0.14" source = "registry+https://github.com/rust-lang/crates.io-index" checksum = "adb9e6ca4f869e1180728b7950e35922a7fc6397f7b641499e8f3ef06e50dc83" bytemuck_derive-1.10.2/Cargo.toml0000644000000023240000000000100122750ustar # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g., crates.io) dependencies. # # If you are reading this file be aware that the original Cargo.toml # will likely look very different (and much more reasonable). # See Cargo.toml.orig for the original contents. [package] edition = "2018" rust-version = "1.61" name = "bytemuck_derive" version = "1.10.2" authors = ["Lokathor "] build = false autolib = false autobins = false autoexamples = false autotests = false autobenches = false description = "derive proc-macros for `bytemuck`" readme = "README.md" keywords = [ "transmute", "bytes", "casting", ] categories = [ "encoding", "no-std", ] license = "Zlib OR Apache-2.0 OR MIT" repository = "https://github.com/Lokathor/bytemuck" [lib] name = "bytemuck_derive" path = "src/lib.rs" proc-macro = true [[test]] name = "basic" path = "tests/basic.rs" [dependencies.proc-macro2] version = "1.0.60" [dependencies.quote] version = "1" [dependencies.syn] version = "2.0.1" [dev-dependencies] bytemuck_derive-1.10.2/Cargo.toml.orig000064400000000000000000000013371046102023000157610ustar 00000000000000[package] name = "bytemuck_derive" description = "derive proc-macros for `bytemuck`" version = "1.10.2" authors = ["Lokathor "] repository = "https://github.com/Lokathor/bytemuck" readme = "README.md" keywords = ["transmute", "bytes", "casting"] categories = ["encoding", "no-std"] edition = "2018" license = "Zlib OR Apache-2.0 OR MIT" rust-version = "1.61" #note(lokathor): do not publish with this set #resolver = "3" [lib] name = "bytemuck_derive" proc-macro = true [dependencies] # syn seems to have broken backwards compatibility in this version https://github.com/dtolnay/syn/issues/1194 syn = "2.0.1" quote = "1" proc-macro2 = "1.0.60" [dev-dependencies] bytemuck = { path = "../", features = ["derive"] } bytemuck_derive-1.10.2/LICENSE-APACHE000064400000000000000000000242361046102023000150210ustar 00000000000000Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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This notice may not be removed or altered from any source distribution. bytemuck_derive-1.10.2/README.md000064400000000000000000000001231046102023000143410ustar 00000000000000 # bytemuck_derive Derive macros for [bytemuck](https://docs.rs/bytemuck) traits. bytemuck_derive-1.10.2/changelog.md000064400000000000000000000065711046102023000153500ustar 00000000000000 ## `bytemuck_derive` changelog ## 1.10.2 * [Extend #[derive(TransparentWrapper)](https://github.com/Lokathor/bytemuck/pull/147) ## 1.10.1 * changes the derive macros to not use `transmute` size matching when checking fof padding in a type. instead, an actual assert is used in a const block. ## 1.10.0 * add support for deriving NoUninit on enums with fields. ## 1.9.2 * Removes the `resolver` key from the manifest. This breaks the build with cryptic error messages despite current docs vaguely saying otherwise. ## 1.9.1 * Fix the derive of CheckedBitPattern when used with a packed struct. The Debug impl did not account for possibly-unaligned fields. ## 1.9.0 * The crate now declares an MSRV, so updates going forward should be simpler. ## 1.8.1 * https://github.com/Lokathor/bytemuck/pull/287 ## 1.8 * [#257](https://github.com/Lokathor/bytemuck/pull/257): Allows deriving Zeroable on some enums. ## 1.7.1 * Adds the `bytemuck` attribute to the `NoUninit` derive, allowing it to be used when re-exported. ## 1.7.0 * Allow generics in `derive(ByteEq, ByteHash)` https://github.com/Lokathor/bytemuck/pull/219 ## 1.6.0 * This allows `CheckedBitPattern` to be derived for enums with fields. The repr must be one of the following: * `#[repr(C)]` * `#[repr(C, int)]` * `#[repr(int)]` * `#[repr(transparent)]` ## 1.5.0 * The `Zeroable` derive now allows custom bounds. See the rustdoc for an explanation. ## 1.4.1 * Move the `syn` dependency to use version 2. This should not affect the public API in any way. ## 1.4.0 * `ByteEq` and `ByteHash` derives will make `Eq` and `Hash` impls that treat the value as a `&[u8]` during equality checks and hashing. This provides a large codegen improvement for some types. * Derives of `repr(int)` enums should now accept byte literal values as the discriminant. ## 1.3.0 * Allow `repr(transparent)` to be used generically in `derive(Pod)`. ## 1.2.1 * Fixed a regression of the `align(N)` attribute that occurred during otherwise routine cleanup. ## 1.2.0 * Apparently our minimum required version of `syn` went up without anyone noticing for a while. Because of a bump in our `syn` requirements, we're also issuing this minor version bump in the `bytemuck_derive` crate. Because it's possible to *reduce* the minimum required version of a dep in only a patch release, I'm going to ratchet the required version of `syn` all the way up to "current" (1.0.99). If absolutely necessary we could probably reduce the minimum `syn` version again in a patch release for 1.2, but I don't want to play this dance too much so I'd rather make each jump as big as can possibly be. [Issue 122](https://github.com/Lokathor/bytemuck/issues/122). **Note:** While the core `bytemuck` crate continues to keep building on rustc-1.34.0, the `bytemuck_derive` crate is considered an opt-in bonus feature (which doesn't do anything you couldn't trivially do yourself) and so it does not support a specific MSRV. ## 1.1.1 * Adjusted the license files to use full files rather than symlinks. [PR](https://github.com/Lokathor/bytemuck/pull/118) The license is unchanged, just no more symlinks. ## 1.1.0 * Updated to work with `bytemuck-1.9.0` ## 1.0.1 * [yanchith](https://github.com/yanchith) fixed the derive checks code to make clippy more happy. [PR 45](https://github.com/Lokathor/bytemuck/pull/45) ## 1.0.0 * Initial stable release. bytemuck_derive-1.10.2/src/lib.rs000064400000000000000000000517671046102023000150110ustar 00000000000000//! Derive macros for [bytemuck](https://docs.rs/bytemuck) traits. extern crate proc_macro; mod traits; use proc_macro2::TokenStream; use quote::quote; use syn::{parse_macro_input, DeriveInput, Result}; use crate::traits::{ bytemuck_crate_name, AnyBitPattern, CheckedBitPattern, Contiguous, Derivable, NoUninit, Pod, TransparentWrapper, Zeroable, }; /// Derive the `Pod` trait for a struct /// /// The macro ensures that the struct follows all the the safety requirements /// for the `Pod` trait. /// /// The following constraints need to be satisfied for the macro to succeed /// /// - All fields in the struct must implement `Pod` /// - The struct must be `#[repr(C)]` or `#[repr(transparent)]` /// - The struct must not contain any padding bytes /// - The struct contains no generic parameters, if it is not /// `#[repr(transparent)]` /// /// ## Examples /// /// ```rust /// # use std::marker::PhantomData; /// # use bytemuck_derive::{Pod, Zeroable}; /// #[derive(Copy, Clone, Pod, Zeroable)] /// #[repr(C)] /// struct Test { /// a: u16, /// b: u16, /// } /// /// #[derive(Copy, Clone, Pod, Zeroable)] /// #[repr(transparent)] /// struct Generic { /// a: A, /// b: PhantomData, /// } /// ``` /// /// If the struct is generic, it must be `#[repr(transparent)]` also. /// /// ```compile_fail /// # use bytemuck::{Pod, Zeroable}; /// # use std::marker::PhantomData; /// #[derive(Copy, Clone, Pod, Zeroable)] /// #[repr(C)] // must be `#[repr(transparent)]` /// struct Generic { /// a: A, /// } /// ``` /// /// If the struct is generic and `#[repr(transparent)]`, then it is only `Pod` /// when all of its generics are `Pod`, not just its fields. /// /// ``` /// # use bytemuck::{Pod, Zeroable}; /// # use std::marker::PhantomData; /// #[derive(Copy, Clone, Pod, Zeroable)] /// #[repr(transparent)] /// struct Generic { /// a: A, /// b: PhantomData, /// } /// /// let _: u32 = bytemuck::cast(Generic { a: 4u32, b: PhantomData:: }); /// ``` /// /// ```compile_fail /// # use bytemuck::{Pod, Zeroable}; /// # use std::marker::PhantomData; /// # #[derive(Copy, Clone, Pod, Zeroable)] /// # #[repr(transparent)] /// # struct Generic { /// # a: A, /// # b: PhantomData, /// # } /// struct NotPod; /// /// let _: u32 = bytemuck::cast(Generic { a: 4u32, b: PhantomData:: }); /// ``` #[proc_macro_derive(Pod, attributes(bytemuck))] pub fn derive_pod(input: proc_macro::TokenStream) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!(input as DeriveInput)); proc_macro::TokenStream::from(expanded) } /// Derive the `AnyBitPattern` trait for a struct /// /// The macro ensures that the struct follows all the the safety requirements /// for the `AnyBitPattern` trait. /// /// The following constraints need to be satisfied for the macro to succeed /// /// - All fields in the struct must to implement `AnyBitPattern` #[proc_macro_derive(AnyBitPattern, attributes(bytemuck))] pub fn derive_anybitpattern( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!