1use std::ops::ControlFlow;
2use std::sync::Arc;
3
4use rustc_ast::*;
5use rustc_ast_pretty::pprust::expr_to_string;
6use rustc_data_structures::stack::ensure_sufficient_stack;
7use rustc_hir as hir;
8use rustc_hir::attrs::AttributeKind;
9use rustc_hir::def::{DefKind, Res};
10use rustc_hir::{HirId, find_attr};
11use rustc_middle::span_bug;
12use rustc_middle::ty::TyCtxt;
13use rustc_session::errors::report_lit_error;
14use rustc_span::source_map::{Spanned, respan};
15use rustc_span::{DUMMY_SP, DesugaringKind, Ident, Span, Symbol, sym};
16use thin_vec::{ThinVec, thin_vec};
17use visit::{Visitor, walk_expr};
18
19use super::errors::{
20 AsyncCoroutinesNotSupported, AwaitOnlyInAsyncFnAndBlocks, ClosureCannotBeStatic,
21 CoroutineTooManyParameters, FunctionalRecordUpdateDestructuringAssignment,
22 InclusiveRangeWithNoEnd, MatchArmWithNoBody, NeverPatternWithBody, NeverPatternWithGuard,
23 UnderscoreExprLhsAssign,
24};
25use super::{
26 GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode, ResolverAstLoweringExt,
27};
28use crate::errors::{InvalidLegacyConstGenericArg, UseConstGenericArg, YieldInClosure};
29use crate::{AllowReturnTypeNotation, FnDeclKind, ImplTraitPosition, fluent_generated};
30
31struct WillCreateDefIdsVisitor {}
32
33impl<'v> rustc_ast::visit::Visitor<'v> for WillCreateDefIdsVisitor {
34 type Result = ControlFlow<Span>;
35
36 fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
37 ControlFlow::Break(c.value.span)
38 }
39
40 fn visit_item(&mut self, item: &'v Item) -> Self::Result {
41 ControlFlow::Break(item.span)
42 }
43
44 fn visit_expr(&mut self, ex: &'v Expr) -> Self::Result {
45 match ex.kind {
46 ExprKind::Gen(..) | ExprKind::ConstBlock(..) | ExprKind::Closure(..) => {
47 ControlFlow::Break(ex.span)
48 }
49 _ => walk_expr(self, ex),
50 }
51 }
52}
53
54impl<'hir> LoweringContext<'_, 'hir> {
55 fn lower_exprs(&mut self, exprs: &[Box<Expr>]) -> &'hir [hir::Expr<'hir>] {
56 self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x)))
57 }
58
59 pub(super) fn lower_expr(&mut self, e: &Expr) -> &'hir hir::Expr<'hir> {
60 self.arena.alloc(self.lower_expr_mut(e))
61 }
62
63 pub(super) fn lower_expr_mut(&mut self, e: &Expr) -> hir::Expr<'hir> {
64 ensure_sufficient_stack(|| {
65 match &e.kind {
66 ExprKind::Paren(ex) => {
68 let mut ex = self.lower_expr_mut(ex);
69 if e.span.contains(ex.span) {
71 ex.span = self.lower_span(e.span);
72 }
73 if !e.attrs.is_empty() {
75 let old_attrs = self.attrs.get(&ex.hir_id.local_id).copied().unwrap_or(&[]);
76 let new_attrs = self
77 .lower_attrs_vec(&e.attrs, e.span, ex.hir_id)
78 .into_iter()
79 .chain(old_attrs.iter().cloned());
80 let new_attrs = &*self.arena.alloc_from_iter(new_attrs);
81 if new_attrs.is_empty() {
82 return ex;
83 }
84 self.attrs.insert(ex.hir_id.local_id, new_attrs);
85 }
86 return ex;
87 }
88 ExprKind::ForLoop { pat, iter, body, label, kind } => {
94 return self.lower_expr_for(e, pat, iter, body, *label, *kind);
95 }
96 _ => (),
97 }
98
99 let expr_hir_id = self.lower_node_id(e.id);
100 let attrs = self.lower_attrs(expr_hir_id, &e.attrs, e.span);
101
102 let kind = match &e.kind {
103 ExprKind::Array(exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
104 ExprKind::ConstBlock(c) => hir::ExprKind::ConstBlock(self.lower_const_block(c)),
