diff options
Diffstat (limited to 'compiler/rustc_ast_lowering/src')
| -rw-r--r-- | compiler/rustc_ast_lowering/src/delegation.rs | 348 | ||||
| -rw-r--r-- | compiler/rustc_ast_lowering/src/item.rs | 41 | ||||
| -rw-r--r-- | compiler/rustc_ast_lowering/src/lib.rs | 1 |
3 files changed, 386 insertions, 4 deletions
diff --git a/compiler/rustc_ast_lowering/src/delegation.rs b/compiler/rustc_ast_lowering/src/delegation.rs new file mode 100644 index 00000000000..6ccf39b0cb1 --- /dev/null +++ b/compiler/rustc_ast_lowering/src/delegation.rs @@ -0,0 +1,348 @@ +//! This module implements expansion of delegation items with early resolved paths. +//! It includes a delegation to a free functions: +//! +//! ```ignore (illustrative) +//! reuse module::name { target_expr_template } +//! ``` +//! +//! And delegation to a trait methods: +//! +//! ```ignore (illustrative) +//! reuse <Type as Trait>::name { target_expr_template } +//! ``` +//! +//! After expansion for both cases we get: +//! +//! ```ignore (illustrative) +//! fn name( +//! arg0: InferDelegation(sig_id, Input(0)), +//! arg1: InferDelegation(sig_id, Input(1)), +//! ..., +//! argN: InferDelegation(sig_id, Input(N)), +//! ) -> InferDelegation(sig_id, Output) { +//! callee_path(target_expr_template(arg0), arg1, ..., argN) +//! } +//! ``` +//! +//! Where `callee_path` is a path in delegation item e.g. `<Type as Trait>::name`. +//! `sig_id` is a id of item from which the signature is inherited. It may be a delegation +//! item id (`item_id`) in case of impl trait or path resolution id (`path_id`) otherwise. +//! +//! Since we do not have a proper way to obtain function type information by path resolution +//! in AST, we mark each function parameter type as `InferDelegation` and inherit it in `AstConv`. +//! +//! Similarly generics, predicates and header are set to the "default" values. +//! In case of discrepancy with callee function the `NotSupportedDelegation` error will +//! also be emitted in `AstConv`. + +use crate::{ImplTraitPosition, ResolverAstLoweringExt}; + +use super::{ImplTraitContext, LoweringContext, ParamMode}; + +use ast::visit::Visitor; +use hir::def::{DefKind, PartialRes, Res}; +use hir::{BodyId, HirId}; +use rustc_ast as ast; +use rustc_ast::*; +use rustc_errors::ErrorGuaranteed; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_middle::span_bug; +use rustc_middle::ty::ResolverAstLowering; +use rustc_span::{symbol::Ident, Span}; +use rustc_target::spec::abi; +use std::iter; + +pub(crate) struct DelegationResults<'hir> { + pub body_id: hir::BodyId, + pub sig: hir::FnSig<'hir>, + pub generics: &'hir hir::Generics<'hir>, +} + +impl<'hir> LoweringContext<'_, 'hir> { + pub(crate) fn delegation_has_self(&self, item_id: NodeId, path_id: NodeId, span: Span) -> bool { + let sig_id = self.get_delegation_sig_id(item_id, path_id, span); + let Ok(sig_id) = sig_id else { + return false; + }; + if let Some(local_sig_id) = sig_id.as_local() { + self.resolver.has_self.contains(&local_sig_id) + } else { + match self.tcx.def_kind(sig_id) { + DefKind::Fn => false, + DefKind::AssocFn => self.tcx.associated_item(sig_id).fn_has_self_parameter, + _ => span_bug!