diff options
Diffstat (limited to 'compiler/rustc_index_macros')
| -rw-r--r-- | compiler/rustc_index_macros/Cargo.toml | 17 | ||||
| -rw-r--r-- | compiler/rustc_index_macros/src/lib.rs | 41 | ||||
| -rw-r--r-- | compiler/rustc_index_macros/src/newtype.rs | 324 |
3 files changed, 382 insertions, 0 deletions
diff --git a/compiler/rustc_index_macros/Cargo.toml b/compiler/rustc_index_macros/Cargo.toml new file mode 100644 index 000000000..c4ca29db3 --- /dev/null +++ b/compiler/rustc_index_macros/Cargo.toml @@ -0,0 +1,17 @@ +[package] +name = "rustc_index_macros" +version = "0.0.0" +edition = "2021" + +[lib] +proc-macro = true + +[dependencies] +synstructure = "0.13.0" +syn = { version = "2.0.9", features = ["full"] } +proc-macro2 = "1" +quote = "1" + +[features] +default = ["nightly"] +nightly = []
\ No newline at end of file diff --git a/compiler/rustc_index_macros/src/lib.rs b/compiler/rustc_index_macros/src/lib.rs new file mode 100644 index 000000000..ac374a41e --- /dev/null +++ b/compiler/rustc_index_macros/src/lib.rs @@ -0,0 +1,41 @@ +#![cfg_attr(feature = "nightly", feature(allow_internal_unstable))] +#![cfg_attr(feature = "nightly", allow(internal_features))] + +use proc_macro::TokenStream; + +mod newtype; + +/// Creates a struct type `S` that can be used as an index with +/// `IndexVec` and so on. +/// +/// There are two ways of interacting with these indices: +/// +/// - The `From` impls are the preferred way. So you can do +/// `S::from(v)` with a `usize` or `u32`. And you can convert back +/// to an integer with `u32::from(s)`. +/// +/// - Alternatively, you can use the methods `S::new(v)` and `s.index()` +/// to create/return a value. +/// +/// Internally, the index uses a u32, so the index must not exceed +/// `u32::MAX`. +/// +/// The impls provided by default are Clone, Copy, PartialEq, Eq, and Hash. +/// +/// Accepted attributes for customization: +/// - `#[derive(HashStable_Generic)]`/`#[derive(HashStable)]`: derives +/// `HashStable`, as normal. +/// - `#[encodable]`: derives `Encodable`/`Decodable`. +/// - `#[orderable]`: derives `PartialOrd`/`Ord`, plus step-related methods. +/// - `#[debug_format = "Foo({})"]`: derives `Debug` with particular output. +/// - `#[max = 0xFFFF_FFFD]`: specifies the max value, which allows niche +/// optimizations. The default max value is 0xFFFF_FF00. +/// - `#[gate_rustc_only]`: makes parts of the generated code nightly-only. +#[proc_macro] +#[cfg_attr( + feature = "nightly", + allow_internal_unstable(step_trait, rustc_attrs, trusted_step, spec_option_partial_eq) +)] +pub fn newtype_index(input: TokenStream) -> TokenStream { + newtype::newtype(input) +} diff --git a/compiler/rustc_index_macros/src/newtype.rs b/compiler/rustc_index_macros/src/newtype.rs new file mode 100644 index 000000000..df1318c83 --- /dev/null +++ b/compiler/rustc_index_macros/src/newtype.rs @@ -0,0 +1,324 @@ +use proc_macro2::{Span, TokenStream}; +use quote::quote; +use syn::parse::*; +use syn::*; + +// We parse the input and emit the output in a single step. +// This field stores the final macro output +struct Newtype(TokenStream); + +impl Parse for Newtype { + fn parse(input: ParseStream<'_>) -> Result<Self> { + let mut attrs = input.call(Attribute::parse_outer)?; + let vis: Visibility = input.parse()?; + input.parse::<Token![struct]>()?; + let name: Ident = input.parse()?; + + let body; + braced!