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Commit | Line | Data |
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1 | use super::errors::{InvalidAbi, InvalidAbiSuggestion, MisplacedRelaxTraitBound}; | |
2 | use super::ResolverAstLoweringExt; | |
3 | use super::{AstOwner, ImplTraitContext, ImplTraitPosition}; | |
4 | use super::{FnDeclKind, LoweringContext, ParamMode}; | |
5 | ||
6 | use rustc_ast::ptr::P; | |
7 | use rustc_ast::visit::AssocCtxt; | |
8 | use rustc_ast::*; | |
9 | use rustc_data_structures::sorted_map::SortedMap; | |
10 | use rustc_errors::ErrorGuaranteed; | |
11 | use rustc_hir as hir; | |
12 | use rustc_hir::def::{DefKind, Res}; | |
13 | use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID}; | |
14 | use rustc_hir::PredicateOrigin; | |
15 | use rustc_index::vec::{Idx, IndexVec}; | |
16 | use rustc_middle::ty::{DefIdTree, ResolverAstLowering, TyCtxt}; | |
17 | use rustc_span::edit_distance::find_best_match_for_name; | |
18 | use rustc_span::source_map::DesugaringKind; | |
19 | use rustc_span::symbol::{kw, sym, Ident}; | |
20 | use rustc_span::{Span, Symbol}; | |
21 | use rustc_target::spec::abi; | |
22 | use smallvec::{smallvec, SmallVec}; | |
23 | use thin_vec::ThinVec; | |
24 | ||
25 | pub(super) struct ItemLowerer<'a, 'hir> { | |
26 | pub(super) tcx: TyCtxt<'hir>, | |
27 | pub(super) resolver: &'a mut ResolverAstLowering, | |
28 | pub(super) ast_index: &'a IndexVec<LocalDefId, AstOwner<'a>>, | |
29 | pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>, | |
30 | } | |
31 | ||
32 | /// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span | |
33 | /// to the where clause that is preferred, if it exists. Otherwise, it sets the span to the other where | |
34 | /// clause if it exists. | |
35 | fn add_ty_alias_where_clause( | |
36 | generics: &mut ast::Generics, | |
37 | mut where_clauses: (TyAliasWhereClause, TyAliasWhereClause), | |
38 | prefer_first: bool, | |
39 | ) { | |
40 | if !prefer_first { | |
41 | where_clauses = (where_clauses.1, where_clauses.0); | |
42 | } | |
43 | if where_clauses.0.0 || !where_clauses.1.0 { | |
44 | generics.where_clause.has_where_token = where_clauses.0.0; | |
45 | generics.where_clause.span = where_clauses.0.1; | |
46 | } else { | |
47 | generics.where_clause.has_where_token = where_clauses.1.0; | |
48 | generics.where_clause.span = where_clauses.1.1; | |
49 | } | |
50 | } | |
51 | ||
52 | impl<'a, 'hir> ItemLowerer<'a, 'hir> { | |
53 | fn with_lctx( | |
54 | &mut self, | |
55 | owner: NodeId, | |
56 | f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>, | |
57 | ) { | |
58 | let mut lctx = LoweringContext { | |
59 | // Pseudo-globals. | |
60 | tcx: self.tcx, | |
61 | resolver: self.resolver, | |
62 | arena: self.tcx.hir_arena, | |
63 | ||
64 | // HirId handling. | |
65 | bodies: Vec::new(), | |
66 | attrs: SortedMap::default(), | |
67 | children: Vec::default(), | |
68 | current_hir_id_owner: hir::CRATE_OWNER_ID, | |
69 | item_local_id_counter: hir::ItemLocalId::new(0), | |
70 | node_id_to_local_id: Default::default(), | |
71 | trait_map: Default::default(), | |
72 | ||
73 | // Lowering state. | |
74 | catch_scope: None, | |
75 | loop_scope: None, | |
76 | is_in_loop_condition: false, | |
77 | is_in_trait_impl: false, | |
78 | is_in_dyn_type: false, | |
79 | generator_kind: None, | |
80 | task_context: None, | |
81 | current_item: None, | |
82 | impl_trait_defs: Vec::new(), | |
83 | impl_trait_bounds: Vec::new(), | |
84 | allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()), | |
85 | allow_gen_future: Some([sym::gen_future, sym::closure_track_caller][..].into()), | |
86 | allow_into_future: Some([sym::into_future][..].into()), | |
87 | generics_def_id_map: Default::default(), | |
88 | }; | |
89 | lctx.with_hir_id_owner(owner, |lctx| f(lctx)); | |
90 | ||
91 | for (def_id, info) in lctx.children { | |
92 | self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom); | |
93 | debug_assert!(matches!(self.owners[def_id], hir::MaybeOwner::Phantom)); | |
94 | self.owners[def_id] = info; | |
95 | } | |
96 | } | |
97 | ||
98 | pub(super) fn lower_node( | |
99 | &mut self, | |
100 | def_id: LocalDefId, | |
101 | ) -> hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>> { | |
102 | self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom); | |
103 | if let hir::MaybeOwner::Phantom = self.owners[def_id] { | |
104 | let node = self.ast_index[def_id]; | |
105 | match node { | |
106 | AstOwner::NonOwner => {} | |
107 | AstOwner::Crate(c) => self.lower_crate(c), | |
108 | AstOwner::Item(item) => self.lower_item(item), | |
109 | AstOwner::AssocItem(item, ctxt) => self.lower_assoc_item(item, ctxt), | |
110 | AstOwner::ForeignItem(item) => self.lower_foreign_item(item), | |
111 | } | |
112 | } | |
113 | ||
114 | self.owners[def_id] | |
115 | } | |
116 | ||
117 | #[instrument(level = "debug", skip(self, c))] | |
118 | fn lower_crate(&mut self, c: &Crate) { | |
119 | debug_assert_eq!(self.resolver.node_id_to_def_id[&CRATE_NODE_ID], CRATE_DEF_ID); | |
120 | self.with_lctx(CRATE_NODE_ID, |lctx| { | |
121 | let module = lctx.lower_mod(&c.items, &c.spans); | |
122 | lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs); | |
123 | hir::OwnerNode::Crate(module) | |
124 | }) | |
125 | } | |
126 | ||
127 | #[instrument(level = "debug", skip(self))] | |
128 | fn lower_item(&mut self, item: &Item) { | |
129 | self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item))) | |
130 | } | |
131 | ||
132 | fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) { | |
133 | let def_id = self.resolver.node_id_to_def_id[&item.id]; | |
134 | ||
135 | let parent_id = self.tcx.local_parent(def_id); | |
136 | let parent_hir = self.lower_node(parent_id).unwrap(); | |
137 | self.with_lctx(item.id, |lctx| { | |
138 | // Evaluate with the lifetimes in `params` in-scope. | |
139 | // This is used to track which lifetimes have already been defined, | |
140 | // and which need to be replicated when lowering an async fn. | |
141 | match parent_hir.node().expect_item().kind { | |
142 | hir::ItemKind::Impl(hir::Impl { of_trait, .. }) => { | |
143 | lctx.is_in_trait_impl = of_trait.is_some(); | |
144 | } | |
145 | _ => {} | |
146 | }; | |
147 | ||
148 | match ctxt { | |
149 | AssocCtxt::Trait => hir::OwnerNode::TraitItem(lctx.lower_trait_item(item)), | |
150 | AssocCtxt::Impl => hir::OwnerNode::ImplItem(lctx.lower_impl_item(item)), | |
151 | } | |
152 | }) | |
153 | } | |
154 | ||
155 | fn lower_foreign_item(&mut self, item: &ForeignItem) { | |
156 | self.with_lctx(item.id, |lctx| hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item))) | |
157 | } | |
158 | } | |
159 | ||
160 | impl<'hir> LoweringContext<'_, 'hir> { | |
161 | pub(super) fn lower_mod( | |
162 | &mut self, | |
163 | items: &[P<Item>], | |
164 | spans: &ModSpans, | |
165 | ) -> &'hir hir::Mod<'hir> { | |
166 | self.arena.alloc(hir::Mod { | |
167 | spans: hir::ModSpans { | |
168 | inner_span: self.lower_span(spans.inner_span), | |
169 | inject_use_span: self.lower_span(spans.inject_use_span), | |
170 | }, | |
171 | item_ids: self.arena.alloc_from_iter(items.iter().flat_map(|x| self.lower_item_ref(x))), | |
