1use std::mem;
2use std::ops::ControlFlow;
3use std::sync::Arc;
4
5use rustc_ast::*;
6use rustc_ast_pretty::pprust::expr_to_string;
7use rustc_data_structures::stack::ensure_sufficient_stack;
8use rustc_hir as hir;
9use rustc_hir::attrs::AttributeKind;
10use rustc_hir::def::{DefKind, Res};
11use rustc_hir::definitions::DefPathData;
12use rustc_hir::{HirId, Target, find_attr};
13use rustc_middle::span_bug;
14use rustc_middle::ty::TyCtxt;
15use rustc_session::errors::report_lit_error;
16use rustc_span::source_map::{Spanned, respan};
17use rustc_span::{ByteSymbol, DUMMY_SP, DesugaringKind, Ident, Span, Symbol, sym};
18use thin_vec::{ThinVec, thin_vec};
19use visit::{Visitor, walk_expr};
20
21use super::errors::{
22 AsyncCoroutinesNotSupported, AwaitOnlyInAsyncFnAndBlocks, ClosureCannotBeStatic,
23 CoroutineTooManyParameters, FunctionalRecordUpdateDestructuringAssignment,
24 InclusiveRangeWithNoEnd, MatchArmWithNoBody, NeverPatternWithBody, NeverPatternWithGuard,
25 UnderscoreExprLhsAssign,
26};
27use super::{
28 GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode, ResolverAstLoweringExt,
29};
30use crate::errors::{InvalidLegacyConstGenericArg, UseConstGenericArg, YieldInClosure};
31use crate::{
32 AllowReturnTypeNotation, FnDeclKind, ImplTraitPosition, TryBlockScope, fluent_generated,
33};
34
35struct WillCreateDefIdsVisitor {}
36
37impl<'v> rustc_ast::visit::Visitor<'v> for WillCreateDefIdsVisitor {
38 type Result = ControlFlow<Span>;
39
40 fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
41 ControlFlow::Break(c.value.span)
42 }
43
44 fn visit_item(&mut self, item: &'v Item) -> Self::Result {
45 ControlFlow::Break(item.span)
46 }
47
48 fn visit_expr(&mut self, ex: &'v Expr) -> Self::Result {
49 match ex.kind {
50 ExprKind::Gen(..) | ExprKind::ConstBlock(..) | ExprKind::Closure(..) => {
51 ControlFlow::Break(ex.span)
52 }
53 _ => walk_expr(self, ex),
54 }
55 }
56}
57
58impl<'hir> LoweringContext<'_, 'hir> {
59 fn lower_exprs(&mut self, exprs: &[Box<Expr>]) -> &'hir [hir::Expr<'hir>] {
60 self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x)))
61 }
62
63 pub(super) fn lower_expr(&mut self, e: &Expr) -> &'hir hir::Expr<'hir> {
64 self.arena.alloc(self.lower_expr_mut(e))
65 }
66
67 pub(super) fn lower_expr_mut(&mut self, e: &Expr) -> hir::Expr<'hir> {
68 ensure_sufficient_stack(|| {
69 let mut span = self.lower_span(e.span);
70 match &e.kind {
71 ExprKind::Paren(ex) => {
73 let mut ex = self.lower_expr_mut(ex);
74 if e.span.contains(ex.span) {
76 ex.span = self.lower_span(e.span.with_ctxt(ex.span.ctxt()));
77 }
78 if !e.attrs.is_empty() {
80 let old_attrs = self.attrs.get(&ex.hir_id.local_id).copied().unwrap_or(&[]);
81 let new_attrs = self
82 .lower_attrs_vec(&e.attrs, e.span, ex.hir_id, Target::from_expr(e))
83 .into_iter()
84 .chain(old_attrs.iter().cloned());
85 let new_attrs = &*self.arena.alloc_from_iter(new_attrs);
86 if new_attrs.is_empty() {
87 return ex;
88 }
89 self.attrs.insert(ex.hir_id.local_id, new_attrs);
90 }
91 return ex;
92 }
93 ExprKind::ForLoop { pat, iter, body, label, kind } => {
99 return self.lower_expr_for(e, pat, iter, body, *label, *kind);
100 }
101 _ => (),
102 }
103
104 let expr_hir_id = self.lower_node_id(e.id);
105 let attrs = self.lower_attrs(expr_hir_id, &e.attrs, e.span, Target::from_expr(e));
106
107 let kind = match &e.kind {
108 ExprKind::Array(exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
109 ExprKind::ConstBlock(c) => hir::ExprKind::ConstBlock(self.lower_const_block(c)),
110 ExprKind::Repeat(expr, count) => {
111 let expr = self.lower_expr(expr);
112 let count = self.lower_array_length_to_const_arg(count);
113 hir::ExprKind::Repeat(expr, count)
114 }
115 ExprKind::Tup(elts) => hir::ExprKind::Tup(self.lower_exprs(elts)),
116 ExprKind::Call(f, args) => {
117 if let Some(legacy_args) = self.resolver.legacy_const_generic_args(f, self.tcx)
118 {
119 self.lower_legacy_const_generics((**f).clone(), args.clone(), &legacy_args)
120 } else {
121 let f = self.lower_expr(f);
122 hir::ExprKind::Call(f, self.lower_exprs(args))
123 }
124 }
125 ExprKind::MethodCall(box MethodCall { seg, receiver, args, span }) => {
126 let hir_seg = self.arena.alloc(self.lower_path_segment(
127 e.span,
128 seg,
129 ParamMode::Optional,
130 GenericArgsMode::Err,
131 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
132 None,
134 ));
135 let receiver = self.lower_expr(receiver);
136 let args =
137 self.arena.alloc_from_iter(args.iter().map(|x| self.lower_expr_mut(x)));
138 hir::ExprKind::MethodCall(hir_seg, receiver, args, self.lower_span(*span))
139 }
140 ExprKind::Binary(binop, lhs, rhs) => {
141 let binop = self.lower_binop(*binop);
142 let lhs = self.lower_expr(lhs);
143 let rhs = self.lower_expr(rhs);
144 hir::ExprKind::Binary(binop, lhs, rhs)
145 }
146 ExprKind::Unary(op, ohs) => {
147 let op = self.lower_unop(*op);
148 let ohs = self.lower_expr(ohs);
149 hir::ExprKind::Unary(op, ohs)
150 }
151 ExprKind::Lit(token_lit) => hir::ExprKind::Lit(self.lower_lit(token_lit, e.span)),
152 ExprKind::IncludedBytes(byte_sym) => {
153 let lit = respan(
154 self.lower_span(e.span),
155 LitKind::ByteStr(*byte_sym, StrStyle::Cooked),
156 );
157 hir::ExprKind::Lit(lit)
158 }
159 ExprKind::Cast(expr, ty) => {
160 let expr = self.lower_expr(expr);
161 let ty = self
162 .lower_ty_alloc(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
163 hir::ExprKind::Cast(expr, ty)
164 }
165 ExprKind::Type(expr, ty) => {
166 let expr = self.lower_expr(expr);
167 let ty = self
168 .lower_ty_alloc(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
169 hir::ExprKind::Type(expr, ty)
170 }
171 ExprKind::AddrOf(k, m, ohs) => {
172 let ohs = self.lower_expr(ohs);
173 hir::ExprKind::AddrOf(*k, *m, ohs)
174 }
175 ExprKind::Let(pat, scrutinee, span, recovered) => {
176 hir::ExprKind::Let(self.arena.alloc(hir::LetExpr {
177 span: self.lower_span(*span),
178 pat: self.lower_pat(pat),
179 ty: None,
180 init: self.lower_expr(scrutinee),
181 recovered: *recovered,
182 }))
183 }
184 ExprKind::If(cond, then, else_opt) => {
185 self.lower_expr_if(cond, then, else_opt.as_deref())
186 }
187 ExprKind::While(cond, body, opt_label) => {
188 self.with_loop_scope(expr_hir_id, |this| {
189 let span =
190 this.mark_span_with_reason(DesugaringKind::WhileLoop, e.span, None);
191 let opt_label = this.lower_label(*opt_label, e.id, expr_hir_id);
192 this.lower_expr_while_in_loop_scope(span, cond, body, opt_label)
193 })
194 }
195 ExprKind::Loop(body, opt_label, span) => {
196 self.with_loop_scope(expr_hir_id, |this| {
197 let opt_label = this.lower_label(*opt_label, e.id, expr_hir_id);
198 hir::ExprKind::Loop(
199 this.lower_block(body, false),
200 opt_label,
201 hir::LoopSource::Loop,
202 this.lower_span(*span),
203 )
204 })
205 }
206 ExprKind::TryBlock(body, opt_ty) => {
207 self.lower_expr_try_block(body, opt_ty.as_deref())
208 }
209 ExprKind::Match(expr, arms, kind) => hir::ExprKind::Match(
210 self.lower_expr(expr),
211 self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))),
212 match kind {
213 MatchKind::Prefix => hir::MatchSource::Normal,
214 MatchKind::Postfix => hir::MatchSource::Postfix,
215 },
216 ),
217 ExprKind::Await(expr, await_kw_span) => self.lower_expr_await(*await_kw_span, expr),
218 ExprKind::Use(expr, use_kw_span) => self.lower_expr_use(*use_kw_span, expr),
219 ExprKind::Closure(box Closure {
220 binder,
221 capture_clause,
222 constness,
223 coroutine_kind,
224 movability,
225 fn_decl,
226 body,
227 fn_decl_span,
228 fn_arg_span,
229 }) => match coroutine_kind {
230 Some(coroutine_kind) => self.lower_expr_coroutine_closure(
231 binder,
232 *capture_clause,
233 e.id,
234 expr_hir_id,
235 *coroutine_kind,
236 fn_decl,
237 body,
238 *fn_decl_span,
239 *fn_arg_span,
240 ),
241 None => self.lower_expr_closure(
242 attrs,
243 binder,
244 *capture_clause,
245 e.id,
246 *constness,
247 *movability,
248 fn_decl,
249 body,
250 *fn_decl_span,
251 *fn_arg_span,
252 ),
253 },
254 ExprKind::Gen(capture_clause, block, genblock_kind, decl_span) => {
255 let desugaring_kind = match genblock_kind {
256 GenBlockKind::Async => hir::CoroutineDesugaring::Async,
257 GenBlockKind::Gen => hir::CoroutineDesugaring::Gen,
258 GenBlockKind::AsyncGen => hir::CoroutineDesugaring::AsyncGen,
259 };
260 self.make_desugared_coroutine_expr(
261 *capture_clause,
262 e.id,
263 None,
264 *decl_span,
265 e.span,
266 desugaring_kind,
267 hir::CoroutineSource::Block,
268 |this| this.with_new_scopes(e.span, |this| this.lower_block_expr(block)),
269 )
270 }
271 ExprKind::Block(blk, opt_label) => {
272 let block_hir_id = self.lower_node_id(blk.id);
275 let opt_label = self.lower_label(*opt_label, blk.id, block_hir_id);
276 let hir_block = self.arena.alloc(self.lower_block_noalloc(
277 block_hir_id,
278 blk,
279 opt_label.is_some(),
280 ));
281 hir::ExprKind::Block(hir_block, opt_label)
282 }
283 ExprKind::Assign(el, er, span) => self.lower_expr_assign(el, er, *span, e.span),