105 ExprKind::Repeat(expr, count) => {
106 let expr = self.lower_expr(expr);
107 let count = self.lower_array_length_to_const_arg(count);
108 hir::ExprKind::Repeat(expr, count)
109 }
110 ExprKind::Tup(elts) => hir::ExprKind::Tup(self.lower_exprs(elts)),
111 ExprKind::Call(f, args) => {
112 if let Some(legacy_args) = self.resolver.legacy_const_generic_args(f) {
113 self.lower_legacy_const_generics((**f).clone(), args.clone(), &legacy_args)
114 } else {
115 let f = self.lower_expr(f);
116 hir::ExprKind::Call(f, self.lower_exprs(args))
117 }
118 }
119 ExprKind::MethodCall(box MethodCall { seg, receiver, args, span }) => {
120 let hir_seg = self.arena.alloc(self.lower_path_segment(
121 e.span,
122 seg,
123 ParamMode::Optional,
124 GenericArgsMode::Err,
125 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
126 None,
128 ));
129 let receiver = self.lower_expr(receiver);
130 let args =
131 self.arena.alloc_from_iter(args.iter().map(|x| self.lower_expr_mut(x)));
132 hir::ExprKind::MethodCall(hir_seg, receiver, args, self.lower_span(*span))
133 }
134 ExprKind::Binary(binop, lhs, rhs) => {
135 let binop = self.lower_binop(*binop);
136 let lhs = self.lower_expr(lhs);
137 let rhs = self.lower_expr(rhs);
138 hir::ExprKind::Binary(binop, lhs, rhs)
139 }
140 ExprKind::Unary(op, ohs) => {
141 let op = self.lower_unop(*op);
142 let ohs = self.lower_expr(ohs);
143 hir::ExprKind::Unary(op, ohs)
144 }
145 ExprKind::Lit(token_lit) => hir::ExprKind::Lit(self.lower_lit(token_lit, e.span)),
146 ExprKind::IncludedBytes(byte_sym) => {
147 let lit = respan(
148 self.lower_span(e.span),
149 LitKind::ByteStr(*byte_sym, StrStyle::Cooked),
150 );
151 hir::ExprKind::Lit(lit)
152 }
153 ExprKind::Cast(expr, ty) => {
154 let expr = self.lower_expr(expr);
155 let ty =
156 self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
157 hir::ExprKind::Cast(expr, ty)
158 }
159 ExprKind::Type(expr, ty) => {
160 let expr = self.lower_expr(expr);
161 let ty =
162 self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast));
163 hir::ExprKind::Type(expr, ty)
164 }
165 ExprKind::AddrOf(k, m, ohs) => {
166 let ohs = self.lower_expr(ohs);
167 hir::ExprKind::AddrOf(*k, *m, ohs)
168 }
169 ExprKind::Let(pat, scrutinee, span, recovered) => {
170 hir::ExprKind::Let(self.arena.alloc(hir::LetExpr {
171 span: self.lower_span(*span),
172 pat: self.lower_pat(pat),
173 ty: None,
174 init: self.lower_expr(scrutinee),
175 recovered: *recovered,
176 }))
177 }
178 ExprKind::If(cond, then, else_opt) => {
179 self.lower_expr_if(cond, then, else_opt.as_deref())
180 }
181 ExprKind::While(cond, body, opt_label) => {
182 self.with_loop_scope(expr_hir_id, |this| {
183 let span =
184 this.mark_span_with_reason(DesugaringKind::WhileLoop, e.span, None);
185 let opt_label = this.lower_label(*opt_label, e.id, expr_hir_id);
186 this.lower_expr_while_in_loop_scope(span, cond, body, opt_label)
187 })
188 }
189 ExprKind::Loop(body, opt_label, span) => {
190 self.with_loop_scope(expr_hir_id, |this| {
191 let opt_label = this.lower_label(*opt_label, e.id, expr_hir_id);
192 hir::ExprKind::Loop(
193 this.lower_block(body, false),
194 opt_label,
195 hir::LoopSource::Loop,
196 this.lower_span(*span),
197 )
198 })
199 }
200 ExprKind::TryBlock(body) => self.lower_expr_try_block(body),