( input as DeriveInput )); proc_macro::TokenStream::from(expanded) } /// Derive the `Zeroable` trait for a type. /// /// The macro ensures that the type follows all the the safety requirements /// for the `Zeroable` trait. /// /// The following constraints need to be satisfied for the macro to succeed on a /// struct: /// /// - All fields in the struct must implement `Zeroable` /// /// The following constraints need to be satisfied for the macro to succeed on /// an enum: /// /// - The enum has an explicit `#[repr(Int)]`, `#[repr(C)]`, or `#[repr(C, /// Int)]`. /// - The enum has a variant with discriminant 0 (explicitly or implicitly). /// - All fields in the variant with discriminant 0 (if any) must implement /// `Zeroable` /// /// The macro always succeeds on unions. /// /// ## Example /// /// ```rust /// # use bytemuck_derive::{Zeroable}; /// #[derive(Copy, Clone, Zeroable)] /// #[repr(C)] /// struct Test { /// a: u16, /// b: u16, /// } /// ``` /// ```rust /// # use bytemuck_derive::{Zeroable}; /// #[derive(Copy, Clone, Zeroable)] /// #[repr(i32)] /// enum Values { /// A = 0, /// B = 1, /// C = 2, /// } /// #[derive(Clone, Zeroable)] /// #[repr(C)] /// enum Implicit { /// A(bool, u8, char), /// B(String), /// C(std::num::NonZeroU8), /// } /// ``` /// /// # Custom bounds /// /// Custom bounds for the derived `Zeroable` impl can be given using the /// `#[zeroable(bound = "")]` helper attribute. /// /// Using this attribute additionally opts-in to "perfect derive" semantics, /// where instead of adding bounds for each generic type parameter, bounds are /// added for each field's type. /// /// ## Examples /// /// ```rust /// # use bytemuck::Zeroable; /// # use std::marker::PhantomData; /// #[derive(Clone, Zeroable)] /// #[zeroable(bound = "")] /// struct AlwaysZeroable { /// a: PhantomData, /// } /// /// AlwaysZeroable::::zeroed(); /// ``` /// ```rust /// # use bytemuck::{Zeroable}; /// #[derive(Copy, Clone, Zeroable)] /// #[repr(u8)] /// #[zeroable(bound = "")] /// enum MyOption { /// None, /// Some(T), /// } /// /// assert!(matches!(MyOption::::zeroed(), MyOption::None)); /// ``` /// /// ```rust,compile_fail /// # use bytemuck::Zeroable; /// # use std::marker::PhantomData; /// #[derive(Clone, Zeroable)] /// #[zeroable(bound = "T: Copy")] /// struct ZeroableWhenTIsCopy { /// a: PhantomData, /// } /// /// ZeroableWhenTIsCopy::::zeroed(); /// ``` /// /// The restriction that all fields must be Zeroable is still applied, and this /// is enforced using the mentioned "perfect derive" semantics. /// /// ```rust /// # use bytemuck::Zeroable; /// #[derive(Clone, Zeroable)] /// #[zeroable(bound = "")] /// struct ZeroableWhenTIsZeroable { /// a: T, /// } /// ZeroableWhenTIsZeroable::::zeroed(); /// ``` /// /// ```rust,compile_fail /// # use bytemuck::Zeroable; /// # #[derive(Clone, Zeroable)] /// # #[zeroable(bound = "")] /// # struct ZeroableWhenTIsZeroable { /// # a: T, /// # } /// ZeroableWhenTIsZeroable::::zeroed(); /// ``` #[proc_macro_derive(Zeroable, attributes(bytemuck, zeroable))] pub fn derive_zeroable( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!(input as DeriveInput)); proc_macro::TokenStream::from(expanded) } /// Derive the `NoUninit` trait for a struct or enum /// /// The macro ensures that the type follows all the the safety requirements /// for the `NoUninit` trait. /// /// The following constraints need to be satisfied for the macro to succeed /// (the rest of the constraints are guaranteed by the `NoUninit` subtrait /// bounds, i.e. the type must be `Sized + Copy + 'static`): /// /// If applied to a struct: /// - All fields in the struct must implement `NoUninit` /// - The struct must be `#[repr(C)]` or `#[repr(transparent)]` /// - The struct must not contain any padding bytes /// - The struct must contain no generic parameters /// /// If applied to an enum: /// - The enum must be explicit `#[repr(Int)]`, `#[repr(C)]`, or both /// - If the enum has fields: /// - All fields must implement `NoUninit` /// - All variants must not contain any padding bytes /// - All variants must be of the the same size /// - There must be no padding bytes between the discriminant and any of the /// variant fields /// - The enum must contain no generic parameters #[proc_macro_derive(NoUninit, attributes(bytemuck))] pub fn derive_no_uninit( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!(input as DeriveInput)); proc_macro::TokenStream::from(expanded) } /// Derive the `CheckedBitPattern` trait for a struct or enum. /// /// The macro ensures that the type follows all the the safety requirements /// for the `CheckedBitPattern` trait and derives the required `Bits` type /// definition and `is_valid_bit_pattern` method for the type automatically. /// /// The following constraints need to be satisfied for the macro to succeed: /// /// If applied to a struct: /// - All fields must implement `CheckedBitPattern` /// - The struct must be `#[repr(C)]` or `#[repr(transparent)]` /// - The struct must contain no generic parameters /// /// If applied to an enum: /// - The enum must be explicit `#[repr(Int)]` /// - All fields in variants must implement `CheckedBitPattern` /// - The enum must contain no generic parameters #[proc_macro_derive(CheckedBitPattern)] pub fn derive_maybe_pod( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!( input as DeriveInput )); proc_macro::TokenStream::from(expanded) } /// Derive the `TransparentWrapper` trait for a struct /// /// The macro ensures that the struct follows all the the safety requirements /// for the `TransparentWrapper` trait. /// /// The following constraints need to be satisfied for the macro to succeed /// /// - The struct must be `#[repr(transparent)]` /// - The struct must contain the `Wrapped` type /// - Any ZST fields must be [`Zeroable`][derive@Zeroable]. /// /// If the struct only contains a single field, the `Wrapped` type will /// automatically be determined. If there is more then one field in the struct, /// you need to specify the `Wrapped` type using `#[transparent(T)]`. Due to /// technical limitations, the type in the `#[transparent(Type)]` needs to be /// the exact same token sequence as the corresponding type in the struct /// definition. /// /// ## Examples /// /// ```rust /// # use bytemuck_derive::TransparentWrapper; /// # use std::marker::PhantomData; /// #[derive(Copy, Clone, TransparentWrapper)] /// #[repr(transparent)] /// #[transparent(u16)] /// struct Test { /// inner: u16, /// extra: PhantomData, /// } /// ``` /// /// If the struct contains more than one field, the `Wrapped` type must be /// explicitly specified. /// /// ```rust,compile_fail /// # use bytemuck_derive::TransparentWrapper; /// # use std::marker::PhantomData; /// #[derive(Copy, Clone, TransparentWrapper)] /// #[repr(transparent)] /// // missing `#[transparent(u16)]` /// struct Test { /// inner: u16, /// extra: PhantomData, /// } /// ``` /// /// Any ZST fields must be `Zeroable`. /// /// ```rust,compile_fail /// # use bytemuck_derive::TransparentWrapper; /// # use std::marker::PhantomData; /// struct NonTransparentSafeZST; /// /// #[derive(TransparentWrapper)] /// #[repr(transparent)] /// #[transparent(u16)] /// struct Test { /// inner: u16, /// extra: PhantomData, /// another_extra: NonTransparentSafeZST, // not `Zeroable` /// } /// ``` #[proc_macro_derive(TransparentWrapper, attributes(bytemuck, transparent))] pub fn derive_transparent( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!( input as DeriveInput )); proc_macro::TokenStream::from(expanded) } /// Derive the `Contiguous` trait for an enum /// /// The macro ensures that the enum follows all the the safety requirements /// for the `Contiguous` trait. /// /// The following constraints need to be satisfied for the macro to succeed /// /// - The enum must be `#[repr(Int)]` /// - The enum must be fieldless /// - The enum discriminants must form a contiguous range /// /// ## Example /// /// ```rust /// # use bytemuck_derive::{Contiguous}; /// /// #[derive(Copy, Clone, Contiguous)] /// #[repr(u8)] /// enum Test { /// A = 0, /// B = 1, /// C = 2, /// } /// ``` #[proc_macro_derive(Contiguous)] pub fn derive_contiguous( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let expanded = derive_marker_trait::(parse_macro_input!(input as DeriveInput)); proc_macro::TokenStream::from(expanded) } /// Derive the `PartialEq` and `Eq` trait for a type /// /// The macro implements `PartialEq` and `Eq` by casting both sides of the /// comparison to a byte slice and then compares those. /// /// ## Warning /// /// Since this implements a byte wise comparison, the behavior of floating point /// numbers does not match their usual comparison behavior. Additionally other /// custom comparison behaviors of the individual fields are also ignored. This /// also does not implement `StructuralPartialEq` / `StructuralEq` like /// `PartialEq` / `Eq` would. This means you can't pattern match on the values. /// /// ## Examples /// /// ```rust /// # use bytemuck_derive::{ByteEq, NoUninit}; /// #[derive(Copy, Clone, NoUninit, ByteEq)] /// #[repr(C)] /// struct Test { /// a: u32, /// b: char, /// c: f32, /// } /// ``` /// /// ```rust /// # use bytemuck_derive::ByteEq; /// # use bytemuck::NoUninit; /// #[derive(Copy, Clone, ByteEq)] /// #[repr(C)] /// struct Test { /// a: [u32; N], /// } /// unsafe impl NoUninit for Test {} /// ``` #[proc_macro_derive(ByteEq)] pub fn derive_byte_eq( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let input = parse_macro_input!(input as DeriveInput); let crate_name = bytemuck_crate_name(&input); let ident = input.ident; let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); proc_macro::TokenStream::from(quote! { impl #impl_generics ::core::cmp::PartialEq for #ident #ty_generics #where_clause { #[inline] #[must_use] fn eq(&self, other: &Self) -> bool { #crate_name::bytes_of(self) == #crate_name::bytes_of(other) } } impl #impl_generics ::core::cmp::Eq for #ident #ty_generics #where_clause { } }) } /// Derive the `Hash` trait for a type /// /// The macro implements `Hash` by casting the value to a byte slice and hashing /// that. /// /// ## Warning /// /// The hash does not match the standard library's `Hash` derive. /// /// ## Examples /// /// ```rust /// # use bytemuck_derive::{ByteHash, NoUninit}; /// #[derive(Copy, Clone, NoUninit, ByteHash)] /// #[repr(C)] /// struct Test { /// a: u32, /// b: char, /// c: f32, /// } /// ``` /// /// ```rust /// # use bytemuck_derive::ByteHash; /// # use bytemuck::NoUninit; /// #[derive(Copy, Clone, ByteHash)] /// #[repr(C)] /// struct Test { /// a: [u32; N], /// } /// unsafe impl NoUninit for Test {} /// ``` #[proc_macro_derive(ByteHash)] pub fn derive_byte_hash( input: proc_macro::TokenStream, ) -> proc_macro::TokenStream { let input = parse_macro_input!