284 ExprKind::AssignOp(op, el, er) => hir::ExprKind::AssignOp(
285 self.lower_assign_op(*op),
286 self.lower_expr(el),
287 self.lower_expr(er),
288 ),
289 ExprKind::Field(el, ident) => {
290 hir::ExprKind::Field(self.lower_expr(el), self.lower_ident(*ident))
291 }
292 ExprKind::Index(el, er, brackets_span) => hir::ExprKind::Index(
293 self.lower_expr(el),
294 self.lower_expr(er),
295 self.lower_span(*brackets_span),
296 ),
297 ExprKind::Range(e1, e2, lims) => {
298 span = self.mark_span_with_reason(DesugaringKind::RangeExpr, span, None);
299 self.lower_expr_range(span, e1.as_deref(), e2.as_deref(), *lims)
300 }
301 ExprKind::Underscore => {
302 let guar = self.dcx().emit_err(UnderscoreExprLhsAssign { span: e.span });
303 hir::ExprKind::Err(guar)
304 }
305 ExprKind::Path(qself, path) => {
306 let qpath = self.lower_qpath(
307 e.id,
308 qself,
309 path,
310 ParamMode::Optional,
311 AllowReturnTypeNotation::No,
312 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
313 None,
314 );
315 hir::ExprKind::Path(qpath)
316 }
317 ExprKind::Break(opt_label, opt_expr) => {
318 let opt_expr = opt_expr.as_ref().map(|x| self.lower_expr(x));
319 hir::ExprKind::Break(self.lower_jump_destination(e.id, *opt_label), opt_expr)
320 }
321 ExprKind::Continue(opt_label) => {
322 hir::ExprKind::Continue(self.lower_jump_destination(e.id, *opt_label))
323 }
324 ExprKind::Ret(e) => {
325 let expr = e.as_ref().map(|x| self.lower_expr(x));
326 self.checked_return(expr)
327 }
328 ExprKind::Yeet(sub_expr) => self.lower_expr_yeet(e.span, sub_expr.as_deref()),
329 ExprKind::Become(sub_expr) => {
330 let sub_expr = self.lower_expr(sub_expr);
331 hir::ExprKind::Become(sub_expr)
332 }
333 ExprKind::InlineAsm(asm) => {
334 hir::ExprKind::InlineAsm(self.lower_inline_asm(e.span, asm))
335 }
336 ExprKind::FormatArgs(fmt) => self.lower_format_args(e.span, fmt),
337 ExprKind::OffsetOf(container, fields) => hir::ExprKind::OffsetOf(
338 self.lower_ty_alloc(
339 container,
340 ImplTraitContext::Disallowed(ImplTraitPosition::OffsetOf),
341 ),
342 self.arena.alloc_from_iter(fields.iter().map(|&ident| self.lower_ident(ident))),
343 ),
344 ExprKind::Struct(se) => {
345 let rest = match &se.rest {
346 StructRest::Base(e) => hir::StructTailExpr::Base(self.lower_expr(e)),
347 StructRest::Rest(sp) => {
348 hir::StructTailExpr::DefaultFields(self.lower_span(*sp))
349 }
350 StructRest::None => hir::StructTailExpr::None,
351 };
352 hir::ExprKind::Struct(
353 self.arena.alloc(self.lower_qpath(
354 e.id,
355 &se.qself,
356 &se.path,
357 ParamMode::Optional,
358 AllowReturnTypeNotation::No,
359 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
360 None,
361 )),
362 self.arena
363 .alloc_from_iter(se.fields.iter().map(|x| self.lower_expr_field(x))),
364 rest,
365 )
366 }
367 ExprKind::Yield(kind) => self.lower_expr_yield(e.span, kind.expr().map(|x| &**x)),
368 ExprKind::Err(guar) => hir::ExprKind::Err(*guar),
369
370 ExprKind::UnsafeBinderCast(kind, expr, ty) => hir::ExprKind::UnsafeBinderCast(
371 *kind,
372 self.lower_expr(expr),
373 ty.as_ref().map(|ty| {
374 self.lower_ty_alloc(
375 ty,
376 ImplTraitContext::Disallowed(ImplTraitPosition::Cast),
377 )
378 }),
379 ),
380
381 ExprKind::Dummy => {
382 span_bug!(e.span, "lowered ExprKind::Dummy")
383 }
384
385 ExprKind::Try(sub_expr) => self.lower_expr_try(e.span, sub_expr),
386
387 ExprKind::Paren(_) | ExprKind::ForLoop { .. } => {
388 unreachable!("already handled")
389 }
390
391 ExprKind::MacCall(_) => panic!("{:?} shouldn't exist here", e.span),
392 };
393
394 hir::Expr { hir_id: expr_hir_id, kind, span }
395 })
396 }
397
398 pub(crate) fn lower_const_block(&mut self, c: &AnonConst) -> hir::ConstBlock {
399 self.with_new_scopes(c.value.span, |this| {
400 let def_id = this.local_def_id(c.id);
401 hir::ConstBlock {
402 def_id,
403 hir_id: this.lower_node_id(c.id),
404 body: this.lower_const_body(c.value.span, Some(&c.value)),
405 }
406 })
407 }
408
409 pub(crate) fn lower_lit(&mut self, token_lit: &token::Lit, span: Span) -> hir::Lit {
410 let lit_kind = match LitKind::from_token_lit(*token_lit) {
411 Ok(lit_kind) => lit_kind,
412 Err(err) => {
413 let guar = report_lit_error(&self.tcx.sess.psess, err, *token_lit, span);
414 LitKind::Err(guar)
415 }
416 };
417 respan(self.lower_span(span), lit_kind)
418 }
419
420 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
421 match u {
422 UnOp::Deref => hir::UnOp::Deref,
423 UnOp::Not => hir::UnOp::Not,
424 UnOp::Neg => hir::UnOp::Neg,
425 }
426 }
427
428 fn lower_binop(&mut self, b: BinOp) -> BinOp {
429 Spanned { node: b.node, span: self.lower_span(b.span) }
430 }
431
432 fn lower_assign_op(&mut self, a: AssignOp) -> AssignOp {
433 Spanned { node: a.node, span: self.lower_span(a.span) }
434 }
435
436 fn lower_legacy_const_generics(
437 &mut self,
438 mut f: Expr,
439 args: ThinVec<Box<Expr>>,
440 legacy_args_idx: &[usize],
441 ) -> hir::ExprKind<'hir> {
442 let ExprKind::Path(None, path) = &mut f.kind else {
443 unreachable!();
444 };
445
446 let mut error = None;
447 let mut invalid_expr_error = |tcx: TyCtxt<'_>, span| {
448 if error.is_none() {
450 let mut const_args = vec![];
451 let mut other_args = vec![];
452 for (idx, arg) in args.iter().enumerate() {
453 if legacy_args_idx.contains(&idx) {
454 const_args.push(format!("{{ {} }}", expr_to_string(arg)));
455 } else {
456 other_args.push(expr_to_string(arg));
457 }
458 }
459 let suggestion = UseConstGenericArg {
460 end_of_fn: f.span.shrink_to_hi(),
461 const_args: const_args.join(", "),
462 other_args: other_args.join(", "),
463 call_args: args[0].span.to(args.last().unwrap().span),
464 };
465 error = Some(tcx.dcx().emit_err(InvalidLegacyConstGenericArg { span, suggestion }));
466 }
467 error.unwrap()
468 };
469
470 let mut real_args = vec![];
472 let mut generic_args = ThinVec::new();
473 for (idx, arg) in args.iter().cloned().enumerate() {
474 if legacy_args_idx.contains(&idx) {
475 let node_id = self.next_node_id();
476 self.create_def(
477 node_id,
478 None,
479 DefKind::AnonConst,
480 DefPathData::LateAnonConst,
481 f.span,
482 );
483 let mut visitor = WillCreateDefIdsVisitor {};
484 let const_value = if let ControlFlow::Break(span) = visitor.visit_expr(&arg) {
485 Box::new(Expr {
486 id: self.next_node_id(),
487 kind: ExprKind::Err(invalid_expr_error(self.tcx, span)),
488 span: f.span,
489 attrs: [].into(),
490 tokens: None,
491 })
492 } else {
493 arg
494 };
495
496 let anon_const = AnonConst {
497 id: node_id,
498 value: const_value,
499 mgca_disambiguation: MgcaDisambiguation::AnonConst,
500 };
501 generic_args.push(AngleBracketedArg::Arg(GenericArg::Const(anon_const)));
502 } else {
503 real_args.push(arg);
504 }
505 }
506
507 let last_segment = path.segments.last_mut().unwrap();
509 assert!(last_segment.args.is_none());
510 last_segment.args = Some(Box::new(GenericArgs::AngleBracketed(AngleBracketedArgs {
511 span: DUMMY_SP,
512 args: generic_args,
513 })));
514
515 let f = self.lower_expr(&f);
517 hir::ExprKind::Call(f, self.lower_exprs(&real_args))
518 }
519
520 fn lower_expr_if(
521 &mut self,
522 cond: &Expr,
523 then: &Block,
524 else_opt: Option<&Expr>,
525 ) -> hir::ExprKind<'hir> {
526 let lowered_cond = self.lower_expr(cond);
527 let then_expr = self.lower_block_expr(then);
528 if let Some(rslt) = else_opt {
529 hir::ExprKind::If(
530 lowered_cond,
531 self.arena.alloc(then_expr),
532 Some(self.lower_expr(rslt)),
533 )
534 } else {
535 hir::ExprKind::If(lowered_cond, self.arena.alloc(then_expr), None)
536 }
537 }
538
539 fn lower_expr_while_in_loop_scope(
556 &mut self,
557 span: Span,
558 cond: &Expr,
559 body: &Block,
560 opt_label: Option<Label>,
561 ) -> hir::ExprKind<'hir> {
562 let lowered_cond = self.with_loop_condition_scope(|t| t.lower_expr(cond));
563 let then = self.lower_block_expr(body);
564 let expr_break = self.expr_break(span);
565 let stmt_break = self.stmt_expr(span, expr_break);
566 let else_blk = self.block_all(span, arena_vec![self; stmt_break], None);
567 let else_expr = self.arena.alloc(self.expr_block(else_blk));
568 let if_kind = hir::ExprKind::If(lowered_cond, self.arena.alloc(then), Some(else_expr));
569 let if_expr = self.expr(span, if_kind);
570 let block = self.block_expr(self.arena.alloc(if_expr));
571 let span = self.lower_span(span.with_hi(cond.span.hi()));
572 hir::ExprKind::Loop(block, opt_label, hir::LoopSource::While, span)
573 }
574
575 fn lower_expr_try_block(&mut self, body: &Block, opt_ty: Option<&Ty>) -> hir::ExprKind<'hir> {
579 let body_hir_id = self.lower_node_id(body.id);
580 let new_scope = if opt_ty.is_some() {
581 TryBlockScope::Heterogeneous(body_hir_id)
582 } else {
583 TryBlockScope::Homogeneous(body_hir_id)
584 };
585 let whole_block = self.with_try_block_scope(new_scope, |this| {
586 let mut block = this.lower_block_noalloc(body_hir_id, body, true);
587
588 let (try_span, tail_expr) = if let Some(expr) = block.expr.take() {
590 (
