1632 lines
59 KiB
Rust
1632 lines
59 KiB
Rust
//! Some code that abstracts away much of the boilerplate of writing
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//! `derive` instances for traits. Among other things it manages getting
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//! access to the fields of the 4 different sorts of structs and enum
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//! variants, as well as creating the method and impl ast instances.
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//!
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//! Supported features (fairly exhaustive):
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//!
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//! - Methods taking any number of parameters of any type, and returning
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//! any type, other than vectors, bottom and closures.
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//! - Generating `impl`s for types with type parameters and lifetimes
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//! (e.g., `Option<T>`), the parameters are automatically given the
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//! current trait as a bound. (This includes separate type parameters
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//! and lifetimes for methods.)
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//! - Additional bounds on the type parameters (`TraitDef.additional_bounds`)
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//!
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//! The most important thing for implementors is the `Substructure` and
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//! `SubstructureFields` objects. The latter groups 5 possibilities of the
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//! arguments:
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//!
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//! - `Struct`, when `Self` is a struct (including tuple structs, e.g
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//! `struct T(i32, char)`).
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//! - `EnumMatching`, when `Self` is an enum and all the arguments are the
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//! same variant of the enum (e.g., `Some(1)`, `Some(3)` and `Some(4)`)
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//! - `EnumTag` when `Self` is an enum, for comparing the enum tags.
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//! - `StaticEnum` and `StaticStruct` for static methods, where the type
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//! being derived upon is either an enum or struct respectively. (Any
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//! argument with type Self is just grouped among the non-self
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//! arguments.)
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//!
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//! In the first two cases, the values from the corresponding fields in
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//! all the arguments are grouped together.
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//!
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//! The non-static cases have `Option<ident>` in several places associated
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//! with field `expr`s. This represents the name of the field it is
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//! associated with. It is only not `None` when the associated field has
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//! an identifier in the source code. For example, the `x`s in the
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//! following snippet
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//!
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//! ```rust
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//! # #![allow(dead_code)]
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//! struct A { x : i32 }
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//!
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//! struct B(i32);
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//!
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//! enum C {
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//! C0(i32),
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//! C1 { x: i32 }
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//! }
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//! ```
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//!
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//! The `i32`s in `B` and `C0` don't have an identifier, so the
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//! `Option<ident>`s would be `None` for them.
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//!
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//! In the static cases, the structure is summarized, either into the just
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//! spans of the fields or a list of spans and the field idents (for tuple
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//! structs and record structs, respectively), or a list of these, for
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//! enums (one for each variant). For empty struct and empty enum
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//! variants, it is represented as a count of 0.
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//!
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//! # "`cs`" functions
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//!
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//! The `cs_...` functions ("combine substructure") are designed to
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//! make life easier by providing some pre-made recipes for common
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//! threads; mostly calling the function being derived on all the
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//! arguments and then combining them back together in some way (or
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//! letting the user chose that). They are not meant to be the only
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//! way to handle the structures that this code creates.
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//!
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//! # Examples
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//!
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//! The following simplified `PartialEq` is used for in-code examples:
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//!
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//! ```rust
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//! trait PartialEq {
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//! fn eq(&self, other: &Self) -> bool;
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//! }
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//! impl PartialEq for i32 {
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//! fn eq(&self, other: &i32) -> bool {
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//! *self == *other
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//! }
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//! }
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//! ```
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//!
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//! Some examples of the values of `SubstructureFields` follow, using the
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//! above `PartialEq`, `A`, `B` and `C`.
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//!
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//! ## Structs
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//!
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//! When generating the `expr` for the `A` impl, the `SubstructureFields` is
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//!
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//! ```{.text}
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//! Struct(vec![FieldInfo {
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//! span: <span of x>
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x]
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//! }])
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//! ```
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//!
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//! For the `B` impl, called with `B(a)` and `B(b)`,
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//!
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//! ```{.text}
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//! Struct(vec![FieldInfo {
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//! span: <span of `i32`>,
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//! name: None,
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//! self_: <expr for &a>
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//! other: vec![<expr for &b>]
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//! }])
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//! ```
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//!
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//! ## Enums
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//!
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//! When generating the `expr` for a call with `self == C0(a)` and `other
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//! == C0(b)`, the SubstructureFields is
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//!
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//! ```{.text}
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//! EnumMatching(0, <ast::Variant for C0>,
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//! vec![FieldInfo {
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//! span: <span of i32>
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//! name: None,
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//! self_: <expr for &a>,
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//! other: vec![<expr for &b>]
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//! }])
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//! ```
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//!
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//! For `C1 {x}` and `C1 {x}`,
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//!
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//! ```{.text}
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//! EnumMatching(1, <ast::Variant for C1>,
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//! vec![FieldInfo {
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//! span: <span of x>
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//! name: Some(<ident of x>),
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//! self_: <expr for &self.x>,
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//! other: vec![<expr for &other.x>]
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//! }])
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//! ```
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//!
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//! For the tags,
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//!
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//! ```{.text}
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//! EnumTag(
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//! &[<ident of self tag>, <ident of other tag>], <expr to combine with>)
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//! ```
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//! Note that this setup doesn't allow for the brute-force "match every variant
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//! against every other variant" approach, which is bad because it produces a
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//! quadratic amount of code (see #15375).
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//!
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//! ## Static
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//!
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//! A static method on the types above would result in,
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//!
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//! ```{.text}
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//! StaticStruct(<ast::VariantData of A>, Named(vec![(<ident of x>, <span of x>)]))
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//!
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//! StaticStruct(<ast::VariantData of B>, Unnamed(vec![<span of x>]))
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//!
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//! StaticEnum(<ast::EnumDef of C>,
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//! vec![(<ident of C0>, <span of C0>, Unnamed(vec![<span of i32>])),
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//! (<ident of C1>, <span of C1>, Named(vec![(<ident of x>, <span of x>)]))])
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//! ```
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pub use StaticFields::*;
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pub use SubstructureFields::*;
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use crate::deriving;
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use rustc_ast::ptr::P;
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use rustc_ast::{
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self as ast, BindingAnnotation, ByRef, EnumDef, Expr, Generics, Mutability, PatKind,
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};
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use rustc_ast::{GenericArg, GenericParamKind, VariantData};
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use rustc_attr as attr;
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use rustc_expand::base::{Annotatable, ExtCtxt};
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use rustc_span::symbol::{kw, sym, Ident, Symbol};
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use rustc_span::{Span, DUMMY_SP};
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use std::cell::RefCell;
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use std::iter;
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use std::ops::Not;
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use std::vec;
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use thin_vec::thin_vec;
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use ty::{Bounds, Path, Ref, Self_, Ty};
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pub mod ty;
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pub struct TraitDef<'a> {
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/// The span for the current #[derive(Foo)] header.
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pub span: Span,
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/// Path of the trait, including any type parameters
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pub path: Path,
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/// Whether to skip adding the current trait as a bound to the type parameters of the type.
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pub skip_path_as_bound: bool,
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/// Additional bounds required of any type parameters of the type,
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/// other than the current trait
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pub additional_bounds: Vec<Ty>,
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/// Can this trait be derived for unions?
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pub supports_unions: bool,
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pub methods: Vec<MethodDef<'a>>,
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pub associated_types: Vec<(Ident, Ty)>,
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pub is_const: bool,
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}
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pub struct MethodDef<'a> {
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/// name of the method
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pub name: Symbol,
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/// List of generics, e.g., `R: rand::Rng`
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pub generics: Bounds,
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/// Is there is a `&self` argument? If not, it is a static function.
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pub explicit_self: bool,
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/// Arguments other than the self argument.
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pub nonself_args: Vec<(Ty, Symbol)>,
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/// Returns type
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pub ret_ty: Ty,
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pub attributes: ast::AttrVec,
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/// Can we combine fieldless variants for enums into a single match arm?
