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 hir::definitions::DefPathData;
7 use rustc_ast::ptr::P;
8 use rustc_ast::visit::AssocCtxt;
9 use rustc_ast::*;
10 use rustc_data_structures::sorted_map::SortedMap;
11 use rustc_errors::ErrorGuaranteed;
12 use rustc_hir as hir;
13 use rustc_hir::def::{DefKind, Res};
14 use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
15 use rustc_hir::PredicateOrigin;
16 use rustc_index::{Idx, IndexSlice, IndexVec};
17 use rustc_middle::ty::{ResolverAstLowering, TyCtxt};
18 use rustc_span::edit_distance::find_best_match_for_name;
19 use rustc_span::source_map::DesugaringKind;
20 use rustc_span::symbol::{kw, sym, Ident};
21 use rustc_span::{Span, Symbol};
22 use rustc_target::spec::abi;
23 use smallvec::{smallvec, SmallVec};
24 use thin_vec::ThinVec;
25
26 pub(super) struct ItemLowerer<'a, 'hir> {
27 pub(super) tcx: TyCtxt<'hir>,
28 pub(super) resolver: &'a mut ResolverAstLowering,
29 pub(super) ast_index: &'a IndexSlice<LocalDefId, AstOwner<'a>>,
30 pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
31 }
32
33 /// When we have a ty alias we *may* have two where clauses. To give the best diagnostics, we set the span
34 /// to the where clause that is preferred, if it exists. Otherwise, it sets the span to the other where
35 /// clause if it exists.
add_ty_alias_where_clause( generics: &mut ast::Generics, mut where_clauses: (TyAliasWhereClause, TyAliasWhereClause), prefer_first: bool, )36 fn add_ty_alias_where_clause(
37 generics: &mut ast::Generics,
38 mut where_clauses: (TyAliasWhereClause, TyAliasWhereClause),
39 prefer_first: bool,
40 ) {
41 if !prefer_first {
42 where_clauses = (where_clauses.1, where_clauses.0);
43 }
44 if where_clauses.0.0 || !where_clauses.1.0 {
45 generics.where_clause.has_where_token = where_clauses.0.0;
46 generics.where_clause.span = where_clauses.0.1;
47 } else {
48 generics.where_clause.has_where_token = where_clauses.1.0;
49 generics.where_clause.span = where_clauses.1.1;
50 }
51 }
52
53 impl<'a, 'hir> ItemLowerer<'a, 'hir> {
with_lctx( &mut self, owner: NodeId, f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>, )54 fn with_lctx(
55 &mut self,
56 owner: NodeId,
57 f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
58 ) {
59 let mut lctx = LoweringContext {
60 // Pseudo-globals.
61 tcx: self.tcx,
62 resolver: self.resolver,
63 arena: self.tcx.hir_arena,
64
65 // HirId handling.
66 bodies: Vec::new(),
67 attrs: SortedMap::default(),
68 children: Vec::default(),
69 current_hir_id_owner: hir::CRATE_OWNER_ID,
70 item_local_id_counter: hir::ItemLocalId::new(0),
71 node_id_to_local_id: Default::default(),
72 trait_map: Default::default(),
73
74 // Lowering state.
75 catch_scope: None,
76 loop_scope: None,
77 is_in_loop_condition: false,
78 is_in_trait_impl: false,
79 is_in_dyn_type: false,
80 generator_kind: None,
81 task_context: None,
82 current_item: None,
83 impl_trait_defs: Vec::new(),
84 impl_trait_bounds: Vec::new(),
85 allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
86 allow_gen_future: Some([sym::gen_future, sym::closure_track_caller][..].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 let owner = self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
93 debug_assert!(matches!(owner, hir::MaybeOwner::Phantom));
94 *owner = info;
95 }
96 }
97
lower_node( &mut self, def_id: LocalDefId, ) -> hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>98 pub(super) fn lower_node(
99 &mut self,
100 def_id: LocalDefId,
101 ) -> hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>> {
102 let owner = self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
103 if let hir::MaybeOwner::Phantom = owner {
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))]
lower_crate(&mut self, c: &Crate)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))]
lower_item(&mut self, item: &Item)128 fn lower_item(&mut self, item: &Item) {
129 self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
130 }
131
lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt)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
142 if let hir::ItemKind::Impl(impl_) = parent_hir.node().expect_item().kind {
143 lctx.is_in_trait_impl = impl_.of_trait.is_some();
144 }
145
146 match ctxt {
147 AssocCtxt::Trait => hir::OwnerNode::TraitItem(lctx.lower_trait_item(item)),
148 AssocCtxt::Impl => hir::OwnerNode::ImplItem(lctx.lower_impl_item(item)),
149 }
150 })
151 }
152
lower_foreign_item(&mut self, item: &ForeignItem)153 fn lower_foreign_item(&mut self, item: &ForeignItem) {
154 self.with_lctx(item.id, |lctx| hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item)))
155 }
156 }
157
158 impl<'hir> LoweringContext<'_, 'hir> {
lower_mod( &mut self, items: &[P<Item>], spans: &ModSpans, ) -> &'hir hir::Mod<'hir>159 pub(super) fn lower_mod(
160 &mut self,
161 items: &[P<Item>],
162 spans: &ModSpans,
163 ) -> &'hir hir::Mod<'hir> {
164 self.arena.alloc(hir::Mod {
165 spans: hir::ModSpans {
166 inner_span: self.lower_span(spans.inner_span),
167 inject_use_span: self.lower_span(spans.inject_use_span),
168 },
169 item_ids: self.arena.alloc_from_iter(items.iter().flat_map(|x| self.lower_item_ref(x))),
170 })
171 }
172
lower_item_ref(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]>173 pub(super) fn lower_item_ref(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]> {
174 let mut node_ids =
175 smallvec![hir::ItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }];
176 if let ItemKind::Use(use_tree) = &i.kind {
177 self.lower_item_id_use_tree(use_tree, &mut node_ids);
178 }
179 node_ids
180 }
181
lower_item_id_use_tree(&mut self, tree: &UseTree, vec: &mut SmallVec<[hir::ItemId; 1]>)182 fn lower_item_id_use_tree(&mut self, tree: &UseTree, vec: &mut SmallVec<[hir::ItemId; 1]>) {
183 match &tree.kind {
184 UseTreeKind::Nested(nested_vec) => {
185 for &(ref nested, id) in nested_vec {
186 vec.push(hir::ItemId {
187 owner_id: hir::OwnerId { def_id: self.local_def_id(id) },
188 });
189 self.lower_item_id_use_tree(nested, vec);
190 }
191 }
192 UseTreeKind::Simple(..) | UseTreeKind::Glob => {}
193 }
194 }
195
lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir>196 fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
197 let mut ident = i.ident;
198 let vis_span = self.lower_span(i.vis.span);
199 let hir_id = self.lower_node_id(i.id);
200 let attrs = self.lower_attrs(hir_id, &i.attrs);
201 let kind = self.lower_item_kind(i.span, i.id, hir_id, &mut ident, attrs, vis_span, &i.kind);
202 let item = hir::Item {
203 owner_id: hir_id.expect_owner(),
204 ident: self.lower_ident(ident),
205 kind,
206 vis_span,
207 span: self.lower_span(i.span),
208 };
209 self.arena.alloc(item)
210 }
211
lower_item_kind( &mut self, span: Span, id: NodeId, hir_id: hir::HirId, ident: &mut Ident, attrs: Option<&'hir [Attribute]>, vis_span: Span, i: &ItemKind, ) -> hir::ItemKind<'hir>212 fn lower_item_kind(
213 &mut self,
214 span: Span,
215 id: NodeId,
216 hir_id: hir::HirId,
217 ident: &mut Ident,
218 attrs: Option<&'hir [Attribute]>,
219 vis_span: Span,
220 i: &ItemKind,
221 ) -> hir::ItemKind<'hir> {
222 match i {
223 ItemKind::ExternCrate(orig_name) => hir::ItemKind::ExternCrate(*orig_name),
224 ItemKind::Use(use_tree) => {
225 // Start with an empty prefix.