(input as DeriveInput); let crate_name = bytemuck_crate_name(&input); let ident = input.ident; let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); proc_macro::TokenStream::from(quote! { impl #impl_generics ::core::hash::Hash for #ident #ty_generics #where_clause { #[inline] fn hash(&self, state: &mut H) { ::core::hash::Hash::hash_slice(#crate_name::bytes_of(self), state) } #[inline] fn hash_slice(data: &[Self], state: &mut H) { ::core::hash::Hash::hash_slice(#crate_name::cast_slice::<_, u8>(data), state) } } }) } /// Basic wrapper for error handling fn derive_marker_trait(input: DeriveInput) -> TokenStream { derive_marker_trait_inner::(input) .unwrap_or_else(|err| err.into_compile_error()) } /// Find `#[name(key = "value")]` helper attributes on the struct, and return /// their `"value"`s parsed with `parser`. /// /// Returns an error if any attributes with the given `name` do not match the /// expected format. Returns `Ok([])` if no attributes with `name` are found. fn find_and_parse_helper_attributes( attributes: &[syn::Attribute], name: &str, key: &str, parser: P, example_value: &str, invalid_value_msg: &str, ) -> Result> { let invalid_format_msg = format!("{name} attribute must be `{name}({key} = \"{example_value}\")`",); let values_to_check = attributes.iter().filter_map(|attr| match &attr.meta { // If a `Path` matches our `name`, return an error, else ignore it. // e.g. `#[zeroable]` syn::Meta::Path(path) => path .is_ident(name) .then(|| Err(syn::Error::new_spanned(path, &invalid_format_msg))), // If a `NameValue` matches our `name`, return an error, else ignore it. // e.g. `#[zeroable = "hello"]` syn::Meta::NameValue(namevalue) => { namevalue.path.is_ident(name).then(|| { Err(syn::Error::new_spanned(&namevalue.path, &invalid_format_msg)) }) } // If a `List` matches our `name`, match its contents to our format, else // ignore it. If its contents match our format, return the value, else // return an error. syn::Meta::List(list) => list.path.is_ident(name).then(|| { let namevalue: syn::MetaNameValue = syn::parse2(list.tokens.clone()) .map_err(|_| { syn::Error::new_spanned(&list.tokens, &invalid_format_msg) })?; if namevalue.path.is_ident(key) { match namevalue.value { syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Str(strlit), .. }) => Ok(strlit), _ => { Err(syn::Error::new_spanned(&namevalue.path, &invalid_format_msg)) } } } else { Err(syn::Error::new_spanned(&namevalue.path, &invalid_format_msg)) } }), }); // Parse each value found with the given parser, and return them if no errors // occur. values_to_check .map(|lit| { let lit = lit?; lit.parse_with(parser).map_err(|err| { syn::Error::new_spanned(&lit, format!("{invalid_value_msg}: {err}")) }) }) .collect() } fn derive_marker_trait_inner( mut input: DeriveInput, ) -> Result { let crate_name = bytemuck_crate_name(&input); let trait_ = Trait::ident(&input, &crate_name)?; // If this trait allows explicit bounds, and any explicit bounds were given, // then use those explicit bounds. Else, apply the default bounds (bound // each generic type on this trait). if let Some(name) = Trait::explicit_bounds_attribute_name() { // See if any explicit bounds were given in attributes. let explicit_bounds = find_and_parse_helper_attributes( &input.attrs, name, "bound", >::parse_terminated, "Type: Trait", "invalid where predicate", )?; if !explicit_bounds.is_empty() { // Explicit bounds were given. // Enforce explicitly given bounds, and emit "perfect derive" (i.e. add // bounds for each field's type). let explicit_bounds = explicit_bounds .into_iter() .flatten() .collect::>(); let fields = match (Trait::perfect_derive_fields(&input), &input.data) { (Some(fields), _) => fields, (None, syn::Data::Struct(syn::DataStruct { fields, .. })) => { fields.clone() } (None, syn::Data::Union(_)) => { return Err(syn::Error::new_spanned( trait_, &"perfect derive is not supported for unions", )); } (None, syn::Data::Enum(_)) => { return Err(syn::Error::new_spanned( trait_, &"perfect derive is not supported for enums", )); } }; let predicates = &mut input.generics.make_where_clause().predicates; predicates.extend(explicit_bounds); for field in fields { let ty = field.ty; predicates.push(syn::parse_quote!( #ty: #trait_ )); } } else { // No explicit bounds were given. // Enforce trait bound on all type generics. add_trait_marker(&mut input.generics, &trait_); } } else { // This trait does not allow explicit bounds. // Enforce trait bound on all type generics. add_trait_marker(&mut input.generics, &trait_); } let name = &input.ident; let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); Trait::check_attributes(&input.data, &input.attrs)?; let asserts = Trait::asserts(&input, &crate_name)?; let (trait_impl_extras, trait_impl) = Trait::trait_impl(&input, &crate_name)?; let implies_trait = if let Some(implies_trait) = Trait::implies_trait(&crate_name) { quote!(unsafe impl #impl_generics #implies_trait for #name #ty_generics #where_clause {}) } else { quote!() }; let where_clause = if Trait::requires_where_clause() { where_clause } else { None }; Ok(quote! { #asserts #trait_impl_extras unsafe impl #impl_generics #trait_ for #name #ty_generics #where_clause { #trait_impl } #implies_trait }) } /// Add a trait marker to the generics if it is not already present fn add_trait_marker(generics: &mut syn::Generics, trait_name: &syn::Path) { // Get each generic type parameter. let type_params = generics .type_params() .map(|param| ¶m.ident) .map(|param| { syn::parse_quote!( #param: #trait_name ) }) .collect::>(); generics.make_where_clause().predicates.extend(type_params); } bytemuck_derive-1.10.2/src/traits.rs000064400000000000000000001473351046102023000155460ustar 00000000000000#![allow(unused_imports)] use std::{cmp, convert::TryFrom}; use proc_macro2::{Ident, Span, TokenStream, TokenTree}; use quote::{quote, ToTokens}; use syn::{ parse::{Parse, ParseStream, Parser}, 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(input: &DeriveInput, crate_name: &TokenStream) -> Result; fn implies_trait(_crate_name: &TokenStream) -> Option { None } fn asserts( _input: &DeriveInput, _crate_name: &TokenStream, ) -> Result { Ok(quote!()) } fn check_attributes(_ty: &Data, _attributes: &[Attribute]) -> Result<()> { Ok(()) } fn trait_impl( _input: &DeriveInput, _crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { Ok((quote!(), quote!())) } fn requires_where_clause() -> bool { true } fn explicit_bounds_attribute_name() -> Option<&'static str> { None } /// If this trait has a custom meaning for "perfect derive", this function /// should be overridden to return `Some`. /// /// The default is "the fields of a struct; unions and enums not supported". fn perfect_derive_fields(_input: &DeriveInput) -> Option { None } } pub struct Pod; impl Derivable for Pod { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::Pod)) } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { let repr = get_repr(&input.attrs)?; let completly_packed = repr.packed == Some(1) || repr.repr == Repr::Transparent; if !completly_packed && !input.generics.params.is_empty() { 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 { Data::Struct(_) => { let assert_no_padding = if !completly_packed { Some(generate_assert_no_padding(input, None, "Pod")?) } else { None }; let assert_fields_are_pod = generate_fields_are_trait( input, None, Self::ident(input, crate_name)?, )?; Ok(quote!( #assert_no_padding #assert_fields_are_pod )) } 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<()> { let repr = get_repr(attributes)?; match repr.repr { Repr::C => Ok(()), Repr::Transparent => Ok(()), _ => { bail!("Pod requires the type to be #[repr(C)] or #[repr(transparent)]") } } } } pub struct AnyBitPattern; impl Derivable for AnyBitPattern { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::AnyBitPattern)) } fn implies_trait(crate_name: &TokenStream) -> Option { Some(quote!(#crate_name::Zeroable)) } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { match &input.data { Data::Union(_) => Ok(quote!()), // unions are always `AnyBitPattern` Data::Struct(_) => { generate_fields_are_trait(input, None, Self::ident(input, crate_name)?) } Data::Enum(_) => { bail!("Deriving AnyBitPattern is not supported for enums") } } } } pub struct Zeroable; /// Helper function to get the variant with discriminant zero (implicit or /// explicit). fn get_zero_variant(enum_: &DataEnum) -> Result> { let iter = VariantDiscriminantIterator::new(enum_.variants.iter()); let mut zero_variant = None; for res in iter { let (discriminant, variant) = res?; if discriminant == 0 { zero_variant = Some(variant); break; } } Ok(zero_variant) } impl Derivable for Zeroable { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::Zeroable)) } fn check_attributes(ty: &Data, attributes: &[Attribute]) -> Result<()> { let repr = get_repr(attributes)?; match ty { Data::Struct(_) => Ok(()), Data::Enum(_) => { if !matches!( repr.repr, Repr::C | Repr::Integer(_) | Repr::CWithDiscriminant(_) ) { bail!("Zeroable requires the enum to be an explicit #[repr(Int)] and/or #[repr(C)]") } // We ensure there is a zero variant in `asserts`, since it is needed // there anyway. Ok(()) } Data::Union(_) => Ok(()), } } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { match &input.data { Data::Union(_) => Ok(quote!()), // unions are always `Zeroable` Data::Struct(_) => { generate_fields_are_trait(input, None, Self::ident(input, crate_name)?) } Data::Enum(enum_) => { let zero_variant = get_zero_variant(enum_)?; if zero_variant.is_none() { bail!