ref-cast-impl-1.0.18/.cargo_vcs_info.json0000644000000001440000000000100135650ustar { "git": { "sha1": "a3e78d25f72f322dc2fd23efc59225c109e94557" }, "path_in_vcs": "derive" }ref-cast-impl-1.0.18/Cargo.toml0000644000000020340000000000100115630ustar # 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 = "1.56" name = "ref-cast-impl" version = "1.0.18" authors = ["David Tolnay "] description = "Derive implementation for ref_cast::RefCast." documentation = "https://docs.rs/ref-cast" license = "MIT OR Apache-2.0" repository = "https://github.com/dtolnay/ref-cast" [package.metadata.docs.rs] targets = ["x86_64-unknown-linux-gnu"] [lib] proc-macro = true [dependencies.proc-macro2] version = "1.0.63" [dependencies.quote] version = "1.0.29" [dependencies.syn] version = "2.0.23" [dev-dependencies.ref-cast] version = "1" ref-cast-impl-1.0.18/Cargo.toml.orig000064400000000000000000000010111046102023000152360ustar 00000000000000[package] name = "ref-cast-impl" version = "1.0.18" authors = ["David Tolnay "] description = "Derive implementation for ref_cast::RefCast." documentation = "https://docs.rs/ref-cast" edition = "2018" license = "MIT OR Apache-2.0" repository = "https://github.com/dtolnay/ref-cast" rust-version = "1.56" [lib] proc-macro = true [dependencies] proc-macro2 = "1.0.63" quote = "1.0.29" syn = "2.0.23" [dev-dependencies] ref-cast = "1" [package.metadata.docs.rs] targets = ["x86_64-unknown-linux-gnu"] ref-cast-impl-1.0.18/LICENSE-APACHE000064400000000000000000000227731046102023000143150ustar 00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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END OF TERMS AND CONDITIONS ref-cast-impl-1.0.18/LICENSE-MIT000064400000000000000000000017771046102023000140260ustar 00000000000000Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. ref-cast-impl-1.0.18/src/lib.rs000064400000000000000000000401001046102023000142540ustar 00000000000000#![allow(clippy::needless_pass_by_value, clippy::if_not_else)] extern crate proc_macro; use proc_macro::TokenStream; use proc_macro2::{Ident, Span, TokenStream as TokenStream2, TokenTree}; use quote::{quote, quote_spanned}; use syn::parse::{Nothing, ParseStream, Parser}; use syn::punctuated::Punctuated; use syn::{ parenthesized, parse_macro_input, token, Abi, Attribute, Data, DeriveInput, Error, Expr, Field, Generics, Path, Result, Token, Type, Visibility, }; /// Derive the `RefCast` trait. /// /// See the [crate-level documentation](./index.html) for usage examples! /// /// # Attributes /// /// Use the `#[trivial]` attribute to mark any zero-sized fields that are *not* /// the one that references are going to be converted from. /// /// ``` /// use ref_cast::RefCast; /// use std::marker::PhantomData; /// /// #[derive(RefCast)] /// #[repr(transparent)] /// pub struct Generic { /// raw: Vec, /// #[trivial] /// aux: Variance, /// } /// /// type Variance = PhantomData U>; /// ``` /// /// Fields with a type named `PhantomData` or `PhantomPinned` are automatically /// recognized and do not need to be marked with this attribute. /// /// ``` /// use ref_cast::RefCast; /// use std::marker::{PhantomData, PhantomPinned}; /// /// #[derive(RefCast)] // generates a conversion from &[u8] to &Bytes<'_> /// #[repr(transparent)] /// pub struct Bytes<'arena> { /// lifetime: PhantomData<&'arena ()>, /// pin: PhantomPinned, /// bytes: [u8], /// } /// ``` #[proc_macro_derive(RefCast, attributes(trivial))] pub fn derive_ref_cast(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); expand_ref_cast(input) .unwrap_or_else(Error::into_compile_error) .into() } /// Derive that makes the `ref_cast_custom` attribute able to generate /// freestanding reference casting functions for a type. /// /// Please refer to the documentation of /// [`#[ref_cast_custom]`][macro@ref_cast_custom] where these two macros are /// documented together. #[proc_macro_derive(RefCastCustom, attributes(trivial))] pub fn derive_ref_cast_custom(input: TokenStream) -> TokenStream { let input = parse_macro_input!(input as DeriveInput); expand_ref_cast_custom(input) .unwrap_or_else(Error::into_compile_error) .into() } /// Create a function for a RefCast-style reference cast. Call site gets control /// of the visibility, function name, argument name, `const`ness, unsafety, and /// documentation. /// /// The `derive(RefCast)` macro produces a trait impl, which means the function /// names are predefined, and public if your type is public, and not callable in /// `const` (at least today on stable Rust). As an alternative to that, /// `derive(RefCastCustom)` exposes greater flexibility so that instead of a /// trait impl, the casting functions can be made associated functions or free /// functions, can be named