1 use super::errors::{InvalidAbi, InvalidAbiSuggestion, MisplacedRelaxTraitBound};
2 use super::ResolverAstLoweringExt;
3 use super::{Arena, AstOwner, ImplTraitContext, ImplTraitPosition};
4 use super::{FnDeclKind, LoweringContext, ParamMode};
7 use rustc_ast::visit::AssocCtxt;
9 use rustc_data_structures::sorted_map::SortedMap;
11 use rustc_hir::def::{DefKind, Res};
12 use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
13 use rustc_hir::PredicateOrigin;
14 use rustc_index::vec::{Idx, IndexVec};
15 use rustc_middle::ty::{DefIdTree, ResolverAstLowering, TyCtxt};
16 use rustc_span::lev_distance::find_best_match_for_name;
17 use rustc_span::source_map::DesugaringKind;
18 use rustc_span::symbol::{kw, sym, Ident};
19 use rustc_span::{Span, Symbol};
20 use rustc_target::spec::abi;
21 use smallvec::{smallvec, SmallVec};
23 use thin_vec::ThinVec;
25 pub(super) struct ItemLowerer<'a, 'hir> {
26 pub(super) tcx: TyCtxt<'hir>,
27 pub(super) resolver: &'a mut ResolverAstLowering,
28 pub(super) ast_arena: &'a Arena<'static>,
29 pub(super) ast_index: &'a IndexVec<LocalDefId, AstOwner<'a>>,
30 pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
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.
36 fn add_ty_alias_where_clause(
37 generics: &mut ast::Generics,
38 mut where_clauses: (TyAliasWhereClause, TyAliasWhereClause),
42 where_clauses = (where_clauses.1, where_clauses.0);
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;
48 generics.where_clause.has_where_token = where_clauses.1.0;
49 generics.where_clause.span = where_clauses.1.1;
53 impl<'a, 'hir> ItemLowerer<'a, 'hir> {
57 f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
59 let mut lctx = LoweringContext {
62 resolver: self.resolver,
63 arena: self.tcx.hir_arena,
64 ast_arena: self.ast_arena,
68 attrs: SortedMap::default(),
69 children: Vec::default(),
70 current_hir_id_owner: hir::CRATE_OWNER_ID,
71 item_local_id_counter: hir::ItemLocalId::new(0),
72 node_id_to_local_id: Default::default(),
73 local_id_to_def_id: SortedMap::new(),
74 trait_map: Default::default(),
79 is_in_loop_condition: false,
80 is_in_trait_impl: false,
81 is_in_dyn_type: false,
85 impl_trait_defs: Vec::new(),
86 impl_trait_bounds: Vec::new(),
87 allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
88 allow_gen_future: Some([sym::gen_future, sym::closure_track_caller][..].into()),
89 allow_into_future: Some([sym::into_future][..].into()),
90 generics_def_id_map: Default::default(),
92 lctx.with_hir_id_owner(owner, |lctx| f(lctx));
94 for (def_id, info) in lctx.children {
95 self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
96 debug_assert!(matches!(self.owners[def_id], hir::MaybeOwner::Phantom));
97 self.owners[def_id] = info;
101 pub(super) fn lower_node(
104 ) -> hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>> {
105 self.owners.ensure_contains_elem(def_id, || hir::MaybeOwner::Phantom);
106 if let hir::MaybeOwner::Phantom = self.owners[def_id] {
107 let node = self.ast_index[def_id];
109 AstOwner::NonOwner => {}
110 AstOwner::Crate(c) => self.lower_crate(c),
111 AstOwner::Item(item) => self.lower_item(item),
112 AstOwner::AssocItem(item, ctxt) => self.lower_assoc_item(item, ctxt),
113 AstOwner::ForeignItem(item) => self.lower_foreign_item(item),
120 #[instrument(level = "debug", skip(self, c))]
121 fn lower_crate(&mut self, c: &Crate) {
122 debug_assert_eq!(self.resolver.node_id_to_def_id[&CRATE_NODE_ID], CRATE_DEF_ID);
123 self.with_lctx(CRATE_NODE_ID, |lctx| {
124 let module = lctx.lower_mod(&c.items, &c.spans);
125 lctx.lower_attrs(hir::CRATE_HIR_ID, &c.attrs);
126 hir::OwnerNode::Crate(module)
130 #[instrument(level = "debug", skip(self))]
131 fn lower_item(&mut self, item: &Item) {
132 self.with_lctx(item.id, |lctx| hir::OwnerNode::Item(lctx.lower_item(item)))
135 fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) {
136 let def_id = self.resolver.node_id_to_def_id[&item.id];
138 let parent_id = self.tcx.local_parent(def_id);
139 let parent_hir = self.lower_node(parent_id).unwrap();
140 self.with_lctx(item.id, |lctx| {
141 // Evaluate with the lifetimes in `params` in-scope.
142 // This is used to track which lifetimes have already been defined,
143 // and which need to be replicated when lowering an async fn.