201 ExprKind::Match(expr, arms, kind) => hir::ExprKind::Match(
202 self.lower_expr(expr),
203 self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))),
204 match kind {
205 MatchKind::Prefix => hir::MatchSource::Normal,
206 MatchKind::Postfix => hir::MatchSource::Postfix,
207 },
208 ),
209 ExprKind::Await(expr, await_kw_span) => self.lower_expr_await(*await_kw_span, expr),
210 ExprKind::Use(expr, use_kw_span) => self.lower_expr_use(*use_kw_span, expr),
211 ExprKind::Closure(box Closure {
212 binder,
213 capture_clause,
214 constness,
215 coroutine_kind,
216 movability,
217 fn_decl,
218 body,
219 fn_decl_span,
220 fn_arg_span,
221 }) => match coroutine_kind {
222 Some(coroutine_kind) => self.lower_expr_coroutine_closure(
223 binder,
224 *capture_clause,
225 e.id,
226 expr_hir_id,
227 *coroutine_kind,
228 fn_decl,
229 body,
230 *fn_decl_span,
231 *fn_arg_span,
232 ),
233 None => self.lower_expr_closure(
234 attrs,
235 binder,
236 *capture_clause,
237 e.id,
238 *constness,
239 *movability,
240 fn_decl,
241 body,
242 *fn_decl_span,
243 *fn_arg_span,
244 ),
245 },
246 ExprKind::Gen(capture_clause, block, genblock_kind, decl_span) => {
247 let desugaring_kind = match genblock_kind {
248 GenBlockKind::Async => hir::CoroutineDesugaring::Async,
249 GenBlockKind::Gen => hir::CoroutineDesugaring::Gen,
250 GenBlockKind::AsyncGen => hir::CoroutineDesugaring::AsyncGen,
251 };
252 self.make_desugared_coroutine_expr(
253 *capture_clause,
254 e.id,
255 None,
256 *decl_span,
257 e.span,
258 desugaring_kind,
259 hir::CoroutineSource::Block,
260 |this| this.with_new_scopes(e.span, |this| this.lower_block_expr(block)),
261 )
262 }
263 ExprKind::Block(blk, opt_label) => {
264 let block_hir_id = self.lower_node_id(blk.id);
267 let opt_label = self.lower_label(*opt_label, blk.id, block_hir_id);
268 let hir_block = self.arena.alloc(self.lower_block_noalloc(
269 block_hir_id,
270 blk,
271 opt_label.is_some(),
272 ));
273 hir::ExprKind::Block(hir_block, opt_label)
274 }
275 ExprKind::Assign(el, er, span) => self.lower_expr_assign(el, er, *span, e.span),
276 ExprKind::AssignOp(op, el, er) => hir::ExprKind::AssignOp(
277 self.lower_assign_op(*op),
278 self.lower_expr(el),
279 self.lower_expr(er),
280 ),
281 ExprKind::Field(el, ident) => {
282 hir::ExprKind::Field(self.lower_expr(el), self.lower_ident(*ident))
283 }
284 ExprKind::Index(el, er, brackets_span) => hir::ExprKind::Index(
285 self.lower_expr(el),
286 self.lower_expr(er),
287 self.lower_span(*brackets_span),
288 ),
289 ExprKind::Range(e1, e2, lims) => {
290 self.lower_expr_range(e.span, e1.as_deref(), e2.as_deref(), *lims)
291 }
292 ExprKind::Underscore => {
293 let guar = self.dcx().emit_err(UnderscoreExprLhsAssign { span: e.span });
294 hir::ExprKind::Err(guar)
295 }
296 ExprKind::Path(qself, path) => {
297 let qpath = self.lower_qpath(
298 e.id,
299 qself,
300 path,
301 ParamMode::Optional,
302 AllowReturnTypeNotation::No,
303 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
304 None,
305 );
306 hir::ExprKind::Path(qpath)
307 }
308 ExprKind::Break(opt_label, opt_expr) => {
309 let opt_expr = opt_expr.as_ref().map(|x| self.lower_expr(x));
310 hir::ExprKind::Break(self.lower_jump_destination(e.id, *opt_label), opt_expr)
311 }
312 ExprKind::Continue(opt_label) => {
