| //! Some code that abstracts away much of the boilerplate of writing |
| //! `derive` instances for traits. Among other things it manages getting |
| //! access to the fields of the 4 different sorts of structs and enum |
| //! variants, as well as creating the method and impl ast instances. |
| //! |
| //! Supported features (fairly exhaustive): |
| //! |
| //! - Methods taking any number of parameters of any type, and returning |
| //! any type, other than vectors, bottom and closures. |
| //! - Generating `impl`s for types with type parameters and lifetimes |
| //! (e.g., `Option<T>`), the parameters are automatically given the |
| //! current trait as a bound. (This includes separate type parameters |
| //! and lifetimes for methods.) |
| //! - Additional bounds on the type parameters (`TraitDef.additional_bounds`) |
| //! |
| //! The most important thing for implementors is the `Substructure` and |
| //! `SubstructureFields` objects. The latter groups 5 possibilities of the |
| //! arguments: |
| //! |
| //! - `Struct`, when `Self` is a struct (including tuple structs, e.g |
| //! `struct T(i32, char)`). |
| //! - `EnumMatching`, when `Self` is an enum and all the arguments are the |
| //! same variant of the enum (e.g., `Some(1)`, `Some(3)` and `Some(4)`) |
| //! - `EnumTag` when `Self` is an enum, for comparing the enum tags. |
| //! - `StaticEnum` and `StaticStruct` for static methods, where the type |
| //! being derived upon is either an enum or struct respectively. (Any |
| //! argument with type Self is just grouped among the non-self |
| //! arguments.) |
| //! |
| //! In the first two cases, the values from the corresponding fields in |
| //! all the arguments are grouped together. |
| //! |
| //! The non-static cases have `Option<ident>` in several places associated |
| //! with field `expr`s. This represents the name of the field it is |
| //! associated with. It is only not `None` when the associated field has |
| //! an identifier in the source code. For example, the `x`s in the |
| //! following snippet |
| //! |
| //! ```rust |
| //! # #![allow(dead_code)] |
| //! struct A { x : i32 } |
| //! |
| //! struct B(i32); |
| //! |
| //! enum C { |
| //! C0(i32), |
| //! C1 { x: i32 } |
| //! } |
| //! ``` |
| //! |
| //! The `i32`s in `B` and `C0` don't have an identifier, so the |
| //! `Option<ident>`s would be `None` for them. |
| //! |
| //! In the static cases, the structure is summarized, either into the just |
| //! spans of the fields or a list of spans and the field idents (for tuple |
| //! structs and record structs, respectively), or a list of these, for |
| //! enums (one for each variant). For empty struct and empty enum |
| //! variants, it is represented as a count of 0. |
| //! |
| //! # "`cs`" functions |
| //! |
| //! The `cs_...` functions ("combine substructure") are designed to |
| //! make life easier by providing some pre-made recipes for common |
| //! threads; mostly calling the function being derived on all the |
| //! arguments and then combining them back together in some way (or |
| //! letting the user chose that). They are not meant to be the only |
| //! way to handle the structures that this code creates. |
| //! |
| //! # Examples |
| //! |
| //! The following simplified `PartialEq` is used for in-code examples: |
| //! |
| //! ```rust |
| //! trait PartialEq { |
| //! fn eq(&self, other: &Self) -> bool; |
| //! } |
| //! impl PartialEq for i32 { |
| //! fn eq(&self, other: &i32) -> bool { |
| //! *self == *other |
| //! } |
| //! } |
| //! ``` |
| //! |
| //! Some examples of the values of `SubstructureFields` follow, using the |
| //! above `PartialEq`, `A`, `B` and `C`. |
| //! |
| //! ## Structs |
| //! |
| //! When generating the `expr` for the `A` impl, the `SubstructureFields` is |