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/// If true, indicates that the trait operation uses the enum tag in some
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/// way.
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pub unify_fieldless_variants: bool,
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pub combine_substructure: RefCell<CombineSubstructureFunc<'a>>,
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}
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/// All the data about the data structure/method being derived upon.
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pub struct Substructure<'a> {
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/// ident of self
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pub type_ident: Ident,
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/// Verbatim access to any non-selflike arguments, i.e. arguments that
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/// don't have type `&Self`.
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pub nonselflike_args: &'a [P<Expr>],
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pub fields: &'a SubstructureFields<'a>,
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}
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/// Summary of the relevant parts of a struct/enum field.
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pub struct FieldInfo {
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pub span: Span,
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/// None for tuple structs/normal enum variants, Some for normal
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/// structs/struct enum variants.
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pub name: Option<Ident>,
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/// The expression corresponding to this field of `self`
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/// (specifically, a reference to it).
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pub self_expr: P<Expr>,
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/// The expressions corresponding to references to this field in
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/// the other selflike arguments.
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pub other_selflike_exprs: Vec<P<Expr>>,
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}
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/// Fields for a static method
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pub enum StaticFields {
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/// Tuple and unit structs/enum variants like this.
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Unnamed(Vec<Span>, bool /*is tuple*/),
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/// Normal structs/struct variants.
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Named(Vec<(Ident, Span)>),
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}
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/// A summary of the possible sets of fields.
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pub enum SubstructureFields<'a> {
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/// A non-static method with `Self` is a struct.
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Struct(&'a ast::VariantData, Vec<FieldInfo>),
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/// Matching variants of the enum: variant index, variant count, ast::Variant,
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/// fields: the field name is only non-`None` in the case of a struct
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/// variant.
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EnumMatching(usize, usize, &'a ast::Variant, Vec<FieldInfo>),
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/// The tag of an enum. The first field is a `FieldInfo` for the tags, as
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/// if they were fields. The second field is the expression to combine the
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/// tag expression with; it will be `None` if no match is necessary.
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EnumTag(FieldInfo, Option<P<Expr>>),
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/// A static method where `Self` is a struct.
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StaticStruct(&'a ast::VariantData, StaticFields),
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/// A static method where `Self` is an enum.
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StaticEnum(&'a ast::EnumDef, Vec<(Ident, Span, StaticFields)>),
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}
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/// Combine the values of all the fields together. The last argument is
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/// all the fields of all the structures.
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pub type CombineSubstructureFunc<'a> =
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Box<dyn FnMut(&mut ExtCtxt<'_>, Span, &Substructure<'_>) -> BlockOrExpr + 'a>;
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pub fn combine_substructure(
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f: CombineSubstructureFunc<'_>,
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) -> RefCell<CombineSubstructureFunc<'_>> {
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RefCell::new(f)
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}
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|
struct TypeParameter {
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bound_generic_params: Vec<ast::GenericParam>,
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ty: P<ast::Ty>,
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}
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|
// The code snippets built up for derived code are sometimes used as blocks
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// (e.g. in a function body) and sometimes used as expressions (e.g. in a match
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// arm). This structure avoids committing to either form until necessary,
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// avoiding the insertion of any unnecessary blocks.
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//
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// The statements come before the expression.
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|
pub struct BlockOrExpr(Vec<ast::Stmt>, Option<P<Expr>>);
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|
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impl BlockOrExpr {
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pub fn new_stmts(stmts: Vec<ast::Stmt>) -> BlockOrExpr {
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BlockOrExpr(stmts, None)
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|
}
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pub fn new_expr(expr: P<Expr>) -> BlockOrExpr {
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BlockOrExpr(vec![], Some(expr))
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}
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pub fn new_mixed(stmts: Vec<ast::Stmt>, expr: Option<P<Expr>>) -> BlockOrExpr {
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BlockOrExpr(stmts, expr)
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}
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|
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|
// Converts it into a block.
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|
fn into_block(mut self, cx: &ExtCtxt<'_>, span: Span) -> P<ast::Block> {
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if let Some(expr) = self.1 {
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self.0.push(cx.stmt_expr(expr));
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|
}
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|
cx.block(span, self.0)
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|
}
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|
|
|
// Converts it into an expression.
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|
fn into_expr(self, cx: &ExtCtxt<'_>, span: Span) -> P<Expr> {
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|
if self.0.is_empty() {
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match self.1 {
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|
None => cx.expr_block(cx.block(span, vec![])),
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|
Some(expr) => expr,
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|
}
|
|
} else if self.0.len() == 1
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|
&& let ast::StmtKind::Expr(expr) = &self.0[0].kind
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|
&& self.1.is_none()
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|
{
|
|
// There's only a single statement expression. Pull it out.
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|
expr.clone()
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|
} else {
|
|
// Multiple statements and/or expressions.
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|
cx.expr_block(self.into_block(cx, span))
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|
}
|
|
}
|
|
}
|
|
|
|
/// This method helps to extract all the type parameters referenced from a
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|
/// type. For a type parameter `<T>`, it looks for either a `TyPath` that
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|
/// is not global and starts with `T`, or a `TyQPath`.
|
|
/// Also include bound generic params from the input type.
|
|
fn find_type_parameters(
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|
ty: &ast::Ty,
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|
ty_param_names: &[Symbol],
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|
cx: &ExtCtxt<'_>,
|
|
) -> Vec<TypeParameter> {
|
|
use rustc_ast::visit;
|
|
|
|
struct Visitor<'a, 'b> {
|
|
cx: &'a ExtCtxt<'b>,
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|
ty_param_names: &'a [Symbol],
|
|
bound_generic_params_stack: Vec<ast::GenericParam>,
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|
type_params: Vec<TypeParameter>,
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|
}
|
|
|
|
impl<'a, 'b> visit::Visitor<'a> for Visitor<'a, 'b> {
|
|
fn visit_ty(&mut self, ty: &'a ast::Ty) {
|
|
if let ast::TyKind::Path(_, ref path) = ty.kind {
|
|
if let Some(segment) = path.segments.first() {
|
|
if self.ty_param_names.contains(&segment.ident.name) {
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|
self.type_params.push(TypeParameter {
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|
bound_generic_params: self.bound_generic_params_stack.clone(),
|
|
ty: P(ty.clone()),
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|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
visit::walk_ty(self, ty)
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|
}
|
|
|
|
// Place bound generic params on a stack, to extract them when a type is encountered.