("No variant's discriminant is 0") }; generate_fields_are_trait( input, zero_variant, Self::ident(input, crate_name)?, ) } } } fn explicit_bounds_attribute_name() -> Option<&'static str> { Some("zeroable") } fn perfect_derive_fields(input: &DeriveInput) -> Option { match &input.data { Data::Struct(struct_) => Some(struct_.fields.clone()), Data::Enum(enum_) => { // We handle `Err` returns from `get_zero_variant` in `asserts`, so it's // fine to just ignore them here and return `None`. // Otherwise, we clone the `fields` of the zero variant (if any). Some(get_zero_variant(enum_).ok()??.fields.clone()) } Data::Union(_) => None, } } } pub struct NoUninit; impl Derivable for NoUninit { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::NoUninit)) } fn check_attributes(ty: &Data, attributes: &[Attribute]) -> Result<()> { let repr = get_repr(attributes)?; match ty { Data::Struct(_) => match repr.repr { Repr::C | Repr::Transparent => Ok(()), _ => bail!("NoUninit requires the struct to be #[repr(C)] or #[repr(transparent)]"), }, Data::Enum(DataEnum { variants,.. }) => { if !enum_has_fields(variants.iter()) { if matches!(repr.repr, Repr::C | Repr::Integer(_)) { Ok(()) } else { bail!("NoUninit requires the enum to be #[repr(C)] or #[repr(Int)]") } } else if matches!(repr.repr, Repr::Rust) { bail!("NoUninit requires an explicit repr annotation because `repr(Rust)` doesn't have a specified type layout") } else { Ok(()) } }, Data::Union(_) => bail!("NoUninit can only be derived on enums and structs") } } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { if !input.generics.params.is_empty() { bail!("NoUninit cannot be derived for structs containing generic parameters because the padding requirements can't be verified for generic structs"); } match &input.data { Data::Struct(DataStruct { .. }) => { let assert_no_padding = generate_assert_no_padding(&input, None, "NoUninit")?; let assert_fields_are_no_padding = generate_fields_are_trait( &input, None, Self::ident(input, crate_name)?, )?; Ok(quote!( #assert_no_padding #assert_fields_are_no_padding )) } Data::Enum(DataEnum { variants, .. }) => { if enum_has_fields(variants.iter()) { // There are two different C representations for enums with fields: // There's `#[repr(C)]`/`[repr(C, int)]` and `#[repr(int)]`. // `#[repr(C)]` is equivalent to a struct containing the discriminant // and a union of structs representing each variant's fields. // `#[repr(int)]` is equivalent to a union containing structs of the // discriminant and the fields. // // See https://doc.rust-lang.org/reference/type-layout.html#r-layout.repr.c.adt // and https://doc.rust-lang.org/reference/type-layout.html#r-layout.repr.primitive.adt // // In practice the only difference between the two is whether and // where padding bytes are placed. For `#[repr(C)]` enums, the first // enum fields of all variants start at the same location (the first // byte in the union). For `#[repr(int)]` enums, the structs // representing each variant are layed out individually and padding // does not depend on other variants, but only on the size of the // discriminant and the alignment of the first field. The location of // the first field might differ between variants, potentially // resulting in less padding or padding placed later in the enum. // // The `NoUninit` derive macro asserts that no padding exists by // removing all padding with `#[repr(packed)]` and checking that this // doesn't change the size. Since the location and presence of // padding bytes is the only difference between the two // representations and we're removing all padding bytes, the resuling // layout would identical for both representations. This means that // we can just pick one of the representations and don't have to // implement desugaring for both. We chose to implement the // desugaring for `#[repr(int)]`. let enum_discriminant = generate_enum_discriminant(input)?; let variant_assertions = variants .iter() .map(|variant| { let assert_no_padding = generate_assert_no_padding(&input, Some(variant), "NoUninit")?; let assert_fields_are_no_padding = generate_fields_are_trait( &input, Some(variant), Self::ident(input, crate_name)?, )?; Ok(quote!( #assert_no_padding #assert_fields_are_no_padding )) }) .collect::>>()?; Ok(quote! { const _: () = { #enum_discriminant #(#variant_assertions)* }; }) } else { Ok(quote!()) } } 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, _crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { Ok((quote!(), quote!())) } } pub struct CheckedBitPattern; impl Derivable for CheckedBitPattern { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::CheckedBitPattern)) } fn check_attributes(ty: &Data, attributes: &[Attribute]) -> Result<()> { let repr = get_repr(attributes)?; match ty { Data::Struct(_) => match repr.repr { Repr::C | Repr::Transparent => Ok(()), _ => bail!("CheckedBitPattern derive requires the struct to be #[repr(C)] or #[repr(transparent)]"), }, Data::Enum(DataEnum { variants,.. }) => { if !enum_has_fields(variants.iter()){ if matches!(repr.repr, Repr::C | Repr::Integer(_)) { Ok(()) } else { bail!("CheckedBitPattern requires the enum to be #[repr(C)] or #[repr(Int)]") } } else if matches!(repr.repr, Repr::Rust) { bail!("CheckedBitPattern requires an explicit repr annotation because `repr(Rust)` doesn't have a specified type layout") } else { Ok(()) } } Data::Union(_) => bail!("CheckedBitPattern can only be derived on enums and structs") } } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { if !input.generics.params.is_empty() { bail!("CheckedBitPattern cannot be derived for structs containing generic parameters"); } match &input.data { Data::Struct(DataStruct { .. }) => { let assert_fields_are_maybe_pod = generate_fields_are_trait( &input, None, Self::ident(input, crate_name)?, )?; Ok(assert_fields_are_maybe_pod) } // nothing needed, already guaranteed OK by NoUninit. Data::Enum(_) => Ok(quote!()), 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, crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { match &input.data { Data::Struct(DataStruct { fields, .. }) => { generate_checked_bit_pattern_struct( &input.ident, fields, &input.attrs, crate_name, ) } Data::Enum(DataEnum { variants, .. }) => { generate_checked_bit_pattern_enum(input, variants, crate_name) } Data::Union(_) => bail!("Internal error in CheckedBitPattern derive"), /* shouldn't be possible since we already error in attribute check for this case */ } } } pub struct TransparentWrapper; struct WrappedType { wrapped_type: syn::Type, /// Was the type given with a #[transparent(Type)] attribute. explicit: bool, } impl TransparentWrapper { fn get_wrapped_type( attributes: &[Attribute], fields: &Fields, ) -> Option { let transparent_param = get_type_from_simple_attr(attributes, "transparent") .map(|wrapped_type| WrappedType { wrapped_type, explicit: true }); transparent_param.or_else(|| { let mut types = get_field_types(&fields); let first_type = types.next(); if let Some(_) = types.next() { // can't guess param type if there is more than one field return None; } else { first_type .cloned() .map(|wrapped_type| WrappedType { wrapped_type, explicit: false }) } }) } } impl Derivable for TransparentWrapper { fn ident(input: &DeriveInput, crate_name: &TokenStream) -> Result { let fields = get_struct_fields(input)?; let WrappedType { wrapped_type: ty, .. } = match Self::get_wrapped_type(&input.attrs, &fields) { Some(ty) => ty, None => bail!("when deriving TransparentWrapper for a struct with more \ than one field, you need to specify the transparent field \ using #[transparent(T)]"), }; Ok(syn::parse_quote!(#crate_name::TransparentWrapper<#ty>)) } fn asserts( input: &DeriveInput, crate_name: &TokenStream, ) -> Result { let (impl_generics, _ty_generics, where_clause) = input.generics.split_for_impl(); let fields = get_struct_fields(input)?; let (wrapped_type, explicit) = match Self::get_wrapped_type(&input.attrs, &fields) { Some(WrappedType { wrapped_type, explicit }) => { (wrapped_type.to_token_stream().to_string(), explicit) } None => unreachable!(), /* other code will already reject this derive */ }; let mut wrapped_field_ty = None; let mut nonwrapped_field_tys = vec![]; for field in fields.iter() { let field_ty = &field.ty; if field_ty.to_token_stream().to_string() == wrapped_type { if wrapped_field_ty.is_some() { if explicit { bail!("TransparentWrapper must have one field of the wrapped type. \ The type given in `#[transparent(Type)]` must match tokenwise \ with the type in the struct definition, not just be the same type. \ You may be able to use a type alias to work around this limitation."); } else { bail!("TransparentWrapper must have one field of the wrapped type"); } } wrapped_field_ty = Some(field_ty); } else { nonwrapped_field_tys.push(field_ty); } } if let Some(wrapped_field_ty) = wrapped_field_ty { Ok(quote!( const _: () = { #[repr(transparent)] #[allow(clippy::multiple_bound_locations)] struct AssertWrappedIsWrapped #impl_generics((u8, ::core::marker::PhantomData<#wrapped_field_ty>), #(#nonwrapped_field_tys),*) #where_clause; fn assert_zeroable() {} #[allow(clippy::multiple_bound_locations)] fn check #impl_generics () #where_clause { #( assert_zeroable::<#nonwrapped_field_tys>(); )* } }; )) } else { bail!("TransparentWrapper must have one field of the wrapped type") } } fn check_attributes(_ty: &Data, attributes: &[Attribute]) -> Result<()> { let repr = get_repr(attributes)?; match repr.repr { Repr::Transparent => Ok(()), _ => { bail!( "TransparentWrapper requires the struct to be #[repr(transparent)]" ) } } } fn requires_where_clause() -> bool { false } } pub struct Contiguous; impl Derivable for Contiguous { fn ident(_: &DeriveInput, crate_name: &TokenStream) -> Result { Ok(syn::parse_quote!(#crate_name::Contiguous)) } fn trait_impl( input: &DeriveInput, _crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { let repr = get_repr(&input.attrs)?; let integer_ty = if let Some(integer_ty) = repr.repr.as_integer() { integer_ty } else { bail!