172 | }) | |
173 | } | |
174 | ||
175 | pub(super) fn lower_item_ref(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]> { | |
176 | let mut node_ids = | |
177 | smallvec![hir::ItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }]; | |
178 | if let ItemKind::Use(use_tree) = &i.kind { | |
179 | self.lower_item_id_use_tree(use_tree, &mut node_ids); | |
180 | } | |
181 | node_ids | |
182 | } | |
183 | ||
184 | fn lower_item_id_use_tree(&mut self, tree: &UseTree, vec: &mut SmallVec<[hir::ItemId; 1]>) { | |
185 | match &tree.kind { | |
186 | UseTreeKind::Nested(nested_vec) => { | |
187 | for &(ref nested, id) in nested_vec { | |
188 | vec.push(hir::ItemId { | |
189 | owner_id: hir::OwnerId { def_id: self.local_def_id(id) }, | |
190 | }); | |
191 | self.lower_item_id_use_tree(nested, vec); | |
192 | } | |
193 | } | |
194 | UseTreeKind::Simple(..) | UseTreeKind::Glob => {} | |
195 | } | |
196 | } | |
197 | ||
198 | fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> { | |
199 | let mut ident = i.ident; | |
200 | let vis_span = self.lower_span(i.vis.span); | |
201 | let hir_id = self.lower_node_id(i.id); | |
202 | let attrs = self.lower_attrs(hir_id, &i.attrs); | |
203 | let kind = self.lower_item_kind(i.span, i.id, hir_id, &mut ident, attrs, vis_span, &i.kind); | |
204 | let item = hir::Item { | |
205 | owner_id: hir_id.expect_owner(), | |
206 | ident: self.lower_ident(ident), | |
207 | kind, | |
208 | vis_span, | |
209 | span: self.lower_span(i.span), | |
210 | }; | |
211 | self.arena.alloc(item) | |
212 | } | |
213 | ||
214 | fn lower_item_kind( | |
215 | &mut self, | |
216 | span: Span, | |
217 | id: NodeId, | |
218 | hir_id: hir::HirId, | |
219 | ident: &mut Ident, | |
220 | attrs: Option<&'hir [Attribute]>, | |
221 | vis_span: Span, | |
222 | i: &ItemKind, | |
223 | ) -> hir::ItemKind<'hir> { | |
224 | match i { | |
225 | ItemKind::ExternCrate(orig_name) => hir::ItemKind::ExternCrate(*orig_name), | |
226 | ItemKind::Use(use_tree) => { | |
227 | // Start with an empty prefix. | |
228 | let prefix = Path { segments: ThinVec::new(), span: use_tree.span, tokens: None }; | |
229 | ||
230 | self.lower_use_tree(use_tree, &prefix, id, vis_span, ident, attrs) | |
231 | } | |
232 | ItemKind::Static(t, m, e) => { | |
233 | let (ty, body_id) = self.lower_const_item(t, span, e.as_deref()); | |
234 | hir::ItemKind::Static(ty, *m, body_id) | |
235 | } | |
236 | ItemKind::Const(_, t, e) => { | |
237 | let (ty, body_id) = self.lower_const_item(t, span, e.as_deref()); | |
238 | hir::ItemKind::Const(ty, body_id) | |
239 | } | |
240 | ItemKind::Fn(box Fn { | |
241 | sig: FnSig { decl, header, span: fn_sig_span }, | |
242 | generics, | |
243 | body, | |
244 | .. | |
245 | }) => { | |
246 | self.with_new_scopes(|this| { | |
247 | this.current_item = Some(ident.span); | |
248 | ||
249 | // Note: we don't need to change the return type from `T` to | |
250 | // `impl Future<Output = T>` here because lower_body | |
251 | // only cares about the input argument patterns in the function | |
252 | // declaration (decl), not the return types. | |
253 | let asyncness = header.asyncness; | |
254 | let body_id = this.lower_maybe_async_body( | |
255 | span, | |
256 | hir_id, | |
257 | &decl, | |
258 | asyncness, | |
259 | body.as_deref(), | |
260 | ); | |
261 | ||
262 | let itctx = ImplTraitContext::Universal; | |
263 | let (generics, decl) = this.lower_generics(generics, id, &itctx, |this| { | |
264 | let ret_id = asyncness.opt_return_id(); | |
265 | this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id) | |
266 | }); | |
267 | let sig = hir::FnSig { | |
268 | decl, | |
269 | header: this.lower_fn_header(*header), | |
270 | span: this.lower_span(*fn_sig_span), | |
271 | }; | |
272 | hir::ItemKind::Fn(sig, generics, body_id) | |
273 | }) | |
274 | } | |
275 | ItemKind::Mod(_, mod_kind) => match mod_kind { | |
276 | ModKind::Loaded(items, _, spans) => { | |
277 | hir::ItemKind::Mod(self.lower_mod(items, spans)) | |
278 | } | |
279 | ModKind::Unloaded => panic!("`mod` items should have been loaded by now"), | |
280 | }, | |
281 | ItemKind::ForeignMod(fm) => hir::ItemKind::ForeignMod { | |
282 | abi: fm.abi.map_or(abi::Abi::FALLBACK, |abi| self.lower_abi(abi)), | |
283 | items: self | |
284 | .arena | |
285 | .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))), | |
286 | }, | |
287 | ItemKind::GlobalAsm(asm) => hir::ItemKind::GlobalAsm(self.lower_inline_asm(span, asm)), | |
288 | ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => { | |
289 | // We lower | |
290 | // | |
291 | // type Foo = impl Trait | |
292 | // | |
293 | // to | |
294 | // | |
295 | // type Foo = Foo1 | |
296 | // opaque type Foo1: Trait | |
297 | let mut generics = generics.clone(); | |
298 | add_ty_alias_where_clause(&mut generics, *where_clauses, true); | |
299 | let (generics, ty) = self.lower_generics( | |
300 | &generics, | |
301 | id, | |
302 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
303 | |this| match ty { | |
304 | None => { | |
305 | let guar = this.tcx.sess.delay_span_bug( | |
306 | span, | |
307 | "expected to lower type alias type, but it was missing", | |
308 | ); | |
309 | this.arena.alloc(this.ty(span, hir::TyKind::Err(guar))) | |
310 | } | |
311 | Some(ty) => this.lower_ty(ty, &ImplTraitContext::TypeAliasesOpaqueTy), | |
312 | }, | |
313 | ); | |
314 | hir::ItemKind::TyAlias(ty, generics) | |
315 | } | |
316 | ItemKind::Enum(enum_definition, generics) => { | |
317 | let (generics, variants) = self.lower_generics( | |
318 | generics, | |
319 | id, | |
320 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
321 | |this| { | |
322 | this.arena.alloc_from_iter( | |
323 | enum_definition.variants.iter().map(|x| this.lower_variant(x)), | |
324 | ) | |
325 | }, | |
326 | ); | |
327 | hir::ItemKind::Enum(hir::EnumDef { variants }, generics) | |
328 | } | |
329 | ItemKind::Struct(struct_def, generics) => { | |
330 | let (generics, struct_def) = self.lower_generics( | |
331 | generics, | |
332 | id, | |
333 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
334 | |this| this.lower_variant_data(hir_id, struct_def), | |
335 | ); | |
336 | hir::ItemKind::Struct(struct_def, generics) | |
337 | } | |
338 | ItemKind::Union(vdata, generics) => { | |
339 | let (generics, vdata) = self.lower_generics( | |
340 | generics, | |
341 | id, | |
342 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
343 | |this| this.lower_variant_data(hir_id, vdata), | |
344 | ); | |
345 | hir::ItemKind::Union(vdata, generics) | |
346 | } | |
347 | ItemKind::Impl(box Impl { | |
348 | unsafety, | |
349 | polarity, | |
350 | defaultness, | |
351 | constness, | |
352 | generics: ast_generics, | |
353 | of_trait: trait_ref, | |
354 | self_ty: ty, | |
355 | items: impl_items, | |
356 | }) => { | |
357 | // Lower the "impl header" first. This ordering is important | |
358 | // for in-band lifetimes! Consider `'a` here: | |
359 | // | |
360 | // impl Foo<'a> for u32 { | |
361 | // fn method(&'a self) { .. } | |
362 | // } | |
363 | // | |
364 | // Because we start by lowering the `Foo<'a> for u32` | |
365 | // part, we will add `'a` to the list of generics on | |