|
|
fn visit_poly_trait_ref(&mut self, trait_ref: &'a ast::PolyTraitRef) {
|
|
let stack_len = self.bound_generic_params_stack.len();
|
|
self.bound_generic_params_stack.extend(trait_ref.bound_generic_params.iter().cloned());
|
|
|
|
visit::walk_poly_trait_ref(self, trait_ref);
|
|
|
|
self.bound_generic_params_stack.truncate(stack_len);
|
|
}
|
|
|
|
fn visit_mac_call(&mut self, mac: &ast::MacCall) {
|
|
self.cx.span_err(mac.span(), "`derive` cannot be used on items with type macros");
|
|
}
|
|
}
|
|
|
|
let mut visitor = Visitor {
|
|
cx,
|
|
ty_param_names,
|
|
bound_generic_params_stack: Vec::new(),
|
|
type_params: Vec::new(),
|
|
};
|
|
visit::Visitor::visit_ty(&mut visitor, ty);
|
|
|
|
visitor.type_params
|
|
}
|
|
|
|
impl<'a> TraitDef<'a> {
|
|
pub fn expand(
|
|
self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
mitem: &ast::MetaItem,
|
|
item: &'a Annotatable,
|
|
push: &mut dyn FnMut(Annotatable),
|
|
) {
|
|
self.expand_ext(cx, mitem, item, push, false);
|
|
}
|
|
|
|
pub fn expand_ext(
|
|
self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
mitem: &ast::MetaItem,
|
|
item: &'a Annotatable,
|
|
push: &mut dyn FnMut(Annotatable),
|
|
from_scratch: bool,
|
|
) {
|
|
match *item {
|
|
Annotatable::Item(ref item) => {
|
|
let is_packed = item.attrs.iter().any(|attr| {
|
|
for r in attr::find_repr_attrs(&cx.sess, attr) {
|
|
if let attr::ReprPacked(_) = r {
|
|
return true;
|
|
}
|
|
}
|
|
false
|
|
});
|
|
let has_no_type_params = match item.kind {
|
|
ast::ItemKind::Struct(_, ref generics)
|
|
| ast::ItemKind::Enum(_, ref generics)
|
|
| ast::ItemKind::Union(_, ref generics) => !generics
|
|
.params
|
|
.iter()
|
|
.any(|param| matches!(param.kind, ast::GenericParamKind::Type { .. })),
|
|
_ => unreachable!(),
|
|
};
|
|
let container_id = cx.current_expansion.id.expn_data().parent.expect_local();
|
|
let always_copy = has_no_type_params && cx.resolver.has_derive_copy(container_id);
|
|
|
|
let newitem = match item.kind {
|
|
ast::ItemKind::Struct(ref struct_def, ref generics) => self.expand_struct_def(
|
|
cx,
|
|
&struct_def,
|
|
item.ident,
|
|
generics,
|
|
from_scratch,
|
|
is_packed,
|
|
always_copy,
|
|
),
|
|
ast::ItemKind::Enum(ref enum_def, ref generics) => {
|
|
// We ignore `is_packed`/`always_copy` here, because
|
|
// `repr(packed)` enums cause an error later on.
|
|
//
|
|
// This can only cause further compilation errors
|
|
// downstream in blatantly illegal code, so it
|
|
// is fine.
|
|
self.expand_enum_def(cx, enum_def, item.ident, generics, from_scratch)
|
|
}
|
|
ast::ItemKind::Union(ref struct_def, ref generics) => {
|
|
if self.supports_unions {
|
|
self.expand_struct_def(
|
|
cx,
|
|
&struct_def,
|
|
item.ident,
|
|
generics,
|
|
from_scratch,
|
|
is_packed,
|
|
always_copy,
|
|
)
|
|
} else {
|
|
cx.span_err(mitem.span, "this trait cannot be derived for unions");
|
|
return;
|
|
}
|
|
}
|
|
_ => unreachable!(),
|
|
};
|
|
// Keep the lint attributes of the previous item to control how the
|
|
// generated implementations are linted
|
|
let mut attrs = newitem.attrs.clone();
|
|
attrs.extend(
|
|
item.attrs
|
|
.iter()
|
|
.filter(|a| {
|
|
[
|
|
sym::allow,
|
|
sym::warn,
|
|
sym::deny,
|
|
sym::forbid,
|
|
sym::stable,
|
|
sym::unstable,
|
|
]
|
|
.contains(&a.name_or_empty())
|
|
})
|
|
.cloned(),
|
|
);
|
|
push(Annotatable::Item(P(ast::Item { attrs, ..(*newitem).clone() })))
|
|
}
|
|
_ => unreachable!(),
|
|
}
|
|
}
|
|
|
|
/// Given that we are deriving a trait `DerivedTrait` for a type like:
|
|
///
|
|
/// ```ignore (only-for-syntax-highlight)
|
|
/// struct Struct<'a, ..., 'z, A, B: DeclaredTrait, C, ..., Z> where C: WhereTrait {
|
|
/// a: A,
|
|
/// b: B::Item,
|
|
/// b1: <B as DeclaredTrait>::Item,
|
|
/// c1: <C as WhereTrait>::Item,
|
|
/// c2: Option<<C as WhereTrait>::Item>,
|
|
/// ...
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// create an impl like:
|
|
///
|
|
/// ```ignore (only-for-syntax-highlight)
|
|
/// impl<'a, ..., 'z, A, B: DeclaredTrait, C, ... Z> where
|
|
/// C: WhereTrait,
|
|
/// A: DerivedTrait + B1 + ... + BN,
|
|
/// B: DerivedTrait + B1 + ... + BN,
|
|
/// C: DerivedTrait + B1 + ... + BN,
|
|
/// B::Item: DerivedTrait + B1 + ... + BN,
|
|
/// <C as WhereTrait>::Item: DerivedTrait + B1 + ... + BN,
|
|
/// ...
|
|
/// {
|
|
/// ...
|
|
/// }
|
|
/// ```
|
|
///
|
|
/// where B1, ..., BN are the bounds given by `bounds_paths`.'. Z is a phantom type, and
|
|
/// therefore does not get bound by the derived trait.
|
|
fn create_derived_impl(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
type_ident: Ident,
|
|
generics: &Generics,
|
|
field_tys: Vec<P<ast::Ty>>,
|
|
methods: Vec<P<ast::AssocItem>>,
|
|
) -> P<ast::Item> {
|
|
let trait_path = self.path.to_path(cx, self.span, type_ident, generics);
|
|
|
|
// Transform associated types from `deriving::ty::Ty` into `ast::AssocItem`
|
|
let associated_types = self.associated_types.iter().map(|&(ident, ref type_def)| {
|
|
P(ast::AssocItem {
|
|
id: ast::DUMMY_NODE_ID,
|
|
span: self.span,
|
|
ident,
|
|
vis: ast::Visibility {
|
|
span: self.span.shrink_to_lo(),
|
|
kind: ast::VisibilityKind::Inherited,
|
|
tokens: None,
|
|
},
|
|
attrs: ast::AttrVec::new(),
|
|
kind: ast::AssocItemKind::Type(Box::new(ast::TyAlias {
|
|
defaultness: ast::Defaultness::Final,
|
|
generics: Generics::default(),
|
|
where_clauses: (
|
|
ast::TyAliasWhereClause::default(),
|
|
ast::TyAliasWhereClause::default(),
|
|
),
|
|
where_predicates_split: 0,
|
|
bounds: Vec::new(),
|
|
ty: Some(type_def.to_ty(cx, self.span, type_ident, generics)),
|
|
})),
|
|
tokens: None,
|
|
})
|
|
});
|
|
|
|
let mut where_clause = ast::WhereClause::default();
|
|
where_clause.span = generics.where_clause.span;
|
|
let ctxt = self.span.ctxt();
|
|
let span = generics.span.with_ctxt(ctxt);
|
|
|
|
// Create the generic parameters
|
|
let params: Vec<_> = generics
|
|
.params
|
|
.iter()
|
|
.map(|param| match ¶m.kind {
|
|
GenericParamKind::Lifetime { .. } => param.clone(),
|
|
GenericParamKind::Type { .. } => {
|
|
// I don't think this can be moved out of the loop, since
|
|
// a GenericBound requires an ast id
|
|
let bounds: Vec<_> =
|
|
// extra restrictions on the generics parameters to the
|
|
// type being derived upon
|
|
self.additional_bounds.iter().map(|p| {
|
|
cx.trait_bound(p.to_path(cx, self.span, type_ident, generics))
|
|
}).chain(
|
|
// require the current trait
|
|
self.skip_path_as_bound.not().then(|| cx.trait_bound(trait_path.clone()))
|
|
).chain(
|
|
// also add in any bounds from the declaration
|
|
param.bounds.iter().cloned()
|
|
).collect();
|
|
|
|
cx.typaram(param.ident.span.with_ctxt(ctxt), param.ident, bounds, None)
|
|
}
|
|
GenericParamKind::Const { ty, kw_span, .. } => {
|
|
let const_nodefault_kind = GenericParamKind::Const {
|
|
ty: ty.clone(),
|
|
kw_span: kw_span.with_ctxt(ctxt),
|
|
|
|
// We can't have default values inside impl block
|
|
default: None,
|
|
};
|
|