591 this.mark_span_with_reason(
592 DesugaringKind::TryBlock,
593 expr.span,
594 Some(Arc::clone(&this.allow_try_trait)),
595 ),
596 expr,
597 )
598 } else {
599 let try_span = this.mark_span_with_reason(
600 DesugaringKind::TryBlock,
601 this.tcx.sess.source_map().end_point(body.span),
602 Some(Arc::clone(&this.allow_try_trait)),
603 );
604
605 (try_span, this.expr_unit(try_span))
606 };
607
608 let ok_wrapped_span =
609 this.mark_span_with_reason(DesugaringKind::TryBlock, tail_expr.span, None);
610
611 block.expr = Some(this.wrap_in_try_constructor(
613 hir::LangItem::TryTraitFromOutput,
614 try_span,
615 tail_expr,
616 ok_wrapped_span,
617 ));
618
619 this.arena.alloc(block)
620 });
621
622 if let Some(ty) = opt_ty {
623 let ty = self.lower_ty_alloc(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Path));
624 let block_expr = self.arena.alloc(self.expr_block(whole_block));
625 hir::ExprKind::Type(block_expr, ty)
626 } else {
627 hir::ExprKind::Block(whole_block, None)
628 }
629 }
630
631 fn wrap_in_try_constructor(
632 &mut self,
633 lang_item: hir::LangItem,
634 method_span: Span,
635 expr: &'hir hir::Expr<'hir>,
636 overall_span: Span,
637 ) -> &'hir hir::Expr<'hir> {
638 let constructor = self.arena.alloc(self.expr_lang_item_path(method_span, lang_item));
639 self.expr_call(overall_span, constructor, std::slice::from_ref(expr))
640 }
641
642 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> {
643 let pat = self.lower_pat(&arm.pat);
644 let guard = arm.guard.as_ref().map(|cond| self.lower_expr(cond));
645 let hir_id = self.next_id();
646 let span = self.lower_span(arm.span);
647 self.lower_attrs(hir_id, &arm.attrs, arm.span, Target::Arm);
648 let is_never_pattern = pat.is_never_pattern();
649 let body = arm.body.as_ref().map(|x| self.lower_expr(x));
652 let body = if let Some(body) = body
653 && !is_never_pattern
654 {
655 body
656 } else {
657 if !is_never_pattern {
659 if self.tcx.features().never_patterns() {
660 let suggestion = span.shrink_to_hi();
662 self.dcx().emit_err(MatchArmWithNoBody { span, suggestion });
663 }
664 } else if let Some(body) = &arm.body {
665 self.dcx().emit_err(NeverPatternWithBody { span: body.span });
666 } else if let Some(g) = &arm.guard {
667 self.dcx().emit_err(NeverPatternWithGuard { span: g.span });
668 }
669
670 let block = self.arena.alloc(hir::Block {
673 stmts: &[],
674 expr: None,
675 hir_id: self.next_id(),
676 rules: hir::BlockCheckMode::DefaultBlock,
677 span,
678 targeted_by_break: false,
679 });
680 self.arena.alloc(hir::Expr {
681 hir_id: self.next_id(),
682 kind: hir::ExprKind::Loop(block, None, hir::LoopSource::Loop, span),
683 span,
684 })
685 };
686 hir::Arm { hir_id, pat, guard, body, span }
687 }
688
689 fn lower_capture_clause(&mut self, capture_clause: CaptureBy) -> CaptureBy {
690 match capture_clause {
691 CaptureBy::Ref => CaptureBy::Ref,
692 CaptureBy::Use { use_kw } => CaptureBy::Use { use_kw: self.lower_span(use_kw) },
693 CaptureBy::Value { move_kw } => CaptureBy::Value { move_kw: self.lower_span(move_kw) },
694 }
695 }
696
697 pub(super) fn make_desugared_coroutine_expr(
709 &mut self,
710 capture_clause: CaptureBy,
711 closure_node_id: NodeId,
712 return_ty: Option<hir::FnRetTy<'hir>>,
713 fn_decl_span: Span,
714 span: Span,
715 desugaring_kind: hir::CoroutineDesugaring,
716 coroutine_source: hir::CoroutineSource,
717 body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
718 ) -> hir::ExprKind<'hir> {
719 let closure_def_id = self.local_def_id(closure_node_id);
720 let coroutine_kind = hir::CoroutineKind::Desugared(desugaring_kind, coroutine_source);
721
722 let (inputs, params, task_context): (&[_], &[_], _) = match desugaring_kind {
725 hir::CoroutineDesugaring::Async | hir::CoroutineDesugaring::AsyncGen => {
726 let unstable_span = self.mark_span_with_reason(
728 DesugaringKind::Async,
729 self.lower_span(span),
730 Some(Arc::clone(&self.allow_gen_future)),
731 );
732 let resume_ty =
733 self.make_lang_item_qpath(hir::LangItem::ResumeTy, unstable_span, None);
734 let input_ty = hir::Ty {
735 hir_id: self.next_id(),
736 kind: hir::TyKind::Path(resume_ty),
737 span: unstable_span,
738 };
739 let inputs = arena_vec![self; input_ty];
740
741 let (pat, task_context_hid) = self.pat_ident_binding_mode(
743 span,
744 Ident::with_dummy_span(sym::_task_context),
745 hir::BindingMode::MUT,
746 );
747 let param = hir::Param {
748 hir_id: self.next_id(),
749 pat,
750 ty_span: self.lower_span(span),
751 span: self.lower_span(span),
752 };
753 let params = arena_vec![self; param];
754
755 (inputs, params, Some(task_context_hid))
756 }
757 hir::CoroutineDesugaring::Gen => (&[], &[], None),
758 };
759
760 let output =
761 return_ty.unwrap_or_else(|| hir::FnRetTy::DefaultReturn(self.lower_span(span)));
762
763 let fn_decl = self.arena.alloc(hir::FnDecl {
764 inputs,
765 output,
766 c_variadic: false,
767 implicit_self: hir::ImplicitSelfKind::None,
768 lifetime_elision_allowed: false,
769 });
770
771 let body = self.lower_body(move |this| {
772 this.coroutine_kind = Some(coroutine_kind);
773
774 let old_ctx = this.task_context;
775 if task_context.is_some() {
776 this.task_context = task_context;
777 }
778 let res = body(this);
779 this.task_context = old_ctx;
780
781 (params, res)
782 });
783
784 hir::ExprKind::Closure(self.arena.alloc(hir::Closure {
786 def_id: closure_def_id,
787 binder: hir::ClosureBinder::Default,
788 capture_clause: self.lower_capture_clause(capture_clause),
789 bound_generic_params: &[],
790 fn_decl,
791 body,
792 fn_decl_span: self.lower_span(fn_decl_span),
793 fn_arg_span: None,
794 kind: hir::ClosureKind::Coroutine(coroutine_kind),
795 constness: hir::Constness::NotConst,
796 }))
797 }
798
799 pub(super) fn maybe_forward_track_caller(
802 &mut self,
803 span: Span,
804 outer_hir_id: HirId,
805 inner_hir_id: HirId,
806 ) {
807 if self.tcx.features().async_fn_track_caller()
808 && let Some(attrs) = self.attrs.get(&outer_hir_id.local_id)
809 && find_attr!(*attrs, AttributeKind::TrackCaller(_))
810 {
811 let unstable_span = self.mark_span_with_reason(
812 DesugaringKind::Async,
813 span,
814 Some(Arc::clone(&self.allow_gen_future)),
815 );
816 self.lower_attrs(
817 inner_hir_id,
818 &[Attribute {
819 kind: AttrKind::Normal(Box::new(NormalAttr::from_ident(Ident::new(
820 sym::track_caller,
821 span,
822 )))),
823 id: self.tcx.sess.psess.attr_id_generator.mk_attr_id(),
824 style: AttrStyle::Outer,
825 span: unstable_span,
826 }],
827 span,
828 Target::Fn,
829 );
830 }
831 }
832
833 fn lower_expr_await(&mut self, await_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
849 let expr = self.arena.alloc(self.lower_expr_mut(expr));
850 self.make_lowered_await(await_kw_span, expr, FutureKind::Future)
851 }
852
853 fn make_lowered_await(
855 &mut self,
856 await_kw_span: Span,
857 expr: &'hir hir::Expr<'hir>,
858 await_kind: FutureKind,
859 ) -> hir::ExprKind<'hir> {
860 let full_span = expr.span.to(await_kw_span);
861
862 let is_async_gen = match self.coroutine_kind {
863 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)) => false,
864 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)) => true,
865 Some(hir::CoroutineKind::Coroutine(_))
866 | Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _))
867 | None => {
868 let stmt_id = self.next_id();
871 let expr_err = self.expr(
872 expr.span,
873 hir::ExprKind::Err(self.dcx().emit_err(AwaitOnlyInAsyncFnAndBlocks {
874 await_kw_span,
875 item_span: self.current_item,
876 })),
877 );
878 return hir::ExprKind::Block(
879 self.block_all(
880 expr.span,
881 arena_vec![self; hir::Stmt {
882 hir_id: stmt_id,
883 kind: hir::StmtKind::Semi(expr),
884 span: expr.span,
885 }],
886 Some(self.arena.alloc(expr_err)),
887 ),
888 None,
889 );
890 }
891 };
892
893 let features = match await_kind {
894 FutureKind::Future if is_async_gen => Some(Arc::clone(&self.allow_async_gen)),
895 FutureKind::Future => None,
896 FutureKind::AsyncIterator => Some(Arc::clone(&self.allow_for_await)),
897 };
898 let span = self.mark_span_with_reason(DesugaringKind::Await, await_kw_span, features);
899 let gen_future_span = self.mark_span_with_reason(
900 DesugaringKind::Await,
901 full_span,
902 Some(Arc::clone(&self.allow_gen_future)),
903 );
904 let expr_hir_id = expr.hir_id;
905
906 let awaitee_ident = Ident::with_dummy_span(sym::__awaitee);
910 let (awaitee_pat, awaitee_pat_hid) =
911 self.pat_ident_binding_mode(gen_future_span, awaitee_ident, hir::BindingMode::MUT);
912
913 let task_context_ident = Ident::with_dummy_span(sym::_task_context);
914
915 let poll_expr = {
922 let awaitee = self.expr_ident(span, awaitee_ident, awaitee_pat_hid);
923 let ref_mut_awaitee = self.expr_mut_addr_of(span, awaitee);
924
925 let Some(task_context_hid) = self.task_context else {
926 unreachable!("use of `await` outside of an async context.");
927 };
928
929 let task_context = self.expr_ident_mut(span, task_context_ident, task_context_hid);