366 | // the impl. When we then encounter it later in the | |
367 | // method, it will not be considered an in-band | |
368 | // lifetime to be added, but rather a reference to a | |
369 | // parent lifetime. | |
370 | let itctx = ImplTraitContext::Universal; | |
371 | let (generics, (trait_ref, lowered_ty)) = | |
372 | self.lower_generics(ast_generics, id, &itctx, |this| { | |
373 | let trait_ref = trait_ref.as_ref().map(|trait_ref| { | |
374 | this.lower_trait_ref( | |
375 | trait_ref, | |
376 | &ImplTraitContext::Disallowed(ImplTraitPosition::Trait), | |
377 | ) | |
378 | }); | |
379 | ||
380 | let lowered_ty = this.lower_ty( | |
381 | ty, | |
382 | &ImplTraitContext::Disallowed(ImplTraitPosition::ImplSelf), | |
383 | ); | |
384 | ||
385 | (trait_ref, lowered_ty) | |
386 | }); | |
387 | ||
388 | let new_impl_items = self | |
389 | .arena | |
390 | .alloc_from_iter(impl_items.iter().map(|item| self.lower_impl_item_ref(item))); | |
391 | ||
392 | // `defaultness.has_value()` is never called for an `impl`, always `true` in order | |
393 | // to not cause an assertion failure inside the `lower_defaultness` function. | |
394 | let has_val = true; | |
395 | let (defaultness, defaultness_span) = self.lower_defaultness(*defaultness, has_val); | |
396 | let polarity = match polarity { | |
397 | ImplPolarity::Positive => ImplPolarity::Positive, | |
398 | ImplPolarity::Negative(s) => ImplPolarity::Negative(self.lower_span(*s)), | |
399 | }; | |
400 | hir::ItemKind::Impl(self.arena.alloc(hir::Impl { | |
401 | unsafety: self.lower_unsafety(*unsafety), | |
402 | polarity, | |
403 | defaultness, | |
404 | defaultness_span, | |
405 | constness: self.lower_constness(*constness), | |
406 | generics, | |
407 | of_trait: trait_ref, | |
408 | self_ty: lowered_ty, | |
409 | items: new_impl_items, | |
410 | })) | |
411 | } | |
412 | ItemKind::Trait(box Trait { is_auto, unsafety, generics, bounds, items }) => { | |
413 | let (generics, (unsafety, items, bounds)) = self.lower_generics( | |
414 | generics, | |
415 | id, | |
416 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
417 | |this| { | |
418 | let bounds = this.lower_param_bounds( | |
419 | bounds, | |
420 | &ImplTraitContext::Disallowed(ImplTraitPosition::Bound), | |
421 | ); | |
422 | let items = this.arena.alloc_from_iter( | |
423 | items.iter().map(|item| this.lower_trait_item_ref(item)), | |
424 | ); | |
425 | let unsafety = this.lower_unsafety(*unsafety); | |
426 | (unsafety, items, bounds) | |
427 | }, | |
428 | ); | |
429 | hir::ItemKind::Trait(*is_auto, unsafety, generics, bounds, items) | |
430 | } | |
431 | ItemKind::TraitAlias(generics, bounds) => { | |
432 | let (generics, bounds) = self.lower_generics( | |
433 | generics, | |
434 | id, | |
435 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
436 | |this| { | |
437 | this.lower_param_bounds( | |
438 | bounds, | |
439 | &ImplTraitContext::Disallowed(ImplTraitPosition::Bound), | |
440 | ) | |
441 | }, | |
442 | ); | |
443 | hir::ItemKind::TraitAlias(generics, bounds) | |
444 | } | |
445 | ItemKind::MacroDef(MacroDef { body, macro_rules }) => { | |
446 | let body = P(self.lower_delim_args(body)); | |
447 | let macro_kind = self.resolver.decl_macro_kind(self.local_def_id(id)); | |
448 | hir::ItemKind::Macro(ast::MacroDef { body, macro_rules: *macro_rules }, macro_kind) | |
449 | } | |
450 | ItemKind::MacCall(..) => { | |
451 | panic!("`TyMac` should have been expanded by now") | |
452 | } | |
453 | } | |
454 | } | |
455 | ||
456 | fn lower_const_item( | |
457 | &mut self, | |
458 | ty: &Ty, | |
459 | span: Span, | |
460 | body: Option<&Expr>, | |
461 | ) -> (&'hir hir::Ty<'hir>, hir::BodyId) { | |
462 | let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy)); | |
463 | (ty, self.lower_const_body(span, body)) | |
464 | } | |
465 | ||
466 | #[instrument(level = "debug", skip(self))] | |
467 | fn lower_use_tree( | |
468 | &mut self, | |
469 | tree: &UseTree, | |
470 | prefix: &Path, | |
471 | id: NodeId, | |
472 | vis_span: Span, | |
473 | ident: &mut Ident, | |
474 | attrs: Option<&'hir [Attribute]>, | |
475 | ) -> hir::ItemKind<'hir> { | |
476 | let path = &tree.prefix; | |
477 | let segments = prefix.segments.iter().chain(path.segments.iter()).cloned().collect(); | |
478 | ||
479 | match tree.kind { | |
480 | UseTreeKind::Simple(rename) => { | |
481 | *ident = tree.ident(); | |
482 | ||
483 | // First, apply the prefix to the path. | |
484 | let mut path = Path { segments, span: path.span, tokens: None }; | |
485 | ||
486 | // Correctly resolve `self` imports. | |
487 | if path.segments.len() > 1 | |
488 | && path.segments.last().unwrap().ident.name == kw::SelfLower | |
489 | { | |
490 | let _ = path.segments.pop(); | |
491 | if rename.is_none() { | |
492 | *ident = path.segments.last().unwrap().ident; | |
493 | } | |
494 | } | |
495 | ||
496 | let res = | |
497 | self.expect_full_res_from_use(id).map(|res| self.lower_res(res)).collect(); | |
498 | let path = self.lower_use_path(res, &path, ParamMode::Explicit); | |
499 | hir::ItemKind::Use(path, hir::UseKind::Single) | |
500 | } | |
501 | UseTreeKind::Glob => { | |
502 | let res = self.expect_full_res(id); | |
503 | let res = smallvec![self.lower_res(res)]; | |
504 | let path = Path { segments, span: path.span, tokens: None }; | |
505 | let path = self.lower_use_path(res, &path, ParamMode::Explicit); | |
506 | hir::ItemKind::Use(path, hir::UseKind::Glob) | |
507 | } | |
508 | UseTreeKind::Nested(ref trees) => { | |
509 | // Nested imports are desugared into simple imports. | |
510 | // So, if we start with | |
511 | // | |
512 | // ``` | |
513 | // pub(x) use foo::{a, b}; | |
514 | // ``` | |
515 | // | |
516 | // we will create three items: | |
517 | // | |
518 | // ``` | |
519 | // pub(x) use foo::a; | |
520 | // pub(x) use foo::b; | |
521 | // pub(x) use foo::{}; // <-- this is called the `ListStem` | |
522 | // ``` | |
523 | // | |
524 | // The first two are produced by recursively invoking | |
525 | // `lower_use_tree` (and indeed there may be things | |
526 | // like `use foo::{a::{b, c}}` and so forth). They | |
527 | // wind up being directly added to | |
528 | // `self.items`. However, the structure of this | |
529 | // function also requires us to return one item, and | |
530 | // for that we return the `{}` import (called the | |
531 | // `ListStem`). | |
532 | ||
533 | let prefix = Path { segments, span: prefix.span.to(path.span), tokens: None }; | |
534 | ||
535 | // Add all the nested `PathListItem`s to the HIR. | |
536 | for &(ref use_tree, id) in trees { | |
537 | let new_hir_id = self.local_def_id(id); | |
538 | ||
539 | let mut prefix = prefix.clone(); | |
540 | ||
541 | // Give the segments new node-ids since they are being cloned. | |
542 | for seg in &mut prefix.segments { | |
543 | // Give the cloned segment the same resolution information | |
544 | // as the old one (this is needed for stability checking). | |
545 | let new_id = self.next_node_id(); | |
546 | self.resolver.clone_res(seg.id, new_id); | |
547 | seg.id = new_id; | |
548 | } | |
549 | ||
550 | // Each `use` import is an item and thus are owners of the | |
551 | // names in the path. Up to this point the nested import is | |