226 let prefix = Path { segments: ThinVec::new(), span: use_tree.span, tokens: None };
227
228 self.lower_use_tree(use_tree, &prefix, id, vis_span, ident, attrs)
229 }
230 ItemKind::Static(box ast::StaticItem { ty: t, mutability: m, expr: e }) => {
231 let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
232 hir::ItemKind::Static(ty, *m, body_id)
233 }
234 ItemKind::Const(box ast::ConstItem { ty, expr, .. }) => {
235 let (ty, body_id) = self.lower_const_item(ty, span, expr.as_deref());
236 hir::ItemKind::Const(ty, body_id)
237 }
238 ItemKind::Fn(box Fn {
239 sig: FnSig { decl, header, span: fn_sig_span },
240 generics,
241 body,
242 ..
243 }) => {
244 self.with_new_scopes(|this| {
245 this.current_item = Some(ident.span);
246
247 // Note: we don't need to change the return type from `T` to
248 // `impl Future<Output = T>` here because lower_body
249 // only cares about the input argument patterns in the function
250 // declaration (decl), not the return types.
251 let asyncness = header.asyncness;
252 let body_id = this.lower_maybe_async_body(
253 span,
254 hir_id,
255 &decl,
256 asyncness,
257 body.as_deref(),
258 );
259
260 let itctx = ImplTraitContext::Universal;
261 let (generics, decl) =
262 this.lower_generics(generics, header.constness, id, &itctx, |this| {
263 let ret_id = asyncness.opt_return_id();
264 this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id)
265 });
266 let sig = hir::FnSig {
267 decl,
268 header: this.lower_fn_header(*header),
269 span: this.lower_span(*fn_sig_span),
270 };
271 hir::ItemKind::Fn(sig, generics, body_id)
272 })
273 }
274 ItemKind::Mod(_, mod_kind) => match mod_kind {
275 ModKind::Loaded(items, _, spans) => {
276 hir::ItemKind::Mod(self.lower_mod(items, spans))
277 }
278 ModKind::Unloaded => panic!("`mod` items should have been loaded by now"),
279 },
280 ItemKind::ForeignMod(fm) => hir::ItemKind::ForeignMod {
281 abi: fm.abi.map_or(abi::Abi::FALLBACK, |abi| self.lower_abi(abi)),
282 items: self
283 .arena
284 .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
285 },
286 ItemKind::GlobalAsm(asm) => hir::ItemKind::GlobalAsm(self.lower_inline_asm(span, asm)),
287 ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty, .. }) => {
288 // We lower
289 //
290 // type Foo = impl Trait
291 //
292 // to
293 //
294 // type Foo = Foo1
295 // opaque type Foo1: Trait
296 let mut generics = generics.clone();
297 add_ty_alias_where_clause(&mut generics, *where_clauses, true);
298 let (generics, ty) = self.lower_generics(
299 &generics,
300 Const::No,
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(
312 ty,
313 &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: false },
314 ),
315 },
316 );
317 hir::ItemKind::TyAlias(ty, generics)
318 }
319 ItemKind::Enum(enum_definition, generics) => {
320 let (generics, variants) = self.lower_generics(
321 generics,
322 Const::No,
323 id,
324 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
325 |this| {
326 this.arena.alloc_from_iter(
327 enum_definition.variants.iter().map(|x| this.lower_variant(x)),
328 )
329 },
330 );
331 hir::ItemKind::Enum(hir::EnumDef { variants }, generics)
332 }
333 ItemKind::Struct(struct_def, generics) => {
334 let (generics, struct_def) = self.lower_generics(
335 generics,
336 Const::No,
337 id,
338 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
339 |this| this.lower_variant_data(hir_id, struct_def),
340 );
341 hir::ItemKind::Struct(struct_def, generics)
342 }
343 ItemKind::Union(vdata, generics) => {
344 let (generics, vdata) = self.lower_generics(
345 generics,
346 Const::No,
347 id,
348 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
349 |this| this.lower_variant_data(hir_id, vdata),
350 );
351 hir::ItemKind::Union(vdata, generics)
352 }
353 ItemKind::Impl(box Impl {
354 unsafety,
355 polarity,
356 defaultness,
357 constness,
358 generics: ast_generics,
359 of_trait: trait_ref,
360 self_ty: ty,
361 items: impl_items,
362 }) => {
363 // Lower the "impl header" first. This ordering is important
364 // for in-band lifetimes! Consider `'a` here:
365 //
366 // impl Foo<'a> for u32 {
367 // fn method(&'a self) { .. }
368 // }
369 //
370 // Because we start by lowering the `Foo<'a> for u32`
371 // part, we will add `'a` to the list of generics on
372 // the impl. When we then encounter it later in the
373 // method, it will not be considered an in-band
374 // lifetime to be added, but rather a reference to a
375 // parent lifetime.
376 let itctx = ImplTraitContext::Universal;
377 let (generics, (trait_ref, lowered_ty)) =
378 self.lower_generics(ast_generics, *constness, id, &itctx, |this| {
379 let trait_ref = trait_ref.as_ref().map(|trait_ref| {
380 this.lower_trait_ref(
381 trait_ref,
382 &ImplTraitContext::Disallowed(ImplTraitPosition::Trait),
383 )
384 });
385
386 let lowered_ty = this.lower_ty(
387 ty,
388 &ImplTraitContext::Disallowed(ImplTraitPosition::ImplSelf),
389 );
390
391 (trait_ref, lowered_ty)
392 });
393
394 let new_impl_items = self
395 .arena
396 .alloc_from_iter(impl_items.iter().map(|item| self.lower_impl_item_ref(item)));
397
398 // `defaultness.has_value()` is never called for an `impl`, always `true` in order
399 // to not cause an assertion failure inside the `lower_defaultness` function.