930
931 let new_unchecked = self.expr_call_lang_item_fn_mut(
932 span,
933 hir::LangItem::PinNewUnchecked,
934 arena_vec![self; ref_mut_awaitee],
935 );
936 let get_context = self.expr_call_lang_item_fn_mut(
937 gen_future_span,
938 hir::LangItem::GetContext,
939 arena_vec![self; task_context],
940 );
941 let call = match await_kind {
942 FutureKind::Future => self.expr_call_lang_item_fn(
943 span,
944 hir::LangItem::FuturePoll,
945 arena_vec![self; new_unchecked, get_context],
946 ),
947 FutureKind::AsyncIterator => self.expr_call_lang_item_fn(
948 span,
949 hir::LangItem::AsyncIteratorPollNext,
950 arena_vec![self; new_unchecked, get_context],
951 ),
952 };
953 self.arena.alloc(self.expr_unsafe(span, call))
954 };
955
956 let loop_node_id = self.next_node_id();
958 let loop_hir_id = self.lower_node_id(loop_node_id);
959 let ready_arm = {
960 let x_ident = Ident::with_dummy_span(sym::result);
961 let (x_pat, x_pat_hid) = self.pat_ident(gen_future_span, x_ident);
962 let x_expr = self.expr_ident(gen_future_span, x_ident, x_pat_hid);
963 let ready_field = self.single_pat_field(gen_future_span, x_pat);
964 let ready_pat = self.pat_lang_item_variant(span, hir::LangItem::PollReady, ready_field);
965 let break_x = self.with_loop_scope(loop_hir_id, move |this| {
966 let expr_break =
967 hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr));
968 this.arena.alloc(this.expr(gen_future_span, expr_break))
969 });
970 self.arm(ready_pat, break_x)
971 };
972
973 let pending_arm = {
975 let pending_pat = self.pat_lang_item_variant(span, hir::LangItem::PollPending, &[]);
976 let empty_block = self.expr_block_empty(span);
977 self.arm(pending_pat, empty_block)
978 };
979
980 let inner_match_stmt = {
981 let match_expr = self.expr_match(
982 span,
983 poll_expr,
984 arena_vec![self; ready_arm, pending_arm],
985 hir::MatchSource::AwaitDesugar,
986 );
987 self.stmt_expr(span, match_expr)
988 };
989
990 let yield_stmt = {
994 let yielded = if is_async_gen {
995 self.arena.alloc(self.expr_lang_item_path(span, hir::LangItem::AsyncGenPending))
996 } else {
997 self.expr_unit(span)
998 };
999
1000 let yield_expr = self.expr(
1001 span,
1002 hir::ExprKind::Yield(yielded, hir::YieldSource::Await { expr: Some(expr_hir_id) }),
1003 );
1004 let yield_expr = self.arena.alloc(yield_expr);
1005
1006 let Some(task_context_hid) = self.task_context else {
1007 unreachable!("use of `await` outside of an async context.");
1008 };
1009
1010 let lhs = self.expr_ident(span, task_context_ident, task_context_hid);
1011 let assign =
1012 self.expr(span, hir::ExprKind::Assign(lhs, yield_expr, self.lower_span(span)));
1013 self.stmt_expr(span, assign)
1014 };
1015
1016 let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None);
1017
1018 let loop_expr = self.arena.alloc(hir::Expr {
1020 hir_id: loop_hir_id,
1021 kind: hir::ExprKind::Loop(
1022 loop_block,
1023 None,
1024 hir::LoopSource::Loop,
1025 self.lower_span(span),
1026 ),
1027 span: self.lower_span(span),
1028 });
1029
1030 let awaitee_arm = self.arm(awaitee_pat, loop_expr);
1032
1033 let into_future_expr = match await_kind {
1035 FutureKind::Future => self.expr_call_lang_item_fn(
1036 span,
1037 hir::LangItem::IntoFutureIntoFuture,
1038 arena_vec![self; *expr],
1039 ),
1040 FutureKind::AsyncIterator => expr,
1043 };
1044
1045 hir::ExprKind::Match(
1049 into_future_expr,
1050 arena_vec![self; awaitee_arm],
1051 hir::MatchSource::AwaitDesugar,
1052 )
1053 }
1054
1055 fn lower_expr_use(&mut self, use_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
1056 hir::ExprKind::Use(self.lower_expr(expr), self.lower_span(use_kw_span))
1057 }
1058
1059 fn lower_expr_closure(
1060 &mut self,
1061 attrs: &[rustc_hir::Attribute],
1062 binder: &ClosureBinder,
1063 capture_clause: CaptureBy,
1064 closure_id: NodeId,
1065 constness: Const,
1066 movability: Movability,
1067 decl: &FnDecl,
1068 body: &Expr,
1069 fn_decl_span: Span,
1070 fn_arg_span: Span,
1071 ) -> hir::ExprKind<'hir> {
1072 let closure_def_id = self.local_def_id(closure_id);
1073 let (binder_clause, generic_params) = self.lower_closure_binder(binder);
1074
1075 let (body_id, closure_kind) = self.with_new_scopes(fn_decl_span, move |this| {
1076
1077 let mut coroutine_kind = find_attr!(attrs, AttributeKind::Coroutine(_) => hir::CoroutineKind::Coroutine(Movability::Movable));
1078
1079 let body_id = this.lower_fn_body(decl, None, |this| {
1081 this.coroutine_kind = coroutine_kind;
1082 let e = this.lower_expr_mut(body);
1083 coroutine_kind = this.coroutine_kind;
1084 e
1085 });
1086 let coroutine_option =
1087 this.closure_movability_for_fn(decl, fn_decl_span, coroutine_kind, movability);
1088 (body_id, coroutine_option)
1089 });
1090
1091 let bound_generic_params = self.lower_lifetime_binder(closure_id, generic_params);
1092 let fn_decl = self.lower_fn_decl(decl, closure_id, fn_decl_span, FnDeclKind::Closure, None);
1094
1095 let c = self.arena.alloc(hir::Closure {
1096 def_id: closure_def_id,
1097 binder: binder_clause,
1098 capture_clause: self.lower_capture_clause(capture_clause),
1099 bound_generic_params,
1100 fn_decl,
1101 body: body_id,
1102 fn_decl_span: self.lower_span(fn_decl_span),
1103 fn_arg_span: Some(self.lower_span(fn_arg_span)),
1104 kind: closure_kind,
1105 constness: self.lower_constness(constness),
1106 });
1107
1108 hir::ExprKind::Closure(c)
1109 }
1110
1111 fn closure_movability_for_fn(
1112 &mut self,
1113 decl: &FnDecl,
1114 fn_decl_span: Span,
1115 coroutine_kind: Option<hir::CoroutineKind>,
1116 movability: Movability,
1117 ) -> hir::ClosureKind {
1118 match coroutine_kind {
1119 Some(hir::CoroutineKind::Coroutine(_)) => {
1120 if decl.inputs.len() > 1 {
1121 self.dcx().emit_err(CoroutineTooManyParameters { fn_decl_span });
1122 }
1123 hir::ClosureKind::Coroutine(hir::CoroutineKind::Coroutine(movability))
1124 }
1125 Some(
1126 hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)
1127 | hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)
1128 | hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _),
1129 ) => {
1130 panic!("non-`async`/`gen` closure body turned `async`/`gen` during lowering");
1131 }
1132 None => {
1133 if movability == Movability::Static {
1134 self.dcx().emit_err(ClosureCannotBeStatic { fn_decl_span });
1135 }
1136 hir::ClosureKind::Closure
1137 }
1138 }
1139 }
1140
1141 fn lower_closure_binder<'c>(
1142 &mut self,
1143 binder: &'c ClosureBinder,
1144 ) -> (hir::ClosureBinder, &'c [GenericParam]) {
1145 let (binder, params) = match binder {
1146 ClosureBinder::NotPresent => (hir::ClosureBinder::Default, &[][..]),
1147 ClosureBinder::For { span, generic_params } => {
1148 let span = self.lower_span(*span);
1149 (hir::ClosureBinder::For { span }, &**generic_params)
1150 }
1151 };
1152
1153 (binder, params)
1154 }
1155
1156 fn lower_expr_coroutine_closure(
1157 &mut self,
1158 binder: &ClosureBinder,
1159 capture_clause: CaptureBy,
1160 closure_id: NodeId,
1161 closure_hir_id: HirId,
1162 coroutine_kind: CoroutineKind,
1163 decl: &FnDecl,
1164 body: &Expr,
1165 fn_decl_span: Span,
1166 fn_arg_span: Span,
1167 ) -> hir::ExprKind<'hir> {
1168 let closure_def_id = self.local_def_id(closure_id);
1169 let (binder_clause, generic_params) = self.lower_closure_binder(binder);
1170
1171 let coroutine_desugaring = match coroutine_kind {
1172 CoroutineKind::Async { .. } => hir::CoroutineDesugaring::Async,
1173 CoroutineKind::Gen { .. } => hir::CoroutineDesugaring::Gen,
1174 CoroutineKind::AsyncGen { span, .. } => {
1175 span_bug!(span, "only async closures and `iter!` closures are supported currently")
1176 }
1177 };
1178
1179 let body = self.with_new_scopes(fn_decl_span, |this| {
1180 let inner_decl =
1181 FnDecl { inputs: decl.inputs.clone(), output: FnRetTy::Default(fn_decl_span) };
1182
1183 let body_id = this.lower_body(|this| {
1186 let (parameters, expr) = this.lower_coroutine_body_with_moved_arguments(
1187 &inner_decl,
1188 |this| this.with_new_scopes(fn_decl_span, |this| this.lower_expr_mut(body)),
1189 fn_decl_span,
1190 body.span,
1191 coroutine_kind,
1192 hir::CoroutineSource::Closure,
1193 );
1194
1195 this.maybe_forward_track_caller(body.span, closure_hir_id, expr.hir_id);
1196
1197 (parameters, expr)
1198 });
1199 body_id
1200 });
1201
1202 let bound_generic_params = self.lower_lifetime_binder(closure_id, generic_params);
1203 let fn_decl =
1207 self.lower_fn_decl(&decl, closure_id, fn_decl_span, FnDeclKind::Closure, None);
1208
1209 let c = self.arena.alloc(hir::Closure {
1210 def_id: closure_def_id,
1211 binder: binder_clause,
1212 capture_clause: self.lower_capture_clause(capture_clause),
1213 bound_generic_params,
1214 fn_decl,
1215 body,
1216 fn_decl_span: self.lower_span(fn_decl_span),
1217 fn_arg_span: Some(self.lower_span(fn_arg_span)),
1218 kind: hir::ClosureKind::CoroutineClosure(coroutine_desugaring),
1222 constness: hir::Constness::NotConst,
1223 });
1224 hir::ExprKind::Closure(c)