552 | // the current owner, since we want each desugared import to | |
553 | // own its own names, we have to adjust the owner before | |
554 | // lowering the rest of the import. | |
555 | self.with_hir_id_owner(id, |this| { | |
556 | let mut ident = *ident; | |
557 | ||
558 | let kind = | |
559 | this.lower_use_tree(use_tree, &prefix, id, vis_span, &mut ident, attrs); | |
560 | if let Some(attrs) = attrs { | |
561 | this.attrs.insert(hir::ItemLocalId::new(0), attrs); | |
562 | } | |
563 | ||
564 | let item = hir::Item { | |
565 | owner_id: hir::OwnerId { def_id: new_hir_id }, | |
566 | ident: this.lower_ident(ident), | |
567 | kind, | |
568 | vis_span, | |
569 | span: this.lower_span(use_tree.span), | |
570 | }; | |
571 | hir::OwnerNode::Item(this.arena.alloc(item)) | |
572 | }); | |
573 | } | |
574 | ||
575 | let res = | |
576 | self.expect_full_res_from_use(id).map(|res| self.lower_res(res)).collect(); | |
577 | let path = self.lower_use_path(res, &prefix, ParamMode::Explicit); | |
578 | hir::ItemKind::Use(path, hir::UseKind::ListStem) | |
579 | } | |
580 | } | |
581 | } | |
582 | ||
583 | fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> { | |
584 | let hir_id = self.lower_node_id(i.id); | |
585 | let owner_id = hir_id.expect_owner(); | |
586 | self.lower_attrs(hir_id, &i.attrs); | |
587 | let item = hir::ForeignItem { | |
588 | owner_id, | |
589 | ident: self.lower_ident(i.ident), | |
590 | kind: match &i.kind { | |
591 | ForeignItemKind::Fn(box Fn { sig, generics, .. }) => { | |
592 | let fdec = &sig.decl; | |
593 | let itctx = ImplTraitContext::Universal; | |
594 | let (generics, (fn_dec, fn_args)) = | |
595 | self.lower_generics(generics, i.id, &itctx, |this| { | |
596 | ( | |
597 | // Disallow `impl Trait` in foreign items. | |
598 | this.lower_fn_decl( | |
599 | fdec, | |
600 | i.id, | |
601 | sig.span, | |
602 | FnDeclKind::ExternFn, | |
603 | None, | |
604 | ), | |
605 | this.lower_fn_params_to_names(fdec), | |
606 | ) | |
607 | }); | |
608 | ||
609 | hir::ForeignItemKind::Fn(fn_dec, fn_args, generics) | |
610 | } | |
611 | ForeignItemKind::Static(t, m, _) => { | |
612 | let ty = self | |
613 | .lower_ty(t, &ImplTraitContext::Disallowed(ImplTraitPosition::StaticTy)); | |
614 | hir::ForeignItemKind::Static(ty, *m) | |
615 | } | |
616 | ForeignItemKind::TyAlias(..) => hir::ForeignItemKind::Type, | |
617 | ForeignItemKind::MacCall(_) => panic!("macro shouldn't exist here"), | |
618 | }, | |
619 | vis_span: self.lower_span(i.vis.span), | |
620 | span: self.lower_span(i.span), | |
621 | }; | |
622 | self.arena.alloc(item) | |
623 | } | |
624 | ||
625 | fn lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemRef { | |
626 | hir::ForeignItemRef { | |
627 | id: hir::ForeignItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }, | |
628 | ident: self.lower_ident(i.ident), | |
629 | span: self.lower_span(i.span), | |
630 | } | |
631 | } | |
632 | ||
633 | fn lower_variant(&mut self, v: &Variant) -> hir::Variant<'hir> { | |
634 | let hir_id = self.lower_node_id(v.id); | |
635 | self.lower_attrs(hir_id, &v.attrs); | |
636 | hir::Variant { | |
637 | hir_id, | |
638 | def_id: self.local_def_id(v.id), | |
639 | data: self.lower_variant_data(hir_id, &v.data), | |
640 | disr_expr: v.disr_expr.as_ref().map(|e| self.lower_anon_const(e)), | |
641 | ident: self.lower_ident(v.ident), | |
642 | span: self.lower_span(v.span), | |
643 | } | |
644 | } | |
645 | ||
646 | fn lower_variant_data( | |
647 | &mut self, | |
648 | parent_id: hir::HirId, | |
649 | vdata: &VariantData, | |
650 | ) -> hir::VariantData<'hir> { | |
651 | match vdata { | |
652 | VariantData::Struct(fields, recovered) => hir::VariantData::Struct( | |
653 | self.arena | |
654 | .alloc_from_iter(fields.iter().enumerate().map(|f| self.lower_field_def(f))), | |
655 | *recovered, | |
656 | ), | |
657 | VariantData::Tuple(fields, id) => { | |
658 | let ctor_id = self.lower_node_id(*id); | |
659 | self.alias_attrs(ctor_id, parent_id); | |
660 | hir::VariantData::Tuple( | |
661 | self.arena.alloc_from_iter( | |
662 | fields.iter().enumerate().map(|f| self.lower_field_def(f)), | |
663 | ), | |
664 | ctor_id, | |
665 | self.local_def_id(*id), | |
666 | ) | |
667 | } | |
668 | VariantData::Unit(id) => { | |
669 | let ctor_id = self.lower_node_id(*id); | |
670 | self.alias_attrs(ctor_id, parent_id); | |
671 | hir::VariantData::Unit(ctor_id, self.local_def_id(*id)) | |
672 | } | |
673 | } | |
674 | } | |
675 | ||
676 | fn lower_field_def(&mut self, (index, f): (usize, &FieldDef)) -> hir::FieldDef<'hir> { | |
677 | let ty = if let TyKind::Path(qself, path) = &f.ty.kind { | |
678 | let t = self.lower_path_ty( | |
679 | &f.ty, | |
680 | qself, | |
681 | path, | |
682 | ParamMode::ExplicitNamed, // no `'_` in declarations (Issue #61124) | |
683 | &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy), | |
684 | ); | |
685 | self.arena.alloc(t) | |
686 | } else { | |
687 | self.lower_ty(&f.ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy)) | |
688 | }; | |
689 | let hir_id = self.lower_node_id(f.id); | |
690 | self.lower_attrs(hir_id, &f.attrs); | |
691 | hir::FieldDef { | |
692 | span: self.lower_span(f.span), | |
693 | hir_id, | |
694 | def_id: self.local_def_id(f.id), | |
695 | ident: match f.ident { | |
696 | Some(ident) => self.lower_ident(ident), | |
697 | // FIXME(jseyfried): positional field hygiene. | |
698 | None => Ident::new(sym::integer(index), self.lower_span(f.span)), | |
699 | }, | |
700 | vis_span: self.lower_span(f.vis.span), | |
701 | ty, | |
702 | } | |
703 | } | |
704 | ||
705 | fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> { | |
706 | let hir_id = self.lower_node_id(i.id); | |
707 | self.lower_attrs(hir_id, &i.attrs); | |
708 | let trait_item_def_id = hir_id.expect_owner(); | |
709 | ||
710 | let (generics, kind, has_default) = match &i.kind { | |
711 | AssocItemKind::Const(_, ty, default) => { | |
712 | let ty = | |
713 | self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy)); | |
714 | let body = default.as_ref().map(|x| self.lower_const_body(i.span, Some(x))); | |
715 | (hir::Generics::empty(), hir::TraitItemKind::Const(ty, body), body.is_some()) | |
716 | } | |
717 | AssocItemKind::Fn(box Fn { sig, generics, body: None, .. }) => { | |
718 | let asyncness = sig.header.asyncness; | |
719 | let names = self.lower_fn_params_to_names(&sig.decl); | |
720 | let (generics, sig) = self.lower_method_sig( | |
721 | generics, | |
722 | sig, | |
723 | i.id, | |
724 | FnDeclKind::Trait, | |
725 | asyncness.opt_return_id(), | |
726 | ); | |
727 | (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Required(names)), false) | |
728 | } | |
729 | AssocItemKind::Fn(box Fn { sig, generics, body: Some(body), .. }) => { | |
730 | let asyncness = sig.header.asyncness; | |
731 | let body_id = | |
732 | self.lower_maybe_async_body(i.span, hir_id, &sig.decl, asyncness, Some(&body)); | |
733 | let (generics, sig) = self.lower_method_sig( | |
734 | generics, | |
735 | sig, | |
736 | i.id, | |
737 | FnDeclKind::Trait, | |
738 | asyncness.opt_return_id(), | |
739 | ); | |
740 | (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)), true) | |