400 let has_val = true;
401 let (defaultness, defaultness_span) = self.lower_defaultness(*defaultness, has_val);
402 let polarity = match polarity {
403 ImplPolarity::Positive => ImplPolarity::Positive,
404 ImplPolarity::Negative(s) => ImplPolarity::Negative(self.lower_span(*s)),
405 };
406 hir::ItemKind::Impl(self.arena.alloc(hir::Impl {
407 unsafety: self.lower_unsafety(*unsafety),
408 polarity,
409 defaultness,
410 defaultness_span,
411 constness: self.lower_constness(*constness),
412 generics,
413 of_trait: trait_ref,
414 self_ty: lowered_ty,
415 items: new_impl_items,
416 }))
417 }
418 ItemKind::Trait(box Trait { is_auto, unsafety, generics, bounds, items }) => {
419 // FIXME(const_trait_impl, effects, fee1-dead) this should be simplified if possible
420 let constness = attrs
421 .unwrap_or(&[])
422 .iter()
423 .find(|x| x.has_name(sym::const_trait))
424 .map_or(Const::No, |x| Const::Yes(x.span));
425 let (generics, (unsafety, items, bounds)) = self.lower_generics(
426 generics,
427 constness,
428 id,
429 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
430 |this| {
431 let bounds = this.lower_param_bounds(
432 bounds,
433 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
434 );
435 let items = this.arena.alloc_from_iter(
436 items.iter().map(|item| this.lower_trait_item_ref(item)),
437 );
438 let unsafety = this.lower_unsafety(*unsafety);
439 (unsafety, items, bounds)
440 },
441 );
442 hir::ItemKind::Trait(*is_auto, unsafety, generics, bounds, items)
443 }
444 ItemKind::TraitAlias(generics, bounds) => {
445 let (generics, bounds) = self.lower_generics(
446 generics,
447 Const::No,
448 id,
449 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
450 |this| {
451 this.lower_param_bounds(
452 bounds,
453 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
454 )
455 },
456 );
457 hir::ItemKind::TraitAlias(generics, bounds)
458 }
459 ItemKind::MacroDef(MacroDef { body, macro_rules }) => {
460 let body = P(self.lower_delim_args(body));
461 let macro_kind = self.resolver.decl_macro_kind(self.local_def_id(id));
462 let macro_def = self.arena.alloc(ast::MacroDef { body, macro_rules: *macro_rules });
463 hir::ItemKind::Macro(macro_def, macro_kind)
464 }
465 ItemKind::MacCall(..) => {
466 panic!("`TyMac` should have been expanded by now")
467 }
468 }
469 }
470
lower_const_item( &mut self, ty: &Ty, span: Span, body: Option<&Expr>, ) -> (&'hir hir::Ty<'hir>, hir::BodyId)471 fn lower_const_item(
472 &mut self,
473 ty: &Ty,
474 span: Span,
475 body: Option<&Expr>,
476 ) -> (&'hir hir::Ty<'hir>, hir::BodyId) {
477 let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
478 (ty, self.lower_const_body(span, body))
479 }
480
481 #[instrument(level = "debug", skip(self))]
lower_use_tree( &mut self, tree: &UseTree, prefix: &Path, id: NodeId, vis_span: Span, ident: &mut Ident, attrs: Option<&'hir [Attribute]>, ) -> hir::ItemKind<'hir>482 fn lower_use_tree(
483 &mut self,
484 tree: &UseTree,
485 prefix: &Path,
486 id: NodeId,
487 vis_span: Span,
488 ident: &mut Ident,
489 attrs: Option<&'hir [Attribute]>,
490 ) -> hir::ItemKind<'hir> {
491 let path = &tree.prefix;
492 let segments = prefix.segments.iter().chain(path.segments.iter()).cloned().collect();
493
494 match tree.kind {
495 UseTreeKind::Simple(rename) => {
496 *ident = tree.ident();
497
498 // First, apply the prefix to the path.
499 let mut path = Path { segments, span: path.span, tokens: None };
500
501 // Correctly resolve `self` imports.
502 if path.segments.len() > 1
503 && path.segments.last().unwrap().ident.name == kw::SelfLower
504 {
505 let _ = path.segments.pop();
506 if rename.is_none() {
507 *ident = path.segments.last().unwrap().ident;
508 }
509 }
510
511 let res =
512 self.expect_full_res_from_use(id).map(|res| self.lower_res(res)).collect();
513 let path = self.lower_use_path(res, &path, ParamMode::Explicit);
514 hir::ItemKind::Use(path, hir::UseKind::Single)
515 }
516 UseTreeKind::Glob => {
517 let res = self.expect_full_res(id);
518 let res = smallvec![self.lower_res(res)];
519 let path = Path { segments, span: path.span, tokens: None };
520 let path = self.lower_use_path(res, &path, ParamMode::Explicit);
521 hir::ItemKind::Use(path, hir::UseKind::Glob)
522 }
523 UseTreeKind::Nested(ref trees) => {
524 // Nested imports are desugared into simple imports.
525 // So, if we start with
526 //
527 // ```
528 // pub(x) use foo::{a, b};
529 // ```
530 //
531 // we will create three items:
532 //
533 // ```
534 // pub(x) use foo::a;
535 // pub(x) use foo::b;
536 // pub(x) use foo::{}; // <-- this is called the `ListStem`
537 // ```
538 //
539 // The first two are produced by recursively invoking
540 // `lower_use_tree` (and indeed there may be things
541 // like `use foo::{a::{b, c}}` and so forth). They
542 // wind up being directly added to
543 // `self.items`. However, the structure of this
544 // function also requires us to return one item, and
545 // for that we return the `{}` import (called the
546 // `ListStem`).
547
548 let prefix = Path { segments, span: prefix.span.to(path.span), tokens: None };
549
550 // Add all the nested `PathListItem`s to the HIR.
551 for &(ref use_tree, id) in trees {
552 let new_hir_id = self.local_def_id(id);
553
554 let mut prefix = prefix.clone();
555
556 // Give the segments new node-ids since they are being cloned.
557 for seg in &mut prefix.segments {
558 // Give the cloned segment the same resolution information
559 // as the old one (this is needed for stability checking).
560 let new_id = self.next_node_id();
561 self.resolver.clone_res(seg.id, new_id);
562 seg.id = new_id;
563 }
564
565 // Each `use` import is an item and thus are owners of the
566 // names in the path. Up to this point the nested import is
567 // the current owner, since we want each desugared import to
568 // own its own names, we have to adjust the owner before
569 // lowering the rest of the import.
570 self.with_hir_id_owner(id, |this| {
571 let mut ident = *ident;
572
573 let kind =
574 this.lower_use_tree(use_tree, &prefix, id, vis_span, &mut ident, attrs);
575 if let Some(attrs) = attrs {
576 this.attrs.insert(hir::ItemLocalId::new(0), attrs);
577 }
578
579 let item = hir::Item {
580 owner_id: hir::OwnerId { def_id: new_hir_id },
581 ident: this.lower_ident(ident),
582 kind,
583 vis_span,
584 span: this.lower_span(use_tree.span),
585 };
586 hir::OwnerNode::Item(this.arena.alloc(item))
587 });
588 }
589
590 let res =
591 self.expect_full_res_from_use(id).map(|res| self.lower_res(res)).collect();
592 let path = self.lower_use_path(res, &prefix, ParamMode::Explicit);
593 hir::ItemKind::Use(path, hir::UseKind::ListStem)
594 }
595 }
596 }
597
lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir>598 fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
599 let hir_id = self.lower_node_id(i.id);
600 let owner_id = hir_id.expect_owner();
601 self.lower_attrs(hir_id, &i.attrs);
602 let item = hir::ForeignItem {
603 owner_id,
604 ident: self.lower_ident(i.ident),
605 kind: match &i.kind {
606 ForeignItemKind::Fn(box Fn { sig, generics, .. }) => {
607 let fdec = &sig.decl;
608 let itctx = ImplTraitContext::Universal;
609 let (generics, (fn_dec, fn_args)) =
610 self.lower_generics(generics, Const::No, i.id, &itctx, |this| {
611 (
612 // Disallow `impl Trait` in foreign items.