313 hir::ExprKind::Continue(self.lower_jump_destination(e.id, *opt_label))
314 }
315 ExprKind::Ret(e) => {
316 let expr = e.as_ref().map(|x| self.lower_expr(x));
317 self.checked_return(expr)
318 }
319 ExprKind::Yeet(sub_expr) => self.lower_expr_yeet(e.span, sub_expr.as_deref()),
320 ExprKind::Become(sub_expr) => {
321 let sub_expr = self.lower_expr(sub_expr);
322 hir::ExprKind::Become(sub_expr)
323 }
324 ExprKind::InlineAsm(asm) => {
325 hir::ExprKind::InlineAsm(self.lower_inline_asm(e.span, asm))
326 }
327 ExprKind::FormatArgs(fmt) => self.lower_format_args(e.span, fmt),
328 ExprKind::OffsetOf(container, fields) => hir::ExprKind::OffsetOf(
329 self.lower_ty(
330 container,
331 ImplTraitContext::Disallowed(ImplTraitPosition::OffsetOf),
332 ),
333 self.arena.alloc_from_iter(fields.iter().map(|&ident| self.lower_ident(ident))),
334 ),
335 ExprKind::Struct(se) => {
336 let rest = match &se.rest {
337 StructRest::Base(e) => hir::StructTailExpr::Base(self.lower_expr(e)),
338 StructRest::Rest(sp) => {
339 hir::StructTailExpr::DefaultFields(self.lower_span(*sp))
340 }
341 StructRest::None => hir::StructTailExpr::None,
342 };
343 hir::ExprKind::Struct(
344 self.arena.alloc(self.lower_qpath(
345 e.id,
346 &se.qself,
347 &se.path,
348 ParamMode::Optional,
349 AllowReturnTypeNotation::No,
350 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
351 None,
352 )),
353 self.arena
354 .alloc_from_iter(se.fields.iter().map(|x| self.lower_expr_field(x))),
355 rest,
356 )
357 }
358 ExprKind::Yield(kind) => self.lower_expr_yield(e.span, kind.expr().map(|x| &**x)),
359 ExprKind::Err(guar) => hir::ExprKind::Err(*guar),
360
361 ExprKind::UnsafeBinderCast(kind, expr, ty) => hir::ExprKind::UnsafeBinderCast(
362 *kind,
363 self.lower_expr(expr),
364 ty.as_ref().map(|ty| {
365 self.lower_ty(ty, ImplTraitContext::Disallowed(ImplTraitPosition::Cast))
366 }),
367 ),
368
369 ExprKind::Dummy => {
370 span_bug!(e.span, "lowered ExprKind::Dummy")
371 }
372
373 ExprKind::Try(sub_expr) => self.lower_expr_try(e.span, sub_expr),
374
375 ExprKind::Paren(_) | ExprKind::ForLoop { .. } => {
376 unreachable!("already handled")
377 }
378
379 ExprKind::MacCall(_) => panic!("{:?} shouldn't exist here", e.span),
380 };
381
382 hir::Expr { hir_id: expr_hir_id, kind, span: self.lower_span(e.span) }
383 })
384 }
385
386 fn checked_return(&mut self, opt_expr: Option<&'hir hir::Expr<'hir>>) -> hir::ExprKind<'hir> {
389 let checked_ret =
390 if let Some((check_span, check_ident, check_hir_id)) = self.contract_ensures {
391 let expr = opt_expr.unwrap_or_else(|| self.expr_unit(check_span));
392 Some(self.inject_ensures_check(expr, check_span, check_ident, check_hir_id))
393 } else {
394 opt_expr
395 };
396 hir::ExprKind::Ret(checked_ret)
397 }
398
399 pub(crate) fn inject_ensures_check(
401 &mut self,
402 expr: &'hir hir::Expr<'hir>,
403 span: Span,
404 cond_ident: Ident,
405 cond_hir_id: HirId,
406 ) -> &'hir hir::Expr<'hir> {
407 let cond_fn = self.expr_ident(span, cond_ident, cond_hir_id);
408 let call_expr = self.expr_call_lang_item_fn_mut(
409 span,
410 hir::LangItem::ContractCheckEnsures,
411 arena_vec![self; *cond_fn, *expr],
412 );
413 self.arena.alloc(call_expr)
414 }
415
416 pub(crate) fn lower_const_block(&mut self, c: &AnonConst) -> hir::ConstBlock {