| //! |
| //! ```{.text} |
| //! Struct(vec![FieldInfo { |
| //! span: <span of x> |
| //! name: Some(<ident of x>), |
| //! self_: <expr for &self.x>, |
| //! other: vec![<expr for &other.x] |
| //! }]) |
| //! ``` |
| //! |
| //! For the `B` impl, called with `B(a)` and `B(b)`, |
| //! |
| //! ```{.text} |
| //! Struct(vec![FieldInfo { |
| //! span: <span of `i32`>, |
| //! name: None, |
| //! self_: <expr for &a> |
| //! other: vec![<expr for &b>] |
| //! }]) |
| //! ``` |
| //! |
| //! ## Enums |
| //! |
| //! When generating the `expr` for a call with `self == C0(a)` and `other |
| //! == C0(b)`, the SubstructureFields is |
| //! |
| //! ```{.text} |
| //! EnumMatching(0, <ast::Variant for C0>, |
| //! vec![FieldInfo { |
| //! span: <span of i32> |
| //! name: None, |
| //! self_: <expr for &a>, |
| //! other: vec![<expr for &b>] |
| //! }]) |
| //! ``` |
| //! |
| //! For `C1 {x}` and `C1 {x}`, |
| //! |
| //! ```{.text} |
| //! EnumMatching(1, <ast::Variant for C1>, |
| //! vec![FieldInfo { |
| //! span: <span of x> |
| //! name: Some(<ident of x>), |
| //! self_: <expr for &self.x>, |
| //! other: vec![<expr for &other.x>] |
| //! }]) |
| //! ``` |
| //! |
| //! For the tags, |
| //! |
| //! ```{.text} |
| //! EnumTag( |
| //! &[<ident of self tag>, <ident of other tag>], <expr to combine with>) |
| //! ``` |
| //! Note that this setup doesn't allow for the brute-force "match every variant |
| //! against every other variant" approach, which is bad because it produces a |
| //! quadratic amount of code (see #15375). |
| //! |
| //! ## Static |
| //! |
| //! A static method on the types above would result in, |
| //! |
| //! ```{.text} |
| //! StaticStruct(<ast::VariantData of A>, Named(vec![(<ident of x>, <span of x>)])) |
| //! |
| //! StaticStruct(<ast::VariantData of B>, Unnamed(vec![<span of x>])) |
| //! |
| //! StaticEnum(<ast::EnumDef of C>, |
| //! vec![(<ident of C0>, <span of C0>, Unnamed(vec![<span of i32>])), |
| //! (<ident of C1>, <span of C1>, Named(vec![(<ident of x>, <span of x>)]))]) |
| //! ``` |
| |
| pub use StaticFields::*; |
| pub use SubstructureFields::*; |
| |
| use crate::{deriving, errors}; |
| use rustc_ast::ptr::P; |
| use rustc_ast::{ |
| self as ast, BindingAnnotation, ByRef, EnumDef, Expr, GenericArg, GenericParamKind, Generics, |
| Mutability, PatKind, TyKind, VariantData, |
| }; |
| use rustc_attr as attr; |
| use rustc_expand::base::{Annotatable, ExtCtxt}; |
| use rustc_session::lint::builtin::BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE; |
| use rustc_span::symbol::{kw, sym, Ident, Symbol}; |
| use rustc_span::{Span, DUMMY_SP}; |
| use std::cell::RefCell; |
| use std::iter; |
| use std::ops::Not; |
| use std::vec; |
| use thin_vec::{thin_vec, ThinVec}; |
| use ty::{Bounds, Path, Ref, Self_, Ty}; |
| |
| pub mod ty; |
| |
| pub struct TraitDef<'a> { |
| /// The span for the current #[derive(Foo)] header. |
| pub span: Span, |
| |
| /// Path of the trait, including any type parameters |
| pub path: Path, |
| |
| /// Whether to skip adding the current trait as a bound to the type parameters of the type. |
| pub skip_path_as_bound: bool, |
| |
| /// Whether `Copy` is needed as an additional bound on type parameters in a packed struct. |
| pub needs_copy_as_bound_if_packed: bool, |
| |
| /// Additional bounds required of any type parameters of the type, |
| /// other than the current trait |
| pub additional_bounds: Vec<Ty>, |
| |
| /// Can this trait be derived for unions? |
| pub supports_unions: bool, |
| |
| pub methods: Vec<MethodDef<'a>>, |
| |
| pub associated_types: Vec<(Ident, Ty)>, |
| |
| pub is_const: bool, |
| } |
| |
| pub struct MethodDef<'a> { |
| /// name of the method |
| pub name: Symbol, |
| /// List of generics, e.g., `R: rand::Rng` |