("Contiguous requires the enum to be #[repr(Int)]"); }; let variants = get_enum_variants(input)?; if enum_has_fields(variants.clone()) { return Err(Error::new_spanned( &input, "Only fieldless enums are supported", )); } let mut variants_with_discriminant = VariantDiscriminantIterator::new(variants); let (min, max, count) = variants_with_discriminant.try_fold( (i128::MAX, i128::MIN, 0), |(min, max, count), res| { let (discriminant, _variant) = res?; Ok::<_, Error>(( i128::min(min, discriminant), i128::max(max, discriminant), count + 1, )) }, )?; if max - min != count - 1 { bail! { "Contiguous requires the enum discriminants to be contiguous", } } let min_lit = LitInt::new(&format!("{}", min), input.span()); let max_lit = LitInt::new(&format!("{}", max), input.span()); // `from_integer` and `into_integer` are usually provided by the trait's // default implementation. We override this implementation because it // goes through `transmute_copy`, which can lead to inefficient assembly as seen in https://github.com/Lokathor/bytemuck/issues/175 . Ok(( quote!(), quote! { type Int = #integer_ty; #[allow(clippy::missing_docs_in_private_items)] const MIN_VALUE: #integer_ty = #min_lit; #[allow(clippy::missing_docs_in_private_items)] const MAX_VALUE: #integer_ty = #max_lit; #[inline] fn from_integer(value: Self::Int) -> Option { #[allow(clippy::manual_range_contains)] if Self::MIN_VALUE <= value && value <= Self::MAX_VALUE { Some(unsafe { ::core::mem::transmute(value) }) } else { None } } #[inline] fn into_integer(self) -> Self::Int { self as #integer_ty } }, )) } } fn get_struct_fields(input: &DeriveInput) -> Result<&Fields> { if let Data::Struct(DataStruct { fields, .. }) = &input.data { Ok(fields) } else { bail!("deriving this trait is only supported for structs") } } /// Extract the `Fields` off a `DeriveInput`, or, in the `enum` case, off /// those of the `enum_variant`, when provided (e.g., for `Zeroable`). /// /// We purposely allow not providing an `enum_variant` for cases where /// the caller wants to reject supporting `enum`s (e.g., `NoPadding`). fn get_fields( input: &DeriveInput, enum_variant: Option<&Variant>, ) -> Result { match &input.data { Data::Struct(DataStruct { fields, .. }) => Ok(fields.clone()), Data::Union(DataUnion { fields, .. }) => Ok(Fields::Named(fields.clone())), Data::Enum(_) => match enum_variant { Some(variant) => Ok(variant.fields.clone()), None => bail!("deriving this trait is not supported for enums"), }, } } fn get_enum_variants<'a>( input: &'a DeriveInput, ) -> Result + Clone + 'a> { if let Data::Enum(DataEnum { variants, .. }) = &input.data { Ok(variants.iter()) } else { bail!("deriving this trait is only supported for enums") } } fn get_field_types<'a>( fields: &'a Fields, ) -> impl Iterator + 'a { fields.iter().map(|field| &field.ty) } fn generate_checked_bit_pattern_struct( input_ident: &Ident, fields: &Fields, attrs: &[Attribute], crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { let bits_ty = Ident::new(&format!("{}Bits", input_ident), input_ident.span()); let repr = get_repr(attrs)?; let field_names = fields .iter() .enumerate() .map(|(i, field)| { field.ident.clone().unwrap_or_else(|| { Ident::new(&format!("field{}", i), input_ident.span()) }) }) .collect::>(); let field_tys = fields.iter().map(|field| &field.ty).collect::>(); let field_name = &field_names[..]; let field_ty = &field_tys[..]; Ok(( quote! { #[doc = #GENERATED_TYPE_DOCUMENTATION] #repr #[derive(Clone, Copy, #crate_name::AnyBitPattern)] #[allow(missing_docs)] pub struct #bits_ty { #(#field_name: <#field_ty as #crate_name::CheckedBitPattern>::Bits,)* } #[allow(unexpected_cfgs)] const _: () = { #[cfg(not(target_arch = "spirv"))] impl ::core::fmt::Debug for #bits_ty { fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { let mut debug_struct = ::core::fmt::Formatter::debug_struct(f, ::core::stringify!(#bits_ty)); #(::core::fmt::DebugStruct::field(&mut debug_struct, ::core::stringify!(#field_name), &{ self.#field_name });)* ::core::fmt::DebugStruct::finish(&mut debug_struct) } } }; }, quote! { type Bits = #bits_ty; #[inline] #[allow(clippy::double_comparisons, unused)] fn is_valid_bit_pattern(bits: &#bits_ty) -> bool { #(<#field_ty as #crate_name::CheckedBitPattern>::is_valid_bit_pattern(&{ bits.#field_name }) && )* true } }, )) } fn generate_checked_bit_pattern_enum( input: &DeriveInput, variants: &Punctuated, crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { if enum_has_fields(variants.iter()) { generate_checked_bit_pattern_enum_with_fields(input, variants, crate_name) } else { generate_checked_bit_pattern_enum_without_fields( input, variants, crate_name, ) } } fn generate_checked_bit_pattern_enum_without_fields( input: &DeriveInput, variants: &Punctuated, crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { let span = input.span(); let mut variants_with_discriminant = VariantDiscriminantIterator::new(variants.iter()); let (min, max, count) = variants_with_discriminant.try_fold( (i128::MAX, i128::MIN, 0), |(min, max, count), res| { let (discriminant, _variant) = res?; Ok::<_, Error>(( i128::min(min, discriminant), i128::max(max, discriminant), count + 1, )) }, )?; let check = if count == 0 { quote!(false) } else if max - min == count - 1 { // contiguous range let min_lit = LitInt::new(&format!("{}", min), span); let max_lit = LitInt::new(&format!("{}", max), span); quote!(*bits >= #min_lit && *bits <= #max_lit) } else { // not contiguous range, check for each let variant_discriminant_lits = VariantDiscriminantIterator::new(variants.iter()) .map(|res| { let (discriminant, _variant) = res?; Ok(LitInt::new(&format!("{}", discriminant), span)) }) .collect::>>()?; // count is at least 1 let first = &variant_discriminant_lits[0]; let rest = &variant_discriminant_lits[1..]; quote!(matches!(*bits, #first #(| #rest )*)) }; let (integer, defs) = get_enum_discriminant(input, crate_name)?; Ok(( quote!(#defs), quote! { type Bits = #integer; #[inline] #[allow(clippy::double_comparisons)] fn is_valid_bit_pattern(bits: &Self::Bits) -> bool { #check } }, )) } fn generate_checked_bit_pattern_enum_with_fields( input: &DeriveInput, variants: &Punctuated, crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { let representation = get_repr(&input.attrs)?; let vis = &input.vis; match representation.repr { Repr::Rust => unreachable!(), Repr::C | Repr::CWithDiscriminant(_) => { let (integer, defs) = get_enum_discriminant(input, crate_name)?; let input_ident = &input.ident; let bits_repr = Representation { repr: Repr::C, ..representation }; // the enum manually re-configured as the actual tagged union it // represents, thus circumventing the requirements rust imposes on // the tag even when using #[repr(C)] enum layout // see: https://doc.rust-lang.org/reference/type-layout.html#reprc-enums-with-fields let bits_ty_ident = Ident::new(&format!("{input_ident}Bits"), input.span()); // the variants union part of the tagged union. These get put into a union // which gets the AnyBitPattern derive applied to it, thus checking // that the fields of the union obey the requriements of AnyBitPattern. // The types that actually go in the union are one more level of // indirection deep: we generate new structs for each variant // (`variant_struct_definitions`) which themselves have the // `CheckedBitPattern` derive applied, thus generating // `{variant_struct_ident}Bits` structs, which are the ones that go // into this union. let variants_union_ident = Ident::new(&format!("{}Variants", input.ident), input.span()); let variant_struct_idents = variants.iter().map(|v| { Ident::new(&format!("{input_ident}Variant{}", v.ident), v.span()) }); let variant_struct_definitions = variant_struct_idents.clone().zip(variants.iter()).map(|(variant_struct_ident, v)| { let fields = v.fields.iter().map(|v| &v.ty); quote! { #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::CheckedBitPattern)] #[repr(C)] #vis struct #variant_struct_ident(#(#fields),*); } }); let union_fields = variant_struct_idents .clone() .zip(variants.iter()) .map(|(variant_struct_ident, v)| { let variant_struct_bits_ident = Ident::new(&format!("{variant_struct_ident}Bits"), input.span()); let field_ident = &v.ident; quote! { #field_ident: #variant_struct_bits_ident } }); let variant_checks = variant_struct_idents .clone() .zip(VariantDiscriminantIterator::new(variants.iter())) .zip(variants.iter()) .map(|((variant_struct_ident, discriminant), v)| -> Result<_> { let (discriminant, _variant) = discriminant?; let discriminant = LitInt::new(&discriminant.to_string(), v.span()); let ident = &v.ident; Ok(quote! { #discriminant => { let payload = unsafe { &bits.payload.#ident }; <#variant_struct_ident as #crate_name::CheckedBitPattern>::is_valid_bit_pattern(payload) } }) }) .collect::>>()?; Ok(( quote! { #defs #[doc = #GENERATED_TYPE_DOCUMENTATION] #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::AnyBitPattern)] #bits_repr #vis struct #bits_ty_ident { tag: #integer, payload: #variants_union_ident, } #[allow(unexpected_cfgs)] const _: () = { #[cfg(not(target_arch = "spirv"))] impl ::core::fmt::Debug for #bits_ty_ident { fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { let mut debug_struct = ::core::fmt::Formatter::debug_struct(f, ::core::stringify!(#bits_ty_ident)); ::core::fmt::DebugStruct::field(&mut debug_struct, "tag", &self.tag); ::core::fmt::DebugStruct::field(&mut debug_struct, "payload", &self.payload); ::core::fmt::DebugStruct::finish(&mut debug_struct) } } }; #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::AnyBitPattern)] #[repr(C)] #[allow(non_snake_case)] #vis union #variants_union_ident { #(#union_fields,)* } #[allow(unexpected_cfgs)] const _: () = { #[cfg(not(target_arch = "spirv"))] impl ::core::fmt::Debug for #variants_union_ident { fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { let mut debug_struct = ::core::fmt::Formatter::debug_struct(f, ::core::stringify!(#variants_union_ident)); ::core::fmt::DebugStruct::finish_non_exhaustive(&mut debug_struct) } } }; #(#variant_struct_definitions)* }, quote! { type Bits = #bits_ty_ident; #[inline] #[allow(clippy::double_comparisons)] fn is_valid_bit_pattern(bits: &Self::Bits) -> bool { match bits.tag { #(#variant_checks)* _ => false, } } }, )) } Repr::Transparent => { if variants.len() != 1 { bail!