613 this.lower_fn_decl(
614 fdec,
615 i.id,
616 sig.span,
617 FnDeclKind::ExternFn,
618 None,
619 ),
620 this.lower_fn_params_to_names(fdec),
621 )
622 });
623
624 hir::ForeignItemKind::Fn(fn_dec, fn_args, generics)
625 }
626 ForeignItemKind::Static(t, m, _) => {
627 let ty = self
628 .lower_ty(t, &ImplTraitContext::Disallowed(ImplTraitPosition::StaticTy));
629 hir::ForeignItemKind::Static(ty, *m)
630 }
631 ForeignItemKind::TyAlias(..) => hir::ForeignItemKind::Type,
632 ForeignItemKind::MacCall(_) => panic!("macro shouldn't exist here"),
633 },
634 vis_span: self.lower_span(i.vis.span),
635 span: self.lower_span(i.span),
636 };
637 self.arena.alloc(item)
638 }
639
lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemRef640 fn lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemRef {
641 hir::ForeignItemRef {
642 id: hir::ForeignItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } },
643 ident: self.lower_ident(i.ident),
644 span: self.lower_span(i.span),
645 }
646 }
647
lower_variant(&mut self, v: &Variant) -> hir::Variant<'hir>648 fn lower_variant(&mut self, v: &Variant) -> hir::Variant<'hir> {
649 let hir_id = self.lower_node_id(v.id);
650 self.lower_attrs(hir_id, &v.attrs);
651 hir::Variant {
652 hir_id,
653 def_id: self.local_def_id(v.id),
654 data: self.lower_variant_data(hir_id, &v.data),
655 disr_expr: v.disr_expr.as_ref().map(|e| self.lower_anon_const(e)),
656 ident: self.lower_ident(v.ident),
657 span: self.lower_span(v.span),
658 }
659 }
660
lower_variant_data( &mut self, parent_id: hir::HirId, vdata: &VariantData, ) -> hir::VariantData<'hir>661 fn lower_variant_data(
662 &mut self,
663 parent_id: hir::HirId,
664 vdata: &VariantData,
665 ) -> hir::VariantData<'hir> {
666 match vdata {
667 VariantData::Struct(fields, recovered) => hir::VariantData::Struct(
668 self.arena
669 .alloc_from_iter(fields.iter().enumerate().map(|f| self.lower_field_def(f))),
670 *recovered,
671 ),
672 VariantData::Tuple(fields, id) => {
673 let ctor_id = self.lower_node_id(*id);
674 self.alias_attrs(ctor_id, parent_id);
675 hir::VariantData::Tuple(
676 self.arena.alloc_from_iter(
677 fields.iter().enumerate().map(|f| self.lower_field_def(f)),
678 ),
679 ctor_id,
680 self.local_def_id(*id),
681 )
682 }
683 VariantData::Unit(id) => {
684 let ctor_id = self.lower_node_id(*id);
685 self.alias_attrs(ctor_id, parent_id);
686 hir::VariantData::Unit(ctor_id, self.local_def_id(*id))
687 }
688 }
689 }
690
lower_field_def(&mut self, (index, f): (usize, &FieldDef)) -> hir::FieldDef<'hir>691 fn lower_field_def(&mut self, (index, f): (usize, &FieldDef)) -> hir::FieldDef<'hir> {
692 let ty = if let TyKind::Path(qself, path) = &f.ty.kind {
693 let t = self.lower_path_ty(
694 &f.ty,
695 qself,
696 path,
697 ParamMode::ExplicitNamed, // no `'_` in declarations (Issue #61124)
698 &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy),
699 );
700 self.arena.alloc(t)
701 } else {
702 self.lower_ty(&f.ty, &ImplTraitContext::Disallowed(ImplTraitPosition::FieldTy))
703 };
704 let hir_id = self.lower_node_id(f.id);
705 self.lower_attrs(hir_id, &f.attrs);
706 hir::FieldDef {
707 span: self.lower_span(f.span),
708 hir_id,
709 def_id: self.local_def_id(f.id),
710 ident: match f.ident {
711 Some(ident) => self.lower_ident(ident),
712 // FIXME(jseyfried): positional field hygiene.
713 None => Ident::new(sym::integer(index), self.lower_span(f.span)),
714 },
715 vis_span: self.lower_span(f.vis.span),
716 ty,
717 }
718 }
719
lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir>720 fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
721 let hir_id = self.lower_node_id(i.id);
722 self.lower_attrs(hir_id, &i.attrs);
723 let trait_item_def_id = hir_id.expect_owner();
724
725 let (generics, kind, has_default) = match &i.kind {
726 AssocItemKind::Const(box ConstItem { ty, expr, .. }) => {
727 let ty =
728 self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
729 let body = expr.as_ref().map(|x| self.lower_const_body(i.span, Some(x)));
730 (hir::Generics::empty(), hir::TraitItemKind::Const(ty, body), body.is_some())
731 }
732 AssocItemKind::Fn(box Fn { sig, generics, body: None, .. }) => {
733 let asyncness = sig.header.asyncness;
734 let names = self.lower_fn_params_to_names(&sig.decl);
735 let (generics, sig) = self.lower_method_sig(
736 generics,
737 sig,
738 i.id,
739 FnDeclKind::Trait,
740 asyncness.opt_return_id(),
741 );
742 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Required(names)), false)
743 }
744 AssocItemKind::Fn(box Fn { sig, generics, body: Some(body), .. }) => {
745 let asyncness = sig.header.asyncness;
746 let body_id =
747 self.lower_maybe_async_body(i.span, hir_id, &sig.decl, asyncness, Some(&body));
748 let (generics, sig) = self.lower_method_sig(
749 generics,
750 sig,
751 i.id,
752 FnDeclKind::Trait,
753 asyncness.opt_return_id(),
754 );
755 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)), true)
756 }
757 AssocItemKind::Type(box TyAlias { generics, where_clauses, bounds, ty, .. }) => {
758 let mut generics = generics.clone();
759 add_ty_alias_where_clause(&mut generics, *where_clauses, false);
760 let (generics, kind) = self.lower_generics(
761 &generics,
762 Const::No,
763 i.id,
764 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
765 |this| {
766 let ty = ty.as_ref().map(|x| {
767 this.lower_ty(
768 x,
769 &ImplTraitContext::Disallowed(ImplTraitPosition::AssocTy),
770 )
771 });
772 hir::TraitItemKind::Type(
773 this.lower_param_bounds(
774 bounds,
775 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
776 ),
777 ty,
778 )
779 },
780 );
781 (generics, kind, ty.is_some())
782 }
783 AssocItemKind::MacCall(..) => panic!("macro item shouldn't exist at this point"),
784 };
785
786 let item = hir::TraitItem {
787 owner_id: trait_item_def_id,
788 ident: self.lower_ident(i.ident),
789 generics,
790 kind,
791 span: self.lower_span(i.span),
792 defaultness: hir::Defaultness::Default { has_value: has_default },
793 };
794 self.arena.alloc(item)
795 }
796
lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemRef797 fn lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemRef {
798 let kind = match &i.kind {
799 AssocItemKind::Const(..) => hir::AssocItemKind::Const,
800 AssocItemKind::Type(..) => hir::AssocItemKind::Type,
801 AssocItemKind::Fn(box Fn { sig, .. }) => {
802 hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
803 }
804 AssocItemKind::MacCall(..) => unimplemented!(),
805 };
806 let id = hir::TraitItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } };
807 hir::TraitItemRef {
808 id,
809 ident: self.lower_ident(i.ident),
810 span: self.lower_span(i.span),
811 kind,
812 }
813 }
814
815 /// Construct `ExprKind::Err` for the given `span`.
expr_err(&mut self, span: Span, guar: ErrorGuaranteed) -> hir::Expr<'hir>816 pub(crate) fn expr_err(&mut self, span: Span, guar: ErrorGuaranteed) -> hir::Expr<'hir> {
817 self.expr(span, hir::ExprKind::Err(guar))
818 }
819
lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir>820 fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
821 // Since `default impl` is not yet implemented, this is always true in impls.