144 match parent_hir.node().expect_item().kind {
145 hir::ItemKind::Impl(hir::Impl { of_trait, .. }) => {
146 lctx.is_in_trait_impl = of_trait.is_some();
152 AssocCtxt::Trait => hir::OwnerNode::TraitItem(lctx.lower_trait_item(item)),
153 AssocCtxt::Impl => hir::OwnerNode::ImplItem(lctx.lower_impl_item(item)),
158 fn lower_foreign_item(&mut self, item: &ForeignItem) {
159 self.with_lctx(item.id, |lctx| hir::OwnerNode::ForeignItem(lctx.lower_foreign_item(item)))
163 impl<'hir> LoweringContext<'_, 'hir> {
164 pub(super) fn lower_mod(
168 ) -> &'hir hir::Mod<'hir> {
169 self.arena.alloc(hir::Mod {
170 spans: hir::ModSpans {
171 inner_span: self.lower_span(spans.inner_span),
172 inject_use_span: self.lower_span(spans.inject_use_span),
174 item_ids: self.arena.alloc_from_iter(items.iter().flat_map(|x| self.lower_item_ref(x))),
178 pub(super) fn lower_item_ref(&mut self, i: &Item) -> SmallVec<[hir::ItemId; 1]> {
180 smallvec![hir::ItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } }];
181 if let ItemKind::Use(use_tree) = &i.kind {
182 self.lower_item_id_use_tree(use_tree, i.id, &mut node_ids);
187 fn lower_item_id_use_tree(
191 vec: &mut SmallVec<[hir::ItemId; 1]>,
194 UseTreeKind::Nested(nested_vec) => {
195 for &(ref nested, id) in nested_vec {
196 vec.push(hir::ItemId {
197 owner_id: hir::OwnerId { def_id: self.local_def_id(id) },
199 self.lower_item_id_use_tree(nested, id, vec);
202 UseTreeKind::Glob => {}
203 UseTreeKind::Simple(_, id1, id2) => {
205 iter::zip(self.expect_full_res_from_use(base_id).skip(1), [*id1, *id2])
207 vec.push(hir::ItemId {
208 owner_id: hir::OwnerId { def_id: self.local_def_id(id) },
215 fn lower_item(&mut self, i: &Item) -> &'hir hir::Item<'hir> {
216 let mut ident = i.ident;
217 let vis_span = self.lower_span(i.vis.span);
218 let hir_id = self.lower_node_id(i.id);
219 let attrs = self.lower_attrs(hir_id, &i.attrs);
220 let kind = self.lower_item_kind(i.span, i.id, hir_id, &mut ident, attrs, vis_span, &i.kind);
221 let item = hir::Item {
222 owner_id: hir_id.expect_owner(),
223 ident: self.lower_ident(ident),
226 span: self.lower_span(i.span),
228 self.arena.alloc(item)
237 attrs: Option<&'hir [Attribute]>,
240 ) -> hir::ItemKind<'hir> {
242 ItemKind::ExternCrate(orig_name) => hir::ItemKind::ExternCrate(*orig_name),
243 ItemKind::Use(use_tree) => {
244 // Start with an empty prefix.
245 let prefix = Path { segments: ThinVec::new(), span: use_tree.span, tokens: None };
247 self.lower_use_tree(use_tree, &prefix, id, vis_span, ident, attrs)
249 ItemKind::Static(t, m, e) => {
250 let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
251 hir::ItemKind::Static(ty, *m, body_id)
253 ItemKind::Const(_, t, e) => {
254 let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
255 hir::ItemKind::Const(ty, body_id)
257 ItemKind::Fn(box Fn {
258 sig: FnSig { decl, header, span: fn_sig_span },
263 self.with_new_scopes(|this| {
264 this.current_item = Some(ident.span);
266 // Note: we don't need to change the return type from `T` to
267 // `impl Future<Output = T>` here because lower_body
268 // only cares about the input argument patterns in the function
269 // declaration (decl), not the return types.
270 let asyncness = header.asyncness;
272 this.lower_maybe_async_body(span, &decl, asyncness, body.as_deref());
274 let mut itctx = ImplTraitContext::Universal;
275 let (generics, decl) = this.lower_generics(generics, id, &mut itctx, |this| {
276 let ret_id = asyncness.opt_return_id();
277 this.lower_fn_decl(&decl, id, *fn_sig_span, FnDeclKind::Fn, ret_id)
279 let sig = hir::FnSig {
281 header: this.lower_fn_header(*header),
282 span: this.lower_span(*fn_sig_span),
284 hir::ItemKind::Fn(sig, generics, body_id)
287 ItemKind::Mod(_, mod_kind) => match mod_kind {
288 ModKind::Loaded(items, _, spans) => {
289 hir::ItemKind::Mod(self.lower_mod(items, spans))
291 ModKind::Unloaded => panic!("`mod` items should have been loaded by now"),
293 ItemKind::ForeignMod(fm) => hir::ItemKind::ForeignMod {
294 abi: fm.abi.map_or(abi::Abi::FALLBACK, |abi| self.lower_abi(abi)),
297 .alloc_from_iter(fm.items.iter().map(|x| self.lower_foreign_item_ref(x))),
299 ItemKind::GlobalAsm(asm) => hir::ItemKind::GlobalAsm(self.lower_inline_asm(span, asm)),
300 ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty: Some(ty), .. }) => {
303 // type Foo = impl Trait
308 // opaque type Foo1: Trait
309 let mut generics = generics.clone();
310 add_ty_alias_where_clause(&mut generics, *where_clauses, true);
311 let (generics, ty) = self.lower_generics(
314 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
315 |this| this.lower_ty(ty, &ImplTraitContext::TypeAliasesOpaqueTy),
317 hir::ItemKind::TyAlias(ty, generics)
319 ItemKind::TyAlias(box TyAlias { generics, where_clauses, ty: None, .. }) => {
320 let mut generics = generics.clone();
321 add_ty_alias_where_clause(&mut generics, *where_clauses, true);
322 let (generics, ty) = self.lower_generics(
325 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
326 |this| this.arena.alloc(this.ty(span, hir::TyKind::Err)),
328 hir::ItemKind::TyAlias(ty, generics)
330 ItemKind::Enum(enum_definition, generics) => {
331 let (generics, variants) = self.lower_generics(
334 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
336 this.arena.alloc_from_iter(
337 enum_definition.variants.iter().map(|x| this.lower_variant(x)),
341 hir::ItemKind::Enum(hir::EnumDef { variants }, generics)
343 ItemKind::Struct(struct_def, generics) => {
344 let (generics, struct_def) = self.lower_generics(
347 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
348 |this| this.lower_variant_data(hir_id, struct_def),
350 hir::ItemKind::Struct(struct_def, generics)
352 ItemKind::Union(vdata, generics) => {
353 let (generics, vdata) = self.lower_generics(
356 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
357 |this| this.lower_variant_data(hir_id, vdata),
359 hir::ItemKind::Union(vdata, generics)
361 ItemKind::Impl(box Impl {
366 generics: ast_generics,
371 // Lower the "impl header" first. This ordering is important
372 // for in-band lifetimes! Consider `'a` here:
374 // impl Foo<'a> for u32 {
375 // fn method(&'a self) { .. }
378 // Because we start by lowering the `Foo<'a> for u32`
379 // part, we will add `'a` to the list of generics on
380 // the impl. When we then encounter it later in the
381 // method, it will not be considered an in-band
382 // lifetime to be added, but rather a reference to a
384 let mut itctx = ImplTraitContext::Universal;
385 let (generics, (trait_ref, lowered_ty)) =
386 self.lower_generics(ast_generics, id, &mut itctx, |this| {
387 let trait_ref = trait_ref.as_ref().map(|trait_ref| {
388 this.lower_trait_ref(
390 &ImplTraitContext::Disallowed(ImplTraitPosition::Trait),
394 let lowered_ty = this
395 .lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type));
397 (trait_ref, lowered_ty)
400 let new_impl_items = self
402 .alloc_from_iter(impl_items.iter().map(|item| self.lower_impl_item_ref(item)));
404 // `defaultness.has_value()` is never called for an `impl`, always `true` in order
405 // to not cause an assertion failure inside the `lower_defaultness` function.