("enums with more than one variant cannot be transparent") } let variant = &variants[0]; let bits_ty = Ident::new(&format!("{}Bits", input.ident), input.span()); let fields = variant.fields.iter().map(|v| &v.ty); Ok(( quote! { #[doc = #GENERATED_TYPE_DOCUMENTATION] #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::CheckedBitPattern)] #[repr(C)] #vis struct #bits_ty(#(#fields),*); }, quote! { type Bits = <#bits_ty as #crate_name::CheckedBitPattern>::Bits; #[inline] #[allow(clippy::double_comparisons)] fn is_valid_bit_pattern(bits: &Self::Bits) -> bool { <#bits_ty as #crate_name::CheckedBitPattern>::is_valid_bit_pattern(bits) } }, )) } Repr::Integer(integer) => { let bits_repr = Representation { repr: Repr::C, ..representation }; let input_ident = &input.ident; // the enum manually re-configured as the union it represents. such a // union is the union of variants as a repr(c) struct with the // discriminator type inserted at the beginning. in our case we // union the `Bits` representation of each variant rather than the variant // itself, which we generate via a nested `CheckedBitPattern` derive // on the `variant_struct_definitions` generated below. // // see: https://doc.rust-lang.org/reference/type-layout.html#primitive-representation-of-enums-with-fields let bits_ty_ident = Ident::new(&format!("{input_ident}Bits"), input.span()); let variant_struct_idents = variants.iter().map(|v| { Ident::new(&format!("{input_ident}Variant{}", v.ident), v.span()) }); let variant_struct_definitions = variant_struct_idents.clone().zip(variants.iter()).map(|(variant_struct_ident, v)| { let fields = v.fields.iter().map(|v| &v.ty); // adding the discriminant repr integer as first field, as described above quote! { #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::CheckedBitPattern)] #[repr(C)] #vis struct #variant_struct_ident(#integer, #(#fields),*); } }); let union_fields = variant_struct_idents .clone() .zip(variants.iter()) .map(|(variant_struct_ident, v)| { let variant_struct_bits_ident = Ident::new(&format!("{variant_struct_ident}Bits"), input.span()); let field_ident = &v.ident; quote! { #field_ident: #variant_struct_bits_ident } }); let variant_checks = variant_struct_idents .clone() .zip(VariantDiscriminantIterator::new(variants.iter())) .zip(variants.iter()) .map(|((variant_struct_ident, discriminant), v)| -> Result<_> { let (discriminant, _variant) = discriminant?; let discriminant = LitInt::new(&discriminant.to_string(), v.span()); let ident = &v.ident; Ok(quote! { #discriminant => { let payload = unsafe { &bits.#ident }; <#variant_struct_ident as #crate_name::CheckedBitPattern>::is_valid_bit_pattern(payload) } }) }) .collect::>>()?; Ok(( quote! { #[doc = #GENERATED_TYPE_DOCUMENTATION] #[derive(::core::clone::Clone, ::core::marker::Copy, #crate_name::AnyBitPattern)] #bits_repr #[allow(non_snake_case)] #vis union #bits_ty_ident { __tag: #integer, #(#union_fields,)* } #[allow(unexpected_cfgs)] const _: () = { #[cfg(not(target_arch = "spirv"))] impl ::core::fmt::Debug for #bits_ty_ident { fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { let mut debug_struct = ::core::fmt::Formatter::debug_struct(f, ::core::stringify!(#bits_ty_ident)); ::core::fmt::DebugStruct::field(&mut debug_struct, "tag", unsafe { &self.__tag }); ::core::fmt::DebugStruct::finish_non_exhaustive(&mut debug_struct) } } }; #(#variant_struct_definitions)* }, quote! { type Bits = #bits_ty_ident; #[inline] #[allow(clippy::double_comparisons)] fn is_valid_bit_pattern(bits: &Self::Bits) -> bool { match unsafe { bits.__tag } { #(#variant_checks)* _ => false, } } }, )) } } } /// Check that a struct or enum has no padding by asserting that the size of /// the type is equal to the sum of the size of it's fields and discriminant /// (for enums, this must be asserted for each variant). fn generate_assert_no_padding( input: &DeriveInput, enum_variant: Option<&Variant>, for_trait: &str, ) -> Result { let struct_type = &input.ident; let fields = get_fields(input, enum_variant)?; // If the type is an enum, determine the type of its discriminant. let enum_discriminant = if matches!(input.data, Data::Enum(_)) { let ident = Ident::new(&format!("{}Discriminant", input.ident), input.ident.span()); Some(ident.into_token_stream()) } else { None }; // Prepend the type of the discriminant to the types of the fields. let mut field_types = enum_discriminant .into_iter() .chain(get_field_types(&fields).map(ToTokens::to_token_stream)); let size_sum = if let Some(first) = field_types.next() { let size_first = quote!(::core::mem::size_of::<#first>()); let size_rest = quote!(#( + ::core::mem::size_of::<#field_types>() )*); quote!(#size_first #size_rest) } else { quote!(0) }; let message = format!("derive({for_trait}) was applied to a type with padding"); Ok(quote! {const _: () = { assert!( ::core::mem::size_of::<#struct_type>() == (#size_sum), #message, ); };}) } /// Check that all fields implement a given trait fn generate_fields_are_trait( input: &DeriveInput, enum_variant: Option<&Variant>, trait_: syn::Path, ) -> Result { let (impl_generics, _ty_generics, where_clause) = input.generics.split_for_impl(); let fields = get_fields(input, enum_variant)?; let field_types = get_field_types(&fields); Ok(quote! {#(const _: fn() = || { #[allow(clippy::missing_const_for_fn)] #[doc(hidden)] fn check #impl_generics () #where_clause { fn assert_impl() {} assert_impl::<#field_types>(); } };)* }) } /// Get the type of an enum's discriminant. /// /// For `repr(int)` and `repr(C, int)` enums, this will return the known bare /// integer type specified. /// /// For `repr(C)` enums, this will extract the underlying size chosen by rustc. /// It will return a token stream which is a type expression that evaluates to /// a primitive integer type of this size, using our `EnumTagIntegerBytes` /// trait. /// /// For fieldless `repr(C)` enums, we can feed the size of the enum directly /// into the trait. /// /// For `repr(C)` enums with fields, we generate a new fieldless `repr(C)` enum /// with the same variants, then use that in the calculation. This is the /// specified behavior, see https://doc.rust-lang.org/stable/reference/type-layout.html#reprc-enums-with-fields /// /// Returns a tuple of (type ident, auxiliary definitions) fn get_enum_discriminant( input: &DeriveInput, crate_name: &TokenStream, ) -> Result<(TokenStream, TokenStream)> { let repr = get_repr(&input.attrs)?; match repr.repr { Repr::C => { let e = if let Data::Enum(e) = &input.data { e } else { unreachable!() }; if enum_has_fields(e.variants.iter()) { // If the enum has fields, we must first isolate the discriminant by // removing all the fields. let enum_discriminant = generate_enum_discriminant(input)?; let discriminant_ident = Ident::new( &format!("{}Discriminant", input.ident), input.ident.span(), ); Ok(( quote!(<[::core::primitive::u8; ::core::mem::size_of::<#discriminant_ident>()] as #crate_name::derive::EnumTagIntegerBytes>::Integer), quote! { #enum_discriminant }, )) } else { // If the enum doesn't have fields, we can just use it directly. let ident = &input.ident; Ok(( quote!(<[::core::primitive::u8; ::core::mem::size_of::<#ident>()] as #crate_name::derive::EnumTagIntegerBytes>::Integer), quote!(), )) } } Repr::Integer(integer) | Repr::CWithDiscriminant(integer) => { Ok((quote!(#integer), quote!())) } _ => unreachable!(), } } fn generate_enum_discriminant(input: &DeriveInput) -> Result { let e = if let Data::Enum(e) = &input.data { e } else { unreachable!() }; let repr = get_repr(&input.attrs)?; let repr = match repr.repr { Repr::C => quote!(#[repr(C)]), Repr::Integer(int) | Repr::CWithDiscriminant(int) => quote!(#[repr(#int)]), Repr::Rust | Repr::Transparent => unreachable!(), }; let ident = Ident::new(&format!("{}Discriminant", input.ident), input.ident.span()); let variants = e.variants.iter().cloned().map(|mut e| { e.fields = Fields::Unit; e }); Ok(quote! { #repr #[allow(dead_code)] enum #ident { #(#variants,)* } }) } fn get_wrapped_type_from_stream(tokens: TokenStream) -> Option { let mut tokens = tokens.into_iter().peekable(); match tokens.peek() { Some(TokenTree::Group(group)) => { let res = get_wrapped_type_from_stream(group.stream()); tokens.next(); // remove the peeked token tree match tokens.next() { // If there were more tokens, the input was invalid Some(_) => None, None => res, } } _ => syn::parse2(tokens.collect()).ok(), } } /// get a simple `#[foo(bar)]` attribute, returning `bar` fn get_type_from_simple_attr( attributes: &[Attribute], attr_name: &str, ) -> Option { for attr in attributes { if let (AttrStyle::Outer, Meta::List(list)) = (&attr.style, &attr.meta) { if list.path.is_ident(attr_name) { if let Some(ty) = get_wrapped_type_from_stream(list.tokens.clone()) { return Some(ty); } } } } None } fn get_repr(attributes: &[Attribute]) -> Result { attributes .iter() .filter_map(|attr| { if attr.path().is_ident("repr") { Some(attr.parse_args::()) } else { 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"), }, align: match (a.align, b.align) { (Some(a), Some(b)) => Some(cmp::max(a, b)), (a, None) => a, (None, b) => b, }, }) }) } mk_repr! { U8 => u8, I8 => i8, U16 => u16, I16 => i16, U32 => u32, I32 => i32, U64 => u64, I64 => i64, I128 => i128, U128 => u128, Usize => usize, Isize => isize, } // where macro_rules! mk_repr {( $( $Xn:ident => $xn:ident ),* $(,)? ) => ( #[derive(Debug, Clone, Copy, PartialEq, Eq)] enum IntegerRepr { $($Xn),* } impl<'a> TryFrom<&'a str> for IntegerRepr { type Error = &'a str; fn try_from(value: &'a str) -> std::result::Result { match value { $( stringify!($xn) => Ok(Self::$Xn), )* _ => Err(value), } } } impl ToTokens for IntegerRepr { fn to_tokens(&self, tokens: &mut TokenStream) { match self { $( Self::$Xn => tokens.extend(quote!