what you want, documented, `const` or `unsafe` if /// you want, and have your exact choice of visibility. /// /// ```rust /// use ref_cast::{ref_cast_custom, RefCastCustom}; /// /// #[derive(RefCastCustom)] // does not generate any public API by itself /// #[repr(transparent)] /// pub struct Frame([u8]); /// /// impl Frame { /// #[ref_cast_custom] // requires derive(RefCastCustom) on the return type /// pub(crate) const fn new(bytes: &[u8]) -> &Self; /// /// #[ref_cast_custom] /// pub(crate) fn new_mut(bytes: &mut [u8]) -> &mut Self; /// } /// /// // example use of the const fn /// const FRAME: &Frame = Frame::new(b"..."); /// ``` /// /// The above shows associated functions, but you might alternatively want to /// generate free functions: /// /// ```rust /// # use ref_cast::{ref_cast_custom, RefCastCustom}; /// # /// # #[derive(RefCastCustom)] /// # #[repr(transparent)] /// # pub struct Frame([u8]); /// # /// impl Frame { /// pub fn new>(bytes: &T) -> &Self { /// #[ref_cast_custom] /// fn ref_cast(bytes: &[u8]) -> &Frame; /// /// ref_cast(bytes.as_ref()) /// } /// } /// ``` #[proc_macro_attribute] pub fn ref_cast_custom(args: TokenStream, input: TokenStream) -> TokenStream { let input = TokenStream2::from(input); let expanded = match (|input: ParseStream| { let attrs = input.call(Attribute::parse_outer)?; let vis: Visibility = input.parse()?; let constness: Option = input.parse()?; let asyncness: Option = input.parse()?; let unsafety: Option = input.parse()?; let abi: Option = input.parse()?; let fn_token: Token![fn] = input.parse()?; let ident: Ident = input.parse()?; let mut generics: Generics = input.parse()?; let content; let paren_token = parenthesized!(content in input); let arg: Ident = content.parse()?; let colon_token: Token![:] = content.parse()?; let from_type: Type = content.parse()?; let _trailing_comma: Option = content.parse()?; if !content.is_empty() { let rest: TokenStream2 = content.parse()?; return Err(Error::new_spanned( rest, "ref_cast_custom function is required to have a single argument", )); } let arrow_token: Token![->] = input.parse()?; let to_type: Type = input.parse()?; generics.where_clause = input.parse()?; let semi_token: Token![;] = input.parse()?; let _: Nothing = syn::parse::(args)?; Ok(Function { attrs, vis, constness, asyncness, unsafety, abi, fn_token, ident, generics, paren_token, arg, colon_token, from_type, arrow_token, to_type, semi_token, }) }) .parse2(input.clone()) { Ok(function) => expand_function_body(function), Err(parse_error) => { let compile_error = parse_error.to_compile_error(); quote!(#compile_error #input) } }; TokenStream::from(expanded) } struct Function { attrs: Vec, vis: Visibility, constness: Option, asyncness: Option, unsafety: Option, abi: Option, fn_token: Token![fn], ident: Ident, generics: Generics, paren_token: token::Paren, arg: Ident, colon_token: Token![:], from_type: Type, arrow_token: Token![->], to_type: Type, semi_token: Token![;], } fn expand_ref_cast(input: DeriveInput) -> Result { check_repr(&input)?; let name = &input.ident; let name_str = name.to_string(); let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); let fields = fields(&input)?; let from = only_field_ty(fields)?; let trivial = trivial_fields(fields)?; let assert_trivial_fields = if !trivial.is_empty() { Some(quote! { if false { #( ::ref_cast::__private::assert_trivial::<#trivial>(); )* } }) } else { None }; Ok(quote! { impl #impl_generics ::ref_cast::RefCast for #name #ty_generics #where_clause { type From = #from; #[inline] fn ref_cast(_from: &Self::From) -> &Self { #assert_trivial_fields #[cfg(debug_assertions)] { #[allow(unused_imports)] use ::ref_cast::__private::LayoutUnsized; ::ref_cast::__private::assert_layout::( #name_str, ::ref_cast::__private::Layout::::SIZE, ::ref_cast::__private::Layout::::SIZE, ::ref_cast::__private::Layout::::ALIGN, ::ref_cast::__private::Layout::::ALIGN, ); } unsafe { &*(_from as *const Self::From as *const Self) } } #[inline] fn ref_cast_mut(_from: &mut Self::From) -> &mut Self { #[cfg(debug_assertions)] { #[allow(unused_imports)] use ::ref_cast::__private::LayoutUnsized; ::ref_cast::__private::assert_layout::( #name_str, ::ref_cast::__private::Layout::::SIZE, ::ref_cast::__private::Layout::::SIZE, ::ref_cast::__private::Layout::::ALIGN, ::ref_cast::__private::Layout::::ALIGN, ); } unsafe { &mut *(_from as *mut Self::From as *mut Self) } } } }) } fn expand_ref_cast_custom(input: DeriveInput) -> Result { check_repr(&input)?; let vis = &input.vis; let name = &input.ident; let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl(); let fields = fields(&input)?; let from = only_field_ty(fields)?; let trivial = trivial_fields(fields)?; let assert_trivial_fields = if !trivial.is_empty() { Some(quote! { fn __static_assert() { if false { #( ::ref_cast::__private::assert_trivial::<#trivial>(); )* } } }) } else { None }; Ok(quote! { const _: () = { #[non_exhaustive] #vis struct RefCastCurrentCrate {} unsafe impl #impl_generics ::ref_cast::__private::RefCastCustom<#from> for #name #ty_generics #where_clause { type CurrentCrate = RefCastCurrentCrate; #assert_trivial_fields } }; }) } fn expand_function_body(function: Function) -> TokenStream2 { let Function { attrs, vis, constness, asyncness, unsafety, abi, fn_token, ident, generics, paren_token, arg, colon_token, from_type, arrow_token, to_type, semi_token, } = function; let args = quote_spanned! {paren_token.span=> (#arg #colon_token #from_type) }; let allow_unused_unsafe = if unsafety.is_some() { Some(quote!(#[allow(unused_unsafe)])) } else { None }; let mut inline_attr = Some(quote!(#[inline])); for attr in &attrs { if attr.path().is_ident("inline") { inline_attr = None; break; } } quote_spanned! {semi_token.span=> #(#attrs)* #inline_attr #vis #constness #asyncness #unsafety #abi #fn_token #ident #generics #args #arrow_token #to_type { // check lifetime let _ = || { ::ref_cast::__private::ref_cast_custom::<#from_type, #to_type>(#arg); }; // check same crate let _ = ::ref_cast::__private::CurrentCrate::<#from_type, #to_type> {}; #allow_unused_unsafe // in case they are building with deny(unsafe_op_in_unsafe_fn) unsafe { ::ref_cast::__private::transmute::<#from_type, #to_type>(#arg) } } } } fn check_repr(input: &DeriveInput) -> Result<()> { let mut has_repr = false; let mut errors = None; let mut push_error = |error| match &mut errors { Some(errors) => Error::combine(errors, error), None => errors = Some(error), }; for attr in &input.attrs { if attr.path().is_ident("repr") { if let Err(error) = attr.parse_args_with(|input: ParseStream| { while !input.is_empty() { let path = input.call(Path::parse_mod_style)?; if path.is_ident("transparent") || path.is_ident("C") { has_repr = true; } else if path.is_ident("packed") { // ignore } else { let meta_item_span = if input.peek(token::Paren) { let group: TokenTree = input.parse()?; quote!(#path #group) } else if input.peek(Token![=]) { let eq_token: Token![=] = input.parse()?; let value: Expr = input.parse()?; quote!(#path #eq_token #value) } else { quote!(#path) }; let msg = if path.is_ident("align") { "aligned repr on struct that implements RefCast is not supported" } else { "unrecognized repr on struct that implements RefCast" }; push_error(Error::new_spanned(meta_item_span, msg)); } if !input.is_empty() { input.parse::()?; } } Ok(()) }) { push_error(error); } } } if !has_repr { let mut requires_repr = Error::new( Span::call_site(), "RefCast trait requires #[repr(transparent)]", ); if let Some(errors) = errors { requires_repr.combine(errors); } errors = Some(requires_repr); } match errors { None => Ok(()), Some(errors) => Err(errors), } } type Fields = Punctuated; fn fields(input: &DeriveInput) -> Result<&Fields> { use syn::Fields; match &input.data { Data::Struct(data) => match &data.fields { Fields::Named(fields) => Ok(&fields.named), Fields::Unnamed(fields) => Ok(&fields.unnamed), Fields::Unit => Err(Error::new( Span::call_site(), "RefCast does not support unit structs", )), }, Data::Enum(_) => Err(Error::new( Span::call_site(), "RefCast does not support enums", )), Data::Union(_) => Err(Error::new( Span::call_site(), "RefCast does not support unions", )), } } fn only_field_ty(fields: &Fields) -> Result<&Type> { let is_trivial = decide_trivial(fields)?; let mut only_field = None; for field in fields { if !is_trivial(field)? { if only_field.take().is_some() { break; } only_field = Some(&field.ty); } } only_field.ok_or_else(|| { Error::new( Span::call_site(), "RefCast requires a struct with a single field", ) }) } fn trivial_fields(fields: &Fields) -> Result> { let is_trivial = decide_trivial(fields)?; let mut trivial = Vec::new(); for field in fields { if is_trivial(field)? { trivial.push(&field.ty); } } Ok(trivial) } fn decide_trivial(fields: &Fields) -> Result Result> { for field in fields { if is_explicit_trivial(field)? { return Ok(is_explicit_trivial); } } Ok(is_implicit_trivial) } #[allow(clippy::unnecessary_wraps)] // match signature of is_explicit_trivial fn is_implicit_trivial(field: &Field) -> Result { match &field.ty { Type::Tuple(ty) => Ok(ty.elems.is_empty()), Type::Path(ty) => { let ident = &ty.path.segments.last().unwrap().ident; Ok(ident == "PhantomData" || ident == "PhantomPinned") } _ => Ok(false), } } fn is_explicit_trivial(field: &Field) -> Result { for attr in &field.attrs { if attr.path().is_ident("trivial") { attr.meta.require_path_only()?; return Ok(true); } } Ok(false) }