| pub generics: Bounds, |
| |
| /// Is there is a `&self` argument? If not, it is a static function. |
| pub explicit_self: bool, |
| |
| /// Arguments other than the self argument. |
| pub nonself_args: Vec<(Ty, Symbol)>, |
| |
| /// Returns type |
| pub ret_ty: Ty, |
| |
| pub attributes: ast::AttrVec, |
| |
| pub fieldless_variants_strategy: FieldlessVariantsStrategy, |
| |
| pub combine_substructure: RefCell<CombineSubstructureFunc<'a>>, |
| } |
| |
| /// How to handle fieldless enum variants. |
| #[derive(PartialEq)] |
| pub enum FieldlessVariantsStrategy { |
| /// Combine fieldless variants into a single match arm. |
| /// This assumes that relevant information has been handled |
| /// by looking at the enum's discriminant. |
| Unify, |
| /// Don't do anything special about fieldless variants. They are |
| /// handled like any other variant. |
| Default, |
| /// If all variants of the enum are fieldless, expand the special |
| /// `AllFieldLessEnum` substructure, so that the entire enum can be handled |
| /// at once. |
| SpecializeIfAllVariantsFieldless, |
| } |
| |
| /// All the data about the data structure/method being derived upon. |
| pub struct Substructure<'a> { |
| /// ident of self |
| pub type_ident: Ident, |
| /// Verbatim access to any non-selflike arguments, i.e. arguments that |
| /// don't have type `&Self`. |
| pub nonselflike_args: &'a [P<Expr>], |
| pub fields: &'a SubstructureFields<'a>, |
| } |
| |
| /// Summary of the relevant parts of a struct/enum field. |
| pub struct FieldInfo { |
| pub span: Span, |
| /// None for tuple structs/normal enum variants, Some for normal |
| /// structs/struct enum variants. |
| pub name: Option<Ident>, |
| /// The expression corresponding to this field of `self` |
| /// (specifically, a reference to it). |
| pub self_expr: P<Expr>, |
| /// The expressions corresponding to references to this field in |
| /// the other selflike arguments. |
| pub other_selflike_exprs: Vec<P<Expr>>, |
| } |
| |
| /// Fields for a static method |
| pub enum StaticFields { |
| /// Tuple and unit structs/enum variants like this. |
| Unnamed(Vec<Span>, bool /*is tuple*/), |
| /// Normal structs/struct variants. |
| Named(Vec<(Ident, Span)>), |
| } |
| |
| /// A summary of the possible sets of fields. |
| pub enum SubstructureFields<'a> { |
| /// A non-static method where `Self` is a struct. |
| Struct(&'a ast::VariantData, Vec<FieldInfo>), |
| |
| /// A non-static method handling the entire enum at once |
| /// (after it has been determined that none of the enum |
| /// variants has any fields). |
| AllFieldlessEnum(&'a ast::EnumDef), |
| |
| /// Matching variants of the enum: variant index, variant count, ast::Variant, |
| /// fields: the field name is only non-`None` in the case of a struct |
| /// variant. |
| EnumMatching(usize, usize, &'a ast::Variant, Vec<FieldInfo>), |
| |
| /// The tag of an enum. The first field is a `FieldInfo` for the tags, as |
| /// if they were fields. The second field is the expression to combine the |
| /// tag expression with; it will be `None` if no match is necessary. |
| EnumTag(FieldInfo, Option<P<Expr>>), |
| |
| /// A static method where `Self` is a struct. |
| StaticStruct(&'a ast::VariantData, StaticFields), |
| |
| /// A static method where `Self` is an enum. |
| StaticEnum(&'a ast::EnumDef, Vec<(Ident, Span, StaticFields)>), |
| } |
| |
| /// Combine the values of all the fields together. The last argument is |
| /// all the fields of all the structures. |
| pub type CombineSubstructureFunc<'a> = |
| Box<dyn FnMut(&mut ExtCtxt<'_>, Span, &Substructure<'_>) -> BlockOrExpr + 'a>; |
| |
| pub fn combine_substructure( |
| f: CombineSubstructureFunc<'_>, |
| ) -> RefCell<CombineSubstructureFunc<'_>> { |
| RefCell::new(f) |