let mut param_clone = param.clone();
|
|
param_clone.kind = const_nodefault_kind;
|
|
param_clone
|
|
}
|
|
})
|
|
.collect();
|
|
|
|
// and similarly for where clauses
|
|
where_clause.predicates.extend(generics.where_clause.predicates.iter().map(|clause| {
|
|
match clause {
|
|
ast::WherePredicate::BoundPredicate(wb) => {
|
|
let span = wb.span.with_ctxt(ctxt);
|
|
ast::WherePredicate::BoundPredicate(ast::WhereBoundPredicate {
|
|
span,
|
|
..wb.clone()
|
|
})
|
|
}
|
|
ast::WherePredicate::RegionPredicate(wr) => {
|
|
let span = wr.span.with_ctxt(ctxt);
|
|
ast::WherePredicate::RegionPredicate(ast::WhereRegionPredicate {
|
|
span,
|
|
..wr.clone()
|
|
})
|
|
}
|
|
ast::WherePredicate::EqPredicate(we) => {
|
|
let span = we.span.with_ctxt(ctxt);
|
|
ast::WherePredicate::EqPredicate(ast::WhereEqPredicate { span, ..we.clone() })
|
|
}
|
|
}
|
|
}));
|
|
|
|
{
|
|
// Extra scope required here so ty_params goes out of scope before params is moved
|
|
|
|
let mut ty_params = params
|
|
.iter()
|
|
.filter(|param| matches!(param.kind, ast::GenericParamKind::Type { .. }))
|
|
.peekable();
|
|
|
|
if ty_params.peek().is_some() {
|
|
let ty_param_names: Vec<Symbol> =
|
|
ty_params.map(|ty_param| ty_param.ident.name).collect();
|
|
|
|
for field_ty in field_tys {
|
|
let field_ty_params = find_type_parameters(&field_ty, &ty_param_names, cx);
|
|
|
|
for field_ty_param in field_ty_params {
|
|
// if we have already handled this type, skip it
|
|
if let ast::TyKind::Path(_, ref p) = field_ty_param.ty.kind {
|
|
if p.segments.len() == 1
|
|
&& ty_param_names.contains(&p.segments[0].ident.name)
|
|
{
|
|
continue;
|
|
};
|
|
}
|
|
let mut bounds: Vec<_> = self
|
|
.additional_bounds
|
|
.iter()
|
|
.map(|p| cx.trait_bound(p.to_path(cx, self.span, type_ident, generics)))
|
|
.collect();
|
|
|
|
// require the current trait
|
|
bounds.push(cx.trait_bound(trait_path.clone()));
|
|
|
|
let predicate = ast::WhereBoundPredicate {
|
|
span: self.span,
|
|
bound_generic_params: field_ty_param.bound_generic_params,
|
|
bounded_ty: field_ty_param.ty,
|
|
bounds,
|
|
};
|
|
|
|
let predicate = ast::WherePredicate::BoundPredicate(predicate);
|
|
where_clause.predicates.push(predicate);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
let trait_generics = Generics { params, where_clause, span };
|
|
|
|
// Create the reference to the trait.
|
|
let trait_ref = cx.trait_ref(trait_path);
|
|
|
|
let self_params: Vec<_> = generics
|
|
.params
|
|
.iter()
|
|
.map(|param| match param.kind {
|
|
GenericParamKind::Lifetime { .. } => {
|
|
GenericArg::Lifetime(cx.lifetime(param.ident.span.with_ctxt(ctxt), param.ident))
|
|
}
|
|
GenericParamKind::Type { .. } => {
|
|
GenericArg::Type(cx.ty_ident(param.ident.span.with_ctxt(ctxt), param.ident))
|
|
}
|
|
GenericParamKind::Const { .. } => {
|
|
GenericArg::Const(cx.const_ident(param.ident.span.with_ctxt(ctxt), param.ident))
|
|
}
|
|
})
|
|
.collect();
|
|
|
|
// Create the type of `self`.
|
|
let path = cx.path_all(self.span, false, vec![type_ident], self_params);
|
|
let self_type = cx.ty_path(path);
|
|
|
|
let attr = cx.attribute(cx.meta_word(self.span, sym::automatically_derived));
|
|
let attrs = thin_vec![attr];
|
|
let opt_trait_ref = Some(trait_ref);
|
|
|
|
cx.item(
|
|
self.span,
|
|
Ident::empty(),
|
|
attrs,
|
|
ast::ItemKind::Impl(Box::new(ast::Impl {
|
|
unsafety: ast::Unsafe::No,
|
|
polarity: ast::ImplPolarity::Positive,
|
|
defaultness: ast::Defaultness::Final,
|
|
constness: if self.is_const { ast::Const::Yes(DUMMY_SP) } else { ast::Const::No },
|
|
generics: trait_generics,
|
|
of_trait: opt_trait_ref,
|
|
self_ty: self_type,
|
|
items: methods.into_iter().chain(associated_types).collect(),
|
|
})),
|
|
)
|
|
}
|
|
|
|
fn expand_struct_def(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
struct_def: &'a VariantData,
|
|
type_ident: Ident,
|
|
generics: &Generics,
|
|
from_scratch: bool,
|
|
is_packed: bool,
|
|
always_copy: bool,
|
|
) -> P<ast::Item> {
|
|
let field_tys: Vec<P<ast::Ty>> =
|
|
struct_def.fields().iter().map(|field| field.ty.clone()).collect();
|
|
|
|
let methods = self
|
|
.methods
|
|
.iter()
|
|
.map(|method_def| {
|
|
let (explicit_self, selflike_args, nonselflike_args, nonself_arg_tys) =
|
|
method_def.extract_arg_details(cx, self, type_ident, generics);
|
|
|
|
let body = if from_scratch || method_def.is_static() {
|
|
method_def.expand_static_struct_method_body(
|
|
cx,
|
|
self,
|
|
struct_def,
|
|
type_ident,
|
|
&nonselflike_args,
|
|
)
|
|
} else {
|
|
method_def.expand_struct_method_body(
|
|
cx,
|
|
self,
|
|
struct_def,
|
|
type_ident,
|
|
&selflike_args,
|
|
&nonselflike_args,
|
|
is_packed,
|
|
always_copy,
|
|
)
|
|
};
|
|
|
|
method_def.create_method(
|
|
cx,
|
|
self,
|
|
type_ident,
|
|
generics,
|
|
explicit_self,
|
|
nonself_arg_tys,
|
|
body,
|
|
)
|
|
})
|
|
.collect();
|
|
|
|
self.create_derived_impl(cx, type_ident, generics, field_tys, methods)
|
|
}
|
|
|
|
fn expand_enum_def(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
enum_def: &'a EnumDef,
|
|
type_ident: Ident,
|
|
generics: &Generics,
|
|
from_scratch: bool,
|
|
) -> P<ast::Item> {
|
|
let mut field_tys = Vec::new();
|
|
|
|
for variant in &enum_def.variants {
|
|
field_tys.extend(variant.data.fields().iter().map(|field| field.ty.clone()));
|
|
}
|
|
|
|
let methods = self
|
|
.methods
|
|
.iter()
|
|
.map(|method_def| {
|
|
let (explicit_self, selflike_args, nonselflike_args, nonself_arg_tys) =
|
|
method_def.extract_arg_details(cx, self, type_ident, generics);
|
|
|
|
let body = if from_scratch || method_def.is_static() {
|
|
method_def.expand_static_enum_method_body(
|
|
cx,
|
|
self,
|
|
enum_def,
|
|
type_ident,
|
|
&nonselflike_args,
|
|
)
|
|
} else {
|
|
method_def.expand_enum_method_body(
|
|
cx,
|
|
self,
|
|
enum_def,
|
|
type_ident,
|
|
selflike_args,
|
|
&nonselflike_args,
|
|
)
|
|
};
|
|
|
|
method_def.create_method(
|
|
cx,
|
|
self,
|
|
type_ident,
|
|
generics,
|
|
explicit_self,
|
|
nonself_arg_tys,
|
|
body,
|
|
)
|
|
})
|
|
.collect();
|
|
|
|
self.create_derived_impl(cx, type_ident, generics, field_tys, methods)
|
|
}
|
|
}
|
|
|
|
impl<'a> MethodDef<'a> {
|
|
fn call_substructure_method(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
type_ident: Ident,
|
|
nonselflike_args: &[P<Expr>],
|
|
fields: &SubstructureFields<'_>,
|
|
) -> BlockOrExpr {
|
|
let span = trait_.span;
|
|
let substructure = Substructure { type_ident, nonselflike_args, fields };
|
|
let mut f = self.combine_substructure.borrow_mut();
|
|
let f: &mut CombineSubstructureFunc<'_> = &mut *f;
|
|
f(cx, span, &substructure)
|
|
}
|
|
|
|
fn get_ret_ty(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
generics: &Generics,
|
|
type_ident: Ident,
|
|
) -> P<ast::Ty> {
|
|
self.ret_ty.to_ty(cx, trait_.span, type_ident, generics)
|
|
}
|
|
|
|
fn is_static(&self) -> bool {
|
|
!self.explicit_self
|
|
}
|
|
|
|
// The return value includes:
|
|
// - explicit_self: The `&self` arg, if present.