417 self.with_new_scopes(c.value.span, |this| {
418 let def_id = this.local_def_id(c.id);
419 hir::ConstBlock {
420 def_id,
421 hir_id: this.lower_node_id(c.id),
422 body: this.lower_const_body(c.value.span, Some(&c.value)),
423 }
424 })
425 }
426
427 pub(crate) fn lower_lit(&mut self, token_lit: &token::Lit, span: Span) -> hir::Lit {
428 let lit_kind = match LitKind::from_token_lit(*token_lit) {
429 Ok(lit_kind) => lit_kind,
430 Err(err) => {
431 let guar = report_lit_error(&self.tcx.sess.psess, err, *token_lit, span);
432 LitKind::Err(guar)
433 }
434 };
435 respan(self.lower_span(span), lit_kind)
436 }
437
438 fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
439 match u {
440 UnOp::Deref => hir::UnOp::Deref,
441 UnOp::Not => hir::UnOp::Not,
442 UnOp::Neg => hir::UnOp::Neg,
443 }
444 }
445
446 fn lower_binop(&mut self, b: BinOp) -> BinOp {
447 Spanned { node: b.node, span: self.lower_span(b.span) }
448 }
449
450 fn lower_assign_op(&mut self, a: AssignOp) -> AssignOp {
451 Spanned { node: a.node, span: self.lower_span(a.span) }
452 }
453
454 fn lower_legacy_const_generics(
455 &mut self,
456 mut f: Expr,
457 args: ThinVec<Box<Expr>>,
458 legacy_args_idx: &[usize],
459 ) -> hir::ExprKind<'hir> {
460 let ExprKind::Path(None, path) = &mut f.kind else {
461 unreachable!();
462 };
463
464 let mut error = None;
465 let mut invalid_expr_error = |tcx: TyCtxt<'_>, span| {
466 if error.is_none() {
468 let mut const_args = vec![];
469 let mut other_args = vec![];
470 for (idx, arg) in args.iter().enumerate() {
471 if legacy_args_idx.contains(&idx) {
472 const_args.push(format!("{{ {} }}", expr_to_string(arg)));
473 } else {
474 other_args.push(expr_to_string(arg));
475 }
476 }
477 let suggestion = UseConstGenericArg {
478 end_of_fn: f.span.shrink_to_hi(),
479 const_args: const_args.join(", "),
480 other_args: other_args.join(", "),
481 call_args: args[0].span.to(args.last().unwrap().span),
482 };
483 error = Some(tcx.dcx().emit_err(InvalidLegacyConstGenericArg { span, suggestion }));
484 }
485 error.unwrap()
486 };
487
488 let mut real_args = vec![];
490 let mut generic_args = ThinVec::new();
491 for (idx, arg) in args.iter().cloned().enumerate() {
492 if legacy_args_idx.contains(&idx) {
493 let node_id = self.next_node_id();
494 self.create_def(node_id, None, DefKind::AnonConst, f.span);
495 let mut visitor = WillCreateDefIdsVisitor {};
496 let const_value = if let ControlFlow::Break(span) = visitor.visit_expr(&arg) {
497 Box::new(Expr {
498 id: self.next_node_id(),
499 kind: ExprKind::Err(invalid_expr_error(self.tcx, span)),
500 span: f.span,
501 attrs: [].into(),
502 tokens: None,
503 })
504 } else {
505 arg
506 };
507
508 let anon_const = AnonConst { id: node_id, value: const_value };
509 generic_args.push(AngleBracketedArg::Arg(GenericArg::Const(anon_const)));
510 } else {
511 real_args.push(arg);
512 }
513 }
514
515 let last_segment = path.segments.last_mut().unwrap();
517 assert!(last_segment.args.is_none());
518 last_segment.args = Some(Box::new(GenericArgs::AngleBracketed(AngleBracketedArgs {
519 span: DUMMY_SP,
520 args: generic_args,
521 })));
522
523 let f = self.lower_expr(&f);
525 hir::ExprKind::Call(f, self.lower_exprs(&real_args))
526 }
527
528 fn lower_expr_if(
529 &mut self,