407 let (defaultness, defaultness_span) = self.lower_defaultness(*defaultness, has_val);
408 let polarity = match polarity {
409 ImplPolarity::Positive => ImplPolarity::Positive,
410 ImplPolarity::Negative(s) => ImplPolarity::Negative(self.lower_span(*s)),
412 hir::ItemKind::Impl(self.arena.alloc(hir::Impl {
413 unsafety: self.lower_unsafety(*unsafety),
417 constness: self.lower_constness(*constness),
421 items: new_impl_items,
424 ItemKind::Trait(box Trait { is_auto, unsafety, generics, bounds, items }) => {
425 let (generics, (unsafety, items, bounds)) = self.lower_generics(
428 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
430 let bounds = this.lower_param_bounds(
432 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
434 let items = this.arena.alloc_from_iter(
435 items.iter().map(|item| this.lower_trait_item_ref(item)),
437 let unsafety = this.lower_unsafety(*unsafety);
438 (unsafety, items, bounds)
441 hir::ItemKind::Trait(*is_auto, unsafety, generics, bounds, items)
443 ItemKind::TraitAlias(generics, bounds) => {
444 let (generics, bounds) = self.lower_generics(
447 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
449 this.lower_param_bounds(
451 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
455 hir::ItemKind::TraitAlias(generics, bounds)
457 ItemKind::MacroDef(MacroDef { body, macro_rules }) => {
458 let body = P(self.lower_delim_args(body));
459 let macro_kind = self.resolver.decl_macro_kind(self.local_def_id(id));
460 hir::ItemKind::Macro(ast::MacroDef { body, macro_rules: *macro_rules }, macro_kind)
462 ItemKind::MacCall(..) => {
463 panic!("`TyMac` should have been expanded by now")
473 ) -> (&'hir hir::Ty<'hir>, hir::BodyId) {
474 let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type));
475 (ty, self.lower_const_body(span, body))
478 #[instrument(level = "debug", skip(self))]
486 attrs: Option<&'hir [Attribute]>,
487 ) -> hir::ItemKind<'hir> {
488 let path = &tree.prefix;
489 let segments = prefix.segments.iter().chain(path.segments.iter()).cloned().collect();
492 UseTreeKind::Simple(rename, id1, id2) => {
493 *ident = tree.ident();
495 // First, apply the prefix to the path.
496 let mut path = Path { segments, span: path.span, tokens: None };
498 // Correctly resolve `self` imports.
499 if path.segments.len() > 1
500 && path.segments.last().unwrap().ident.name == kw::SelfLower
502 let _ = path.segments.pop();
503 if rename.is_none() {
504 *ident = path.segments.last().unwrap().ident;
508 let mut resolutions = self.expect_full_res_from_use(id).fuse();
509 // We want to return *something* from this function, so hold onto the first item
511 let ret_res = self.lower_res(resolutions.next().unwrap_or(Res::Err));
513 // Here, we are looping over namespaces, if they exist for the definition
514 // being imported. We only handle type and value namespaces because we
515 // won't be dealing with macros in the rest of the compiler.
516 // Essentially a single `use` which imports two names is desugared into
518 for new_node_id in [id1, id2] {
519 let new_id = self.local_def_id(new_node_id);
520 let Some(res) = resolutions.next() else {
521 debug_assert!(self.children.iter().find(|(id, _)| id == &new_id).is_none());
522 // Associate an HirId to both ids even if there is no resolution.
525 hir::MaybeOwner::NonOwner(hir::HirId::make_owner(new_id))),
530 let mut path = path.clone();
531 for seg in &mut path.segments {
532 // Give the cloned segment the same resolution information
533 // as the old one (this is needed for stability checking).
534 let new_id = self.next_node_id();
535 self.resolver.clone_res(seg.id, new_id);
538 let span = path.span;
540 self.with_hir_id_owner(new_node_id, |this| {
541 let res = this.lower_res(res);
542 let path = this.lower_path_extra(res, &path, ParamMode::Explicit);
543 let kind = hir::ItemKind::Use(path, hir::UseKind::Single);
544 if let Some(attrs) = attrs {
545 this.attrs.insert(hir::ItemLocalId::new(0), attrs);
548 let item = hir::Item {
549 owner_id: hir::OwnerId { def_id: new_id },
550 ident: this.lower_ident(ident),
553 span: this.lower_span(span),
555 hir::OwnerNode::Item(this.arena.alloc(item))
559 let path = self.lower_path_extra(ret_res, &path, ParamMode::Explicit);
560 hir::ItemKind::Use(path, hir::UseKind::Single)
562 UseTreeKind::Glob => {
563 let path = self.lower_path(
565 &Path { segments, span: path.span, tokens: None },
568 hir::ItemKind::Use(path, hir::UseKind::Glob)
570 UseTreeKind::Nested(ref trees) => {
571 // Nested imports are desugared into simple imports.