822 let has_value = true;
823 let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value);
824 let hir_id = self.lower_node_id(i.id);
825 self.lower_attrs(hir_id, &i.attrs);
826
827 let (generics, kind) = match &i.kind {
828 AssocItemKind::Const(box ConstItem { ty, expr, .. }) => {
829 let ty =
830 self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
831 (
832 hir::Generics::empty(),
833 hir::ImplItemKind::Const(ty, self.lower_const_body(i.span, expr.as_deref())),
834 )
835 }
836 AssocItemKind::Fn(box Fn { sig, generics, body, .. }) => {
837 self.current_item = Some(i.span);
838 let asyncness = sig.header.asyncness;
839 let body_id = self.lower_maybe_async_body(
840 i.span,
841 hir_id,
842 &sig.decl,
843 asyncness,
844 body.as_deref(),
845 );
846 let (generics, sig) = self.lower_method_sig(
847 generics,
848 sig,
849 i.id,
850 if self.is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent },
851 asyncness.opt_return_id(),
852 );
853
854 (generics, hir::ImplItemKind::Fn(sig, body_id))
855 }
856 AssocItemKind::Type(box TyAlias { generics, where_clauses, ty, .. }) => {
857 let mut generics = generics.clone();
858 add_ty_alias_where_clause(&mut generics, *where_clauses, false);
859 self.lower_generics(
860 &generics,
861 Const::No,
862 i.id,
863 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
864 |this| match ty {
865 None => {
866 let guar = this.tcx.sess.delay_span_bug(
867 i.span,
868 "expected to lower associated type, but it was missing",
869 );
870 let ty = this.arena.alloc(this.ty(i.span, hir::TyKind::Err(guar)));
871 hir::ImplItemKind::Type(ty)
872 }
873 Some(ty) => {
874 let ty = this.lower_ty(
875 ty,
876 &ImplTraitContext::TypeAliasesOpaqueTy { in_assoc_ty: true },
877 );
878 hir::ImplItemKind::Type(ty)
879 }
880 },
881 )
882 }
883 AssocItemKind::MacCall(..) => panic!("`TyMac` should have been expanded by now"),
884 };
885
886 let item = hir::ImplItem {
887 owner_id: hir_id.expect_owner(),
888 ident: self.lower_ident(i.ident),
889 generics,
890 kind,
891 vis_span: self.lower_span(i.vis.span),
892 span: self.lower_span(i.span),
893 defaultness,
894 };
895 self.arena.alloc(item)
896 }
897
lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef898 fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef {
899 hir::ImplItemRef {
900 id: hir::ImplItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } },
901 ident: self.lower_ident(i.ident),
902 span: self.lower_span(i.span),
903 kind: match &i.kind {
904 AssocItemKind::Const(..) => hir::AssocItemKind::Const,
905 AssocItemKind::Type(..) => hir::AssocItemKind::Type,
906 AssocItemKind::Fn(box Fn { sig, .. }) => {
907 hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
908 }
909 AssocItemKind::MacCall(..) => unimplemented!(),
910 },
911 trait_item_def_id: self
912 .resolver
913 .get_partial_res(i.id)
914 .map(|r| r.expect_full_res().def_id()),
915 }
916 }
917
lower_defaultness( &self, d: Defaultness, has_value: bool, ) -> (hir::Defaultness, Option<Span>)918 fn lower_defaultness(
919 &self,
920 d: Defaultness,
921 has_value: bool,
922 ) -> (hir::Defaultness, Option<Span>) {
923 match d {
924 Defaultness::Default(sp) => {
925 (hir::Defaultness::Default { has_value }, Some(self.lower_span(sp)))
926 }
927 Defaultness::Final => {
928 assert!(has_value);
929 (hir::Defaultness::Final, None)
930 }
931 }
932 }
933
record_body( &mut self, params: &'hir [hir::Param<'hir>], value: hir::Expr<'hir>, ) -> hir::BodyId934 fn record_body(
935 &mut self,
936 params: &'hir [hir::Param<'hir>],
937 value: hir::Expr<'hir>,
938 ) -> hir::BodyId {
939 let body = hir::Body {
940 generator_kind: self.generator_kind,
941 params,
942 value: self.arena.alloc(value),
943 };
944 let id = body.id();
945 debug_assert_eq!(id.hir_id.owner, self.current_hir_id_owner);
946 self.bodies.push((id.hir_id.local_id, self.arena.alloc(body)));
947 id
948 }
949
lower_body( &mut self, f: impl FnOnce(&mut Self) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>), ) -> hir::BodyId950 pub(super) fn lower_body(
951 &mut self,
952 f: impl FnOnce(&mut Self) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>),
953 ) -> hir::BodyId {
954 let prev_gen_kind = self.generator_kind.take();
955 let task_context = self.task_context.take();
956 let (parameters, result) = f(self);
957 let body_id = self.record_body(parameters, result);
958 self.task_context = task_context;
959 self.generator_kind = prev_gen_kind;
960 body_id
961 }
962
lower_param(&mut self, param: &Param) -> hir::Param<'hir>963 fn lower_param(&mut self, param: &Param) -> hir::Param<'hir> {
964 let hir_id = self.lower_node_id(param.id);
965 self.lower_attrs(hir_id, ¶m.attrs);
966 hir::Param {
967 hir_id,
968 pat: self.lower_pat(¶m.pat),
969 ty_span: self.lower_span(param.ty.span),
970 span: self.lower_span(param.span),
971 }
972 }
973
lower_fn_body( &mut self, decl: &FnDecl, body: impl FnOnce(&mut Self) -> hir::Expr<'hir>, ) -> hir::BodyId974 pub(super) fn lower_fn_body(
975 &mut self,
976 decl: &FnDecl,
977 body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
978 ) -> hir::BodyId {
979 self.lower_body(|this| {
980 (
981 this.arena.alloc_from_iter(decl.inputs.iter().map(|x| this.lower_param(x))),
982 body(this),
983 )
984 })
985 }
986
lower_fn_body_block( &mut self, span: Span, decl: &FnDecl, body: Option<&Block>, ) -> hir::BodyId987 fn lower_fn_body_block(
988 &mut self,
989 span: Span,
990 decl: &FnDecl,
991 body: Option<&Block>,
992 ) -> hir::BodyId {
993 self.lower_fn_body(decl, |this| this.lower_block_expr_opt(span, body))
994 }
995
lower_block_expr_opt(&mut self, span: Span, block: Option<&Block>) -> hir::Expr<'hir>996 fn lower_block_expr_opt(&mut self, span: Span, block: Option<&Block>) -> hir::Expr<'hir> {
997 match block {
998 Some(block) => self.lower_block_expr(block),
999 None => self.expr_err(span, self.tcx.sess.delay_span_bug(span, "no block")),
1000 }
1001 }
1002
lower_const_body(&mut self, span: Span, expr: Option<&Expr>) -> hir::BodyId1003 pub(super) fn lower_const_body(&mut self, span: Span, expr: Option<&Expr>) -> hir::BodyId {
1004 self.lower_body(|this| {
1005 (
1006 &[],
1007 match expr {
1008 Some(expr) => this.lower_expr_mut(expr),
1009 None => this.expr_err(span, this.tcx.sess.delay_span_bug(span, "no block")),
1010 },
1011 )
1012 })
1013 }
1014
lower_maybe_async_body( &mut self, span: Span, fn_id: hir::HirId, decl: &FnDecl, asyncness: Async, body: Option<&Block>, ) -> hir::BodyId1015 fn lower_maybe_async_body(
1016 &mut self,
1017 span: Span,
1018 fn_id: hir::HirId,
1019 decl: &FnDecl,
1020 asyncness: Async,
1021 body: Option<&Block>,
1022 ) -> hir::BodyId {
1023 let (closure_id, body) = match (asyncness, body) {
1024 (Async::Yes { closure_id, .. }, Some(body)) => (closure_id, body),
1025 _ => return self.lower_fn_body_block(span, decl, body),
1026 };
1027
1028 self.lower_body(|this| {
1029 let mut parameters: Vec<hir::Param<'_>> = Vec::new();
1030 let mut statements: Vec<hir::Stmt<'_>> = Vec::new();
1031
1032 // Async function parameters are lowered into the closure body so that they are
1033 // captured and so that the drop order matches the equivalent non-async functions.