530 cond: &Expr,
531 then: &Block,
532 else_opt: Option<&Expr>,
533 ) -> hir::ExprKind<'hir> {
534 let lowered_cond = self.lower_expr(cond);
535 let then_expr = self.lower_block_expr(then);
536 if let Some(rslt) = else_opt {
537 hir::ExprKind::If(
538 lowered_cond,
539 self.arena.alloc(then_expr),
540 Some(self.lower_expr(rslt)),
541 )
542 } else {
543 hir::ExprKind::If(lowered_cond, self.arena.alloc(then_expr), None)
544 }
545 }
546
547 fn lower_expr_while_in_loop_scope(
564 &mut self,
565 span: Span,
566 cond: &Expr,
567 body: &Block,
568 opt_label: Option<Label>,
569 ) -> hir::ExprKind<'hir> {
570 let lowered_cond = self.with_loop_condition_scope(|t| t.lower_expr(cond));
571 let then = self.lower_block_expr(body);
572 let expr_break = self.expr_break(span);
573 let stmt_break = self.stmt_expr(span, expr_break);
574 let else_blk = self.block_all(span, arena_vec![self; stmt_break], None);
575 let else_expr = self.arena.alloc(self.expr_block(else_blk));
576 let if_kind = hir::ExprKind::If(lowered_cond, self.arena.alloc(then), Some(else_expr));
577 let if_expr = self.expr(span, if_kind);
578 let block = self.block_expr(self.arena.alloc(if_expr));
579 let span = self.lower_span(span.with_hi(cond.span.hi()));
580 hir::ExprKind::Loop(block, opt_label, hir::LoopSource::While, span)
581 }
582
583 fn lower_expr_try_block(&mut self, body: &Block) -> hir::ExprKind<'hir> {
587 let body_hir_id = self.lower_node_id(body.id);
588 self.with_catch_scope(body_hir_id, |this| {
589 let mut block = this.lower_block_noalloc(body_hir_id, body, true);
590
591 let (try_span, tail_expr) = if let Some(expr) = block.expr.take() {
593 (
594 this.mark_span_with_reason(
595 DesugaringKind::TryBlock,
596 expr.span,
597 Some(Arc::clone(&this.allow_try_trait)),
598 ),
599 expr,
600 )
601 } else {
602 let try_span = this.mark_span_with_reason(
603 DesugaringKind::TryBlock,
604 this.tcx.sess.source_map().end_point(body.span),
605 Some(Arc::clone(&this.allow_try_trait)),
606 );
607
608 (try_span, this.expr_unit(try_span))
609 };
610
611 let ok_wrapped_span =
612 this.mark_span_with_reason(DesugaringKind::TryBlock, tail_expr.span, None);
613
614 block.expr = Some(this.wrap_in_try_constructor(
616 hir::LangItem::TryTraitFromOutput,
617 try_span,
618 tail_expr,
619 ok_wrapped_span,
620 ));
621
622 hir::ExprKind::Block(this.arena.alloc(block), None)
623 })
624 }
625
626 fn wrap_in_try_constructor(
627 &mut self,
628 lang_item: hir::LangItem,
629 method_span: Span,
630 expr: &'hir hir::Expr<'hir>,
631 overall_span: Span,
632 ) -> &'hir hir::Expr<'hir> {
633 let constructor = self.arena.alloc(self.expr_lang_item_path(method_span, lang_item));
634 self.expr_call(overall_span, constructor, std::slice::from_ref(expr))
635 }
636
637 fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> {
638 let pat = self.lower_pat(&arm.pat);
639 let guard = arm.guard.as_ref().map(|cond| self.lower_expr(cond));
640 let hir_id = self.next_id();
641 let span = self.lower_span(arm.span);
642 self.lower_attrs(hir_id, &arm.attrs, arm.span);
643 let is_never_pattern = pat.is_never_pattern();
644 let body = arm.body.as_ref().map(|x| self.lower_expr(x));
647 let body = if let Some(body) = body
648 && !is_never_pattern
649 {
650 body
651 } else {
652 if !is_never_pattern {