572 // So, if we start with
575 // pub(x) use foo::{a, b};
578 // we will create three items:
581 // pub(x) use foo::a;
582 // pub(x) use foo::b;
583 // pub(x) use foo::{}; // <-- this is called the `ListStem`
586 // The first two are produced by recursively invoking
587 // `lower_use_tree` (and indeed there may be things
588 // like `use foo::{a::{b, c}}` and so forth). They
589 // wind up being directly added to
590 // `self.items`. However, the structure of this
591 // function also requires us to return one item, and
592 // for that we return the `{}` import (called the
595 let prefix = Path { segments, span: prefix.span.to(path.span), tokens: None };
597 // Add all the nested `PathListItem`s to the HIR.
598 for &(ref use_tree, id) in trees {
599 let new_hir_id = self.local_def_id(id);
601 let mut prefix = prefix.clone();
603 // Give the segments new node-ids since they are being cloned.
604 for seg in &mut prefix.segments {
605 // Give the cloned segment the same resolution information
606 // as the old one (this is needed for stability checking).
607 let new_id = self.next_node_id();
608 self.resolver.clone_res(seg.id, new_id);
612 // Each `use` import is an item and thus are owners of the
613 // names in the path. Up to this point the nested import is
614 // the current owner, since we want each desugared import to
615 // own its own names, we have to adjust the owner before
616 // lowering the rest of the import.
617 self.with_hir_id_owner(id, |this| {
618 let mut ident = *ident;
621 this.lower_use_tree(use_tree, &prefix, id, vis_span, &mut ident, attrs);
622 if let Some(attrs) = attrs {
623 this.attrs.insert(hir::ItemLocalId::new(0), attrs);
626 let item = hir::Item {
627 owner_id: hir::OwnerId { def_id: new_hir_id },
628 ident: this.lower_ident(ident),
631 span: this.lower_span(use_tree.span),
633 hir::OwnerNode::Item(this.arena.alloc(item))
637 let res = self.expect_full_res_from_use(id).next().unwrap_or(Res::Err);
638 let res = self.lower_res(res);
639 let path = self.lower_path_extra(res, &prefix, ParamMode::Explicit);
640 hir::ItemKind::Use(path, hir::UseKind::ListStem)
645 fn lower_foreign_item(&mut self, i: &ForeignItem) -> &'hir hir::ForeignItem<'hir> {
646 let hir_id = self.lower_node_id(i.id);
647 let owner_id = hir_id.expect_owner();
648 self.lower_attrs(hir_id, &i.attrs);
649 let item = hir::ForeignItem {
651 ident: self.lower_ident(i.ident),
652 kind: match &i.kind {
653 ForeignItemKind::Fn(box Fn { sig, generics, .. }) => {
654 let fdec = &sig.decl;
655 let mut itctx = ImplTraitContext::Universal;
656 let (generics, (fn_dec, fn_args)) =
657 self.lower_generics(generics, i.id, &mut itctx, |this| {
659 // Disallow `impl Trait` in foreign items.
664 FnDeclKind::ExternFn,
667 this.lower_fn_params_to_names(fdec),
671 hir::ForeignItemKind::Fn(fn_dec, fn_args, generics)
673 ForeignItemKind::Static(t, m, _) => {
675 self.lower_ty(t, &ImplTraitContext::Disallowed(ImplTraitPosition::Type));
676 hir::ForeignItemKind::Static(ty, *m)
678 ForeignItemKind::TyAlias(..) => hir::ForeignItemKind::Type,
679 ForeignItemKind::MacCall(_) => panic!("macro shouldn't exist here"),
681 vis_span: self.lower_span(i.vis.span),
682 span: self.lower_span(i.span),
684 self.arena.alloc(item)
687 fn lower_foreign_item_ref(&mut self, i: &ForeignItem) -> hir::ForeignItemRef {
688 hir::ForeignItemRef {
689 id: hir::ForeignItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } },
690 ident: self.lower_ident(i.ident),
691 span: self.lower_span(i.span),
695 fn lower_variant(&mut self, v: &Variant) -> hir::Variant<'hir> {
696 let hir_id = self.lower_node_id(v.id);
697 self.lower_attrs(hir_id, &v.attrs);
700 def_id: self.local_def_id(v.id),
701 data: self.lower_variant_data(hir_id, &v.data),
702 disr_expr: v.disr_expr.as_ref().map(|e| self.lower_anon_const(e)),
703 ident: self.lower_ident(v.ident),
704 span: self.lower_span(v.span),
708 fn lower_variant_data(
710 parent_id: hir::HirId,
712 ) -> hir::VariantData<'hir> {
714 VariantData::Struct(fields, recovered) => hir::VariantData::Struct(
716 .alloc_from_iter(fields.iter().enumerate().map(|f| self.lower_field_def(f))),
719 VariantData::Tuple(fields, id) => {
720 let ctor_id = self.lower_node_id(*id);
721 self.alias_attrs(ctor_id, parent_id);
722 hir::VariantData::Tuple(
723 self.arena.alloc_from_iter(
724 fields.iter().enumerate().map(|f| self.lower_field_def(f)),
727 self.local_def_id(*id),
730 VariantData::Unit(id) => {
731 let ctor_id = self.lower_node_id(*id);
732 self.alias_attrs(ctor_id, parent_id);
733 hir::VariantData::Unit(ctor_id, self.local_def_id(*id))
738 fn lower_field_def(&mut self, (index, f): (usize, &FieldDef)) -> hir::FieldDef<'hir> {
739 let ty = if let TyKind::Path(qself, path) = &f.ty.kind {
740 let t = self.lower_path_ty(
744 ParamMode::ExplicitNamed, // no `'_` in declarations (Issue #61124)
745 &ImplTraitContext::Disallowed(ImplTraitPosition::Path),
749 self.lower_ty(&f.ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type))
751 let hir_id = self.lower_node_id(f.id);
752 self.lower_attrs(hir_id, &f.attrs);
754 span: self.lower_span(f.span),
756 def_id: self.local_def_id(f.id),
757 ident: match f.ident {
758 Some(ident) => self.lower_ident(ident),
759 // FIXME(jseyfried): positional field hygiene.