(span, "unexpected DefKind for delegation item"), + } + } + } + + pub(crate) fn lower_delegation( + &mut self, + delegation: &Delegation, + item_id: NodeId, + ) -> DelegationResults<'hir> { + let span = delegation.path.segments.last().unwrap().ident.span; + let sig_id = self.get_delegation_sig_id(item_id, delegation.id, span); + match sig_id { + Ok(sig_id) => { + let decl = self.lower_delegation_decl(sig_id, span); + let sig = self.lower_delegation_sig(span, decl); + let body_id = self.lower_delegation_body(sig.decl, delegation); + + let generics = self.lower_delegation_generics(span); + DelegationResults { body_id, sig, generics } + } + Err(err) => self.generate_delegation_error(err, span), + } + } + + fn get_delegation_sig_id( + &self, + item_id: NodeId, + path_id: NodeId, + span: Span, + ) -> Result<DefId, ErrorGuaranteed> { + let sig_id = if self.is_in_trait_impl { item_id } else { path_id }; + let sig_id = self + .resolver + .get_partial_res(sig_id) + .map(|r| r.expect_full_res().opt_def_id()) + .unwrap_or(None); + + sig_id.ok_or_else(|| { + self.tcx + .dcx() + .span_delayed_bug(span, "LoweringContext: couldn't resolve delegation item") + }) + } + + fn lower_delegation_generics(&mut self, span: Span) -> &'hir hir::Generics<'hir> { + self.arena.alloc(hir::Generics { + params: &[], + predicates: &[], + has_where_clause_predicates: false, + where_clause_span: span, + span: span, + }) + } + + fn lower_delegation_decl( + &mut self, + sig_id: DefId, + param_span: Span, + ) -> &'hir hir::FnDecl<'hir> { + let args_count = if let Some(local_sig_id) = sig_id.as_local() { + // Map may be filled incorrectly due to recursive delegation. + // Error will be emmited later in astconv. + self.resolver.fn_parameter_counts.get(&local_sig_id).cloned().unwrap_or_default() + } else { + self.tcx.fn_arg_names(sig_id).len() + }; + let inputs = self.arena.alloc_from_iter((0..args_count).into_iter().map(|arg| hir::Ty { + hir_id: self.next_id(), + kind: hir::TyKind::InferDelegation(sig_id, hir::InferDelegationKind::Input(arg)), + span: self.lower_span(param_span), + })); + + let output = self.arena.alloc(hir::Ty { + hir_id: self.next_id(), + kind: hir::TyKind::InferDelegation(sig_id, hir::InferDelegationKind::Output), + span: self.lower_span(param_span), + }); + + self.arena.alloc(hir::FnDecl { + inputs, + output: hir::FnRetTy::Return(output), + c_variadic: false, + lifetime_elision_allowed: true, + implicit_self: hir::ImplicitSelfKind::None, + }) + } + + fn lower_delegation_sig( + &mut self, + span: Span, + decl: &'hir hir::FnDecl<'hir>, + ) -> hir::FnSig<'hir> { + hir::FnSig { + decl, + header: hir::FnHeader { + unsafety: hir::Unsafety::Normal, + constness: hir::Constness::NotConst, + asyncness: hir::IsAsync::NotAsync, + abi: abi::Abi::Rust, + }, + span: self.lower_span(span), + } + } + + fn generate_param(&mut self, ty: &'hir hir::Ty<'hir>) -> (hir::Param<'hir>, NodeId) { + let pat_node_id = self.next_node_id(); + let pat_id = self.lower_node_id(pat_node_id); + let pat = self.arena.alloc(hir::Pat { + hir_id: pat_id, + kind: hir::PatKind::Binding(hir::BindingAnnotation::NONE, pat_id, Ident::empty(), None), + span: ty.span, + default_binding_modes: false, + }); + + (hir::Param { hir_id: self.next_id(), pat, ty_span: ty.span, span: ty.span }, pat_node_id) + } + + fn generate_arg(&mut self, ty: &'hir hir::Ty<'hir>, param_id: HirId) -> hir::Expr<'hir> { + let segments = self.arena.alloc_from_iter(iter::once(hir::PathSegment { + ident: Ident::empty(), + hir_id: self.next_id(), + res: Res::Local(param_id), + args: None, + infer_args: false, + })); + + let path = + self.arena.alloc(hir::Path { span: ty.span, res: Res::Local(param_id), segments }); + + hir::Expr { + hir_id: self.next_id(), + kind: hir::ExprKind::Path(hir::QPath::Resolved(None, path)), + span: ty.span, + } + } + + fn lower_delegation_body( + &mut self, + decl: &'hir hir::FnDecl<'hir>, + delegation: &Delegation, + ) -> BodyId { + let path = self.lower_qpath( + delegation.id, + &delegation.qself, + &delegation.path, + ParamMode::Optional, + &ImplTraitContext::Disallowed(ImplTraitPosition::Path), + None, + ); + let block = delegation.body.as_deref(); + + self.lower_body(|this| { + let mut parameters: Vec<hir::Param<'_>> = Vec::new(); + let mut args: Vec<hir::Expr<'hir>> = Vec::new(); + + for (idx, param_ty) in decl.inputs.iter().enumerate() { + let (param, pat_node_id) = this.generate_param(param_ty); + parameters.push(param); + + let arg = if let Some(block) = block + && idx == 0 + { + let mut self_resolver = SelfResolver { + resolver: this.resolver, + path_id: delegation.id, + self_param_id: pat_node_id, + }; + self_resolver.visit_block(block); + let block = this.lower_block(block, false); + hir::Expr { + hir_id: this.next_id(), + kind: hir::ExprKind::Block(block, None), + span: block.span, + } + } else { + let pat_hir_id = this.lower_node_id(pat_node_id); + this.generate_arg(param_ty, pat_hir_id) + }; + args.push(arg); + } + + let args = self.arena.alloc_from_iter(args); + let final_expr = this.generate_call(path, args); + (this.arena.alloc_from_iter(parameters), final_expr) + }) + } + + fn generate_call( + &mut self, + path: hir::QPath<'hir>, + args: &'hir [hir::Expr<'hir>], + ) -> hir::Expr<'hir> { + let callee = self.arena.alloc(hir::Expr { + hir_id: self.next_id(), + kind: hir::ExprKind::Path(path), + span: path.span(), + }); + + let expr = self.arena.alloc(hir::Expr { + hir_id: self.next_id(), + kind: hir::ExprKind::Call(callee, args), + span: path.span(), + }); + + let block = self.arena.alloc(hir::Block { + stmts: &[], + expr: Some(expr), + hir_id: self.next_id(), + rules: hir::BlockCheckMode::DefaultBlock, + span: path.span(), + targeted_by_break: false, + }); + + hir::Expr { + hir_id: self.next_id(), + kind: hir::ExprKind::Block(block, None), + span: path.span(), + } + } + + fn generate_delegation_error( + &mut self, + err: ErrorGuaranteed, + span: Span, + ) -> DelegationResults<'hir> { + let generics = self.lower_delegation_generics(span); + + let decl = self.arena.alloc(hir::FnDecl { + inputs: &[], + output: hir::FnRetTy::DefaultReturn(span), + c_variadic: false, + lifetime_elision_allowed: true, + implicit_self: hir::ImplicitSelfKind::None, + }); + + let sig = self.lower_delegation_sig(span, decl); + let body_id = self.lower_body(|this| { + let expr = + hir::Expr { hir_id: this.next_id(), kind: hir::ExprKind::Err(err), span: span }; + (&[], expr) + }); + DelegationResults { generics, body_id, sig } + } +} + +struct SelfResolver<'a> { + resolver: &'a mut ResolverAstLowering, + path_id: NodeId, + self_param_id: NodeId, +} + +impl<'a> SelfResolver<'a> { + fn try_replace_id(&mut self, id: NodeId) { + if let Some(res) = self.resolver.partial_res_map.get(&id) + && let Some(Res::Local(sig_id)) = res.full_res() + && sig_id == self.path_id + { + let new_res = PartialRes::new(Res::Local(self.self_param_id)); + self.resolver.partial_res_map.insert(id, new_res); + } + } +} + +impl<'ast, 'a> Visitor<'ast> for SelfResolver<'a> { + fn visit_path(&mut self, path: &'ast Path, id: NodeId) { + self.try_replace_id(id); + visit::walk_path(self, path); + } + + fn visit_path_segment(&mut self, seg: &'ast PathSegment) { + self.try_replace_id(seg.id); + visit::walk_path_segment(self, seg); + } +} diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs index d8de447e5b4..a3ff02f5f69 100644 --- a/compiler/rustc_ast_lowering/src/item.rs +++ b/compiler/rustc_ast_lowering/src/item.rs @@ -441,6 +441,14 @@ impl<'hir> LoweringContext<'_, 'hir> { let macro_def = self.arena.alloc(ast::MacroDef { body, macro_rules: *macro_rules }); hir::ItemKind::Macro(macro_def, macro_kind) } + ItemKind::Delegation(box delegation) => { + let delegation_results = self.lower_delegation(delegation, id); + hir::ItemKind::Fn( + delegation_results.sig, + delegation_results.generics, + delegation_results.body_id, + ) + } ItemKind::MacCall(..) => { panic!("`TyMac` should have been expanded by now") } @@ -805,6 +813,14 @@ impl<'hir> LoweringContext<'_, 'hir> { ); (generics, kind, ty.is_some()) } + AssocItemKind::Delegation(box delegation) => { + let delegation_results = self.lower_delegation(delegation, i.id); + let item_kind = hir::TraitItemKind::Fn( + delegation_results.sig, + hir::TraitFn::Provided(delegation_results.body_id), + ); + (delegation_results.generics, item_kind, true) + } AssocItemKind::MacCall(..) => panic!("macro item shouldn't exist at this point"), }; @@ -826,6 +842,9 @@ impl<'hir> LoweringContext<'_, 'hir> { AssocItemKind::Fn(box Fn { sig, .. }) => { hir::AssocItemKind::Fn { has_self: sig.decl.has_self() } } + AssocItemKind::Delegation(box delegation) => hir::AssocItemKind::Fn { + has_self: self.delegation_has_self(i.id, delegation.id, i.span), + }, AssocItemKind::MacCall(..) => unimplemented!(), }; let id = hir::TraitItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }; @@ -908,6 +927,13 @@ impl<'hir> LoweringContext<'_, 'hir> { }, ) } + AssocItemKind::Delegation(box delegation) => { + let delegation_results = self.lower_delegation(delegation, i.id); + ( + delegation_results.generics, + hir::ImplItemKind::Fn(delegation_results.sig, delegation_results.body_id), + ) + } AssocItemKind::MacCall(..) => panic!("`TyMac` should have been expanded by now"), }; @@ -924,6 +950,13 @@ impl<'hir> LoweringContext<'_, 'hir> { } fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef { + let trait_item_def_id = self + .resolver + .get_partial_res(i.id) + .map(|r| r.expect_full_res().opt_def_id()) + .unwrap_or(None); + self.is_in_trait_impl = trait_item_def_id.is_some(); + hir::ImplItemRef { id: hir::ImplItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }, ident: self.lower_ident(i.ident), @@ -934,12 +967,12 @@ impl<'hir> LoweringContext<'_, 'hir> { AssocItemKind::Fn(box Fn { sig, .. }) => { hir::AssocItemKind::Fn { has_self: sig.decl.has_self() } } + AssocItemKind::Delegation(box delegation) => hir::AssocItemKind::Fn { + has_self: self.delegation_has_self(i.id, delegation.id, i.span), + }, AssocItemKind::MacCall(..) => unimplemented!(), }, - trait_item_def_id: self - .resolver - .get_partial_res(i.id) - .map(|r| r.expect_full_res().def_id()), + trait_item_def_id, } } diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs index dc23b1dce7b..d2d42a15808 100644 --- a/compiler/rustc_ast_lowering/src/lib.rs +++ b/compiler/rustc_ast_lowering/src/lib.rs @@ -77,6 +77,7 @@ macro_rules! arena_vec { mod asm; mod block; +mod delegation; mod errors; mod expr; mod format; |