654 if self.tcx.features().never_patterns() {
655 let suggestion = span.shrink_to_hi();
657 self.dcx().emit_err(MatchArmWithNoBody { span, suggestion });
658 }
659 } else if let Some(body) = &arm.body {
660 self.dcx().emit_err(NeverPatternWithBody { span: body.span });
661 } else if let Some(g) = &arm.guard {
662 self.dcx().emit_err(NeverPatternWithGuard { span: g.span });
663 }
664
665 let block = self.arena.alloc(hir::Block {
668 stmts: &[],
669 expr: None,
670 hir_id: self.next_id(),
671 rules: hir::BlockCheckMode::DefaultBlock,
672 span,
673 targeted_by_break: false,
674 });
675 self.arena.alloc(hir::Expr {
676 hir_id: self.next_id(),
677 kind: hir::ExprKind::Loop(block, None, hir::LoopSource::Loop, span),
678 span,
679 })
680 };
681 hir::Arm { hir_id, pat, guard, body, span }
682 }
683
684 fn lower_capture_clause(&mut self, capture_clause: CaptureBy) -> CaptureBy {
685 match capture_clause {
686 CaptureBy::Ref => CaptureBy::Ref,
687 CaptureBy::Use { use_kw } => CaptureBy::Use { use_kw: self.lower_span(use_kw) },
688 CaptureBy::Value { move_kw } => CaptureBy::Value { move_kw: self.lower_span(move_kw) },
689 }
690 }
691
692 pub(super) fn make_desugared_coroutine_expr(
704 &mut self,
705 capture_clause: CaptureBy,
706 closure_node_id: NodeId,
707 return_ty: Option<hir::FnRetTy<'hir>>,
708 fn_decl_span: Span,
709 span: Span,
710 desugaring_kind: hir::CoroutineDesugaring,
711 coroutine_source: hir::CoroutineSource,
712 body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
713 ) -> hir::ExprKind<'hir> {
714 let closure_def_id = self.local_def_id(closure_node_id);
715 let coroutine_kind = hir::CoroutineKind::Desugared(desugaring_kind, coroutine_source);
716
717 let (inputs, params, task_context): (&[_], &[_], _) = match desugaring_kind {
720 hir::CoroutineDesugaring::Async | hir::CoroutineDesugaring::AsyncGen => {
721 let unstable_span = self.mark_span_with_reason(
723 DesugaringKind::Async,
724 self.lower_span(span),
725 Some(Arc::clone(&self.allow_gen_future)),
726 );
727 let resume_ty =
728 self.make_lang_item_qpath(hir::LangItem::ResumeTy, unstable_span, None);
729 let input_ty = hir::Ty {
730 hir_id: self.next_id(),
731 kind: hir::TyKind::Path(resume_ty),
732 span: unstable_span,
733 };
734 let inputs = arena_vec![self; input_ty];
735
736 let (pat, task_context_hid) = self.pat_ident_binding_mode(
738 span,
739 Ident::with_dummy_span(sym::_task_context),
740 hir::BindingMode::MUT,
741 );
742 let param = hir::Param {
743 hir_id: self.next_id(),
744 pat,
745 ty_span: self.lower_span(span),
746 span: self.lower_span(span),
747 };
748 let params = arena_vec![self; param];
749
750 (inputs, params, Some(task_context_hid))
751 }
752 hir::CoroutineDesugaring::Gen => (&[], &[], None),
753 };
754
755 let output =
756 return_ty.unwrap_or_else(|| hir::FnRetTy::DefaultReturn(self.lower_span(span)));
757
758 let fn_decl = self.arena.alloc(hir::FnDecl {
759 inputs,
760 output,
761 c_variadic: false,
762 implicit_self: hir::ImplicitSelfKind::None,
763 lifetime_elision_allowed: false,
764 });
765
766 let body = self.lower_body(move |this| {
767 this.coroutine_kind = Some(coroutine_kind);
768
769 let old_ctx = this.task_context;
770 if task_context.is_some() {
771 this.task_context = task_context;
772 }
773 let res = body(this);