|
|
// - selflike_args: Expressions for `&self` (if present) and also any other
|
|
// args with the same type (e.g. the `other` arg in `PartialEq::eq`).
|
|
// - nonselflike_args: Expressions for all the remaining args.
|
|
// - nonself_arg_tys: Additional information about all the args other than
|
|
// `&self`.
|
|
fn extract_arg_details(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
type_ident: Ident,
|
|
generics: &Generics,
|
|
) -> (Option<ast::ExplicitSelf>, Vec<P<Expr>>, Vec<P<Expr>>, Vec<(Ident, P<ast::Ty>)>) {
|
|
let mut selflike_args = Vec::new();
|
|
let mut nonselflike_args = Vec::new();
|
|
let mut nonself_arg_tys = Vec::new();
|
|
let span = trait_.span;
|
|
|
|
let explicit_self = if self.explicit_self {
|
|
let (self_expr, explicit_self) = ty::get_explicit_self(cx, span);
|
|
selflike_args.push(self_expr);
|
|
Some(explicit_self)
|
|
} else {
|
|
None
|
|
};
|
|
|
|
for (ty, name) in self.nonself_args.iter() {
|
|
let ast_ty = ty.to_ty(cx, span, type_ident, generics);
|
|
let ident = Ident::new(*name, span);
|
|
nonself_arg_tys.push((ident, ast_ty));
|
|
|
|
let arg_expr = cx.expr_ident(span, ident);
|
|
|
|
match ty {
|
|
// Selflike (`&Self`) arguments only occur in non-static methods.
|
|
Ref(box Self_, _) if !self.is_static() => selflike_args.push(arg_expr),
|
|
Self_ => cx.span_bug(span, "`Self` in non-return position"),
|
|
_ => nonselflike_args.push(arg_expr),
|
|
}
|
|
}
|
|
|
|
(explicit_self, selflike_args, nonselflike_args, nonself_arg_tys)
|
|
}
|
|
|
|
fn create_method(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
type_ident: Ident,
|
|
generics: &Generics,
|
|
explicit_self: Option<ast::ExplicitSelf>,
|
|
nonself_arg_tys: Vec<(Ident, P<ast::Ty>)>,
|
|
body: BlockOrExpr,
|
|
) -> P<ast::AssocItem> {
|
|
let span = trait_.span;
|
|
// Create the generics that aren't for `Self`.
|
|
let fn_generics = self.generics.to_generics(cx, span, type_ident, generics);
|
|
|
|
let args = {
|
|
let self_arg = explicit_self.map(|explicit_self| {
|
|
let ident = Ident::with_dummy_span(kw::SelfLower).with_span_pos(span);
|
|
ast::Param::from_self(ast::AttrVec::default(), explicit_self, ident)
|
|
});
|
|
let nonself_args =
|
|
nonself_arg_tys.into_iter().map(|(name, ty)| cx.param(span, name, ty));
|
|
self_arg.into_iter().chain(nonself_args).collect()
|
|
};
|
|
|
|
let ret_type = self.get_ret_ty(cx, trait_, generics, type_ident);
|
|
|
|
let method_ident = Ident::new(self.name, span);
|
|
let fn_decl = cx.fn_decl(args, ast::FnRetTy::Ty(ret_type));
|
|
let body_block = body.into_block(cx, span);
|
|
|
|
let trait_lo_sp = span.shrink_to_lo();
|
|
|
|
let sig = ast::FnSig { header: ast::FnHeader::default(), decl: fn_decl, span };
|
|
let defaultness = ast::Defaultness::Final;
|
|
|
|
// Create the method.
|
|
P(ast::AssocItem {
|
|
id: ast::DUMMY_NODE_ID,
|
|
attrs: self.attributes.clone(),
|
|
span,
|
|
vis: ast::Visibility {
|
|
span: trait_lo_sp,
|
|
kind: ast::VisibilityKind::Inherited,
|
|
tokens: None,
|
|
},
|
|
ident: method_ident,
|
|
kind: ast::AssocItemKind::Fn(Box::new(ast::Fn {
|
|
defaultness,
|
|
sig,
|
|
generics: fn_generics,
|
|
body: Some(body_block),
|
|
})),
|
|
tokens: None,
|
|
})
|
|
}
|
|
|
|
/// The normal case uses field access.
|
|
/// ```
|
|
/// #[derive(PartialEq)]
|
|
/// # struct Dummy;
|
|
/// struct A { x: u8, y: u8 }
|
|
///
|
|
/// // equivalent to:
|
|
/// impl PartialEq for A {
|
|
/// fn eq(&self, other: &A) -> bool {
|
|
/// self.x == other.x && self.y == other.y
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
/// But if the struct is `repr(packed)`, we can't use something like
|
|
/// `&self.x` because that might cause an unaligned ref. So for any trait
|
|
/// method that takes a reference, if the struct impls `Copy` then we use a
|
|
/// local block to force a copy:
|
|
/// ```
|
|
/// # struct A { x: u8, y: u8 }
|
|
/// impl PartialEq for A {
|
|
/// fn eq(&self, other: &A) -> bool {
|
|
/// // Desugars to `{ self.x }.eq(&{ other.y }) && ...`
|
|
/// { self.x } == { other.y } && { self.y } == { other.y }
|
|
/// }
|
|
/// }
|
|
/// impl Hash for A {
|
|
/// fn hash<__H: ::core::hash::Hasher>(&self, state: &mut __H) -> () {
|
|
/// ::core::hash::Hash::hash(&{ self.x }, state);
|
|
/// ::core::hash::Hash::hash(&{ self.y }, state)
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
/// If the struct doesn't impl `Copy`, we use let-destructuring with `ref`:
|
|
/// ```
|
|
/// # struct A { x: u8, y: u8 }
|
|
/// impl PartialEq for A {
|
|
/// fn eq(&self, other: &A) -> bool {
|
|
/// let Self { x: ref __self_0_0, y: ref __self_0_1 } = *self;
|
|
/// let Self { x: ref __self_1_0, y: ref __self_1_1 } = *other;
|
|
/// *__self_0_0 == *__self_1_0 && *__self_0_1 == *__self_1_1
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
/// This latter case only works if the fields match the alignment required
|
|
/// by the `packed(N)` attribute. (We'll get errors later on if not.)