760 None => Ident::new(sym::integer(index), self.lower_span(f.span)),
762 vis_span: self.lower_span(f.vis.span),
767 fn lower_trait_item(&mut self, i: &AssocItem) -> &'hir hir::TraitItem<'hir> {
768 let hir_id = self.lower_node_id(i.id);
769 let trait_item_def_id = hir_id.expect_owner();
771 let (generics, kind, has_default) = match &i.kind {
772 AssocItemKind::Const(_, ty, default) => {
773 let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type));
774 let body = default.as_ref().map(|x| self.lower_const_body(i.span, Some(x)));
775 (hir::Generics::empty(), hir::TraitItemKind::Const(ty, body), body.is_some())
777 AssocItemKind::Fn(box Fn { sig, generics, body: None, .. }) => {
778 let asyncness = sig.header.asyncness;
779 let names = self.lower_fn_params_to_names(&sig.decl);
780 let (generics, sig) = self.lower_method_sig(
785 asyncness.opt_return_id(),
787 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Required(names)), false)
789 AssocItemKind::Fn(box Fn { sig, generics, body: Some(body), .. }) => {
790 let asyncness = sig.header.asyncness;
792 self.lower_maybe_async_body(i.span, &sig.decl, asyncness, Some(&body));
793 let (generics, sig) = self.lower_method_sig(
798 asyncness.opt_return_id(),
800 (generics, hir::TraitItemKind::Fn(sig, hir::TraitFn::Provided(body_id)), true)
802 AssocItemKind::Type(box TyAlias { generics, where_clauses, bounds, ty, .. }) => {
803 let mut generics = generics.clone();
804 add_ty_alias_where_clause(&mut generics, *where_clauses, false);
805 let (generics, kind) = self.lower_generics(
808 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
810 let ty = ty.as_ref().map(|x| {
811 this.lower_ty(x, &ImplTraitContext::Disallowed(ImplTraitPosition::Type))
813 hir::TraitItemKind::Type(
814 this.lower_param_bounds(
816 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
822 (generics, kind, ty.is_some())
824 AssocItemKind::MacCall(..) => panic!("macro item shouldn't exist at this point"),
827 self.lower_attrs(hir_id, &i.attrs);
828 let item = hir::TraitItem {
829 owner_id: trait_item_def_id,
830 ident: self.lower_ident(i.ident),
833 span: self.lower_span(i.span),
834 defaultness: hir::Defaultness::Default { has_value: has_default },
836 self.arena.alloc(item)
839 fn lower_trait_item_ref(&mut self, i: &AssocItem) -> hir::TraitItemRef {
840 let kind = match &i.kind {
841 AssocItemKind::Const(..) => hir::AssocItemKind::Const,
842 AssocItemKind::Type(..) => hir::AssocItemKind::Type,
843 AssocItemKind::Fn(box Fn { sig, .. }) => {
844 hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
846 AssocItemKind::MacCall(..) => unimplemented!(),
848 let id = hir::TraitItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } };
851 ident: self.lower_ident(i.ident),
852 span: self.lower_span(i.span),
857 /// Construct `ExprKind::Err` for the given `span`.
858 pub(crate) fn expr_err(&mut self, span: Span) -> hir::Expr<'hir> {
859 self.expr(span, hir::ExprKind::Err, AttrVec::new())
862 fn lower_impl_item(&mut self, i: &AssocItem) -> &'hir hir::ImplItem<'hir> {
863 // Since `default impl` is not yet implemented, this is always true in impls.
864 let has_value = true;
865 let (defaultness, _) = self.lower_defaultness(i.kind.defaultness(), has_value);
867 let (generics, kind) = match &i.kind {
868 AssocItemKind::Const(_, ty, expr) => {
869 let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type));
871 hir::Generics::empty(),
872 hir::ImplItemKind::Const(ty, self.lower_const_body(i.span, expr.as_deref())),
875 AssocItemKind::Fn(box Fn { sig, generics, body, .. }) => {
876 self.current_item = Some(i.span);
877 let asyncness = sig.header.asyncness;
879 self.lower_maybe_async_body(i.span, &sig.decl, asyncness, body.as_deref());
880 let (generics, sig) = self.lower_method_sig(
884 if self.is_in_trait_impl { FnDeclKind::Impl } else { FnDeclKind::Inherent },
885 asyncness.opt_return_id(),
888 (generics, hir::ImplItemKind::Fn(sig, body_id))
890 AssocItemKind::Type(box TyAlias { generics, where_clauses, ty, .. }) => {
891 let mut generics = generics.clone();
892 add_ty_alias_where_clause(&mut generics, *where_clauses, false);
896 &ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
899 let ty = this.arena.alloc(this.ty(i.span, hir::TyKind::Err));
900 hir::ImplItemKind::Type(ty)
903 let ty = this.lower_ty(ty, &ImplTraitContext::TypeAliasesOpaqueTy);
904 hir::ImplItemKind::Type(ty)
909 AssocItemKind::MacCall(..) => panic!("`TyMac` should have been expanded by now"),
912 let hir_id = self.lower_node_id(i.id);
913 self.lower_attrs(hir_id, &i.attrs);
914 let item = hir::ImplItem {
915 owner_id: hir_id.expect_owner(),
916 ident: self.lower_ident(i.ident),
919 vis_span: self.lower_span(i.vis.span),
920 span: self.lower_span(i.span),
923 self.arena.alloc(item)
926 fn lower_impl_item_ref(&mut self, i: &AssocItem) -> hir::ImplItemRef {
928 id: hir::ImplItemId { owner_id: hir::OwnerId { def_id: self.local_def_id(i.id) } },
929 ident: self.lower_ident(i.ident),
930 span: self.lower_span(i.span),
931 kind: match &i.kind {
932 AssocItemKind::Const(..) => hir::AssocItemKind::Const,
933 AssocItemKind::Type(..) => hir::AssocItemKind::Type,
934 AssocItemKind::Fn(box Fn { sig, .. }) => {
935 hir::AssocItemKind::Fn { has_self: sig.decl.has_self() }
937 AssocItemKind::MacCall(..) => unimplemented!(),
939 trait_item_def_id: self
941 .get_partial_res(i.id)
942 .map(|r| r.expect_full_res().def_id()),
946 fn lower_defaultness(
950 ) -> (hir::Defaultness, Option<Span>) {
952 Defaultness::Default(sp) => {