1225 }
1226
1227 fn lower_expr_assign(
1230 &mut self,
1231 lhs: &Expr,
1232 rhs: &Expr,
1233 eq_sign_span: Span,
1234 whole_span: Span,
1235 ) -> hir::ExprKind<'hir> {
1236 fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool {
1238 match &lhs.kind {
1239 ExprKind::Array(..)
1240 | ExprKind::Struct(..)
1241 | ExprKind::Tup(..)
1242 | ExprKind::Underscore => false,
1243 ExprKind::Path(..) => lower_ctx.extract_unit_struct_path(lhs).is_none(),
1245 ExprKind::Call(callee, ..) => lower_ctx.extract_tuple_struct_path(callee).is_none(),
1247 ExprKind::Paren(e) => {
1248 match e.kind {
1249 ExprKind::Range(None, None, RangeLimits::HalfOpen) => false,
1251 _ => is_ordinary(lower_ctx, e),
1252 }
1253 }
1254 _ => true,
1255 }
1256 }
1257 if is_ordinary(self, lhs) {
1258 return hir::ExprKind::Assign(
1259 self.lower_expr(lhs),
1260 self.lower_expr(rhs),
1261 self.lower_span(eq_sign_span),
1262 );
1263 }
1264
1265 let mut assignments = vec![];
1266
1267 let pat = self.destructure_assign(lhs, eq_sign_span, &mut assignments);
1269 let rhs = self.lower_expr(rhs);
1270
1271 let destructure_let =
1273 self.stmt_let_pat(None, whole_span, Some(rhs), pat, hir::LocalSource::AssignDesugar);
1274
1275 let stmts = self.arena.alloc_from_iter(std::iter::once(destructure_let).chain(assignments));
1277
1278 hir::ExprKind::Block(self.block_all(whole_span, stmts, None), None)
1280 }
1281
1282 fn extract_tuple_struct_path<'a>(
1287 &mut self,
1288 expr: &'a Expr,
1289 ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
1290 if let ExprKind::Path(qself, path) = &expr.kind {
1291 if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
1293 if let Some(res) = partial_res.full_res()
1294 && !res.expected_in_tuple_struct_pat()
1295 {
1296 return None;
1297 }
1298 }
1299 return Some((qself, path));
1300 }
1301 None
1302 }
1303
1304 fn extract_unit_struct_path<'a>(
1309 &mut self,
1310 expr: &'a Expr,
1311 ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
1312 if let ExprKind::Path(qself, path) = &expr.kind {
1313 if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
1315 if let Some(res) = partial_res.full_res()
1316 && !res.expected_in_unit_struct_pat()
1317 {
1318 return None;
1319 }
1320 }
1321 return Some((qself, path));
1322 }
1323 None
1324 }
1325
1326 fn destructure_assign(
1329 &mut self,
1330 lhs: &Expr,
1331 eq_sign_span: Span,
1332 assignments: &mut Vec<hir::Stmt<'hir>>,
1333 ) -> &'hir hir::Pat<'hir> {
1334 self.arena.alloc(self.destructure_assign_mut(lhs, eq_sign_span, assignments))
1335 }
1336
1337 fn destructure_assign_mut(
1338 &mut self,
1339 lhs: &Expr,
1340 eq_sign_span: Span,
1341 assignments: &mut Vec<hir::Stmt<'hir>>,
1342 ) -> hir::Pat<'hir> {
1343 match &lhs.kind {
1344 ExprKind::Underscore => {
1346 return self.pat_without_dbm(lhs.span, hir::PatKind::Wild);
1347 }
1348 ExprKind::Array(elements) => {
1350 let (pats, rest) =
1351 self.destructure_sequence(elements, "slice", eq_sign_span, assignments);
1352 let slice_pat = if let Some((i, span)) = rest {
1353 let (before, after) = pats.split_at(i);
1354 hir::PatKind::Slice(
1355 before,
1356 Some(self.arena.alloc(self.pat_without_dbm(span, hir::PatKind::Wild))),
1357 after,
1358 )
1359 } else {
1360 hir::PatKind::Slice(pats, None, &[])
1361 };
1362 return self.pat_without_dbm(lhs.span, slice_pat);
1363 }
1364 ExprKind::Call(callee, args) => {
1366 if let Some((qself, path)) = self.extract_tuple_struct_path(callee) {
1367 let (pats, rest) = self.destructure_sequence(
1368 args,
1369 "tuple struct or variant",
1370 eq_sign_span,
1371 assignments,
1372 );
1373 let qpath = self.lower_qpath(
1374 callee.id,
1375 qself,
1376 path,
1377 ParamMode::Optional,
1378 AllowReturnTypeNotation::No,
1379 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1380 None,
1381 );
1382 let tuple_struct_pat = hir::PatKind::TupleStruct(
1384 qpath,
1385 pats,
1386 hir::DotDotPos::new(rest.map(|r| r.0)),
1387 );
1388 return self.pat_without_dbm(lhs.span, tuple_struct_pat);
1389 }
1390 }
1391 ExprKind::Path(..) => {
1393 if let Some((qself, path)) = self.extract_unit_struct_path(lhs) {
1394 let qpath = self.lower_qpath(
1395 lhs.id,
1396 qself,
1397 path,
1398 ParamMode::Optional,
1399 AllowReturnTypeNotation::No,
1400 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1401 None,
1402 );
1403 let unit_struct_pat = hir::PatKind::Expr(self.arena.alloc(hir::PatExpr {
1405 kind: hir::PatExprKind::Path(qpath),
1406 hir_id: self.next_id(),
1407 span: self.lower_span(lhs.span),
1408 }));
1409 return self.pat_without_dbm(lhs.span, unit_struct_pat);
1410 }
1411 }
1412 ExprKind::Struct(se) => {
1414 let field_pats = self.arena.alloc_from_iter(se.fields.iter().map(|f| {
1415 let pat = self.destructure_assign(&f.expr, eq_sign_span, assignments);
1416 hir::PatField {
1417 hir_id: self.next_id(),
1418 ident: self.lower_ident(f.ident),
1419 pat,
1420 is_shorthand: f.is_shorthand,
1421 span: self.lower_span(f.span),
1422 }
1423 }));
1424 let qpath = self.lower_qpath(
1425 lhs.id,
1426 &se.qself,
1427 &se.path,
1428 ParamMode::Optional,
1429 AllowReturnTypeNotation::No,
1430 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1431 None,
1432 );
1433 let fields_omitted = match &se.rest {
1434 StructRest::Base(e) => {
1435 self.dcx().emit_err(FunctionalRecordUpdateDestructuringAssignment {
1436 span: e.span,
1437 });
1438 Some(self.lower_span(e.span))
1439 }
1440 StructRest::Rest(span) => Some(self.lower_span(*span)),
1441 StructRest::None => None,
1442 };
1443 let struct_pat = hir::PatKind::Struct(qpath, field_pats, fields_omitted);
1444 return self.pat_without_dbm(lhs.span, struct_pat);
1445 }
1446 ExprKind::Tup(elements) => {
1448 let (pats, rest) =
1449 self.destructure_sequence(elements, "tuple", eq_sign_span, assignments);
1450 let tuple_pat = hir::PatKind::Tuple(pats, hir::DotDotPos::new(rest.map(|r| r.0)));
1451 return self.pat_without_dbm(lhs.span, tuple_pat);
1452 }
1453 ExprKind::Paren(e) => {
1454 if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
1456 let tuple_pat = hir::PatKind::Tuple(&[], hir::DotDotPos::new(Some(0)));
1457 return self.pat_without_dbm(lhs.span, tuple_pat);
1458 } else {
1459 return self.destructure_assign_mut(e, eq_sign_span, assignments);
1460 }
1461 }
1462 _ => {}
1463 }
1464 let ident = Ident::new(sym::lhs, self.lower_span(lhs.span));
1466 let (pat, binding) = self.pat_ident_mut(lhs.span, ident);
1467 let ident = self.expr_ident(lhs.span, ident, binding);
1468 let assign =
1469 hir::ExprKind::Assign(self.lower_expr(lhs), ident, self.lower_span(eq_sign_span));
1470 let expr = self.expr(lhs.span, assign);
1471 assignments.push(self.stmt_expr(lhs.span, expr));
1472 pat
1473 }
1474
1475 fn destructure_sequence(
1481 &mut self,
1482 elements: &[Box<Expr>],
1483 ctx: &str,
1484 eq_sign_span: Span,
1485 assignments: &mut Vec<hir::Stmt<'hir>>,
1486 ) -> (&'hir [hir::Pat<'hir>], Option<(usize, Span)>) {
1487 let mut rest = None;
1488 let elements =
1489 self.arena.alloc_from_iter(elements.iter().enumerate().filter_map(|(i, e)| {
1490 if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
1492 if let Some((_, prev_span)) = rest {
1493 self.ban_extra_rest_pat(e.span, prev_span, ctx);
1494 } else {
1495 rest = Some((i, e.span));
1496 }
1497 None
1498 } else {
1499 Some(self.destructure_assign_mut(e, eq_sign_span, assignments))
1500 }
1501 }));
1502 (elements, rest)
1503 }
1504
1505 fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> {
1507 let e1 = self.lower_expr_mut(e1);
1508 let e2 = self.lower_expr_mut(e2);
1509 let fn_path = self.make_lang_item_qpath(hir::LangItem::RangeInclusiveNew, span, None);
1510 let fn_expr = self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path)));
1511 hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2])
1512 }
1513
1514 fn lower_expr_range(
1515 &mut self,
1516 span: Span,
1517 e1: Option<&Expr>,
1518 e2: Option<&Expr>,
1519 lims: RangeLimits,
1520 ) -> hir::ExprKind<'hir> {