|
|
fn expand_struct_method_body<'b>(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'b>,
|
|
struct_def: &'b VariantData,
|
|
type_ident: Ident,
|
|
selflike_args: &[P<Expr>],
|
|
nonselflike_args: &[P<Expr>],
|
|
is_packed: bool,
|
|
always_copy: bool,
|
|
) -> BlockOrExpr {
|
|
let span = trait_.span;
|
|
assert!(selflike_args.len() == 1 || selflike_args.len() == 2);
|
|
|
|
let mk_body = |cx, selflike_fields| {
|
|
self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&Struct(struct_def, selflike_fields),
|
|
)
|
|
};
|
|
|
|
if !is_packed {
|
|
let selflike_fields =
|
|
trait_.create_struct_field_access_fields(cx, selflike_args, struct_def, false);
|
|
mk_body(cx, selflike_fields)
|
|
} else if always_copy {
|
|
let selflike_fields =
|
|
trait_.create_struct_field_access_fields(cx, selflike_args, struct_def, true);
|
|
mk_body(cx, selflike_fields)
|
|
} else {
|
|
// Packed and not copy. Need to use ref patterns.
|
|
let prefixes: Vec<_> =
|
|
(0..selflike_args.len()).map(|i| format!("__self_{}", i)).collect();
|
|
let selflike_fields = trait_.create_struct_pattern_fields(cx, struct_def, &prefixes);
|
|
let mut body = mk_body(cx, selflike_fields);
|
|
|
|
let struct_path = cx.path(span, vec![Ident::new(kw::SelfUpper, type_ident.span)]);
|
|
let patterns =
|
|
trait_.create_struct_patterns(cx, struct_path, struct_def, &prefixes, ByRef::Yes);
|
|
|
|
// Do the let-destructuring.
|
|
let mut stmts: Vec<_> = iter::zip(selflike_args, patterns)
|
|
.map(|(selflike_arg_expr, pat)| {
|
|
let selflike_arg_expr = cx.expr_deref(span, selflike_arg_expr.clone());
|
|
cx.stmt_let_pat(span, pat, selflike_arg_expr)
|
|
})
|
|
.collect();
|
|
stmts.extend(std::mem::take(&mut body.0));
|
|
BlockOrExpr(stmts, body.1)
|
|
}
|
|
}
|
|
|
|
fn expand_static_struct_method_body(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
struct_def: &VariantData,
|
|
type_ident: Ident,
|
|
nonselflike_args: &[P<Expr>],
|
|
) -> BlockOrExpr {
|
|
let summary = trait_.summarise_struct(cx, struct_def);
|
|
|
|
self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&StaticStruct(struct_def, summary),
|
|
)
|
|
}
|
|
|
|
/// ```
|
|
/// #[derive(PartialEq)]
|
|
/// # struct Dummy;
|
|
/// enum A {
|
|
/// A1,
|
|
/// A2(i32)
|
|
/// }
|
|
/// ```
|
|
/// is equivalent to:
|
|
/// ```
|
|
/// #![feature(core_intrinsics)]
|
|
/// enum A {
|
|
/// A1,
|
|
/// A2(i32)
|
|
/// }
|
|
/// impl ::core::cmp::PartialEq for A {
|
|
/// #[inline]
|
|
/// fn eq(&self, other: &A) -> bool {
|
|
/// let __self_tag = ::core::intrinsics::discriminant_value(self);
|
|
/// let __arg1_tag = ::core::intrinsics::discriminant_value(other);
|
|
/// __self_tag == __arg1_tag &&
|
|
/// match (self, other) {
|
|
/// (A::A2(__self_0), A::A2(__arg1_0)) =>
|
|
/// *__self_0 == *__arg1_0,
|
|
/// _ => true,
|
|
/// }
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
/// Creates a tag check combined with a match for a tuple of all
|
|
/// `selflike_args`, with an arm for each variant with fields, possibly an
|
|
/// arm for each fieldless variant (if `!unify_fieldless_variants` is not
|
|
/// true), and possibly a default arm.
|
|
fn expand_enum_method_body<'b>(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'b>,
|
|
enum_def: &'b EnumDef,
|
|
type_ident: Ident,
|
|
selflike_args: Vec<P<Expr>>,
|
|
nonselflike_args: &[P<Expr>],
|
|
) -> BlockOrExpr {
|
|
let span = trait_.span;
|
|
let variants = &enum_def.variants;
|
|
|
|
// Traits that unify fieldless variants always use the tag(s).
|
|
let uses_tags = self.unify_fieldless_variants;
|
|
|
|
// There is no sensible code to be generated for *any* deriving on a
|
|
// zero-variant enum. So we just generate a failing expression.
|
|
if variants.is_empty() {
|
|
return BlockOrExpr(vec![], Some(deriving::call_unreachable(cx, span)));
|
|
}
|
|
|
|
let prefixes = iter::once("__self".to_string())
|
|
.chain(
|
|
selflike_args
|
|
.iter()
|
|
.enumerate()
|
|
.skip(1)
|
|
.map(|(arg_count, _selflike_arg)| format!("__arg{}", arg_count)),
|
|
)
|
|
.collect::<Vec<String>>();
|
|
|
|
// Build a series of let statements mapping each selflike_arg
|
|
// to its discriminant value.
|
|
//
|
|
// e.g. for `PartialEq::eq` builds two statements:
|
|
// ```
|
|
// let __self_tag = ::core::intrinsics::discriminant_value(self);
|
|
// let __arg1_tag = ::core::intrinsics::discriminant_value(other);
|
|
// ```
|
|
let get_tag_pieces = |cx: &ExtCtxt<'_>| {
|
|
let tag_idents: Vec<_> = prefixes
|
|
.iter()
|
|
.map(|name| Ident::from_str_and_span(&format!("{}_tag", name), span))
|
|
.collect();
|
|
|
|
let mut tag_exprs: Vec<_> = tag_idents
|
|
.iter()
|
|
.map(|&ident| cx.expr_addr_of(span, cx.expr_ident(span, ident)))
|
|
.collect();
|
|
|
|
let self_expr = tag_exprs.remove(0);
|
|
let other_selflike_exprs = tag_exprs;
|
|
let tag_field = FieldInfo { span, name: None, self_expr, other_selflike_exprs };
|
|
|
|
let tag_let_stmts: Vec<_> = iter::zip(&tag_idents, &selflike_args)
|
|
.map(|(&ident, selflike_arg)| {
|
|
let variant_value = deriving::call_intrinsic(
|
|
cx,
|
|
span,
|
|
sym::discriminant_value,
|
|
vec![selflike_arg.clone()],
|
|
);
|
|
cx.stmt_let(span, false, ident, variant_value)
|
|
})
|
|
.collect();
|
|
|
|
(tag_field, tag_let_stmts)
|
|
};
|
|
|
|
// There are some special cases involving fieldless enums where no
|
|
// match is necessary.
|
|
let all_fieldless = variants.iter().all(|v| v.data.fields().is_empty());
|
|
if all_fieldless {
|
|
if uses_tags && variants.len() > 1 {
|
|
// If the type is fieldless and the trait uses the tag and
|
|
// there are multiple variants, we need just an operation on
|
|
// the tag(s).
|
|
let (tag_field, mut tag_let_stmts) = get_tag_pieces(cx);
|
|
let mut tag_check = self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&EnumTag(tag_field, None),
|
|
);
|
|
tag_let_stmts.append(&mut tag_check.0);
|
|
return BlockOrExpr(tag_let_stmts, tag_check.1);
|
|
}
|
|
|
|
if variants.len() == 1 {
|
|
// If there is a single variant, we don't need an operation on
|
|
// the tag(s). Just use the most degenerate result.