953 (hir::Defaultness::Default { has_value }, Some(self.lower_span(sp)))
955 Defaultness::Final => {
957 (hir::Defaultness::Final, None)
964 params: &'hir [hir::Param<'hir>],
965 value: hir::Expr<'hir>,
967 let body = hir::Body {
968 generator_kind: self.generator_kind,
970 value: self.arena.alloc(value),
973 debug_assert_eq!(id.hir_id.owner, self.current_hir_id_owner);
974 self.bodies.push((id.hir_id.local_id, self.arena.alloc(body)));
978 pub(super) fn lower_body(
980 f: impl FnOnce(&mut Self) -> (&'hir [hir::Param<'hir>], hir::Expr<'hir>),
982 let prev_gen_kind = self.generator_kind.take();
983 let task_context = self.task_context.take();
984 let (parameters, result) = f(self);
985 let body_id = self.record_body(parameters, result);
986 self.task_context = task_context;
987 self.generator_kind = prev_gen_kind;
991 fn lower_param(&mut self, param: &Param) -> hir::Param<'hir> {
992 let hir_id = self.lower_node_id(param.id);
993 self.lower_attrs(hir_id, ¶m.attrs);
996 pat: self.lower_pat(¶m.pat),
997 ty_span: self.lower_span(param.ty.span),
998 span: self.lower_span(param.span),
1002 pub(super) fn lower_fn_body(
1005 body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
1007 self.lower_body(|this| {
1009 this.arena.alloc_from_iter(decl.inputs.iter().map(|x| this.lower_param(x))),
1015 fn lower_fn_body_block(
1019 body: Option<&Block>,
1021 self.lower_fn_body(decl, |this| this.lower_block_expr_opt(span, body))
1024 fn lower_block_expr_opt(&mut self, span: Span, block: Option<&Block>) -> hir::Expr<'hir> {
1026 Some(block) => self.lower_block_expr(block),
1027 None => self.expr_err(span),
1031 pub(super) fn lower_const_body(&mut self, span: Span, expr: Option<&Expr>) -> hir::BodyId {
1032 self.lower_body(|this| {
1036 Some(expr) => this.lower_expr_mut(expr),
1037 None => this.expr_err(span),
1043 fn lower_maybe_async_body(
1048 body: Option<&Block>,
1050 let (closure_id, body) = match (asyncness, body) {
1051 (Async::Yes { closure_id, .. }, Some(body)) => (closure_id, body),
1052 _ => return self.lower_fn_body_block(span, decl, body),
1055 self.lower_body(|this| {
1056 let mut parameters: Vec<hir::Param<'_>> = Vec::new();
1057 let mut statements: Vec<hir::Stmt<'_>> = Vec::new();
1059 // Async function parameters are lowered into the closure body so that they are
1060 // captured and so that the drop order matches the equivalent non-async functions.
1064 // async fn foo(<pattern>: <ty>, <pattern>: <ty>, <pattern>: <ty>) {
1070 // fn foo(__arg0: <ty>, __arg1: <ty>, __arg2: <ty>) {
1072 // let __arg2 = __arg2;
1073 // let <pattern> = __arg2;
1074 // let __arg1 = __arg1;
1075 // let <pattern> = __arg1;
1076 // let __arg0 = __arg0;
1077 // let <pattern> = __arg0;
1078 // drop-temps { <body> } // see comments later in fn for details
1082 // If `<pattern>` is a simple ident, then it is lowered to a single
1083 // `let <pattern> = <pattern>;` statement as an optimization.
1085 // Note that the body is embedded in `drop-temps`; an
1086 // equivalent desugaring would be `return { <body>
1087 // };`. The key point is that we wish to drop all the
1088 // let-bound variables and temporaries created in the body
1089 // (and its tail expression!) before we drop the
1090 // parameters (c.f. rust-lang/rust#64512).
1091 for (index, parameter) in decl.inputs.iter().enumerate() {
1092 let parameter = this.lower_param(parameter);
1093 let span = parameter.pat.span;
1095 // Check if this is a binding pattern, if so, we can optimize and avoid adding a
1096 // `let <pat> = __argN;` statement. In this case, we do not rename the parameter.
1097 let (ident, is_simple_parameter) = match parameter.pat.kind {
1098 hir::PatKind::Binding(hir::BindingAnnotation(ByRef::No, _), _, ident, _) => {
1101 // For `ref mut` or wildcard arguments, we can't reuse the binding, but
1102 // we can keep the same name for the parameter.
1103 // This lets rustdoc render it correctly in documentation.
1104 hir::PatKind::Binding(_, _, ident, _) => (ident, false),
1105 hir::PatKind::Wild => {
1106 (Ident::with_dummy_span(rustc_span::symbol::kw::Underscore), false)
1109 // Replace the ident for bindings that aren't simple.
1110 let name = format!("__arg{}", index);
1111 let ident = Ident::from_str(&name);
1117 let desugared_span = this.mark_span_with_reason(DesugaringKind::Async, span, None);
1119 // Construct a parameter representing `__argN: <ty>` to replace the parameter of the
1122 // If this is the simple case, this parameter will end up being the same as the
1123 // original parameter, but with a different pattern id.
1124 let stmt_attrs = this.attrs.get(¶meter.hir_id.local_id).copied();
1125 let (new_parameter_pat, new_parameter_id) = this.pat_ident(desugared_span, ident);
1126 let new_parameter = hir::Param {
1127 hir_id: parameter.hir_id,
1128 pat: new_parameter_pat,
1129 ty_span: this.lower_span(parameter.ty_span),
1130 span: this.lower_span(parameter.span),
1133 if is_simple_parameter {
1134 // If this is the simple case, then we only insert one statement that is
1135 // `let <pat> = <pat>;`. We re-use the original argument's pattern so that
1136 // `HirId`s are densely assigned.
1137 let expr = this.expr_ident(desugared_span, ident, new_parameter_id);
1138 let stmt = this.stmt_let_pat(
1143 hir::LocalSource::AsyncFn,
1145 statements.push(stmt);
1147 // If this is not the simple case, then we construct two statements:
1150 // let __argN = __argN;
1151 // let <pat> = __argN;
1154 // The first statement moves the parameter into the closure and thus ensures
1155 // that the drop order is correct.