1034 //
1035 // from:
1036 //
1037 // async fn foo(<pattern>: <ty>, <pattern>: <ty>, <pattern>: <ty>) {
1038 // <body>
1039 // }
1040 //
1041 // into:
1042 //
1043 // fn foo(__arg0: <ty>, __arg1: <ty>, __arg2: <ty>) {
1044 // async move {
1045 // let __arg2 = __arg2;
1046 // let <pattern> = __arg2;
1047 // let __arg1 = __arg1;
1048 // let <pattern> = __arg1;
1049 // let __arg0 = __arg0;
1050 // let <pattern> = __arg0;
1051 // drop-temps { <body> } // see comments later in fn for details
1052 // }
1053 // }
1054 //
1055 // If `<pattern>` is a simple ident, then it is lowered to a single
1056 // `let <pattern> = <pattern>;` statement as an optimization.
1057 //
1058 // Note that the body is embedded in `drop-temps`; an
1059 // equivalent desugaring would be `return { <body>
1060 // };`. The key point is that we wish to drop all the
1061 // let-bound variables and temporaries created in the body
1062 // (and its tail expression!) before we drop the
1063 // parameters (c.f. rust-lang/rust#64512).
1064 for (index, parameter) in decl.inputs.iter().enumerate() {
1065 let parameter = this.lower_param(parameter);
1066 let span = parameter.pat.span;
1067
1068 // Check if this is a binding pattern, if so, we can optimize and avoid adding a
1069 // `let <pat> = __argN;` statement. In this case, we do not rename the parameter.
1070 let (ident, is_simple_parameter) = match parameter.pat.kind {
1071 hir::PatKind::Binding(hir::BindingAnnotation(ByRef::No, _), _, ident, _) => {
1072 (ident, true)
1073 }
1074 // For `ref mut` or wildcard arguments, we can't reuse the binding, but
1075 // we can keep the same name for the parameter.
1076 // This lets rustdoc render it correctly in documentation.
1077 hir::PatKind::Binding(_, _, ident, _) => (ident, false),
1078 hir::PatKind::Wild => {
1079 (Ident::with_dummy_span(rustc_span::symbol::kw::Underscore), false)
1080 }
1081 _ => {
1082 // Replace the ident for bindings that aren't simple.
1083 let name = format!("__arg{index}");
1084 let ident = Ident::from_str(&name);
1085
1086 (ident, false)
1087 }
1088 };
1089
1090 let desugared_span = this.mark_span_with_reason(DesugaringKind::Async, span, None);
1091
1092 // Construct a parameter representing `__argN: <ty>` to replace the parameter of the
1093 // async function.
1094 //
1095 // If this is the simple case, this parameter will end up being the same as the
1096 // original parameter, but with a different pattern id.
1097 let stmt_attrs = this.attrs.get(¶meter.hir_id.local_id).copied();
1098 let (new_parameter_pat, new_parameter_id) = this.pat_ident(desugared_span, ident);
1099 let new_parameter = hir::Param {
1100 hir_id: parameter.hir_id,
1101 pat: new_parameter_pat,
1102 ty_span: this.lower_span(parameter.ty_span),
1103 span: this.lower_span(parameter.span),
1104 };
1105
1106 if is_simple_parameter {
1107 // If this is the simple case, then we only insert one statement that is
1108 // `let <pat> = <pat>;`. We re-use the original argument's pattern so that
1109 // `HirId`s are densely assigned.
1110 let expr = this.expr_ident(desugared_span, ident, new_parameter_id);
1111 let stmt = this.stmt_let_pat(
1112 stmt_attrs,
1113 desugared_span,
1114 Some(expr),
1115 parameter.pat,
1116 hir::LocalSource::AsyncFn,
1117 );
1118 statements.push(stmt);
1119 } else {
1120 // If this is not the simple case, then we construct two statements:
1121 //
1122 // ```
1123 // let __argN = __argN;
1124 // let <pat> = __argN;
1125 // ```
1126 //
1127 // The first statement moves the parameter into the closure and thus ensures
1128 // that the drop order is correct.
1129 //
1130 // The second statement creates the bindings that the user wrote.
1131
1132 // Construct the `let mut __argN = __argN;` statement. It must be a mut binding
1133 // because the user may have specified a `ref mut` binding in the next
1134 // statement.
1135 let (move_pat, move_id) = this.pat_ident_binding_mode(
1136 desugared_span,
1137 ident,
1138 hir::BindingAnnotation::MUT,
1139 );
1140 let move_expr = this.expr_ident(desugared_span, ident, new_parameter_id);
1141 let move_stmt = this.stmt_let_pat(
1142 None,
1143 desugared_span,
1144 Some(move_expr),
1145 move_pat,
1146 hir::LocalSource::AsyncFn,
1147 );
1148
1149 // Construct the `let <pat> = __argN;` statement. We re-use the original
1150 // parameter's pattern so that `HirId`s are densely assigned.
1151 let pattern_expr = this.expr_ident(desugared_span, ident, move_id);
1152 let pattern_stmt = this.stmt_let_pat(
1153 stmt_attrs,
1154 desugared_span,
1155 Some(pattern_expr),
1156 parameter.pat,
1157 hir::LocalSource::AsyncFn,
1158 );
1159
1160 statements.push(move_stmt);
1161 statements.push(pattern_stmt);
1162 };
1163
1164 parameters.push(new_parameter);
1165 }
1166
1167 let async_expr = this.make_async_expr(
1168 CaptureBy::Value,
1169 closure_id,
1170 None,
1171 body.span,
1172 hir::AsyncGeneratorKind::Fn,
1173 |this| {
1174 // Create a block from the user's function body:
1175 let user_body = this.lower_block_expr(body);
1176
1177 // Transform into `drop-temps { <user-body> }`, an expression:
1178 let desugared_span =
1179 this.mark_span_with_reason(DesugaringKind::Async, user_body.span, None);
1180 let user_body =
1181 this.expr_drop_temps(desugared_span, this.arena.alloc(user_body));
1182
1183 // As noted above, create the final block like
1184 //
1185 // ```
1186 // {
1187 // let $param_pattern = $raw_param;
1188 // ...