1521 use rustc_ast::RangeLimits::*;
1522
1523 let lang_item = match (e1, e2, lims) {
1524 (None, None, HalfOpen) => hir::LangItem::RangeFull,
1525 (Some(..), None, HalfOpen) => {
1526 if self.tcx.features().new_range() {
1527 hir::LangItem::RangeFromCopy
1528 } else {
1529 hir::LangItem::RangeFrom
1530 }
1531 }
1532 (None, Some(..), HalfOpen) => hir::LangItem::RangeTo,
1533 (Some(..), Some(..), HalfOpen) => {
1534 if self.tcx.features().new_range() {
1535 hir::LangItem::RangeCopy
1536 } else {
1537 hir::LangItem::Range
1538 }
1539 }
1540 (None, Some(..), Closed) => {
1541 if self.tcx.features().new_range() {
1542 hir::LangItem::RangeToInclusiveCopy
1543 } else {
1544 hir::LangItem::RangeToInclusive
1545 }
1546 }
1547 (Some(e1), Some(e2), Closed) => {
1548 if self.tcx.features().new_range() {
1549 hir::LangItem::RangeInclusiveCopy
1550 } else {
1551 return self.lower_expr_range_closed(span, e1, e2);
1552 }
1553 }
1554 (start, None, Closed) => {
1555 self.dcx().emit_err(InclusiveRangeWithNoEnd { span });
1556 match start {
1557 Some(..) => {
1558 if self.tcx.features().new_range() {
1559 hir::LangItem::RangeFromCopy
1560 } else {
1561 hir::LangItem::RangeFrom
1562 }
1563 }
1564 None => hir::LangItem::RangeFull,
1565 }
1566 }
1567 };
1568
1569 let fields = self.arena.alloc_from_iter(
1570 e1.iter()
1571 .map(|e| (sym::start, e))
1572 .chain(e2.iter().map(|e| {
1573 (
1574 if matches!(
1575 lang_item,
1576 hir::LangItem::RangeInclusiveCopy | hir::LangItem::RangeToInclusiveCopy
1577 ) {
1578 sym::last
1579 } else {
1580 sym::end
1581 },
1582 e,
1583 )
1584 }))
1585 .map(|(s, e)| {
1586 let span = self.lower_span(e.span);
1587 let span = self.mark_span_with_reason(DesugaringKind::RangeExpr, span, None);
1588 let expr = self.lower_expr(e);
1589 let ident = Ident::new(s, span);
1590 self.expr_field(ident, expr, span)
1591 }),
1592 );
1593
1594 hir::ExprKind::Struct(
1595 self.arena.alloc(self.make_lang_item_qpath(lang_item, span, None)),
1596 fields,
1597 hir::StructTailExpr::None,
1598 )
1599 }
1600
1601 fn lower_label(
1604 &mut self,
1605 opt_label: Option<Label>,
1606 dest_id: NodeId,
1607 dest_hir_id: hir::HirId,
1608 ) -> Option<Label> {
1609 let label = opt_label?;
1610 self.ident_and_label_to_local_id.insert(dest_id, dest_hir_id.local_id);
1611 Some(Label { ident: self.lower_ident(label.ident) })
1612 }
1613
1614 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
1615 let target_id = match destination {
1616 Some((id, _)) => {
1617 if let Some(loop_id) = self.resolver.get_label_res(id) {
1618 let local_id = self.ident_and_label_to_local_id[&loop_id];
1619 let loop_hir_id = HirId { owner: self.current_hir_id_owner, local_id };
1620 Ok(loop_hir_id)
1621 } else {
1622 Err(hir::LoopIdError::UnresolvedLabel)
1623 }
1624 }
1625 None => {
1626 self.loop_scope.map(|id| Ok(id)).unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
1627 }
1628 };
1629 let label = destination
1630 .map(|(_, label)| label)
1631 .map(|label| Label { ident: self.lower_ident(label.ident) });
1632 hir::Destination { label, target_id }
1633 }
1634
1635 fn lower_jump_destination(&mut self, id: NodeId, opt_label: Option<Label>) -> hir::Destination {
1636 if self.is_in_loop_condition && opt_label.is_none() {
1637 hir::Destination {
1638 label: None,
1639 target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition),
1640 }
1641 } else {
1642 self.lower_loop_destination(opt_label.map(|label| (id, label)))
1643 }
1644 }
1645
1646 fn with_try_block_scope<T>(
1647 &mut self,
1648 scope: TryBlockScope,
1649 f: impl FnOnce(&mut Self) -> T,
1650 ) -> T {
1651 let old_scope = mem::replace(&mut self.try_block_scope, scope);
1652 let result = f(self);
1653 self.try_block_scope = old_scope;
1654 result
1655 }
1656
1657 fn with_loop_scope<T>(&mut self, loop_id: hir::HirId, f: impl FnOnce(&mut Self) -> T) -> T {
1658 let was_in_loop_condition = self.is_in_loop_condition;
1660 self.is_in_loop_condition = false;
1661
1662 let old_scope = self.loop_scope.replace(loop_id);
1663 let result = f(self);
1664 self.loop_scope = old_scope;
1665
1666 self.is_in_loop_condition = was_in_loop_condition;
1667
1668 result
1669 }
1670
1671 fn with_loop_condition_scope<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
1672 let was_in_loop_condition = self.is_in_loop_condition;
1673 self.is_in_loop_condition = true;
1674
1675 let result = f(self);
1676
1677 self.is_in_loop_condition = was_in_loop_condition;
1678
1679 result
1680 }
1681
1682 fn lower_expr_field(&mut self, f: &ExprField) -> hir::ExprField<'hir> {
1683 let hir_id = self.lower_node_id(f.id);
1684 self.lower_attrs(hir_id, &f.attrs, f.span, Target::ExprField);
1685 hir::ExprField {
1686 hir_id,
1687 ident: self.lower_ident(f.ident),
1688 expr: self.lower_expr(&f.expr),
1689 span: self.lower_span(f.span),
1690 is_shorthand: f.is_shorthand,
1691 }
1692 }
1693
1694 fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
1695 let yielded =
1696 opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span));
1697
1698 if !self.tcx.features().yield_expr()
1699 && !self.tcx.features().coroutines()
1700 && !self.tcx.features().gen_blocks()
1701 {
1702 rustc_session::parse::feature_err(
1703 &self.tcx.sess,
1704 sym::yield_expr,
1705 span,
1706 fluent_generated::ast_lowering_yield,
1707 )
1708 .emit();
1709 }
1710
1711 let is_async_gen = match self.coroutine_kind {
1712 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)) => false,
1713 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)) => true,
1714 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)) => {
1715 let stmt_id = self.next_id();
1718 let expr_err = self.expr(
1719 yielded.span,
1720 hir::ExprKind::Err(self.dcx().emit_err(AsyncCoroutinesNotSupported { span })),
1721 );
1722 return hir::ExprKind::Block(
1723 self.block_all(
1724 yielded.span,
1725 arena_vec![self; hir::Stmt {
1726 hir_id: stmt_id,
1727 kind: hir::StmtKind::Semi(yielded),
1728 span: yielded.span,
1729 }],
1730 Some(self.arena.alloc(expr_err)),
1731 ),
1732 None,
1733 );
1734 }
1735 Some(hir::CoroutineKind::Coroutine(_)) => false,
1736 None => {
1737 let suggestion = self.current_item.map(|s| s.shrink_to_lo());
1738 self.dcx().emit_err(YieldInClosure { span, suggestion });
1739 self.coroutine_kind = Some(hir::CoroutineKind::Coroutine(Movability::Movable));
1740
1741 false
1742 }
1743 };
1744
1745 if is_async_gen {
1746 let desugar_span = self.mark_span_with_reason(
1750 DesugaringKind::Async,
1751 span,
1752 Some(Arc::clone(&self.allow_async_gen)),
1753 );
1754 let wrapped_yielded = self.expr_call_lang_item_fn(
1755 desugar_span,
1756 hir::LangItem::AsyncGenReady,
1757 std::slice::from_ref(yielded),
1758 );
1759 let yield_expr = self.arena.alloc(
1760 self.expr(span, hir::ExprKind::Yield(wrapped_yielded, hir::YieldSource::Yield)),
1761 );
1762
1763 let Some(task_context_hid) = self.task_context else {
1764 unreachable!("use of `await` outside of an async context.");
1765 };
1766 let task_context_ident = Ident::with_dummy_span(sym::_task_context);
1767 let lhs = self.expr_ident(desugar_span, task_context_ident, task_context_hid);
1768
1769 hir::ExprKind::Assign(lhs, yield_expr, self.lower_span(span))
1770 } else {
1771 hir::ExprKind::Yield(yielded, hir::YieldSource::Yield)
1772 }
1773 }
1774
1775 fn lower_expr_for(
1792 &mut self,
1793 e: &Expr,
1794 pat: &Pat,
1795 head: &Expr,
1796 body: &Block,
1797 opt_label: Option<Label>,
1798 loop_kind: ForLoopKind,
1799 ) -> hir::Expr<'hir> {
1800 let head = self.lower_expr_mut(head);
1801 let pat = self.lower_pat(pat);
1802 let for_span =
1803 self.mark_span_with_reason(DesugaringKind::ForLoop, self.lower_span(e.span), None);
1804 let for_ctxt = for_span.ctxt();
1805
1806 let head_span =
1809 head.span.find_ancestor_in_same_ctxt(e.span).unwrap_or(head.span).with_ctxt(for_ctxt);
1810 let pat_span =
1811 pat.span.find_ancestor_in_same_ctxt(e.span).unwrap_or(pat.span).with_ctxt(for_ctxt);