| } |
| |
| struct TypeParameter { |
| bound_generic_params: ThinVec<ast::GenericParam>, |
| ty: P<ast::Ty>, |
| } |
| |
| /// The code snippets built up for derived code are sometimes used as blocks |
| /// (e.g. in a function body) and sometimes used as expressions (e.g. in a match |
| /// arm). This structure avoids committing to either form until necessary, |
| /// avoiding the insertion of any unnecessary blocks. |
| /// |
| /// The statements come before the expression. |
| pub struct BlockOrExpr(ThinVec<ast::Stmt>, Option<P<Expr>>); |
| |
| impl BlockOrExpr { |
| pub fn new_stmts(stmts: ThinVec<ast::Stmt>) -> BlockOrExpr { |
| BlockOrExpr(stmts, None) |
| } |
| |
| pub fn new_expr(expr: P<Expr>) -> BlockOrExpr { |
| BlockOrExpr(ThinVec::new(), Some(expr)) |
| } |
| |
| pub fn new_mixed(stmts: ThinVec<ast::Stmt>, expr: Option<P<Expr>>) -> BlockOrExpr { |
| BlockOrExpr(stmts, expr) |
| } |
| |
| // Converts it into a block. |
| fn into_block(mut self, cx: &ExtCtxt<'_>, span: Span) -> P<ast::Block> { |
| if let Some(expr) = self.1 { |
| self.0.push(cx.stmt_expr(expr)); |
| } |
| cx.block(span, self.0) |
| } |
| |
| // Converts it into an expression. |
| fn into_expr(self, cx: &ExtCtxt<'_>, span: Span) -> P<Expr> { |
| if self.0.is_empty() { |
| match self.1 { |
| None => cx.expr_block(cx.block(span, ThinVec::new())), |
| Some(expr) => expr, |
| } |
| } else if self.0.len() == 1 |
| && let ast::StmtKind::Expr(expr) = &self.0[0].kind |
| && self.1.is_none() |
| { |
| // There's only a single statement expression. Pull it out. |
| expr.clone() |
| } else { |
| // Multiple statements and/or expressions. |
| cx.expr_block(self.into_block(cx, span)) |
| } |
| } |
| } |
| |
| /// This method helps to extract all the type parameters referenced from a |
| /// type. For a type parameter `<T>`, it looks for either a `TyPath` that |
| /// is not global and starts with `T`, or a `TyQPath`. |
| /// Also include bound generic params from the input type. |
| fn find_type_parameters( |
| ty: &ast::Ty, |
| ty_param_names: &[Symbol], |
| cx: &ExtCtxt<'_>, |
| ) -> Vec<TypeParameter> { |
| use rustc_ast::visit; |
| |
| struct Visitor<'a, 'b> { |
| cx: &'a ExtCtxt<'b>, |
| ty_param_names: &'a [Symbol], |
| bound_generic_params_stack: ThinVec<ast::GenericParam>, |
| type_params: Vec<TypeParameter>, |
| } |
| |
| impl<'a, 'b> visit::Visitor<'a> for Visitor<'a, 'b> { |
| fn visit_ty(&mut self, ty: &'a ast::Ty) { |
| if let ast::TyKind::Path(_, path) = &ty.kind |
| && let Some(segment) = path.segments.first() |
| && self.ty_param_names.contains(&segment.ident.name) |
| { |
| self.type_params.push(TypeParameter { |
| bound_generic_params: self.bound_generic_params_stack.clone(), |
| ty: P(ty.clone()), |
| }); |
| } |
| |
| visit::walk_ty(self, ty) |
| } |
| |
| // 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.emit_err(errors::DeriveMacroCall { span: mac.span() }); |
| } |
| } |
| |
| let mut visitor = Visitor { |
| cx, |
| ty_param_names, |
| bound_generic_params_stack: ThinVec::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(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 newitem = match &item.kind { |
| ast::ItemKind::Struct(struct_def, generics) => self.expand_struct_def( |
| cx, |
| &struct_def, |
| item.ident, |
| generics, |
| from_scratch, |
| is_packed, |
| ), |
| ast::ItemKind::Enum(enum_def, generics) => { |
| // We ignore `is_packed` 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(struct_def, generics) => { |
| if self.supports_unions { |
| self.expand_struct_def( |
| cx, |
| &struct_def, |
| item.ident, |
| generics, |
| from_scratch, |
| is_packed, |
| ) |
| } else { |
| cx.emit_err(errors::DeriveUnion { span: mitem.span }); |
| 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>>, |