1189 // drop-temps { <user-body> }
1190 // }
1191 // ```
1192 let body = this.block_all(
1193 desugared_span,
1194 this.arena.alloc_from_iter(statements),
1195 Some(user_body),
1196 );
1197
1198 this.expr_block(body)
1199 },
1200 );
1201
1202 let hir_id = this.lower_node_id(closure_id);
1203 this.maybe_forward_track_caller(body.span, fn_id, hir_id);
1204 let expr = hir::Expr { hir_id, kind: async_expr, span: this.lower_span(body.span) };
1205
1206 (this.arena.alloc_from_iter(parameters), expr)
1207 })
1208 }
1209
lower_method_sig( &mut self, generics: &Generics, sig: &FnSig, id: NodeId, kind: FnDeclKind, is_async: Option<(NodeId, Span)>, ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>)1210 fn lower_method_sig(
1211 &mut self,
1212 generics: &Generics,
1213 sig: &FnSig,
1214 id: NodeId,
1215 kind: FnDeclKind,
1216 is_async: Option<(NodeId, Span)>,
1217 ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
1218 let header = self.lower_fn_header(sig.header);
1219 let itctx = ImplTraitContext::Universal;
1220 let (generics, decl) =
1221 self.lower_generics(generics, sig.header.constness, id, &itctx, |this| {
1222 this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async)
1223 });
1224 (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
1225 }
1226
lower_fn_header(&mut self, h: FnHeader) -> hir::FnHeader1227 fn lower_fn_header(&mut self, h: FnHeader) -> hir::FnHeader {
1228 hir::FnHeader {
1229 unsafety: self.lower_unsafety(h.unsafety),
1230 asyncness: self.lower_asyncness(h.asyncness),
1231 constness: self.lower_constness(h.constness),
1232 abi: self.lower_extern(h.ext),
1233 }
1234 }
1235
lower_abi(&mut self, abi: StrLit) -> abi::Abi1236 pub(super) fn lower_abi(&mut self, abi: StrLit) -> abi::Abi {
1237 abi::lookup(abi.symbol_unescaped.as_str()).unwrap_or_else(|| {
1238 self.error_on_invalid_abi(abi);
1239 abi::Abi::Rust
1240 })
1241 }
1242
lower_extern(&mut self, ext: Extern) -> abi::Abi1243 pub(super) fn lower_extern(&mut self, ext: Extern) -> abi::Abi {
1244 match ext {
1245 Extern::None => abi::Abi::Rust,
1246 Extern::Implicit(_) => abi::Abi::FALLBACK,
1247 Extern::Explicit(abi, _) => self.lower_abi(abi),
1248 }
1249 }
1250
error_on_invalid_abi(&self, abi: StrLit)1251 fn error_on_invalid_abi(&self, abi: StrLit) {
1252 let abi_names = abi::enabled_names(self.tcx.features(), abi.span)
1253 .iter()
1254 .map(|s| Symbol::intern(s))
1255 .collect::<Vec<_>>();
1256 let suggested_name = find_best_match_for_name(&abi_names, abi.symbol_unescaped, None);
1257 self.tcx.sess.emit_err(InvalidAbi {
1258 abi: abi.symbol_unescaped,
1259 span: abi.span,
1260 suggestion: suggested_name.map(|suggested_name| InvalidAbiSuggestion {
1261 span: abi.span,
1262 suggestion: format!("\"{suggested_name}\""),
1263 }),
1264 command: "rustc --print=calling-conventions".to_string(),
1265 });
1266 }
1267
lower_asyncness(&mut self, a: Async) -> hir::IsAsync1268 fn lower_asyncness(&mut self, a: Async) -> hir::IsAsync {
1269 match a {
1270 Async::Yes { .. } => hir::IsAsync::Async,
1271 Async::No => hir::IsAsync::NotAsync,
1272 }
1273 }
1274
lower_constness(&mut self, c: Const) -> hir::Constness1275 pub(super) fn lower_constness(&mut self, c: Const) -> hir::Constness {
1276 match c {
1277 Const::Yes(_) => hir::Constness::Const,
1278 Const::No => hir::Constness::NotConst,
1279 }
1280 }
1281
lower_unsafety(&mut self, u: Unsafe) -> hir::Unsafety1282 pub(super) fn lower_unsafety(&mut self, u: Unsafe) -> hir::Unsafety {
1283 match u {
1284 Unsafe::Yes(_) => hir::Unsafety::Unsafe,
1285 Unsafe::No => hir::Unsafety::Normal,
1286 }
1287 }
1288
1289 /// Return the pair of the lowered `generics` as `hir::Generics` and the evaluation of `f` with
1290 /// the carried impl trait definitions and bounds.
1291 #[instrument(level = "debug", skip(self, f))]
lower_generics<T>( &mut self, generics: &Generics, constness: Const, parent_node_id: NodeId, itctx: &ImplTraitContext, f: impl FnOnce(&mut Self) -> T, ) -> (&'hir hir::Generics<'hir>, T)1292 fn lower_generics<T>(
1293 &mut self,
1294 generics: &Generics,
1295 constness: Const,
1296 parent_node_id: NodeId,
1297 itctx: &ImplTraitContext,
1298 f: impl FnOnce(&mut Self) -> T,
1299 ) -> (&'hir hir::Generics<'hir>, T) {
1300 debug_assert!(self.impl_trait_defs.is_empty());
1301 debug_assert!(self.impl_trait_bounds.is_empty());
1302
1303 // Error if `?Trait` bounds in where clauses don't refer directly to type parameters.
1304 // Note: we used to clone these bounds directly onto the type parameter (and avoid lowering
1305 // these into hir when we lower thee where clauses), but this makes it quite difficult to
1306 // keep track of the Span info. Now, `add_implicitly_sized` in `AstConv` checks both param bounds and
1307 // where clauses for `?Sized`.
1308 for pred in &generics.where_clause.predicates {
1309 let WherePredicate::BoundPredicate(bound_pred) = pred else {
1310 continue;
1311 };
1312 let compute_is_param = || {
1313 // Check if the where clause type is a plain type parameter.
1314 match self
1315 .resolver
1316 .get_partial_res(bound_pred.bounded_ty.id)
1317 .and_then(|r| r.full_res())
1318 {
1319 Some(Res::Def(DefKind::TyParam, def_id))
1320 if bound_pred.bound_generic_params.is_empty() =>
1321 {
1322 generics
1323 .params
1324 .iter()
1325 .any(|p| def_id == self.local_def_id(p.id).to_def_id())
1326 }
1327 // Either the `bounded_ty` is not a plain type parameter, or
1328 // it's not found in the generic type parameters list.
1329 _ => false,
1330 }
1331 };
1332 // We only need to compute this once per `WherePredicate`, but don't
1333 // need to compute this at all unless there is a Maybe bound.
1334 let mut is_param: Option<bool> = None;
1335 for bound in &bound_pred.bounds {
1336 if !matches!(*bound, GenericBound::Trait(_, TraitBoundModifier::Maybe)) {
1337 continue;
1338 }
1339 let is_param = *is_param.get_or_insert_with(compute_is_param);
1340 if !is_param {
1341 self.tcx.sess.emit_err(MisplacedRelaxTraitBound { span: bound.span() });
1342 }
1343 }
1344 }
1345
1346 let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new();
1347 predicates.extend(generics.params.iter().filter_map(|param| {
1348 self.lower_generic_bound_predicate(
1349 param.ident,
1350 param.id,
1351 ¶m.kind,
1352 ¶m.bounds,
1353 param.colon_span,
1354 generics.span,
1355 itctx,
1356 PredicateOrigin::GenericParam,
1357 )
1358 }));
1359 predicates.extend(
1360 generics
1361 .where_clause
1362 .predicates
1363 .iter()
1364 .map(|predicate| self.lower_where_predicate(predicate)),
1365 );
1366
1367 let mut params: SmallVec<[hir::GenericParam<'hir>; 4]> = self
1368 .lower_generic_params_mut(&generics.params, hir::GenericParamSource::Generics)
1369 .collect();
1370
1371 // Introduce extra lifetimes if late resolution tells us to.
1372 let extra_lifetimes = self.resolver.take_extra_lifetime_params(parent_node_id);
1373 params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
1374 self.lifetime_res_to_generic_param(
1375 ident,
1376 node_id,
1377 res,
1378 hir::GenericParamSource::Generics,
1379 )
1380 }));
1381
1382 let has_where_clause_predicates = !generics.where_clause.predicates.is_empty();
1383 let where_clause_span = self.lower_span(generics.where_clause.span);
1384 let span = self.lower_span(generics.span);
1385 let res = f(self);
1386
1387 let impl_trait_defs = std::mem::take(&mut self.impl_trait_defs);
1388 params.extend(impl_trait_defs.into_iter());
1389
1390 let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
1391 predicates.extend(impl_trait_bounds.into_iter());
1392
1393 // Desugar `~const` bound in generics into an additional `const host: bool` param
1394 // if the effects feature is enabled.