($xn)), )* } } } )} use mk_repr; #[derive(Debug, Clone, Copy, PartialEq, Eq)] enum Repr { Rust, C, Transparent, Integer(IntegerRepr), CWithDiscriminant(IntegerRepr), } impl Repr { fn as_integer(&self) -> Option { if let Self::Integer(v) = self { Some(*v) } else { None } } } #[derive(Debug, Clone, Copy, PartialEq, Eq)] struct Representation { packed: Option, align: Option, repr: Repr, } impl Default for Representation { fn default() -> Self { Self { packed: None, align: None, repr: Repr::Rust } } } impl Parse for Representation { fn parse(input: ParseStream<'_>) -> Result { let mut ret = Representation::default(); while !input.is_empty() { let keyword = input.parse::()?; // 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::(&contents.parse()?)? } else { 1 }); let _: Option = input.parse()?; continue; } "align" => { let contents; parenthesized!(contents in input); let new_align = LitInt::base10_parse::(&contents.parse()?)?; ret.align = Some( ret .align .map_or(new_align, |old_align| cmp::max(old_align, new_align)), ); let _: Option = input.parse()?; continue; } ident => { let primitive = IntegerRepr::try_from(ident) .map_err(|_| input.error("unrecognized representation hint"))?; Repr::Integer(primitive) } }; ret.repr = match (ret.repr, new_repr) { (Repr::Rust, new_repr) => { // This is the first explicit repr. new_repr } (Repr::C, Repr::Integer(integer)) | (Repr::Integer(integer), Repr::C) => { // Both the C repr and an integer repr have been specified // -> merge into a C wit discriminant. Repr::CWithDiscriminant(integer) } (_, _) => { return Err(input.error("duplicate representation hint")); } }; let _: Option = input.parse()?; } Ok(ret) } } impl ToTokens for Representation { fn to_tokens(&self, tokens: &mut TokenStream) { let mut meta = Punctuated::<_, Token![,]>::new(); match self.repr { Repr::Rust => {} Repr::C => meta.push(quote!(C)), Repr::Transparent => meta.push(quote!(transparent)), Repr::Integer(primitive) => meta.push(quote!(#primitive)), Repr::CWithDiscriminant(primitive) => { meta.push(quote!(C)); meta.push(quote!(#primitive)); } } if let Some(packed) = self.packed.as_ref() { let lit = LitInt::new(&packed.to_string(), Span::call_site()); meta.push(quote!(packed(#lit))); } if let Some(align) = self.align.as_ref() { let lit = LitInt::new(&align.to_string(), Span::call_site()); meta.push(quote!(align(#lit))); } tokens.extend(quote!( #[repr(#meta)] )); } } fn enum_has_fields<'a>( mut variants: impl Iterator, ) -> bool { variants.any(|v| matches!(v.fields, Fields::Named(_) | Fields::Unnamed(_))) } struct VariantDiscriminantIterator<'a, I: Iterator + 'a> { inner: I, last_value: i128, } impl<'a, I: Iterator + 'a> VariantDiscriminantIterator<'a, I> { fn new(inner: I) -> Self { VariantDiscriminantIterator { inner, last_value: -1 } } } impl<'a, I: Iterator + 'a> Iterator for VariantDiscriminantIterator<'a, I> { type Item = Result<(i128, &'a Variant)>; fn next(&mut self) -> Option { let variant = self.inner.next()?; if let Some((_, discriminant)) = &variant.discriminant { let discriminant_value = match parse_int_expr(discriminant) { Ok(value) => value, Err(e) => return Some(Err(e)), }; self.last_value = discriminant_value; } else { // If this wraps, then either: // 1. the enum is using repr(u128), so wrapping is correct // 2. the enum is using repr(i<=128 or u<128), so the compiler will // already emit a "wrapping discriminant" E0370 error. self.last_value = self.last_value.wrapping_add(1); // Static assert that there is no integer repr > 128 bits. If that // changes, the above comment is inaccurate and needs to be updated! // FIXME(zachs18): maybe should also do something to ensure `isize::BITS // <= 128`? if let Some(repr) = None:: { match repr { IntegerRepr::U8 | IntegerRepr::I8 | IntegerRepr::U16 | IntegerRepr::I16 | IntegerRepr::U32 | IntegerRepr::I32 | IntegerRepr::U64 | IntegerRepr::I64 | IntegerRepr::I128 | IntegerRepr::U128 | IntegerRepr::Usize | IntegerRepr::Isize => (), } } } Some(Ok((self.last_value, variant))) } } fn parse_int_expr(expr: &Expr) -> Result { 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(), Expr::Lit(ExprLit { lit: Lit::Byte(byte), .. }) => Ok(byte.value().into()), _ => bail!("Not an integer expression"), } } #[cfg(test)] mod tests { use syn::parse_quote; use super::{get_repr, IntegerRepr, Repr, Representation}; #[test] fn parse_basic_repr() { let attr = parse_quote!(#[repr(C)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { repr: Repr::C, ..Default::default() }); let attr = parse_quote!(#[repr(transparent)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!( repr, Representation { repr: Repr::Transparent, ..Default::default() } ); let attr = parse_quote!(#[repr(u8)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!( repr, Representation { repr: Repr::Integer(IntegerRepr::U8), ..Default::default() } ); let attr = parse_quote!(#[repr(packed)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { packed: Some(1), ..Default::default() }); let attr = parse_quote!(#[repr(packed(1))]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { packed: Some(1), ..Default::default() }); let attr = parse_quote!(#[repr(packed(2))]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { packed: Some(2), ..Default::default() }); let attr = parse_quote!(#[repr(align(2))]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { align: Some(2), ..Default::default() }); } #[test] fn parse_advanced_repr() { let attr = parse_quote!(#[repr(align(4), align(2))]); let repr = get_repr(&[attr]).unwrap(); assert_eq!(repr, Representation { align: Some(4), ..Default::default() }); let attr1 = parse_quote!(#[repr(align(1))]); let attr2 = parse_quote!(#[repr(align(4))]); let attr3 = parse_quote!(#[repr(align(2))]); let repr = get_repr(&[attr1, attr2, attr3]).unwrap(); assert_eq!(repr, Representation { align: Some(4), ..Default::default() }); let attr = parse_quote!(#[repr(C, u8)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!( repr, Representation { repr: Repr::CWithDiscriminant(IntegerRepr::U8), ..Default::default() } ); let attr = parse_quote!(#[repr(u8, C)]); let repr = get_repr(&[attr]).unwrap(); assert_eq!( repr, Representation { repr: Repr::CWithDiscriminant(IntegerRepr::U8), ..Default::default() } ); } } pub fn bytemuck_crate_name(input: &DeriveInput) -> TokenStream { const ATTR_NAME: &'static str = "crate"; let mut crate_name = quote!(::bytemuck); for attr in &input.attrs { if !attr.path().is_ident("bytemuck") { continue; } attr.parse_nested_meta(|meta| { if meta.path.is_ident(ATTR_NAME) { let expr: syn::Expr = meta.value()?.parse()?; let mut value = &expr; while let syn::Expr::Group(e) = value { value = &e.expr; } if let syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Str(lit), .. }) = value { let suffix = lit.suffix(); if !suffix.is_empty() { bail!(format!("Unexpected suffix `{}` on string literal", suffix)) } let path: syn::Path = match lit.parse() { Ok(path) => path, Err(_) => { bail!(format!("Failed to parse path: {:?}", lit.value())) } }; crate_name = path.into_token_stream(); } else { bail!( "Expected bytemuck `crate` attribute to be a string: `crate = \"...\"`", ) } } Ok(()) }).unwrap(); } return crate_name; } const GENERATED_TYPE_DOCUMENTATION: &str = " `bytemuck`-generated type for internal purposes only."; bytemuck_derive-1.10.2/tests/basic.rs000064400000000000000000000333731046102023000156700ustar 00000000000000#![allow(dead_code)] #![deny(clippy::allow_attributes)] use bytemuck::{ checked::CheckedCastError, AnyBitPattern, CheckedBitPattern, Contiguous, NoUninit, Pod, TransparentWrapper, Zeroable, }; use std::marker::{PhantomData, PhantomPinned}; #[derive(Copy, Clone, Pod, Zeroable)] #[repr(C)] struct Test { a: u16, b: u16, } #[derive(Pod, Zeroable)] #[repr(C, packed)] struct GenericPackedStruct { a: u32, b: T, c: u32, } impl Clone for GenericPackedStruct { fn clone(&self) -> Self { *self } } impl Copy for GenericPackedStruct {} #[derive(Pod, Zeroable)] #[repr(C, packed(1))] struct GenericPackedStructExplicitPackedAlignment { a: u32, b: T, c: u32, } impl Clone for GenericPackedStructExplicitPackedAlignment { fn clone(&self) -> Self { *self } } impl Copy for GenericPackedStructExplicitPackedAlignment {} #[derive(Zeroable)] struct ZeroGeneric { a: T, } #[derive(Zeroable)] #[repr(u8)] enum ZeroEnum { A = 0, B = 1, C = 2, } #[derive(Zeroable)] #[repr(u8)] enum BasicFieldfulZeroEnum { A(u8) = 0, B = 1, C(String) = 2, } #[derive(Zeroable)] #[repr(C)] enum ReprCFieldfulZeroEnum { A(u8), B(Box<[u8]>), C, } #[derive(Zeroable)] #[repr(C, i32)] enum ReprCIntFieldfulZeroEnum { B(String) = 1, A(u8, bool, char) = 0, C = 2, } #[derive(Zeroable)] #[repr(i32)] enum GenericFieldfulZeroEnum { A(Box) = 1, B(T, T) = 0, } #[derive(Zeroable)] #[repr(i32)] #[zeroable(bound = "")] enum GenericCustomBoundFieldfulZeroEnum { A(Option>), B(String), } #[derive(TransparentWrapper)] #[repr(transparent)] struct TransparentSingle { a: u16, } #[derive(TransparentWrapper)] #[repr(transparent)] #[transparent(u16)] struct TransparentWithZeroSized { a: u16, b: PhantomData, } struct MyZst(PhantomData, [u8; 0], PhantomPinned); unsafe impl Zeroable for MyZst {} #[derive(TransparentWrapper)] #[repr(transparent)] #[transparent(u16)] struct TransparentTupleWithCustomZeroSized(u16, MyZst); #[repr(u8)] #[derive(Clone, Copy, Contiguous)] enum ContiguousWithValues { A = 0, B = 1, C = 2, D = 3, E = 4, } #[repr(i8)] #[derive(Clone, Copy, Contiguous)] enum ContiguousWithImplicitValues { A = -10, B, C, D, E, } #[derive(Copy, Clone, NoUninit)] #[repr(C)] struct NoUninitTest { a: u16, b: u16, } #[derive(Copy, Clone, AnyBitPattern)] #[repr(C)] union UnionTestAnyBitPattern { a: u8, b: u16, } #[repr(u8)] #[derive(Debug, Clone, Copy, NoUninit, CheckedBitPattern, PartialEq, Eq)] enum CheckedBitPatternEnumWithValues { A = 0, B = 1, C = 2, D = 3, E = 4, } #[repr(i8)] #[derive(Clone, Copy, NoUninit, CheckedBitPattern)] enum CheckedBitPatternEnumWithImplicitValues { A = -10, B, C, D, E, } #[repr(u8)] #[derive(Debug, Clone, Copy, NoUninit, CheckedBitPattern, PartialEq, Eq)] enum