(body in input); + + // Any additional `#[derive]` macro paths to apply + let mut derive_paths: Vec<Path> = Vec::new(); + let mut debug_format: Option<Lit> = None; + let mut max = None; + let mut consts = Vec::new(); + let mut encodable = false; + let mut ord = false; + let mut gate_rustc_only = quote! {}; + let mut gate_rustc_only_cfg = quote! { all() }; + + attrs.retain(|attr| match attr.path().get_ident() { + Some(ident) => match &*ident.to_string() { + "gate_rustc_only" => { + gate_rustc_only = quote! { #[cfg(feature = "nightly")] }; + gate_rustc_only_cfg = quote! { feature = "nightly" }; + false + } + "encodable" => { + encodable = true; + false + } + "orderable" => { + ord = true; + false + } + "max" => { + let Meta::NameValue(MetaNameValue { value: Expr::Lit(lit), .. }) = &attr.meta + else { + panic!("#[max = NUMBER] attribute requires max value"); + }; + + if let Some(old) = max.replace(lit.lit.clone()) { + panic!("Specified multiple max: {old:?}"); + } + + false + } + "debug_format" => { + let Meta::NameValue(MetaNameValue { value: Expr::Lit(lit), .. }) = &attr.meta + else { + panic!("#[debug_format = FMT] attribute requires a format"); + }; + + if let Some(old) = debug_format.replace(lit.lit.clone()) { + panic!("Specified multiple debug format options: {old:?}"); + } + + false + } + _ => true, + }, + _ => true, + }); + + loop { + // We've parsed everything that the user provided, so we're done + if body.is_empty() { + break; + } + + // Otherwise, we are parsing a user-defined constant + let const_attrs = body.call(Attribute::parse_outer)?; + body.parse::<Token![const]>()?; + let const_name: Ident = body.parse()?; + body.parse::<Token![=]>()?; + let const_val: Expr = body.parse()?; + body.parse::<Token![;]>()?; + consts.push(quote! { #(#const_attrs)* #vis const #const_name: #name = #name::from_u32(#const_val); }); + } + + let debug_format = + debug_format.unwrap_or_else(|| Lit::Str(LitStr::new("{}", Span::call_site()))); + + // shave off 256 indices at the end to allow space for packing these indices into enums + let max = max.unwrap_or_else(|| Lit::Int(LitInt::new("0xFFFF_FF00", Span::call_site()))); + + let encodable_impls = if encodable { + quote! { + #gate_rustc_only + impl<D: ::rustc_serialize::Decoder> ::rustc_serialize::Decodable<D> for #name { + fn decode(d: &mut D) -> Self { + Self::from_u32(d.read_u32()) + } + } + #gate_rustc_only + impl<E: ::rustc_serialize::Encoder> ::rustc_serialize::Encodable<E> for #name { + fn encode(&self, e: &mut E) { + e.emit_u32(self.private); + } + } + } + } else { + quote! {} + }; + + if ord { + derive_paths.push(parse_quote!(Ord)); + derive_paths.push(parse_quote!(PartialOrd)); + } + + let step = if ord { + quote! { + #gate_rustc_only + impl ::std::iter::Step for #name { + #[inline] + fn steps_between(start: &Self, end: &Self) -> Option<usize> { + <usize as ::std::iter::Step>::steps_between( + &Self::index(*start), + &Self::index(*end), + ) + } + + #[inline] + fn forward_checked(start: Self, u: usize) -> Option<Self> { + Self::index(start).checked_add(u).map(Self::from_usize) + } + + #[inline] + fn backward_checked(start: Self, u: usize) -> Option<Self> { + Self::index(start).checked_sub(u).map(Self::from_usize) + } + } + + // Safety: The implementation of `Step` upholds all invariants. + #gate_rustc_only + unsafe impl ::std::iter::TrustedStep for #name {} + } + } else { + quote! {} + }; + + let debug_impl = quote! { + impl ::std::fmt::Debug for #name { + fn fmt(&self, fmt: &mut ::std::fmt::Formatter<'_>) -> ::std::fmt::Result { + write!