1812
1813 let loop_hir_id = self.lower_node_id(e.id);
1814 let label = self.lower_label(opt_label, e.id, loop_hir_id);
1815
1816 let none_arm = {
1818 let break_expr =
1819 self.with_loop_scope(loop_hir_id, |this| this.expr_break_alloc(for_span));
1820 let pat = self.pat_none(for_span);
1821 self.arm(pat, break_expr)
1822 };
1823
1824 let some_arm = {
1826 let some_pat = self.pat_some(pat_span, pat);
1827 let body_block =
1828 self.with_loop_scope(loop_hir_id, |this| this.lower_block(body, false));
1829 let body_expr = self.arena.alloc(self.expr_block(body_block));
1830 self.arm(some_pat, body_expr)
1831 };
1832
1833 let iter = Ident::with_dummy_span(sym::iter);
1835 let (iter_pat, iter_pat_nid) =
1836 self.pat_ident_binding_mode(head_span, iter, hir::BindingMode::MUT);
1837
1838 let match_expr = {
1839 let iter = self.expr_ident(head_span, iter, iter_pat_nid);
1840 let next_expr = match loop_kind {
1841 ForLoopKind::For => {
1842 let ref_mut_iter = self.expr_mut_addr_of(head_span, iter);
1844 self.expr_call_lang_item_fn(
1845 head_span,
1846 hir::LangItem::IteratorNext,
1847 arena_vec![self; ref_mut_iter],
1848 )
1849 }
1850 ForLoopKind::ForAwait => {
1851 let iter = self.expr_mut_addr_of(head_span, iter);
1858 let iter = self.arena.alloc(self.expr_call_lang_item_fn_mut(
1860 head_span,
1861 hir::LangItem::PinNewUnchecked,
1862 arena_vec![self; iter],
1863 ));
1864 let iter = self.arena.alloc(self.expr_unsafe(head_span, iter));
1866 let kind = self.make_lowered_await(head_span, iter, FutureKind::AsyncIterator);
1867 self.arena.alloc(hir::Expr { hir_id: self.next_id(), kind, span: head_span })
1868 }
1869 };
1870 let arms = arena_vec![self; none_arm, some_arm];
1871
1872 self.expr_match(head_span, next_expr, arms, hir::MatchSource::ForLoopDesugar)
1874 };
1875 let match_stmt = self.stmt_expr(for_span, match_expr);
1876
1877 let loop_block = self.block_all(for_span, arena_vec![self; match_stmt], None);
1878
1879 let kind = hir::ExprKind::Loop(
1881 loop_block,
1882 label,
1883 hir::LoopSource::ForLoop,
1884 self.lower_span(for_span.with_hi(head.span.hi())),
1885 );
1886 let loop_expr = self.arena.alloc(hir::Expr { hir_id: loop_hir_id, kind, span: for_span });
1887
1888 let iter_arm = self.arm(iter_pat, loop_expr);
1890
1891 let match_expr = match loop_kind {
1892 ForLoopKind::For => {
1893 let into_iter_expr = self.expr_call_lang_item_fn(
1895 head_span,
1896 hir::LangItem::IntoIterIntoIter,
1897 arena_vec![self; head],
1898 );
1899
1900 self.arena.alloc(self.expr_match(
1901 for_span,
1902 into_iter_expr,
1903 arena_vec![self; iter_arm],
1904 hir::MatchSource::ForLoopDesugar,
1905 ))
1906 }
1907 ForLoopKind::ForAwait => {
1909 let iter_ident = iter;
1910 let (async_iter_pat, async_iter_pat_id) =
1911 self.pat_ident_binding_mode(head_span, iter_ident, hir::BindingMode::REF_MUT);
1912 let iter = self.expr_ident_mut(head_span, iter_ident, async_iter_pat_id);
1913 let iter = self.arena.alloc(self.expr_call_lang_item_fn_mut(
1915 head_span,
1916 hir::LangItem::PinNewUnchecked,
1917 arena_vec![self; iter],
1918 ));
1919 let iter = self.arena.alloc(self.expr_unsafe(head_span, iter));
1921 let inner_match_expr = self.arena.alloc(self.expr_match(
1922 for_span,
1923 iter,
1924 arena_vec![self; iter_arm],
1925 hir::MatchSource::ForLoopDesugar,
1926 ));
1927
1928 let iter = self.expr_call_lang_item_fn(
1930 head_span,
1931 hir::LangItem::IntoAsyncIterIntoIter,
1932 arena_vec![self; head],
1933 );
1934 let iter_arm = self.arm(async_iter_pat, inner_match_expr);
1935 self.arena.alloc(self.expr_match(
1936 for_span,
1937 iter,
1938 arena_vec![self; iter_arm],
1939 hir::MatchSource::ForLoopDesugar,
1940 ))
1941 }
1942 };
1943
1944 let expr = self.expr_drop_temps_mut(for_span, match_expr);
1951 self.lower_attrs(expr.hir_id, &e.attrs, e.span, Target::from_expr(e));
1952 expr
1953 }
1954
1955 fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> {
1968 let unstable_span = self.mark_span_with_reason(
1969 DesugaringKind::QuestionMark,
1970 span,
1971 Some(Arc::clone(&self.allow_try_trait)),
1972 );
1973 let try_span = self.tcx.sess.source_map().end_point(span);
1974 let try_span = self.mark_span_with_reason(
1975 DesugaringKind::QuestionMark,
1976 try_span,
1977 Some(Arc::clone(&self.allow_try_trait)),
1978 );
1979
1980 let scrutinee = {
1982 let sub_expr = self.lower_expr_mut(sub_expr);
1984
1985 self.expr_call_lang_item_fn(
1986 unstable_span,
1987 hir::LangItem::TryTraitBranch,
1988 arena_vec![self; sub_expr],
1989 )
1990 };
1991
1992 let attrs: AttrVec = thin_vec![self.unreachable_code_attr(try_span)];
1993
1994 let continue_arm = {
1996 let val_ident = Ident::with_dummy_span(sym::val);
1997 let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident);
1998 let val_expr = self.expr_ident(span, val_ident, val_pat_nid);
1999 self.lower_attrs(val_expr.hir_id, &attrs, span, Target::Expression);
2000 let continue_pat = self.pat_cf_continue(unstable_span, val_pat);
2001 self.arm(continue_pat, val_expr)
2002 };
2003
2004 let break_arm = {
2008 let residual_ident = Ident::with_dummy_span(sym::residual);
2009 let (residual_local, residual_local_nid) = self.pat_ident(try_span, residual_ident);
2010 let residual_expr = self.expr_ident_mut(try_span, residual_ident, residual_local_nid);
2011
2012 let (constructor_item, target_id) = match self.try_block_scope {
2013 TryBlockScope::Function => {
2014 (hir::LangItem::TryTraitFromResidual, Err(hir::LoopIdError::OutsideLoopScope))
2015 }
2016 TryBlockScope::Homogeneous(block_id) => {
2017 (hir::LangItem::ResidualIntoTryType, Ok(block_id))
2018 }
2019 TryBlockScope::Heterogeneous(block_id) => {
2020 (hir::LangItem::TryTraitFromResidual, Ok(block_id))
2021 }
2022 };
2023 let from_residual_expr = self.wrap_in_try_constructor(
2024 constructor_item,
2025 try_span,
2026 self.arena.alloc(residual_expr),
2027 unstable_span,
2028 );
2029 let ret_expr = if target_id.is_ok() {
2030 self.arena.alloc(self.expr(
2031 try_span,
2032 hir::ExprKind::Break(
2033 hir::Destination { label: None, target_id },
2034 Some(from_residual_expr),
2035 ),
2036 ))
2037 } else {
2038 let ret_expr = self.checked_return(Some(from_residual_expr));
2039 self.arena.alloc(self.expr(try_span, ret_expr))
2040 };
2041 self.lower_attrs(ret_expr.hir_id, &attrs, span, Target::Expression);
2042
2043 let break_pat = self.pat_cf_break(try_span, residual_local);
2044 self.arm(break_pat, ret_expr)
2045 };
2046
2047 hir::ExprKind::Match(
2048 scrutinee,
2049 arena_vec![self; break_arm, continue_arm],
2050 hir::MatchSource::TryDesugar(scrutinee.hir_id),
2051 )
2052 }
2053
2054 fn lower_expr_yeet(&mut self, span: Span, sub_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
2064 let (yeeted_span, yeeted_expr) = if let Some(sub_expr) = sub_expr {
2066 (sub_expr.span, self.lower_expr(sub_expr))
2067 } else {
2068 (self.mark_span_with_reason(DesugaringKind::YeetExpr, span, None), self.expr_unit(span))
2069 };
2070
2071 let unstable_span = self.mark_span_with_reason(
2072 DesugaringKind::YeetExpr,
2073 span,
2074 Some(Arc::clone(&self.allow_try_trait)),
2075 );
2076
2077 let from_yeet_expr = self.wrap_in_try_constructor(
2078 hir::LangItem::TryTraitFromYeet,
2079 unstable_span,
2080 yeeted_expr,
2081 yeeted_span,
2082 );
2083
2084 match self.try_block_scope {
2085 TryBlockScope::Homogeneous(block_id) | TryBlockScope::Heterogeneous(block_id) => {
2086 hir::ExprKind::Break(
2087 hir::Destination { label: None, target_id: Ok(block_id) },
2088 Some(from_yeet_expr),
2089 )
2090 }
2091 TryBlockScope::Function => self.checked_return(Some(from_yeet_expr)),
2092 }
2093 }
2094
2095 pub(super) fn expr_drop_temps(
2107 &mut self,
2108 span: Span,
2109 expr: &'hir hir::Expr<'hir>,
2110 ) -> &'hir hir::Expr<'hir> {
2111 self.arena.alloc(self.expr_drop_temps_mut(span, expr))
2112 }
2113
2114 pub(super) fn expr_drop_temps_mut(
2115 &mut self,
2116 span: Span,
2117 expr: &'hir hir::Expr<'hir>,