|
|
return self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&EnumMatching(0, 1, &variants[0], Vec::new()),
|
|
);
|
|
};
|
|
}
|
|
|
|
// These arms are of the form:
|
|
// (Variant1, Variant1, ...) => Body1
|
|
// (Variant2, Variant2, ...) => Body2
|
|
// ...
|
|
// where each tuple has length = selflike_args.len()
|
|
let mut match_arms: Vec<ast::Arm> = variants
|
|
.iter()
|
|
.enumerate()
|
|
.filter(|&(_, v)| !(self.unify_fieldless_variants && v.data.fields().is_empty()))
|
|
.map(|(index, variant)| {
|
|
// A single arm has form (&VariantK, &VariantK, ...) => BodyK
|
|
// (see "Final wrinkle" note below for why.)
|
|
|
|
let fields = trait_.create_struct_pattern_fields(cx, &variant.data, &prefixes);
|
|
|
|
let sp = variant.span.with_ctxt(trait_.span.ctxt());
|
|
let variant_path = cx.path(sp, vec![type_ident, variant.ident]);
|
|
let by_ref = ByRef::No; // because enums can't be repr(packed)
|
|
let mut subpats: Vec<_> = trait_.create_struct_patterns(
|
|
cx,
|
|
variant_path,
|
|
&variant.data,
|
|
&prefixes,
|
|
by_ref,
|
|
);
|
|
|
|
// `(VariantK, VariantK, ...)` or just `VariantK`.
|
|
let single_pat = if subpats.len() == 1 {
|
|
subpats.pop().unwrap()
|
|
} else {
|
|
cx.pat_tuple(span, subpats)
|
|
};
|
|
|
|
// For the BodyK, we need to delegate to our caller,
|
|
// passing it an EnumMatching to indicate which case
|
|
// we are in.
|
|
//
|
|
// Now, for some given VariantK, we have built up
|
|
// expressions for referencing every field of every
|
|
// Self arg, assuming all are instances of VariantK.
|
|
// Build up code associated with such a case.
|
|
let substructure = EnumMatching(index, variants.len(), variant, fields);
|
|
let arm_expr = self
|
|
.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&substructure,
|
|
)
|
|
.into_expr(cx, span);
|
|
|
|
cx.arm(span, single_pat, arm_expr)
|
|
})
|
|
.collect();
|
|
|
|
// Add a default arm to the match, if necessary.
|
|
let first_fieldless = variants.iter().find(|v| v.data.fields().is_empty());
|
|
let default = match first_fieldless {
|
|
Some(v) if self.unify_fieldless_variants => {
|
|
// We need a default case that handles all the fieldless
|
|
// variants. The index and actual variant aren't meaningful in
|
|
// this case, so just use dummy values.
|
|
Some(
|
|
self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&EnumMatching(0, variants.len(), v, Vec::new()),
|
|
)
|
|
.into_expr(cx, span),
|
|
)
|
|
}
|
|
_ if variants.len() > 1 && selflike_args.len() > 1 => {
|
|
// Because we know that all the arguments will match if we reach
|
|
// the match expression we add the unreachable intrinsics as the
|
|
// result of the default which should help llvm in optimizing it.
|
|
Some(deriving::call_unreachable(cx, span))
|
|
}
|
|
_ => None,
|
|
};
|
|
if let Some(arm) = default {
|
|
match_arms.push(cx.arm(span, cx.pat_wild(span), arm));
|
|
}
|
|
|
|
// Create a match expression with one arm per discriminant plus
|
|
// possibly a default arm, e.g.:
|
|
// match (self, other) {
|
|
// (Variant1, Variant1, ...) => Body1
|
|
// (Variant2, Variant2, ...) => Body2,
|
|
// ...
|
|
// _ => ::core::intrinsics::unreachable()
|
|
// }
|
|
let get_match_expr = |mut selflike_args: Vec<P<Expr>>| {
|
|
let match_arg = if selflike_args.len() == 1 {
|
|
selflike_args.pop().unwrap()
|
|
} else {
|
|
cx.expr(span, ast::ExprKind::Tup(selflike_args))
|
|
};
|
|
cx.expr_match(span, match_arg, match_arms)
|
|
};
|
|
|
|
// If the trait uses the tag and there are multiple variants, we need
|
|
// to add a tag check operation before the match. Otherwise, the match
|
|
// is enough.
|
|
if uses_tags && variants.len() > 1 {
|
|
let (tag_field, mut tag_let_stmts) = get_tag_pieces(cx);
|
|
|
|
// Combine a tag check with the match.
|
|
let mut tag_check_plus_match = self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&EnumTag(tag_field, Some(get_match_expr(selflike_args))),
|
|
);
|
|
tag_let_stmts.append(&mut tag_check_plus_match.0);
|
|
BlockOrExpr(tag_let_stmts, tag_check_plus_match.1)
|
|
} else {
|
|
BlockOrExpr(vec![], Some(get_match_expr(selflike_args)))
|
|
}
|
|
}
|
|
|
|
fn expand_static_enum_method_body(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_: &TraitDef<'_>,
|
|
enum_def: &EnumDef,
|
|
type_ident: Ident,
|
|
nonselflike_args: &[P<Expr>],
|
|
) -> BlockOrExpr {
|
|
let summary = enum_def
|
|
.variants
|
|
.iter()
|
|
.map(|v| {
|
|
let sp = v.span.with_ctxt(trait_.span.ctxt());
|
|
let summary = trait_.summarise_struct(cx, &v.data);
|
|
(v.ident, sp, summary)
|
|
})
|
|
.collect();
|
|
self.call_substructure_method(
|
|
cx,
|
|
trait_,
|
|
type_ident,
|
|
nonselflike_args,
|
|
&StaticEnum(enum_def, summary),
|
|
)
|
|
}
|
|
}
|
|
|
|
// general helper methods.