(fmt, #debug_format, self.as_u32()) + } + } + }; + + let spec_partial_eq_impl = if let Lit::Int(max) = &max { + if let Ok(max_val) = max.base10_parse::<u32>() { + quote! { + #gate_rustc_only + impl core::option::SpecOptionPartialEq for #name { + #[inline] + fn eq(l: &Option<Self>, r: &Option<Self>) -> bool { + if #max_val < u32::MAX { + l.map(|i| i.private).unwrap_or(#max_val+1) == r.map(|i| i.private).unwrap_or(#max_val+1) + } else { + match (l, r) { + (Some(l), Some(r)) => r == l, + (None, None) => true, + _ => false + } + } + } + } + } + } else { + quote! {} + } + } else { + quote! {} + }; + + Ok(Self(quote! { + #(#attrs)* + #[derive(Clone, Copy, PartialEq, Eq, Hash, #(#derive_paths),*)] + #[cfg_attr(#gate_rustc_only_cfg, rustc_layout_scalar_valid_range_end(#max))] + #[cfg_attr(#gate_rustc_only_cfg, rustc_pass_by_value)] + #vis struct #name { + private: u32, + } + + #(#consts)* + + impl #name { + /// Maximum value the index can take, as a `u32`. + #vis const MAX_AS_U32: u32 = #max; + + /// Maximum value the index can take. + #vis const MAX: Self = Self::from_u32(#max); + + /// Creates a new index from a given `usize`. + /// + /// # Panics + /// + /// Will panic if `value` exceeds `MAX`. + #[inline] + #vis const fn from_usize(value: usize) -> Self { + assert!(value <= (#max as usize)); + // SAFETY: We just checked that `value <= max`. + unsafe { + Self::from_u32_unchecked(value as u32) + } + } + + /// Creates a new index from a given `u32`. + /// + /// # Panics + /// + /// Will panic if `value` exceeds `MAX`. + #[inline] + #vis const fn from_u32(value: u32) -> Self { + assert!(value <= #max); + // SAFETY: We just checked that `value <= max`. + unsafe { + Self::from_u32_unchecked(value) + } + } + + /// Creates a new index from a given `u32`. + /// + /// # Safety + /// + /// The provided value must be less than or equal to the maximum value for the newtype. + /// Providing a value outside this range is undefined due to layout restrictions. + /// + /// Prefer using `from_u32`. + #[inline] + #vis const unsafe fn from_u32_unchecked(value: u32) -> Self { + Self { private: value } + } + + /// Extracts the value of this index as a `usize`. + #[inline] + #vis const fn index(self) -> usize { + self.as_usize() + } + + /// Extracts the value of this index as a `u32`. + #[inline] + #vis const fn as_u32(self) -> u32 { + self.private + } + + /// Extracts the value of this index as a `usize`. + #[inline] + #vis const fn as_usize(self) -> usize { + self.as_u32() as usize + } + } + + impl std::ops::Add<usize> for #name { + type Output = Self; + + fn add(self, other: usize) -> Self { + Self::from_usize(self.index() + other) + } + } + + impl rustc_index::Idx for #name { + #[inline] + fn new(value: usize) -> Self { + Self::from_usize(value) + } + + #[inline] + fn index(self) -> usize { + self.as_usize() + } + } + + #step + + #spec_partial_eq_impl + + impl From<#name> for u32 { + #[inline] + fn from(v: #name) -> u32 { + v.as_u32() + } + } + + impl From<#name> for usize { + #[inline] + fn from(v: #name) -> usize { + v.as_usize() + } + } + + impl From<usize> for #name { + #[inline] + fn from(value: usize) -> Self { + Self::from_usize(value) + } + } + + impl From<u32> for #name { + #[inline] + fn from(value: u32) -> Self { + Self::from_u32(value) + } + } + + #encodable_impls + #debug_impl + })) + } +} + +pub fn newtype(input: proc_macro::TokenStream) -> proc_macro::TokenStream { + let input = parse_macro_input!(input as Newtype); + input.0.into() +} |