| is_packed: bool, |
| ) -> 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: ThinVec<_> = generics |
| .params |
| .iter() |
| .map(|param| match ¶m.kind { |
| GenericParamKind::Lifetime { .. } => param.clone(), |
| GenericParamKind::Type { .. } => { |
| // Extra restrictions on the generics parameters to the |
| // type being derived upon. |
| let bounds: Vec<_> = self |
| .additional_bounds |
| .iter() |
| .map(|p| { |
| cx.trait_bound( |
| p.to_path(cx, self.span, type_ident, generics), |
| self.is_const, |
| ) |
| }) |
| .chain( |
| // Add a bound for the current trait. |
| self.skip_path_as_bound |
| .not() |
| .then(|| cx.trait_bound(trait_path.clone(), self.is_const)), |
| ) |
| .chain({ |
| // Add a `Copy` bound if required. |
| if is_packed && self.needs_copy_as_bound_if_packed { |
| let p = deriving::path_std!(marker::Copy); |
| Some(cx.trait_bound( |
| p.to_path(cx, self.span, type_ident, generics), |
| self.is_const, |
| )) |
| } else { |
| None |
| } |
| }) |
| .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(_, p) = &field_ty_param.ty.kind |
| && let [sole_segment] = &*p.segments |
| && ty_param_names.contains(&sole_segment.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), |
| self.is_const, |
| ) |
| }) |
| .collect(); |
| |
| // Require the current trait. |
| bounds.push(cx.trait_bound(trait_path.clone(), self.is_const)); |
| |
| // Add a `Copy` bound if required. |
| if is_packed && self.needs_copy_as_bound_if_packed { |
| let p = deriving::path_std!(marker::Copy); |
| bounds.push(cx.trait_bound( |
| p.to_path(cx, self.span, type_ident, generics), |
| self.is_const, |
| )); |
| } |
| |
| 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 attrs = thin_vec![cx.attr_word(sym::automatically_derived, self.span),]; |
| 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, |
| ) -> 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, |
| ) |
| }; |
| |
| 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, is_packed) |
| } |
| |
| 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(); |
| |
| let is_packed = false; // enums are never packed |
| self.create_derived_impl(cx, type_ident, generics, field_tys, methods, is_packed) |
| } |
| } |
| |
| 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>, ThinVec<P<Expr>>, Vec<P<Expr>>, Vec<(Ident, P<ast::Ty>)>) { |
| let mut selflike_args = ThinVec::new(); |
| let mut nonselflike_args = Vec::new(); |
| let mut nonself_arg_tys = Vec::new(); |
| let span = trait_.span; |
| |
| let explicit_self = self.explicit_self.then(|| { |
| let (self_expr, explicit_self) = ty::get_explicit_self(cx, span); |
| selflike_args.push(self_expr); |
| explicit_self |
| }); |
| |
| 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, we use a local block to force a copy. |
| /// This requires that the field impl `Copy`. |
| /// ```rust,ignore (example) |
| /// # 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) |
| /// } |
| /// } |
| /// ``` |
| 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, |
| ) -> BlockOrExpr { |
| assert!(selflike_args.len() == 1 || selflike_args.len() == 2); |
| |
| let selflike_fields = |
| trait_.create_struct_field_access_fields(cx, selflike_args, struct_def, is_packed); |
| self.call_substructure_method( |
| cx, |
| trait_, |
| type_ident, |
| nonselflike_args, |
| &Struct(struct_def, selflike_fields), |
| ) |
| } |
| |
| 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 |
| /// `Unify`), 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, |
| mut selflike_args: ThinVec<P<Expr>>, |
| nonselflike_args: &[P<Expr>], |
| ) -> BlockOrExpr { |
| assert!( |
| !selflike_args.is_empty(), |
| "static methods must use `expand_static_enum_method_body`", |
| ); |
| |
| let span = trait_.span; |
| let variants = &enum_def.variants; |