2118 ) -> hir::Expr<'hir> {
2119 self.expr(span, hir::ExprKind::DropTemps(expr))
2120 }
2121
2122 pub(super) fn expr_match(
2123 &mut self,
2124 span: Span,
2125 arg: &'hir hir::Expr<'hir>,
2126 arms: &'hir [hir::Arm<'hir>],
2127 source: hir::MatchSource,
2128 ) -> hir::Expr<'hir> {
2129 self.expr(span, hir::ExprKind::Match(arg, arms, source))
2130 }
2131
2132 fn expr_break(&mut self, span: Span) -> hir::Expr<'hir> {
2133 let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None);
2134 self.expr(span, expr_break)
2135 }
2136
2137 fn expr_break_alloc(&mut self, span: Span) -> &'hir hir::Expr<'hir> {
2138 let expr_break = self.expr_break(span);
2139 self.arena.alloc(expr_break)
2140 }
2141
2142 fn expr_mut_addr_of(&mut self, span: Span, e: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
2143 self.expr(span, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, e))
2144 }
2145
2146 pub(super) fn expr_unit(&mut self, sp: Span) -> &'hir hir::Expr<'hir> {
2147 self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[])))
2148 }
2149
2150 pub(super) fn expr_str(&mut self, sp: Span, value: Symbol) -> hir::Expr<'hir> {
2151 let lit = hir::Lit {
2152 span: self.lower_span(sp),
2153 node: ast::LitKind::Str(value, ast::StrStyle::Cooked),
2154 };
2155 self.expr(sp, hir::ExprKind::Lit(lit))
2156 }
2157
2158 pub(super) fn expr_byte_str(&mut self, sp: Span, value: ByteSymbol) -> hir::Expr<'hir> {
2159 let lit = hir::Lit {
2160 span: self.lower_span(sp),
2161 node: ast::LitKind::ByteStr(value, ast::StrStyle::Cooked),
2162 };
2163 self.expr(sp, hir::ExprKind::Lit(lit))
2164 }
2165
2166 pub(super) fn expr_call_mut(
2167 &mut self,
2168 span: Span,
2169 e: &'hir hir::Expr<'hir>,
2170 args: &'hir [hir::Expr<'hir>],
2171 ) -> hir::Expr<'hir> {
2172 self.expr(span, hir::ExprKind::Call(e, args))
2173 }
2174
2175 pub(super) fn expr_struct(
2176 &mut self,
2177 span: Span,
2178 path: &'hir hir::QPath<'hir>,
2179 fields: &'hir [hir::ExprField<'hir>],
2180 ) -> hir::Expr<'hir> {
2181 self.expr(span, hir::ExprKind::Struct(path, fields, rustc_hir::StructTailExpr::None))
2182 }
2183
2184 pub(super) fn expr_enum_variant(
2185 &mut self,
2186 span: Span,
2187 path: &'hir hir::QPath<'hir>,
2188 fields: &'hir [hir::Expr<'hir>],
2189 ) -> hir::Expr<'hir> {
2190 let fields = self.arena.alloc_from_iter(fields.into_iter().enumerate().map(|(i, f)| {
2191 hir::ExprField {
2192 hir_id: self.next_id(),
2193 ident: Ident::from_str(&i.to_string()),
2194 expr: f,
2195 span: f.span,
2196 is_shorthand: false,
2197 }
2198 }));
2199 self.expr_struct(span, path, fields)
2200 }
2201
2202 pub(super) fn expr_enum_variant_lang_item(
2203 &mut self,
2204 span: Span,
2205 lang_item: hir::LangItem,
2206 fields: &'hir [hir::Expr<'hir>],
2207 ) -> hir::Expr<'hir> {
2208 let path = self.arena.alloc(self.make_lang_item_qpath(lang_item, span, None));
2209 self.expr_enum_variant(span, path, fields)
2210 }
2211
2212 pub(super) fn expr_call(
2213 &mut self,
2214 span: Span,
2215 e: &'hir hir::Expr<'hir>,
2216 args: &'hir [hir::Expr<'hir>],
2217 ) -> &'hir hir::Expr<'hir> {
2218 self.arena.alloc(self.expr_call_mut(span, e, args))
2219 }
2220
2221 pub(super) fn expr_call_lang_item_fn_mut(
2222 &mut self,
2223 span: Span,
2224 lang_item: hir::LangItem,
2225 args: &'hir [hir::Expr<'hir>],
2226 ) -> hir::Expr<'hir> {
2227 let path = self.arena.alloc(self.expr_lang_item_path(span, lang_item));
2228 self.expr_call_mut(span, path, args)
2229 }
2230
2231 pub(super) fn expr_call_lang_item_fn(
2232 &mut self,
2233 span: Span,
2234 lang_item: hir::LangItem,
2235 args: &'hir [hir::Expr<'hir>],
2236 ) -> &'hir hir::Expr<'hir> {
2237 self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args))
2238 }
2239
2240 pub(super) fn expr_lang_item_path(
2241 &mut self,
2242 span: Span,
2243 lang_item: hir::LangItem,
2244 ) -> hir::Expr<'hir> {
2245 let qpath = self.make_lang_item_qpath(lang_item, self.lower_span(span), None);
2246 self.expr(span, hir::ExprKind::Path(qpath))
2247 }
2248
2249 pub(super) fn expr_lang_item_type_relative(
2251 &mut self,
2252 span: Span,
2253 lang_item: hir::LangItem,
2254 name: Symbol,
2255 ) -> hir::Expr<'hir> {
2256 let qpath = self.make_lang_item_qpath(lang_item, self.lower_span(span), None);
2257 let path = hir::ExprKind::Path(hir::QPath::TypeRelative(
2258 self.arena.alloc(self.ty(span, hir::TyKind::Path(qpath))),
2259 self.arena.alloc(hir::PathSegment::new(
2260 Ident::new(name, self.lower_span(span)),
2261 self.next_id(),
2262 Res::Err,
2263 )),
2264 ));
2265 self.expr(span, path)
2266 }
2267
2268 pub(super) fn expr_ident(
2269 &mut self,
2270 sp: Span,
2271 ident: Ident,
2272 binding: HirId,
2273 ) -> &'hir hir::Expr<'hir> {
2274 self.arena.alloc(self.expr_ident_mut(sp, ident, binding))
2275 }
2276
2277 pub(super) fn expr_ident_mut(
2278 &mut self,
2279 span: Span,
2280 ident: Ident,
2281 binding: HirId,
2282 ) -> hir::Expr<'hir> {
2283 let hir_id = self.next_id();
2284 let res = Res::Local(binding);
2285 let expr_path = hir::ExprKind::Path(hir::QPath::Resolved(
2286 None,
2287 self.arena.alloc(hir::Path {
2288 span: self.lower_span(span),
2289 res,
2290 segments: arena_vec![self; hir::PathSegment::new(self.lower_ident(ident), hir_id, res)],
2291 }),
2292 ));
2293
2294 self.expr(span, expr_path)
2295 }
2296
2297 pub(super) fn expr_unsafe(
2298 &mut self,
2299 span: Span,
2300 expr: &'hir hir::Expr<'hir>,
2301 ) -> hir::Expr<'hir> {
2302 let hir_id = self.next_id();
2303 self.expr(
2304 span,
2305 hir::ExprKind::Block(
2306 self.arena.alloc(hir::Block {
2307 stmts: &[],
2308 expr: Some(expr),
2309 hir_id,
2310 rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated),
2311 span: self.lower_span(span),
2312 targeted_by_break: false,
2313 }),
2314 None,
2315 ),
2316 )
2317 }
2318
2319 fn expr_block_empty(&mut self, span: Span) -> &'hir hir::Expr<'hir> {
2320 let blk = self.block_all(span, &[], None);
2321 let expr = self.expr_block(blk);
2322 self.arena.alloc(expr)
2323 }
2324
2325 pub(super) fn expr_block(&mut self, b: &'hir hir::Block<'hir>) -> hir::Expr<'hir> {
2326 self.expr(b.span, hir::ExprKind::Block(b, None))
2327 }
2328
2329 pub(super) fn block_expr_block(
2333 &mut self,
2334 expr: &'hir hir::Expr<'hir>,
2335 ) -> &'hir hir::Expr<'hir> {
2336 let b = self.block_expr(expr);
2337 self.arena.alloc(self.expr_block(b))
2338 }
2339
2340 pub(super) fn expr_ref(&mut self, span: Span, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
2341 self.expr(span, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, expr))
2342 }
2343
2344 pub(super) fn expr_bool_literal(&mut self, span: Span, val: bool) -> hir::Expr<'hir> {
2345 self.expr(span, hir::ExprKind::Lit(Spanned { node: LitKind::Bool(val), span }))
2346 }
2347
2348 pub(super) fn expr(&mut self, span: Span, kind: hir::ExprKind<'hir>) -> hir::Expr<'hir> {
2349 let hir_id = self.next_id();
2350 hir::Expr { hir_id, kind, span: self.lower_span(span) }
2351 }
2352
2353 pub(super) fn expr_field(
2354 &mut self,
2355 ident: Ident,
2356 expr: &'hir hir::Expr<'hir>,
2357 span: Span,
2358 ) -> hir::ExprField<'hir> {
2359 hir::ExprField {
2360 hir_id: self.next_id(),
2361 ident,
2362 span: self.lower_span(span),
2363 expr,
2364 is_shorthand: false,
2365 }
2366 }
2367
2368 pub(super) fn arm(
2369 &mut self,
2370 pat: &'hir hir::Pat<'hir>,
2371 expr: &'hir hir::Expr<'hir>,
2372 ) -> hir::Arm<'hir> {
2373 hir::Arm {
2374 hir_id: self.next_id(),
2375 pat,
2376 guard: None,
2377 span: self.lower_span(expr.span),
2378 body: expr,
2379 }
2380 }
2381
2382 pub(super) fn unreachable_code_attr(&mut self, span: Span) -> Attribute {
2384 let attr = attr::mk_attr_nested_word(
2385 &self.tcx.sess.psess.attr_id_generator,
2386 AttrStyle::Outer,
2387 Safety::Default,
2388 sym::allow,
2389 sym::unreachable_code,
2390 span,
2391 );
2392 attr
2393 }
2394}
2395
2396#[derive(Copy, Clone, Debug, PartialEq, Eq)]
2399enum FutureKind {
2400 Future,
2402 AsyncIterator,
2405}