741 | } | |
742 | AssocItemKind::Type(box TyAlias { generics, where_clauses, bounds, ty, .. }) => { | |
743 | let mut generics = generics.clone(); | |
744 | add_ty_alias_where_clause(&mut generics, *where_clauses, false); | |
745 | let (generics, kind) = self.lower_generics( | |
746 | &generics, | |
747 | i.id, | |
748 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
749 | |this| { | |
750 | let ty = ty.as_ref().map(|x| { | |
751 | this.lower_ty( | |
752 | x, | |
753 | &ImplTraitContext::Disallowed(ImplTraitPosition::AssocTy), | |
754 | ) | |
755 | }); | |
756 | hir::TraitItemKind::Type( | |
757 | this.lower_param_bounds( | |
758 | bounds, | |
759 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
760 | ), | |
761 | ty, | |
762 | ) | |
763 | }, | |
764 | ); | |
765 | (generics, kind, ty.is_some()) | |
766 | } | |
767 | AssocItemKind::MacCall(..) => panic!("macro item shouldn't exist at this point"), | |
768 | }; | |
769 | ||
770 | let item = hir::TraitItem { | |
771 | owner_id: trait_item_def_id, | |
772 | ident: self.lower_ident(i.ident), | |
773 | generics, | |
774 | kind, | |
775 | span: self.lower_span(i.span), | |
776 | defaultness: hir::Defaultness::Default { has_value: has_default }, | |
777 | }; | |
778 | self.arena.alloc(item) | |
779 | } | |
780 | ||
781 | fn lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemRef { | |
782 | let kind = match &i.kind { | |
783 | AssocItemKind::Const(..) => hir::AssocItemKind::Const, | |
784 | AssocItemKind::Type(..) => hir::AssocItemKind::Type, | |
785 | AssocItemKind::Fn(box Fn { sig, .. }) => { | |
786 | hir::AssocItemKind::Fn { has_self: sig.decl.has_self() } | |
787 | } | |
788 | AssocItemKind::MacCall(..) => unimplemented!(), | |
789 | }; | |
790 | let id = hir::TraitItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }; | |
791 | hir::TraitItemRef { | |
792 | id, | |
793 | ident: self.lower_ident(i.ident), | |
794 | span: self.lower_span(i.span), | |
795 | kind, | |
796 | } | |
797 | } | |
798 | ||
799 | /// Construct `ExprKind::Err` for the given `span`. | |
800 | pub(crate) fn expr_err(&mut self, span: Span, guar: ErrorGuaranteed) -> hir::Expr<'hir> { | |
801 | self.expr(span, hir::ExprKind::Err(guar)) | |
802 | } | |
803 | ||
804 | fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> { | |
805 | // Since `default impl` is not yet implemented, this is always true in impls. | |
806 | let has_value = true; | |
807 | let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value); | |
808 | let hir_id = self.lower_node_id(i.id); | |
809 | self.lower_attrs(hir_id, &i.attrs); | |
810 | ||
811 | let (generics, kind) = match &i.kind { | |
812 | AssocItemKind::Const(_, ty, expr) => { | |
813 | let ty = | |
814 | self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy)); | |
815 | ( | |
816 | hir::Generics::empty(), | |
817 | hir::ImplItemKind::Const(ty, self.lower_const_body(i.span, expr.as_deref())), | |
818 | ) | |
819 | } | |
820 | AssocItemKind::Fn(box Fn { sig, generics, body, .. }) => { | |
821 | self.current_item = Some(i.span); | |
822 | let asyncness = sig.header.asyncness; | |
823 | let body_id = self.lower_maybe_async_body( | |
824 | i.span, | |
825 | hir_id, | |
826 | &sig.decl, | |
827 | asyncness, | |
828 | body.as_deref(), | |
829 | ); | |
830 | let (generics, sig) = self.lower_method_sig( | |
831 | generics, | |
832 | sig, | |
833 | i.id, | |
834 | if self.is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent }, | |
835 | asyncness.opt_return_id(), | |
836 | ); | |
837 | ||
838 | (generics, hir::ImplItemKind::Fn(sig, body_id)) | |
839 | } | |
840 | AssocItemKind::Type(box TyAlias { generics, where_clauses, ty, .. }) => { | |
841 | let mut generics = generics.clone(); | |
842 | add_ty_alias_where_clause(&mut generics, *where_clauses, false); | |
843 | self.lower_generics( | |
844 | &generics, | |
845 | i.id, | |
846 | &ImplTraitContext::Disallowed(ImplTraitPosition::Generic), | |
847 | |this| match ty { | |
848 | None => { | |
849 | let guar = this.tcx.sess.delay_span_bug( | |
850 | i.span, | |
851 | "expected to lower associated type, but it was missing", | |
852 | ); | |
853 | let ty = this.arena.alloc(this.ty(i.span, hir::TyKind::Err(guar))); | |
854 | hir::ImplItemKind::Type(ty) | |
855 | } | |
856 | Some(ty) => { | |
857 | let ty = this.lower_ty(ty, &ImplTraitContext::TypeAliasesOpaqueTy); | |
858 | hir::ImplItemKind::Type(ty) | |
859 | } | |
860 | }, | |
861 | ) | |
862 | } | |
863 | AssocItemKind::MacCall(..) => panic!("`TyMac` should have been expanded by now"), | |
864 | }; | |
865 | ||
866 | let item = hir::ImplItem { | |
867 | owner_id: hir_id.expect_owner(), | |
868 | ident: self.lower_ident(i.ident), | |
869 | generics, | |
870 | kind, | |
871 | vis_span: self.lower_span(i.vis.span), | |
872 | span: self.lower_span(i.span), | |
873 | defaultness, | |
874 | }; | |
875 | self.arena.alloc(item) | |
876 | } | |
877 | ||
878 | fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef { | |
879 | hir::ImplItemRef { | |
880 | id: hir::ImplItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }, | |
881 | ident: self.lower_ident(i.ident), | |
882 | span: self.lower_span(i.span), | |
883 | kind: match &i.kind { | |
884 | AssocItemKind::Const(..) => hir::AssocItemKind::Const, | |
885 | AssocItemKind::Type(..) => hir::AssocItemKind::Type, | |
886 | AssocItemKind::Fn(box Fn { sig, .. }) => { | |
887 | hir::AssocItemKind::Fn { has_self: sig.decl.has_self() } | |
888 | } | |
889 | AssocItemKind::MacCall(..) => unimplemented!(), | |
890 | }, | |
891 | trait_item_def_id: self | |
892 | .resolver | |
893 | .get_partial_res(i.id) | |
894 | .map(|r| r.expect_full_res().def_id()), | |
895 | } | |
896 | } | |
897 | ||
898 | fn lower_defaultness( | |
899 | &self, | |
900 | d: Defaultness, | |
901 | has_value: bool, | |
902 | ) -> (hir::Defaultness, Option<Span>) { | |
903 | match d { | |
904 | Defaultness::Default(sp) => { | |
905 | (hir::Defaultness::Default { has_value }, Some(self.lower_span(sp))) | |
906 | } | |
907 | Defaultness::Final => { | |
908 | assert!(has_value); | |
909 | (hir::Defaultness::Final, None) | |
910 | } | |
911 | } | |
912 | } | |
913 | ||
914 | fn record_body( | |
915 | &mut self, | |
916 | params: &'hir [hir::Param<'hir>], | |
917 | value: hir::Expr<'hir>, | |
918 | ) -> hir::BodyId { | |
919 | let body = hir::Body { | |
920 | generator_kind: self.generator_kind, | |
921 | params, | |
922 | value: self.arena.alloc(value), | |
923 | }; | |
924 | let id = body.id(); | |
925 | debug_assert_eq!(id.hir_id.owner, self.current_hir_id_owner); | |
926 | self.bodies.push((id.hir_id.local_id, self.arena.alloc(body))); | |
927 | id | |
928 | } | |
929 | ||
930 | pub(super) fn lower_body( | |
931 | &mut self, | |
932 | f: impl FnOnce(&mut Self) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>), | |
933 | ) -> hir::BodyId { | |
934 | let prev_gen_kind = self.generator_kind.take(); | |
935 | let task_context = self.task_context.take(); | |
936 | let (parameters, result) = f(self); | |
937 | let body_id = self.record_body(parameters, result); | |
938 | self.task_context = task_context; | |
939 | self.generator_kind = prev_gen_kind; | |