1395 if let Const::Yes(span) = constness && self.tcx.features().effects
1396 // Do not add host param if it already has it (manually specified)
1397 && !params.iter().any(|x| {
1398 self.attrs.get(&x.hir_id.local_id).map_or(false, |attrs| {
1399 attrs.iter().any(|x| x.has_name(sym::rustc_host))
1400 })
1401 })
1402 {
1403 let param_node_id = self.next_node_id();
1404 let const_node_id = self.next_node_id();
1405 let def_id = self.create_def(self.local_def_id(parent_node_id), param_node_id, DefPathData::TypeNs(sym::host), span);
1406 let anon_const: LocalDefId = self.create_def(def_id, const_node_id, DefPathData::AnonConst, span);
1407
1408 let hir_id = self.next_id();
1409 let const_id = self.next_id();
1410 let const_expr_id = self.next_id();
1411 let bool_id = self.next_id();
1412
1413 self.children.push((def_id, hir::MaybeOwner::NonOwner(hir_id)));
1414 self.children.push((anon_const, hir::MaybeOwner::NonOwner(const_id)));
1415
1416 let attr_id = self.tcx.sess.parse_sess.attr_id_generator.mk_attr_id();
1417
1418 let attrs = self.arena.alloc_from_iter([
1419 Attribute {
1420 kind: AttrKind::Normal(P(NormalAttr::from_ident(Ident::new(sym::rustc_host, span)))),
1421 span,
1422 id: attr_id,
1423 style: AttrStyle::Outer,
1424 },
1425 ]);
1426 self.attrs.insert(hir_id.local_id, attrs);
1427
1428 let const_body = self.lower_body(|this| {
1429 (
1430 &[],
1431 hir::Expr {
1432 hir_id: const_expr_id,
1433 kind: hir::ExprKind::Lit(
1434 this.arena.alloc(hir::Lit { node: LitKind::Bool(true), span }),
1435 ),
1436 span,
1437 },
1438 )
1439 });
1440
1441 let param = hir::GenericParam {
1442 def_id,
1443 hir_id,
1444 name: hir::ParamName::Plain(Ident { name: sym::host, span }),
1445 span,
1446 kind: hir::GenericParamKind::Const {
1447 ty: self.arena.alloc(self.ty(
1448 span,
1449 hir::TyKind::Path(hir::QPath::Resolved(
1450 None,
1451 self.arena.alloc(hir::Path {
1452 res: Res::PrimTy(hir::PrimTy::Bool),
1453 span,
1454 segments: self.arena.alloc_from_iter([hir::PathSegment {
1455 ident: Ident { name: sym::bool, span },
1456 hir_id: bool_id,
1457 res: Res::PrimTy(hir::PrimTy::Bool),
1458 args: None,
1459 infer_args: false,
1460 }]),
1461 }),
1462 )),
1463 )),
1464 default: Some(hir::AnonConst { def_id: anon_const, hir_id: const_id, body: const_body }),
1465 },
1466 colon_span: None,
1467 pure_wrt_drop: false,
1468 source: hir::GenericParamSource::Generics,
1469 };
1470
1471 params.push(param);
1472 }
1473
1474 let lowered_generics = self.arena.alloc(hir::Generics {
1475 params: self.arena.alloc_from_iter(params),
1476 predicates: self.arena.alloc_from_iter(predicates),
1477 has_where_clause_predicates,
1478 where_clause_span,
1479 span,
1480 });
1481
1482 (lowered_generics, res)
1483 }
1484
lower_generic_bound_predicate( &mut self, ident: Ident, id: NodeId, kind: &GenericParamKind, bounds: &[GenericBound], colon_span: Option<Span>, parent_span: Span, itctx: &ImplTraitContext, origin: PredicateOrigin, ) -> Option<hir::WherePredicate<'hir>>1485 pub(super) fn lower_generic_bound_predicate(
1486 &mut self,
1487 ident: Ident,
1488 id: NodeId,
1489 kind: &GenericParamKind,
1490 bounds: &[GenericBound],
1491 colon_span: Option<Span>,
1492 parent_span: Span,
1493 itctx: &ImplTraitContext,
1494 origin: PredicateOrigin,
1495 ) -> Option<hir::WherePredicate<'hir>> {
1496 // Do not create a clause if we do not have anything inside it.
1497 if bounds.is_empty() {
1498 return None;
1499 }
1500
1501 let bounds = self.lower_param_bounds(bounds, itctx);
1502
1503 let ident = self.lower_ident(ident);
1504 let param_span = ident.span;
1505
1506 // Reconstruct the span of the entire predicate from the individual generic bounds.
1507 let span_start = colon_span.unwrap_or_else(|| param_span.shrink_to_hi());
1508 let span = bounds.iter().fold(span_start, |span_accum, bound| {
1509 match bound.span().find_ancestor_inside(parent_span) {
1510 Some(bound_span) => span_accum.to(bound_span),
1511 None => span_accum,
1512 }
1513 });
1514 let span = self.lower_span(span);
1515
1516 match kind {
1517 GenericParamKind::Const { .. } => None,
1518 GenericParamKind::Type { .. } => {
1519 let def_id = self.local_def_id(id).to_def_id();
1520 let hir_id = self.next_id();
1521 let res = Res::Def(DefKind::TyParam, def_id);
1522 let ty_path = self.arena.alloc(hir::Path {
1523 span: param_span,
1524 res,
1525 segments: self
1526 .arena
1527 .alloc_from_iter([hir::PathSegment::new(ident, hir_id, res)]),
1528 });
1529 let ty_id = self.next_id();
1530 let bounded_ty =
1531 self.ty_path(ty_id, param_span, hir::QPath::Resolved(None, ty_path));
1532 Some(hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1533 hir_id: self.next_id(),
1534 bounded_ty: self.arena.alloc(bounded_ty),
1535 bounds,
1536 span,
1537 bound_generic_params: &[],
1538 origin,
1539 }))
1540 }
1541 GenericParamKind::Lifetime => {
1542 let ident = self.lower_ident(ident);
1543 let lt_id = self.next_node_id();
1544 let lifetime = self.new_named_lifetime(id, lt_id, ident);
1545 Some(hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1546 lifetime,
1547 span,
1548 bounds,
1549 in_where_clause: false,
1550 }))
1551 }
1552 }
1553 }
1554
lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir>1555 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir> {
1556 match pred {
1557 WherePredicate::BoundPredicate(WhereBoundPredicate {
1558 bound_generic_params,
1559 bounded_ty,
1560 bounds,
1561 span,
1562 }) => hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1563 hir_id: self.next_id(),
1564 bound_generic_params: self
1565 .lower_generic_params(bound_generic_params, hir::GenericParamSource::Binder),
1566 bounded_ty: self
1567 .lower_ty(bounded_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
1568 bounds: self.arena.alloc_from_iter(bounds.iter().map(|bound| {
1569 self.lower_param_bound(
1570 bound,
1571 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
1572 )
1573 })),
1574 span: self.lower_span(*span),
1575 origin: PredicateOrigin::WhereClause,
1576 }),
1577 WherePredicate::RegionPredicate(WhereRegionPredicate { lifetime, bounds, span }) => {
1578 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1579 span: self.lower_span(*span),
1580 lifetime: self.lower_lifetime(lifetime),
1581 bounds: self.lower_param_bounds(
1582 bounds,
1583 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
1584 ),
1585 in_where_clause: true,
1586 })
1587 }
1588 WherePredicate::EqPredicate(WhereEqPredicate { lhs_ty, rhs_ty, span }) => {
1589 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
1590 lhs_ty: self
1591 .lower_ty(lhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
1592 rhs_ty: self
1593 .lower_ty(rhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Bound)),
1594 span: self.lower_span(*span),
1595 })
1596 }
1597 }
1598 }
1599 }
1600