1157 // The second statement creates the bindings that the user wrote.
1159 // Construct the `let mut __argN = __argN;` statement. It must be a mut binding
1160 // because the user may have specified a `ref mut` binding in the next
1162 let (move_pat, move_id) = this.pat_ident_binding_mode(
1165 hir::BindingAnnotation::MUT,
1167 let move_expr = this.expr_ident(desugared_span, ident, new_parameter_id);
1168 let move_stmt = this.stmt_let_pat(
1173 hir::LocalSource::AsyncFn,
1176 // Construct the `let <pat> = __argN;` statement. We re-use the original
1177 // parameter's pattern so that `HirId`s are densely assigned.
1178 let pattern_expr = this.expr_ident(desugared_span, ident, move_id);
1179 let pattern_stmt = this.stmt_let_pat(
1184 hir::LocalSource::AsyncFn,
1187 statements.push(move_stmt);
1188 statements.push(pattern_stmt);
1191 parameters.push(new_parameter);
1194 let async_expr = this.make_async_expr(
1199 hir::AsyncGeneratorKind::Fn,
1201 // Create a block from the user's function body:
1202 let user_body = this.lower_block_expr(body);
1204 // Transform into `drop-temps { <user-body> }`, an expression:
1205 let desugared_span =
1206 this.mark_span_with_reason(DesugaringKind::Async, user_body.span, None);
1207 let user_body = this.expr_drop_temps(
1209 this.arena.alloc(user_body),
1213 // As noted above, create the final block like
1217 // let $param_pattern = $raw_param;
1219 // drop-temps { <user-body> }
1222 let body = this.block_all(
1224 this.arena.alloc_from_iter(statements),
1228 this.expr_block(body, AttrVec::new())
1233 this.arena.alloc_from_iter(parameters),
1234 this.expr(body.span, async_expr, AttrVec::new()),
1239 fn lower_method_sig(
1241 generics: &Generics,
1245 is_async: Option<(NodeId, Span)>,
1246 ) -> (&'hir hir::Generics<'hir>, hir::FnSig<'hir>) {
1247 let header = self.lower_fn_header(sig.header);
1248 let mut itctx = ImplTraitContext::Universal;
1249 let (generics, decl) = self.lower_generics(generics, id, &mut itctx, |this| {
1250 this.lower_fn_decl(&sig.decl, id, sig.span, kind, is_async)
1252 (generics, hir::FnSig { header, decl, span: self.lower_span(sig.span) })
1255 fn lower_fn_header(&mut self, h: FnHeader) -> hir::FnHeader {
1257 unsafety: self.lower_unsafety(h.unsafety),
1258 asyncness: self.lower_asyncness(h.asyncness),
1259 constness: self.lower_constness(h.constness),
1260 abi: self.lower_extern(h.ext),
1264 pub(super) fn lower_abi(&mut self, abi: StrLit) -> abi::Abi {
1265 abi::lookup(abi.symbol_unescaped.as_str()).unwrap_or_else(|| {
1266 self.error_on_invalid_abi(abi);
1271 pub(super) fn lower_extern(&mut self, ext: Extern) -> abi::Abi {
1273 Extern::None => abi::Abi::Rust,
1274 Extern::Implicit(_) => abi::Abi::FALLBACK,
1275 Extern::Explicit(abi, _) => self.lower_abi(abi),
1279 fn error_on_invalid_abi(&self, abi: StrLit) {
1280 let abi_names = abi::enabled_names(self.tcx.features(), abi.span)
1282 .map(|s| Symbol::intern(s))
1283 .collect::<Vec<_>>();
1284 let suggested_name = find_best_match_for_name(&abi_names, abi.symbol_unescaped, None);
1285 self.tcx.sess.emit_err(InvalidAbi {
1286 abi: abi.symbol_unescaped,
1288 suggestion: suggested_name.map(|suggested_name| InvalidAbiSuggestion {
1290 suggestion: format!("\"{suggested_name}\""),
1292 command: "rustc --print=calling-conventions".to_string(),
1296 fn lower_asyncness(&mut self, a: Async) -> hir::IsAsync {
1298 Async::Yes { .. } => hir::IsAsync::Async,
1299 Async::No => hir::IsAsync::NotAsync,
1303 fn lower_constness(&mut self, c: Const) -> hir::Constness {
1305 Const::Yes(_) => hir::Constness::Const,
1306 Const::No => hir::Constness::NotConst,
1310 pub(super) fn lower_unsafety(&mut self, u: Unsafe) -> hir::Unsafety {
1312 Unsafe::Yes(_) => hir::Unsafety::Unsafe,
1313 Unsafe::No => hir::Unsafety::Normal,
1317 /// Return the pair of the lowered `generics` as `hir::Generics` and the evaluation of `f` with
1318 /// the carried impl trait definitions and bounds.
1319 #[instrument(level = "debug", skip(self, f))]
1320 fn lower_generics<T>(
1322 generics: &Generics,
1323 parent_node_id: NodeId,
1324 itctx: &ImplTraitContext,
1325 f: impl FnOnce(&mut Self) -> T,
1326 ) -> (&'hir hir::Generics<'hir>, T) {
1327 debug_assert!(self.impl_trait_defs.is_empty());
1328 debug_assert!(self.impl_trait_bounds.is_empty());
1330 // Error if `?Trait` bounds in where clauses don't refer directly to type parameters.
1331 // Note: we used to clone these bounds directly onto the type parameter (and avoid lowering
1332 // these into hir when we lower thee where clauses), but this makes it quite difficult to
1333 // keep track of the Span info. Now, `add_implicitly_sized` in `AstConv` checks both param bounds and
1334 // where clauses for `?Sized`.
1335 for pred in &generics.where_clause.predicates {
1336 let WherePredicate::BoundPredicate(bound_pred) = pred else {
1339 let compute_is_param = || {
1340 // Check if the where clause type is a plain type parameter.