| |
| // Traits that unify fieldless variants always use the tag(s). |
| let unify_fieldless_variants = |
| self.fieldless_variants_strategy == FieldlessVariantsStrategy::Unify; |
| |
| // For zero-variant enum, this function body is unreachable. Generate |
| // `match *self {}`. This produces machine code identical to `unsafe { |
| // core::intrinsics::unreachable() }` while being safe and stable. |
| if variants.is_empty() { |
| selflike_args.truncate(1); |
| let match_arg = cx.expr_deref(span, selflike_args.pop().unwrap()); |
| let match_arms = ThinVec::new(); |
| let expr = cx.expr_match(span, match_arg, match_arms); |
| return BlockOrExpr(ThinVec::new(), Some(expr)); |
| } |
| |
| 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!("{name}_tag"), 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: ThinVec<_> = iter::zip(&tag_idents, &selflike_args) |
| .map(|(&ident, selflike_arg)| { |
| let variant_value = deriving::call_intrinsic( |
| cx, |
| span, |
| sym::discriminant_value, |
| thin_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 variants.len() > 1 { |
| match self.fieldless_variants_strategy { |
| FieldlessVariantsStrategy::Unify => { |
| // 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); |
| } |
| FieldlessVariantsStrategy::SpecializeIfAllVariantsFieldless => { |
| return self.call_substructure_method( |
| cx, |
| trait_, |
| type_ident, |
| nonselflike_args, |
| &AllFieldlessEnum(enum_def), |
| ); |
| } |
| FieldlessVariantsStrategy::Default => (), |
| } |
| } else 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: ThinVec<ast::Arm> = variants |
| .iter() |
| .enumerate() |
| .filter(|&(_, v)| !(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 = 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 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: ThinVec<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 unify_fieldless_variants && 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(ThinVec::new(), 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, |
| ) -> ThinVec<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, |
| is_packed: 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 is_packed { |
| // In general, fields in packed structs are copied via a |
| // block, e.g. `&{self.0}`. The two exceptions are `[u8]` |
| // and `str` fields, which cannot be copied and also never |
| // cause unaligned references. These exceptions are allowed |
| // to handle the `FlexZeroSlice` type in the `zerovec` |
| // crate within `icu4x-0.9.0`. |
| // |
| // Once use of `icu4x-0.9.0` has dropped sufficiently, this |
| // exception should be removed. |
| let is_simple_path = |ty: &P<ast::Ty>, sym| { |
| if let TyKind::Path(None, ast::Path { segments, .. }) = &ty.kind && |
| let [seg] = segments.as_slice() && |
| seg.ident.name == sym && seg.args.is_none() |
| { |
| true |
| } else { |
| false |
| } |
| }; |
| |
| let exception = if let TyKind::Slice(ty) = &struct_field.ty.kind && |
| is_simple_path(ty, sym::u8) |
| { |
| Some("byte") |
| } else if is_simple_path(&struct_field.ty, sym::str) { |
| Some("string") |
| } else { |
| None |
| }; |
| |
| if let Some(ty) = exception { |
| cx.sess.parse_sess.buffer_lint_with_diagnostic( |
| BYTE_SLICE_IN_PACKED_STRUCT_WITH_DERIVE, |
| sp, |
| ast::CRATE_NODE_ID, |
| format!( |
| "{ty} slice in a packed struct that derives a built-in trait" |
| ), |
| rustc_lint_defs::BuiltinLintDiagnostics::ByteSliceInPackedStructWithDerive |
| ); |
| } else { |
| // Wrap the expression in `{...}`, causing a copy. |
| field_expr = cx.expr_block( |
| cx.block(struct_field.span, thin_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`"), |
| AllFieldlessEnum(..) => cx.span_bug(trait_span, "fieldless enum in `derive`"), |
| } |
| } |