|
|
impl<'a> TraitDef<'a> {
|
|
fn summarise_struct(&self, cx: &mut ExtCtxt<'_>, struct_def: &VariantData) -> StaticFields {
|
|
let mut named_idents = Vec::new();
|
|
let mut just_spans = Vec::new();
|
|
for field in struct_def.fields() {
|
|
let sp = field.span.with_ctxt(self.span.ctxt());
|
|
match field.ident {
|
|
Some(ident) => named_idents.push((ident, sp)),
|
|
_ => just_spans.push(sp),
|
|
}
|
|
}
|
|
|
|
let is_tuple = matches!(struct_def, ast::VariantData::Tuple(..));
|
|
match (just_spans.is_empty(), named_idents.is_empty()) {
|
|
(false, false) => {
|
|
cx.span_bug(self.span, "a struct with named and unnamed fields in generic `derive`")
|
|
}
|
|
// named fields
|
|
(_, false) => Named(named_idents),
|
|
// unnamed fields
|
|
(false, _) => Unnamed(just_spans, is_tuple),
|
|
// empty
|
|
_ => Named(Vec::new()),
|
|
}
|
|
}
|
|
|
|
fn create_struct_patterns(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
struct_path: ast::Path,
|
|
struct_def: &'a VariantData,
|
|
prefixes: &[String],
|
|
by_ref: ByRef,
|
|
) -> Vec<P<ast::Pat>> {
|
|
prefixes
|
|
.iter()
|
|
.map(|prefix| {
|
|
let pieces_iter =
|
|
struct_def.fields().iter().enumerate().map(|(i, struct_field)| {
|
|
let sp = struct_field.span.with_ctxt(self.span.ctxt());
|
|
let ident = self.mk_pattern_ident(prefix, i);
|
|
let path = ident.with_span_pos(sp);
|
|
(
|
|
sp,
|
|
struct_field.ident,
|
|
cx.pat(
|
|
path.span,
|
|
PatKind::Ident(
|
|
BindingAnnotation(by_ref, Mutability::Not),
|
|
path,
|
|
None,
|
|
),
|
|
),
|
|
)
|
|
});
|
|
|
|
let struct_path = struct_path.clone();
|
|
match *struct_def {
|
|
VariantData::Struct(..) => {
|
|
let field_pats = pieces_iter
|
|
.map(|(sp, ident, pat)| {
|
|
if ident.is_none() {
|
|
cx.span_bug(
|
|
sp,
|
|
"a braced struct with unnamed fields in `derive`",
|
|
);
|
|
}
|
|
ast::PatField {
|
|
ident: ident.unwrap(),
|
|
is_shorthand: false,
|
|
attrs: ast::AttrVec::new(),
|
|
id: ast::DUMMY_NODE_ID,
|
|
span: pat.span.with_ctxt(self.span.ctxt()),
|
|
pat,
|
|
is_placeholder: false,
|
|
}
|
|
})
|
|
.collect();
|
|
cx.pat_struct(self.span, struct_path, field_pats)
|
|
}
|
|
VariantData::Tuple(..) => {
|
|
let subpats = pieces_iter.map(|(_, _, subpat)| subpat).collect();
|
|
cx.pat_tuple_struct(self.span, struct_path, subpats)
|
|
}
|
|
VariantData::Unit(..) => cx.pat_path(self.span, struct_path),
|
|
}
|
|
})
|
|
.collect()
|
|
}
|
|
|
|
fn create_fields<F>(&self, struct_def: &'a VariantData, mk_exprs: F) -> Vec<FieldInfo>
|
|
where
|
|
F: Fn(usize, &ast::FieldDef, Span) -> Vec<P<ast::Expr>>,
|
|
{
|
|
struct_def
|
|
.fields()
|
|
.iter()
|
|
.enumerate()
|
|
.map(|(i, struct_field)| {
|
|
// For this field, get an expr for each selflike_arg. E.g. for
|
|
// `PartialEq::eq`, one for each of `&self` and `other`.
|
|
let sp = struct_field.span.with_ctxt(self.span.ctxt());
|
|
let mut exprs: Vec<_> = mk_exprs(i, struct_field, sp);
|
|
let self_expr = exprs.remove(0);
|
|
let other_selflike_exprs = exprs;
|
|
FieldInfo {
|
|
span: sp.with_ctxt(self.span.ctxt()),
|
|
name: struct_field.ident,
|
|
self_expr,
|
|
other_selflike_exprs,
|
|
}
|
|
})
|
|
.collect()
|
|
}
|
|
|
|
fn mk_pattern_ident(&self, prefix: &str, i: usize) -> Ident {
|
|
Ident::from_str_and_span(&format!("{}_{}", prefix, i), self.span)
|
|
}
|
|
|
|
fn create_struct_pattern_fields(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
struct_def: &'a VariantData,
|
|
prefixes: &[String],
|
|
) -> Vec<FieldInfo> {
|
|
self.create_fields(struct_def, |i, _struct_field, sp| {
|
|
prefixes
|
|
.iter()
|
|
.map(|prefix| {
|
|
let ident = self.mk_pattern_ident(prefix, i);
|
|
cx.expr_path(cx.path_ident(sp, ident))
|
|
})
|
|
.collect()
|
|
})
|
|
}
|
|
|
|
fn create_struct_field_access_fields(
|
|
&self,
|
|
cx: &mut ExtCtxt<'_>,
|
|
selflike_args: &[P<Expr>],
|
|
struct_def: &'a VariantData,
|
|
copy: bool,
|
|
) -> Vec<FieldInfo> {
|
|
self.create_fields(struct_def, |i, struct_field, sp| {
|
|
selflike_args
|
|
.iter()
|
|
.map(|selflike_arg| {
|
|
// Note: we must use `struct_field.span` rather than `sp` in the
|
|
// `unwrap_or_else` case otherwise the hygiene is wrong and we get
|
|
// "field `0` of struct `Point` is private" errors on tuple
|
|
// structs.
|
|
let mut field_expr = cx.expr(
|
|
sp,
|
|
ast::ExprKind::Field(
|
|
selflike_arg.clone(),
|
|
struct_field.ident.unwrap_or_else(|| {
|
|
Ident::from_str_and_span(&i.to_string(), struct_field.span)
|
|
}),
|
|
),
|
|
);
|
|
if copy {
|
|
field_expr = cx.expr_block(
|
|
cx.block(struct_field.span, vec![cx.stmt_expr(field_expr)]),
|
|
);
|
|
}
|
|
cx.expr_addr_of(sp, field_expr)
|
|
})
|
|
.collect()
|
|
})
|
|
}
|
|
}
|
|
|
|
/// The function passed to `cs_fold` is called repeatedly with a value of this
|
|
/// type. It describes one part of the code generation. The result is always an
|
|
/// expression.
|
|
pub enum CsFold<'a> {
|
|
/// The basic case: a field expression for one or more selflike args. E.g.
|
|
/// for `PartialEq::eq` this is something like `self.x == other.x`.
|
|
Single(&'a FieldInfo),
|
|
|
|
/// The combination of two field expressions. E.g. for `PartialEq::eq` this
|
|
/// is something like `<field1 equality> && <field2 equality>`.
|
|
Combine(Span, P<Expr>, P<Expr>),
|
|
|
|
// The fallback case for a struct or enum variant with no fields.
|
|
Fieldless,
|
|
}
|
|
|
|
/// Folds over fields, combining the expressions for each field in a sequence.
|
|
/// Statics may not be folded over.
|
|
pub fn cs_fold<F>(
|
|
use_foldl: bool,
|
|
cx: &mut ExtCtxt<'_>,
|
|
trait_span: Span,
|
|
substructure: &Substructure<'_>,
|
|
mut f: F,
|
|
) -> P<Expr>
|
|
where
|
|
F: FnMut(&mut ExtCtxt<'_>, CsFold<'_>) -> P<Expr>,
|
|
{
|
|
match substructure.fields {
|
|
EnumMatching(.., all_fields) | Struct(_, all_fields) => {
|
|
if all_fields.is_empty() {
|
|
return f(cx, CsFold::Fieldless);
|
|
}
|
|
|
|
let (base_field, rest) = if use_foldl {
|
|
all_fields.split_first().unwrap()
|
|
} else {
|
|
all_fields.split_last().unwrap()
|
|
};
|
|
|
|
let base_expr = f(cx, CsFold::Single(base_field));
|
|
|
|
let op = |old, field: &FieldInfo| {
|
|
let new = f(cx, CsFold::Single(field));
|
|
f(cx, CsFold::Combine(field.span, old, new))
|
|
};
|
|
|
|
if use_foldl {
|
|
rest.iter().fold(base_expr, op)
|
|
} else {
|
|
rest.iter().rfold(base_expr, op)
|
|
}
|
|
}
|
|
EnumTag(tag_field, match_expr) => {
|
|
let tag_check_expr = f(cx, CsFold::Single(tag_field));
|
|
if let Some(match_expr) = match_expr {
|
|
if use_foldl {
|
|
f(cx, CsFold::Combine(trait_span, tag_check_expr, match_expr.clone()))
|
|
} else {
|
|
f(cx, CsFold::Combine(trait_span, match_expr.clone(), tag_check_expr))
|
|
}
|
|
} else {
|
|
tag_check_expr
|
|
}
|
|
}
|
|
StaticEnum(..) | StaticStruct(..) => cx.span_bug(trait_span, "static function in `derive`"),
|
|
}
|
|
}
|