CheckedBitPatternEnumNonContiguous { A = 1, B = 8, C = 2, D = 3, E = 56, } #[repr(u8)] #[derive(Debug, Clone, Copy, NoUninit, CheckedBitPattern, PartialEq, Eq)] enum CheckedBitPatternEnumByteLit { A = b'A', B = b'B', C = b'C', D = b'D', E = b'E', } #[derive(Debug, Copy, Clone, NoUninit, CheckedBitPattern, PartialEq, Eq)] #[repr(C)] struct CheckedBitPatternStruct { a: u8, b: CheckedBitPatternEnumNonContiguous, } #[derive(Debug, Copy, Clone, NoUninit)] #[repr(C)] enum NoUninitEnum { A, B, } #[derive(Debug, Copy, Clone, NoUninit)] #[repr(C)] enum NoUninitEnumWithFields { A(u32, u32), B(u16, u16, u16, u16), } #[derive(Debug, Copy, Clone, NoUninit)] #[repr(C, u16)] enum NoUninitEnumWithFieldsAndCAndDiscriminant { A(u16, u16), B(u8, u8, u8, u8), } #[derive(Debug, Clone, Copy, NoUninit)] #[repr(u16)] enum NoUninitEnumWithFieldsAndDiscriminant { A(u16, u16), B(u8, u8, u8, u8), } #[derive(Debug, Copy, Clone, AnyBitPattern, PartialEq, Eq)] #[repr(C)] struct AnyBitPatternTest { a: A, b: B, } #[derive(Clone, Copy, CheckedBitPattern)] #[repr(C, align(8))] struct CheckedBitPatternAlignedStruct { a: u16, } #[derive(Clone, Copy, CheckedBitPattern)] #[repr(C, packed)] struct CheckedBitPatternPackedStruct { a: u8, b: u16, } #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(C)] enum CheckedBitPatternCDefaultDiscriminantEnum { A, B, } #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(C)] enum CheckedBitPatternCDefaultDiscriminantEnumWithFields { A(u64), B { c: u64 }, } #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(C, u8)] enum CheckedBitPatternCEnumWithFields { A(u32), B { c: u32 }, } #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(u8)] enum CheckedBitPatternIntEnumWithFields { A(u8), B { c: u32 }, } #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(transparent)] enum CheckedBitPatternTransparentEnumWithFields { A { b: u32 }, } // size 24, align 8. // first byte always the u8 discriminant, then 7 bytes of padding until the // payload union since the align of the payload is the greatest of the align of // all the variants, which is 8 (from // CheckedBitPatternCDefaultDiscriminantEnumWithFields) #[derive(Debug, Clone, Copy, CheckedBitPattern, PartialEq, Eq)] #[repr(C, u8)] enum CheckedBitPatternEnumNested { A(CheckedBitPatternCEnumWithFields), B(CheckedBitPatternCDefaultDiscriminantEnumWithFields), } /// ```compile_fail /// use bytemuck::{Pod, Zeroable}; /// /// #[derive(Pod, Zeroable)] /// #[repr(transparent)] /// struct TransparentSingle(T); /// /// struct NotPod(u32); /// /// let _: u32 = bytemuck::cast(TransparentSingle(NotPod(0u32))); /// ``` #[derive( Debug, Copy, Clone, PartialEq, Eq, Pod, Zeroable, TransparentWrapper, )] #[repr(transparent)] struct NewtypeWrapperTest(T); #[derive(Debug, Clone, PartialEq, Eq, TransparentWrapper)] #[repr(transparent)] struct AlgebraicNewtypeWrapperTest(Vec); #[test] fn algebraic_newtype_corect() { let x: Vec = vec![1, 2, 3, 4]; let y: AlgebraicNewtypeWrapperTest = AlgebraicNewtypeWrapperTest::wrap(x.clone()); assert_eq!(y.0, x); } #[derive(Debug, Clone, PartialEq, Eq, TransparentWrapper)] #[repr(transparent)] #[transparent(Vec)] struct AlgebraicNewtypeWrapperTestWithFields(Vec, PhantomData); #[test] fn algebraic_newtype_fields_corect() { let x: Vec = vec![1, 2, 3, 4]; let y: AlgebraicNewtypeWrapperTestWithFields = AlgebraicNewtypeWrapperTestWithFields::wrap(x.clone()); assert_eq!(y.0, x); } #[test] fn fails_cast_contiguous() { let can_cast = CheckedBitPatternEnumWithValues::is_valid_bit_pattern(&5); assert!(!can_cast); } #[test] fn passes_cast_contiguous() { let res = bytemuck::checked::from_bytes::(&[2u8]); assert_eq!(*res, CheckedBitPatternEnumWithValues::C); } #[test] fn fails_cast_noncontiguous() { let can_cast = CheckedBitPatternEnumNonContiguous::is_valid_bit_pattern(&4); assert!(!can_cast); } #[test] fn passes_cast_noncontiguous() { let res = bytemuck::checked::from_bytes::(&[ 56u8, ]); assert_eq!(*res, CheckedBitPatternEnumNonContiguous::E); } #[test] fn fails_cast_bytelit() { let can_cast = CheckedBitPatternEnumByteLit::is_valid_bit_pattern(&b'a'); assert!(!can_cast); } #[test] fn passes_cast_bytelit() { let res = bytemuck::checked::cast_slice::(b"CAB"); assert_eq!( res, [ CheckedBitPatternEnumByteLit::C, CheckedBitPatternEnumByteLit::A, CheckedBitPatternEnumByteLit::B ] ); } #[test] fn fails_cast_struct() { let pod = [0u8, 24u8]; let res = bytemuck::checked::try_from_bytes::(&pod); assert!(res.is_err()); } #[test] fn passes_cast_struct() { let pod = [0u8, 8u8]; let res = bytemuck::checked::from_bytes::(&pod); assert_eq!( *res, CheckedBitPatternStruct { a: 0, b: CheckedBitPatternEnumNonContiguous::B } ); } #[test] fn anybitpattern_implies_zeroable() { let test = AnyBitPatternTest::::zeroed(); assert_eq!(test, AnyBitPatternTest { a: 0isize, b: 0usize }); } #[test] fn checkedbitpattern_try_pod_read_unaligned() { let pod = [0u8]; let res = bytemuck::checked::try_pod_read_unaligned::< CheckedBitPatternEnumWithValues, >(&pod); assert!(res.is_ok()); let pod = [5u8]; let res = bytemuck::checked::try_pod_read_unaligned::< CheckedBitPatternEnumWithValues, >(&pod); assert!(res.is_err()); } #[test] fn checkedbitpattern_aligned_struct() { let pod = [0u8; 8]; bytemuck::checked::pod_read_unaligned::(&pod); } #[test] fn checkedbitpattern_c_default_discriminant_enum_with_fields() { let pod = [ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0xcc, ]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternCDefaultDiscriminantEnumWithFields, >(&pod); assert_eq!( value, CheckedBitPatternCDefaultDiscriminantEnumWithFields::A(0xcc555555555555cc) ); let pod = [ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0xcc, ]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternCDefaultDiscriminantEnumWithFields, >(&pod); assert_eq!( value, CheckedBitPatternCDefaultDiscriminantEnumWithFields::B { c: 0xcc555555555555cc } ); } #[test] fn checkedbitpattern_c_enum_with_fields() { let pod = [0x00, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0xcc]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternCEnumWithFields, >(&pod); assert_eq!(value, CheckedBitPatternCEnumWithFields::A(0xcc5555cc)); let pod = [0x01, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0xcc]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternCEnumWithFields, >(&pod); assert_eq!(value, CheckedBitPatternCEnumWithFields::B { c: 0xcc5555cc }); } #[test] fn checkedbitpattern_int_enum_with_fields() { let pod = [0x00, 0x55, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternIntEnumWithFields, >(&pod); assert_eq!(value, CheckedBitPatternIntEnumWithFields::A(0x55)); let pod = [0x01, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0xcc]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternIntEnumWithFields, >(&pod); assert_eq!(value, CheckedBitPatternIntEnumWithFields::B { c: 0xcc5555cc }); } #[test] fn checkedbitpattern_nested_enum_with_fields() { // total size 24 bytes. first byte always the u8 discriminant. #[repr(C, align(8))] struct Align8Bytes([u8; 24]); // first we'll check variantA, nested variant A let pod = Align8Bytes([ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // byte 0 discriminant = 0 = variant A, bytes 1-7 irrelevant padding. 0x00, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0xcc, // bytes 8-15 are the nested CheckedBitPatternCEnumWithFields, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // bytes 16-23 padding ]); let value = bytemuck::checked::from_bytes::(&pod.0); assert_eq!( value, &CheckedBitPatternEnumNested::A(CheckedBitPatternCEnumWithFields::A( 0xcc5555cc )) ); // next we'll check invalid first discriminant fails let pod = Align8Bytes([ 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // byte 0 discriminant = 2 = invalid, bytes 1-7 padding 0x00, 0x00, 0x00, 0x00, 0xcc, 0x55, 0x55, 0xcc, // bytes 8-15 are the nested CheckedBitPatternCEnumWithFields = A, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // bytes 16-23 padding ]); let result = bytemuck::checked::try_from_bytes::(&pod.0); assert_eq!(result, Err(CheckedCastError::InvalidBitPattern)); // next we'll check variant B, nested variant B let pod = Align8Bytes([ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // byte 0 discriminant = 1 = variant B, bytes 1-7 padding 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* bytes 8-15 is C int size discriminant of * CheckedBitPatternCDefaultDiscrimimantEnumWithFields, 1 (LE byte * order) = variant B */ 0xcc, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0xcc, // bytes 16-13 is the data contained in nested variant B ]); let value = bytemuck::checked::from_bytes::(&pod.0); assert_eq!( value, &CheckedBitPatternEnumNested::B( CheckedBitPatternCDefaultDiscriminantEnumWithFields::B { c: 0xcc555555555555cc } ) ); // finally we'll check variant B, nested invalid discriminant let pod = Align8Bytes([ 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 1 discriminant = variant B, bytes 1-7 padding 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* bytes 8-15 is C int size discriminant of * CheckedBitPatternCDefaultDiscrimimantEnumWithFields, 0x08 is * invalid */ 0xcc, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0xcc, // bytes 16-13 is the data contained in nested variant B ]); let result = bytemuck::checked::try_from_bytes::(&pod.0); assert_eq!(result, Err(CheckedCastError::InvalidBitPattern)); } #[test] fn checkedbitpattern_transparent_enum_with_fields() { let pod = [0xcc, 0x55, 0x55, 0xcc]; let value = bytemuck::checked::pod_read_unaligned::< CheckedBitPatternTransparentEnumWithFields, >(&pod); assert_eq!( value, CheckedBitPatternTransparentEnumWithFields::A { b: 0xcc5555cc } ); } #[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)] #[repr(C, align(16))] struct Issue127 {} use bytemuck as reexport_name; #[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable, bytemuck::ByteEq)] #[bytemuck(crate = "reexport_name")] #[repr(C)] struct Issue93 {}