940 | body_id | |
941 | } | |
942 | ||
943 | fn lower_param(&mut self, param: &Param) -> hir::Param<'hir> { | |
944 | let hir_id = self.lower_node_id(param.id); | |
945 | self.lower_attrs(hir_id, ¶m.attrs); | |
946 | hir::Param { | |
947 | hir_id, | |
948 | pat: self.lower_pat(¶m.pat), | |
949 | ty_span: self.lower_span(param.ty.span), | |
950 | span: self.lower_span(param.span), | |
951 | } | |
952 | } | |
953 | ||
954 | pub(super) fn lower_fn_body( | |
955 | &mut self, | |
956 | decl: &FnDecl, | |
957 | body: impl FnOnce(&mut Self) -> hir::Expr<'hir>, | |
958 | ) -> hir::BodyId { | |
959 | self.lower_body(|this| { | |
960 | ( | |
961 | this.arena.alloc_from_iter(decl.inputs.iter().map(|x| this.lower_param(x))), | |
962 | body(this), | |
963 | ) | |
964 | }) | |
965 | } | |
966 | ||
967 | fn lower_fn_body_block( | |
968 | &mut self, | |
969 | span: Span, | |
970 | decl: &FnDecl, | |
971 | body: Option<&Block>, | |
972 | ) -> hir::BodyId { | |
973 | self.lower_fn_body(decl, |this| this.lower_block_expr_opt(span, body)) | |
974 | } | |
975 | ||
976 | fn lower_block_expr_opt(&mut self, span: Span, block: Option<&Block>) -> hir::Expr<'hir> { | |
977 | match block { | |
978 | Some(block) => self.lower_block_expr(block), | |
979 | None => self.expr_err(span, self.tcx.sess.delay_span_bug(span, "no block")), | |
980 | } | |
981 | } | |
982 | ||
983 | pub(super) fn lower_const_body(&mut self, span: Span, expr: Option<&Expr>) -> hir::BodyId { | |
984 | self.lower_body(|this| { | |
985 | ( | |
986 | &[], | |
987 | match expr { | |
988 | Some(expr) => this.lower_expr_mut(expr), | |
989 | None => this.expr_err(span, this.tcx.sess.delay_span_bug(span, "no block")), | |
990 | }, | |
991 | ) | |
992 | }) | |
993 | } | |
994 | ||
995 | fn lower_maybe_async_body( | |
996 | &mut self, | |
997 | span: Span, | |
998 | fn_id: hir::HirId, | |
999 | decl: &FnDecl, | |
1000 | asyncness: Async, | |
1001 | body: Option<&Block>, | |
1002 | ) -> hir::BodyId { | |
1003 | let (closure_id, body) = match (asyncness, body) { | |
1004 | (Async::Yes { closure_id, .. }, Some(body)) => (closure_id, body), | |
1005 | _ => return self.lower_fn_body_block(span, decl, body), | |
1006 | }; | |
1007 | ||
1008 | self.lower_body(|this| { | |
1009 | let mut parameters: Vec<hir::Param<'_>> = Vec::new(); | |
1010 | let mut statements: Vec<hir::Stmt<'_>> = Vec::new(); | |
1011 | ||
1012 | // Async function parameters are lowered into the closure body so that they are | |
1013 | // captured and so that the drop order matches the equivalent non-async functions. | |
1014 | // | |
1015 | // from: | |
1016 | // | |
1017 | // async fn foo(<pattern>: <ty>, <pattern>: <ty>, <pattern>: <ty>) { | |
1018 | // <body> | |
1019 | // } | |
1020 | // | |
1021 | // into: | |
1022 | // | |
1023 | // fn foo(__arg0: <ty>, __arg1: <ty>, __arg2: <ty>) { | |
1024 | // async move { | |
1025 | // let __arg2 = __arg2; | |
1026 | // let <pattern> = __arg2; | |
1027 | // let __arg1 = __arg1; | |
1028 | // let <pattern> = __arg1; | |
1029 | // let __arg0 = __arg0; | |
1030 | // let <pattern> = __arg0; | |
1031 | // drop-temps { <body> } // see comments later in fn for details | |
1032 | // } | |
1033 | // } | |
1034 | // | |
1035 | // If `<pattern>` is a simple ident, then it is lowered to a single | |
1036 | // `let <pattern> = <pattern>;` statement as an optimization. | |
1037 | // | |
1038 | // Note that the body is embedded in `drop-temps`; an | |
1039 | // equivalent desugaring would be `return { <body> | |
1040 | // };`. The key point is that we wish to drop all the | |
1041 | // let-bound variables and temporaries created in the body | |
1042 | // (and its tail expression!) before we drop the | |
1043 | // parameters (c.f. rust-lang/rust#64512). | |
1044 | for (index, parameter) in decl.inputs.iter().enumerate() { | |
1045 | let parameter = this.lower_param(parameter); | |
1046 | let span = parameter.pat.span; | |
1047 | ||
1048 | // Check if this is a binding pattern, if so, we can optimize and avoid adding a | |
1049 | // `let <pat> = __argN;` statement. In this case, we do not rename the parameter. | |
1050 | let (ident, is_simple_parameter) = match parameter.pat.kind { | |
1051 | hir::PatKind::Binding(hir::BindingAnnotation(ByRef::No, _), _, ident, _) => { | |
1052 | (ident, true) | |
1053 | } | |
1054 | // For `ref mut` or wildcard arguments, we can't reuse the binding, but | |
1055 | // we can keep the same name for the parameter. | |
1056 | // This lets rustdoc render it correctly in documentation. | |
1057 | hir::PatKind::Binding(_, _, ident, _) => (ident, false), | |
1058 | hir::PatKind::Wild => { | |
1059 | (Ident::with_dummy_span(rustc_span::symbol::kw::Underscore), false) | |
1060 | } | |
1061 | _ => { | |
1062 | // Replace the ident for bindings that aren't simple. | |
1063 | let name = format!("__arg{index}"); | |
1064 | let ident = Ident::from_str(&name); | |
1065 | ||
1066 | (ident, false) | |
1067 | } | |
1068 | }; | |
1069 | ||
1070 | let desugared_span = this.mark_span_with_reason(DesugaringKind::Async, span, None); | |
1071 | ||
1072 | // Construct a parameter representing `__argN: <ty>` to replace the parameter of the | |
1073 | // async function. | |
1074 | // | |
1075 | // If this is the simple case, this parameter will end up being the same as the | |
1076 | // original parameter, but with a different pattern id. | |
1077 | let stmt_attrs = this.attrs.get(¶meter.hir_id.local_id).copied(); | |
1078 | let (new_parameter_pat, new_parameter_id) = this.pat_ident(desugared_span, ident); | |
1079 | let new_parameter = hir::Param { | |
1080 | hir_id: parameter.hir_id, | |
1081 | pat: new_parameter_pat, | |
1082 | ty_span: this.lower_span(parameter.ty_span), | |
1083 | span: this.lower_span(parameter.span), | |
1084 | }; | |
1085 | ||
1086 | if is_simple_parameter { | |
1087 | // If this is the simple case, then we only insert one statement that is | |
1088 | // `let <pat> = <pat>;`. We re-use the original argument's pattern so that | |
1089 | // `HirId`s are densely assigned. | |
1090 | let expr = this.expr_ident(desugared_span, ident, new_parameter_id); | |
1091 | let stmt = this.stmt_let_pat( | |
1092 | stmt_attrs, | |
1093 | desugared_span, | |
1094 | Some(expr), | |
1095 | parameter.pat, | |
1096 | hir::LocalSource::AsyncFn, | |
1097 | ); | |
1098 | statements.push(stmt); | |
1099 | } else { | |
1100 | // If this is not the simple case, then we construct two statements: | |
1101 | // | |
1102 | // ``` | |
1103 | // let __argN = __argN; | |
1104 | // let <pat> = __argN; | |
1105 | // ``` | |
1106 | // | |
1107 | // The first statement moves the parameter into the closure and thus ensures | |
1108 | // that the drop order is correct. | |
1109 | // | |
1110 | // The second statement creates the bindings that the user wrote. | |
1111 | ||
1112 | // Construct the `let mut __argN = __argN;` statement. It must be a mut binding | |
1113 | // because the user may have specified a `ref mut` binding in the next | |
1114 | // statement. | |
1115 | let (move_pat, move_id) = this.pat_ident_binding_mode( | |
1116 | desugared_span, | |
1117 | ident, | |
1118 | hir::BindingAnnotation::MUT, | |