1343 .get_partial_res(bound_pred.bounded_ty.id)
1344 .and_then(|r| r.full_res())
1346 Some(Res::Def(DefKind::TyParam, def_id))
1347 if bound_pred.bound_generic_params.is_empty() =>
1352 .any(|p| def_id == self.local_def_id(p.id).to_def_id())
1354 // Either the `bounded_ty` is not a plain type parameter, or
1355 // it's not found in the generic type parameters list.
1359 // We only need to compute this once per `WherePredicate`, but don't
1360 // need to compute this at all unless there is a Maybe bound.
1361 let mut is_param: Option<bool> = None;
1362 for bound in &bound_pred.bounds {
1363 if !matches!(*bound, GenericBound::Trait(_, TraitBoundModifier::Maybe)) {
1366 let is_param = *is_param.get_or_insert_with(compute_is_param);
1368 self.tcx.sess.emit_err(MisplacedRelaxTraitBound { span: bound.span() });
1373 let mut predicates: SmallVec<[hir::WherePredicate<'hir>; 4]> = SmallVec::new();
1374 predicates.extend(generics.params.iter().filter_map(|param| {
1375 self.lower_generic_bound_predicate(
1381 PredicateOrigin::GenericParam,
1389 .map(|predicate| self.lower_where_predicate(predicate)),
1392 let mut params: SmallVec<[hir::GenericParam<'hir>; 4]> =
1393 self.lower_generic_params_mut(&generics.params).collect();
1395 // Introduce extra lifetimes if late resolution tells us to.
1396 let extra_lifetimes = self.resolver.take_extra_lifetime_params(parent_node_id);
1397 params.extend(extra_lifetimes.into_iter().filter_map(|(ident, node_id, res)| {
1398 self.lifetime_res_to_generic_param(ident, node_id, res)
1401 let has_where_clause_predicates = !generics.where_clause.predicates.is_empty();
1402 let where_clause_span = self.lower_span(generics.where_clause.span);
1403 let span = self.lower_span(generics.span);
1406 let impl_trait_defs = std::mem::take(&mut self.impl_trait_defs);
1407 params.extend(impl_trait_defs.into_iter());
1409 let impl_trait_bounds = std::mem::take(&mut self.impl_trait_bounds);
1410 predicates.extend(impl_trait_bounds.into_iter());
1412 let lowered_generics = self.arena.alloc(hir::Generics {
1413 params: self.arena.alloc_from_iter(params),
1414 predicates: self.arena.alloc_from_iter(predicates),
1415 has_where_clause_predicates,
1420 (lowered_generics, res)
1423 pub(super) fn lower_generic_bound_predicate(
1427 kind: &GenericParamKind,
1428 bounds: &[GenericBound],
1429 itctx: &ImplTraitContext,
1430 origin: PredicateOrigin,
1431 ) -> Option<hir::WherePredicate<'hir>> {
1432 // Do not create a clause if we do not have anything inside it.
1433 if bounds.is_empty() {
1437 let bounds = self.lower_param_bounds(bounds, itctx);
1439 let ident = self.lower_ident(ident);
1440 let param_span = ident.span;
1443 .fold(Some(param_span.shrink_to_hi()), |span: Option<Span>, bound| {
1444 let bound_span = bound.span();
1445 // We include bounds that come from a `#[derive(_)]` but point at the user's code,
1446 // as we use this method to get a span appropriate for suggestions.
1447 if !bound_span.can_be_used_for_suggestions() {
1449 } else if let Some(span) = span {
1450 Some(span.to(bound_span))
1455 .unwrap_or(param_span.shrink_to_hi());
1457 GenericParamKind::Const { .. } => None,
1458 GenericParamKind::Type { .. } => {
1459 let def_id = self.local_def_id(id).to_def_id();
1460 let hir_id = self.next_id();
1461 let res = Res::Def(DefKind::TyParam, def_id);
1462 let ty_path = self.arena.alloc(hir::Path {
1467 .alloc_from_iter([hir::PathSegment::new(ident, hir_id, res)]),
1469 let ty_id = self.next_id();
1471 self.ty_path(ty_id, param_span, hir::QPath::Resolved(None, ty_path));
1472 Some(hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1473 hir_id: self.next_id(),
1474 bounded_ty: self.arena.alloc(bounded_ty),
1477 bound_generic_params: &[],
1481 GenericParamKind::Lifetime => {
1482 let ident = self.lower_ident(ident);
1483 let lt_id = self.next_node_id();
1484 let lifetime = self.new_named_lifetime(id, lt_id, ident);
1485 Some(hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1489 in_where_clause: false,
1495 fn lower_where_predicate(&mut self, pred: &WherePredicate) -> hir::WherePredicate<'hir> {
1497 WherePredicate::BoundPredicate(WhereBoundPredicate {
1498 bound_generic_params,
1502 }) => hir::WherePredicate::BoundPredicate(hir::WhereBoundPredicate {
1503 hir_id: self.next_id(),
1504 bound_generic_params: self.lower_generic_params(bound_generic_params),
1506 .lower_ty(bounded_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type)),
1507 bounds: self.arena.alloc_from_iter(bounds.iter().map(|bound| {
1508 self.lower_param_bound(
1510 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
1513 span: self.lower_span(*span),
1514 origin: PredicateOrigin::WhereClause,
1516 WherePredicate::RegionPredicate(WhereRegionPredicate { lifetime, bounds, span }) => {
1517 hir::WherePredicate::RegionPredicate(hir::WhereRegionPredicate {
1518 span: self.lower_span(*span),
1519 lifetime: self.lower_lifetime(lifetime),
1520 bounds: self.lower_param_bounds(
1522 &ImplTraitContext::Disallowed(ImplTraitPosition::Bound),
1524 in_where_clause: true,
1527 WherePredicate::EqPredicate(WhereEqPredicate { lhs_ty, rhs_ty, span }) => {
1528 hir::WherePredicate::EqPredicate(hir::WhereEqPredicate {
1530 .lower_ty(lhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type)),
1532 .lower_ty(rhs_ty, &ImplTraitContext::Disallowed(ImplTraitPosition::Type)),
1533 span: self.lower_span(*span),