1119 | ); | |
1120 | let move_expr = this.expr_ident(desugared_span, ident, new_parameter_id); | |
1121 | let move_stmt = this.stmt_let_pat( | |
1122 | None, | |
1123 | desugared_span, | |
1124 | Some(move_expr), | |
1125 | move_pat, | |
1126 | hir::LocalSource::AsyncFn, | |
1127 | ); | |
1128 | ||
1129 | // Construct the `let <pat> = __argN;` statement. We re-use the original | |
1130 | // parameter's pattern so that `HirId`s are densely assigned. | |
1131 | let pattern_expr = this.expr_ident(desugared_span, ident, move_id); | |
1132 | let pattern_stmt = this.stmt_let_pat( | |
1133 | stmt_attrs, | |
1134 | desugared_span, | |
1135 | Some(pattern_expr), | |
1136 | parameter.pat, | |
1137 | hir::LocalSource::AsyncFn, | |
1138 | ); | |
1139 | ||
1140 | statements.push(move_stmt); | |
1141 | statements.push(pattern_stmt); | |
1142 | }; | |
1143 | ||
1144 | parameters.push(new_parameter); | |
1145 | } | |
1146 | ||
1147 | let async_expr = this.make_async_expr( | |
1148 | CaptureBy::Value, | |
1149 | fn_id, | |
1150 | closure_id, | |
1151 | None, | |
1152 | body.span, | |
1153 | hir::AsyncGeneratorKind::Fn, | |
1154 | |this| { | |
1155 | // Create a block from the user's function body: | |
1156 | let user_body = this.lower_block_expr(body); | |
1157 | ||
1158 | // Transform into `drop-temps { <user-body> }`, an expression: | |
1159 | let desugared_span = | |
1160 | this.mark_span_with_reason(DesugaringKind::Async, user_body.span, None); | |
1161 | let user_body = | |
1162 | this.expr_drop_temps(desugared_span, this.arena.alloc(user_body)); | |
1163 | ||
1164 | // As noted above, create the final block like | |
1165 | // | |
1166 | // ``` | |
1167 | // { | |
1168 | // let $param_pattern = $raw_param; | |
1169 | // ... | |
1170 | // drop-temps { <user-body> } | |
1171 | // } | |
1172 | // ``` | |
1173 | let body = this.block_all( | |
1174 | desugared_span, | |
1175 | this.arena.alloc_from_iter(statements), | |
1176 | Some(user_body), | |
1177 | ); | |
1178 | ||
1179 | this.expr_block(body) | |
1180 | }, | |
1181 | ); | |
1182 | ||
1183 | (this.arena.alloc_from_iter(parameters), this.expr(body.span, async_expr)) | |
1184 | }) | |
1185 | } | |
1186 | ||
1187 | fn lower_method_sig( | |
1188 | &mut self, | |
1189 | generics: &Generics, | |
1190 | sig: &FnSig, | |
1191 | id: NodeId, | |
1192 | kind: FnDeclKind, | |
1193 | is_async: Option<(NodeId, Span)>, | |
1194 | ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) { | |
1195 | let header = self.lower_fn_header(sig.header); | |
1196 | let itctx = ImplTraitContext::Universal; | |
1197 | let (generics, decl) = self.lower_generics(generics, id, &itctx, |this| { | |
1198 | this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async) | |
1199 | }); | |
1200 | (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) }) | |
1201 | } | |
1202 | ||
1203 | fn lower_fn_header(&mut self, h: FnHeader) -> hir::FnHeader { | |
1204 | hir::FnHeader { | |
1205 | unsafety: self.lower_unsafety(h.unsafety), | |
1206 | asyncness: self.lower_asyncness(h.asyncness), | |
1207 | constness: self.lower_constness(h.constness), | |
1208 | abi: self.lower_extern(h.ext), | |
1209 | } | |
1210 | } | |
1211 | ||
1212 | pub(super) fn lower_abi(&mut self, abi: StrLit) -> abi::Abi { | |
1213 | abi::lookup(abi.symbol_unescaped.as_str()).unwrap_or_else(|| { | |
1214 | self.error_on_invalid_abi(abi); | |
1215 | abi::Abi::Rust | |
1216 | }) | |
1217 | } | |
1218 | ||
1219 | pub(super) fn lower_extern(&mut self, ext: Extern) -> abi::Abi { | |
1220 | match ext { | |
1221 | Extern::None => abi::Abi::Rust, | |
1222 | Extern::Implicit(_) => abi::Abi::FALLBACK, | |
1223 | Extern::Explicit(abi, _) => self.lower_abi(abi), | |
1224 | } | |
1225 | } | |
1226 | ||
1227 | fn error_on_invalid_abi(&self, abi: StrLit) { | |
1228 | let abi_names = abi::enabled_names(self.tcx.features(), abi.span) | |
1229 | .iter() | |
1230 | .map(|s| Symbol::intern(s)) | |
1231 | .collect::<Vec<_>>(); | |
1232 | let suggested_name = find_best_match_for_name(&abi_names, abi.symbol_unescaped, None); | |
1233 | self.tcx.sess.emit_err(InvalidAbi { | |
1234 | abi: abi.symbol_unescaped, | |
1235 | span: abi.span, | |
1236 | suggestion: suggested_name.map(|suggested_name| InvalidAbiSuggestion { | |
1237 | span: abi.span, | |
1238 | suggestion: format!("\"{suggested_name}\""), | |
1239 | }), | |
1240 | command: "rustc --print=calling-conventions".to_string(), | |
1241 | }); | |
1242 | } | |
1243 | ||
1244 | fn lower_asyncness(&mut self, a: Async) -> hir::IsAsync { | |
1245 | match a { | |
1246 | Async::Yes { .. } => hir::IsAsync::Async, | |
1247 | Async::No => hir::IsAsync::NotAsync, | |
1248 | } | |
1249 | } | |
1250 | ||
1251 | pub(super) fn lower_constness(&mut self, c: Const) -> hir::Constness { | |
1252 | match c { | |
1253 | Const::Yes(_) => hir::Constness::Const, | |
1254 | Const::No => hir::Constness::NotConst, | |
1255 | } | |
1256 | } | |
1257 | ||
1258 | pub(super) fn lower_unsafety(&mut self, u: Unsafe) -> hir::Unsafety { | |
1259 | match u { | |
1260 | Unsafe::Yes(_) => hir::Unsafety::Unsafe, | |
1261 | Unsafe::No => hir::Unsafety::Normal, | |
1262 | } | |
1263 | } | |
1264 | ||
1265 | /// Return the pair of the lowered `generics` as `hir::Generics` and the evaluation of `f` with | |
1266 | /// the carried impl trait definitions and bounds. | |
1267 | #[instrument(level = "debug", skip(self, f))] | |
1268 | fn lower_generics<T>( | |
1269 | &mut self, | |
1270 | generics: &Generics, | |
1271 | parent_node_id: NodeId, | |
1272 | itctx: &ImplTraitContext, | |
1273 | f: impl FnOnce(&mut Self) -> T, | |
1274 | ) -> (&'hir hir::Generics<'hir>, T) { | |
1275 | debug_assert!(self.impl_trait_defs.is_empty()); | |
1276 | debug_assert!(self.impl_trait_bounds.is_empty()); | |
1277 | ||
1278 | // Error if `?Trait` bounds in where clauses don't refer directly to type parameters. | |
1279 | // Note: we used to clone these bounds directly onto the type parameter (and avoid lowering | |
1280 | // these into hir when we lower thee where clauses), but this makes it quite difficult to | |
1281 | // keep track of the Span info. Now, `add_implicitly_sized` in `AstConv` checks both param bounds and | |
1282 | // where clauses for `?Sized`. | |
1283 | for pred in &generics.where_clause.predicates { | |
1284 | let WherePredicate::BoundPredicate(bound_pred) = pred else { | |
1285 | continue; | |
1286 | }; | |
1287 | let compute_is_param = || { | |
1288 | // Check if the where clause type is a plain type parameter. | |
1289 | match self | |
1290 | .resolver | |
1291 | .get_partial_res(bound_pred.bounded_ty.id) | |
1292 | .and_then(|r| r.full_res()) | |
1293 | { | |
1294 | Some(Res::Def(DefKind::TyParam, def_id)) | |
1295 | if bound_pred.bound_generic_params.is_empty() => | |
1296 | { | |
1297 | generics | |
1298 | .params | |
1299 | .iter() | |
1300 | .any(|p| def_id == self.local_def_id(p.id).to_def_id()) | |
1301 | } | |
1302 | // Either the `bounded_ty` is not a plain type parameter, or | |
1303 | // it's not found in the generic type parameters list. | |
1304 | _ => false, | |
1305 | } | |
1306 | }; | |
1307 | // We only need to compute this once per `WherePredicate`, but don't | |
1308 | // need to compute this at all unless there is a Maybe bound. | |
1309 | let mut is_param: Option<bool> = None; | |
1310 | for bound in &bound_pred.bounds { | |
1311 | if !matches!(*bound, GenericBound::Trait(_, TraitBoundModifier::Maybe)) { | |
1312 | continue; | |
1313 | } | |
1314 | let is_param = *is_param.get_or_insert_with(compute_is_param); | |
1315 | if !is_param { | |
1316 | self.tcx.sess.emit_err(MisplacedRelaxTraitBound { span: bound.span() }); | |
1317 | } | |
1318 | } | |
1319 | } | |
1320 | ||
1321 | let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new(); | |
1322 | predicates.extend(generics.params.iter().filter_map(|param| { | |
1323 | self.lower_generic_bound_predicate( | |
1324 | param.ident, | |
1325 | param.id, | |
1326 | ¶m.kind, | |
1327 | ¶m.bounds, | |
1328 | param.colon_span, | |
1329 | generics.span, | |
1330 | itctx, | |
1331 | PredicateOrigin::GenericParam, | |
1332 | ) | |
1333 | })); | |
1334 | predicates.extend( | |
1335 | generics | |
1336 | .where_clause | |
1337 | .predicates | |
1338 | .iter() | |
1339 | .map(|predicate| self.lower_where_predicate(predicate)), | |
1340 | ); | |
1341 | ||
1342 | let mut params: SmallVec<[hir::GenericParam<'hir>; 4]> = self | |
1343 | .lower_generic_params_mut(&generics.params, hir::GenericParamSource::Generics) | |
1344 | .collect(); | |
1345 | ||
1346 | // Introduce extra lifetimes if late resolution tells us to. | |
1347 | let extra_lifetimes = self.resolver.take_extra_lifetime_params(parent_node_id); | |
1348 | params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| { | |
1349 | self.lifetime_res_to_generic_param( | |
1350 | ident, | |
1351 | node_id, | |
1352 | res, | |
1353 | hir::GenericParamSource::Generics, | |
1354 | ) | |
1355 | })); | |
1356 | ||
1357 | let has_where_clause_predicates = !generics.where_clause.predicates.is_empty(); | |
1358 | let where_clause_span = self.lower_span(generics.where_clause.span); | |
1359 | let span = self.lower_span(generics.span); | |
1360 | let res = f(self); | |
1361 | ||
1362 | let impl_trait_defs = std::mem::take(&mut self.impl_trait_defs); | |
1363 | params.extend(impl_trait_defs.into_iter()); | |
1364 | ||
1365 | let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds); | |
1366 | predicates.extend(impl_trait_bounds.into_iter()); | |
1367 | ||
1368 | let lowered_generics = self.arena.alloc(hir::Generics { | |
1369 | params: self.arena.alloc_from_iter(params), | |
1370 | predicates: self.arena.alloc_from_iter(predicates), | |
1371 | has_where_clause_predicates, | |
1372 | where_clause_span, | |
1373 | span, | |
1374 | }); | |
1375 | ||
1376 | (lowered_generics, res) | |
1377 | } | |
1378 | ||
1379 | pub(super) fn lower_generic_bound_predicate( | |
1380 | &mut self, | |
1381 | ident: Ident, | |
1382 | id: NodeId, | |
1383 | kind: &GenericParamKind, | |
1384 | bounds: &[GenericBound], | |
1385 | colon_span: Option<Span>, | |
1386 | parent_span: Span, | |
1387 | itctx: &ImplTraitContext, | |
1388 | origin: PredicateOrigin, | |
1389 | ) -> Option<hir::WherePredicate<'hir>> { | |
1390 | // Do not create a clause if we do not have anything inside it. | |
1391 | if bounds.is_empty() { | |
1392 | return None; | |
1393 | } | |
1394 | ||
1395 | let bounds = self.lower_param_bounds(bounds, itctx); | |
1396 | ||
1397 | let ident = self.lower_ident(ident); | |
1398 | let param_span = ident.span; | |
1399 | ||
1400 | // Reconstruct the span of the entire predicate from the individual generic bounds. | |
1401 | let span_start = colon_span.unwrap_or_else(|| param_span.shrink_to_hi()); | |
1402 | let span = bounds.iter().fold(span_start, |span_accum, bound| { | |
1403 | match bound.span().find_ancestor_inside(parent_span) { | |
1404 | Some(bound_span) => span_accum.to(bound_span), | |
1405 | None => span_accum, | |
1406 | } | |
1407 | }); | |
1408 | let span = self.lower_span(span); | |
1409 | ||
1410 | match kind { | |
1411 | GenericParamKind::Const { .. } => None, | |
1412 | GenericParamKind::Type { .. } => { | |
1413 | let def_id = self.local_def_id(id).to_def_id(); | |
1414 | let hir_id = self.next_id(); | |
1415 | let res = Res::Def(DefKind::TyParam, def_id); | |
1416 | let ty_path = self.arena.alloc(hir::Path { | |
1417 | span: param_span, | |
1418 | res, | |
1419 | segments: self | |
1420 | .arena | |
1421 | .alloc_from_iter([hir::PathSegment::new(ident, hir_id, res)]), | |
1422 | }); | |
1423 | let ty_id = self.next_id(); | |
1424 | let bounded_ty = | |
1425 | self.ty_path(ty_id, param_span, hir::QPath::Resolved(None, ty_path)); | |
1426 | Some(hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate { | |
1427 | hir_id: self.next_id(), | |
1428 | bounded_ty: self.arena.alloc(bounded_ty), | |
1429 | bounds, | |
1430 | span, | |
1431 | bound_generic_params: &[], | |
1432 | origin, | |
1433 | })) | |
1434 | } | |
1435 | GenericParamKind::Lifetime => { | |
1436 | let ident = self.lower_ident(ident); | |
1437 | let lt_id = self.next_node_id(); | |
1438 | let lifetime = self.new_named_lifetime(id, lt_id, ident); | |
1439 | Some(hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate { | |
1440 | lifetime, | |
1441 | span, | |
1442 | bounds, | |
1443 | in_where_clause: false, | |
1444 | })) | |
1445 | } | |
1446 | } | |
1447 | } | |
1448 | ||
1449 | fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir> { | |
1450 | match pred { | |
1451 | WherePredicate::BoundPredicate(WhereBoundPredicate { | |
1452 | bound_generic_params, | |
1453 | bounded_ty, | |
1454 | bounds, | |
1455 | span, | |
1456 | }) => hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate { | |
1457 | hir_id: self.next_id(), | |
1458 | bound_generic_params: self | |
1459 | .lower_generic_params(bound_generic_params, hir::GenericParamSource::Binder), | |
1460 | bounded_ty: self | |
1461 | .lower_ty(bounded_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)), | |
1462 | bounds: self.arena.alloc_from_iter(bounds.iter().map(|bound| { | |
1463 | self.lower_param_bound( | |
1464 | bound, | |
1465 | &ImplTraitContext::Disallowed(ImplTraitPosition::Bound), | |
1466 | ) | |
1467 | })), | |
1468 | span: self.lower_span(*span), | |
1469 | origin: PredicateOrigin::WhereClause, | |
1470 | }), | |
1471 | WherePredicate::RegionPredicate(WhereRegionPredicate { lifetime, bounds, span }) => { | |
1472 | hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate { | |
1473 | span: self.lower_span(*span), | |
1474 | lifetime: self.lower_lifetime(lifetime), | |
1475 | bounds: self.lower_param_bounds( | |
1476 | bounds, | |
1477 | &ImplTraitContext::Disallowed(ImplTraitPosition::Bound), | |
1478 | ), | |
1479 | in_where_clause: true, | |
1480 | }) | |
1481 | } | |
1482 | WherePredicate::EqPredicate(WhereEqPredicate { lhs_ty, rhs_ty, span }) => { | |
1483 | hir::WherePredicate::EqPredicate(hir::WhereEqPredicate { | |
1484 | lhs_ty: self | |
1485 | .lower_ty(lhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)), | |
1486 | rhs_ty: self | |
1487 | .lower_ty(rhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)), | |
1488 | span: self.lower_span(*span), | |
1489 | }) | |
1490 | } | |
1491 | } | |
1492 | } | |
1493 | } |