774 this.task_context = old_ctx;
775
776 (params, res)
777 });
778
779 hir::ExprKind::Closure(self.arena.alloc(hir::Closure {
781 def_id: closure_def_id,
782 binder: hir::ClosureBinder::Default,
783 capture_clause: self.lower_capture_clause(capture_clause),
784 bound_generic_params: &[],
785 fn_decl,
786 body,
787 fn_decl_span: self.lower_span(fn_decl_span),
788 fn_arg_span: None,
789 kind: hir::ClosureKind::Coroutine(coroutine_kind),
790 constness: hir::Constness::NotConst,
791 }))
792 }
793
794 pub(super) fn maybe_forward_track_caller(
797 &mut self,
798 span: Span,
799 outer_hir_id: HirId,
800 inner_hir_id: HirId,
801 ) {
802 if self.tcx.features().async_fn_track_caller()
803 && let Some(attrs) = self.attrs.get(&outer_hir_id.local_id)
804 && find_attr!(*attrs, AttributeKind::TrackCaller(_))
805 {
806 let unstable_span = self.mark_span_with_reason(
807 DesugaringKind::Async,
808 span,
809 Some(Arc::clone(&self.allow_gen_future)),
810 );
811 self.lower_attrs(
812 inner_hir_id,
813 &[Attribute {
814 kind: AttrKind::Normal(Box::new(NormalAttr::from_ident(Ident::new(
815 sym::track_caller,
816 span,
817 )))),
818 id: self.tcx.sess.psess.attr_id_generator.mk_attr_id(),
819 style: AttrStyle::Outer,
820 span: unstable_span,
821 }],
822 span,
823 );
824 }
825 }
826
827 fn lower_expr_await(&mut self, await_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
843 let expr = self.arena.alloc(self.lower_expr_mut(expr));
844 self.make_lowered_await(await_kw_span, expr, FutureKind::Future)
845 }
846
847 fn make_lowered_await(
849 &mut self,
850 await_kw_span: Span,
851 expr: &'hir hir::Expr<'hir>,
852 await_kind: FutureKind,
853 ) -> hir::ExprKind<'hir> {
854 let full_span = expr.span.to(await_kw_span);
855
856 let is_async_gen = match self.coroutine_kind {
857 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)) => false,
858 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)) => true,
859 Some(hir::CoroutineKind::Coroutine(_))
860 | Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _))
861 | None => {
862 let stmt_id = self.next_id();
865 let expr_err = self.expr(
866 expr.span,
867 hir::ExprKind::Err(self.dcx().emit_err(AwaitOnlyInAsyncFnAndBlocks {
868 await_kw_span,
869 item_span: self.current_item,
870 })),
871 );
872 return hir::ExprKind::Block(
873 self.block_all(
874 expr.span,
875 arena_vec![self; hir::Stmt {
876 hir_id: stmt_id,
877 kind: hir::StmtKind::Semi(expr),
878 span: expr.span,
879 }],
880 Some(self.arena.alloc(expr_err)),
881 ),
882 None,
883 );
884 }
885 };
886
887 let features = match await_kind {
888 FutureKind::Future => None,
889 FutureKind::AsyncIterator => Some(Arc::clone(&self.allow_for_await)),
890 };
891 let span = self.mark_span_with_reason(DesugaringKind::Await, await_kw_span, features);
892 let gen_future_span = self.mark_span_with_reason(
893 DesugaringKind::Await,
894 full_span,
895 Some(Arc::clone(&self.allow_gen_future)),
896 );
897 let expr_hir_id = expr.hir_id;
898
899 let awaitee_ident = Ident::with_dummy_span(sym::__awaitee);
903 let (awaitee_pat, awaitee_pat_hid) =
904 self.pat_ident_binding_mode(gen_future_span, awaitee_ident, hir::BindingMode::MUT);
905
906 let task_context_ident = Ident::with_dummy_span(sym::_task_context);
907
908 let poll_expr = {
915 let awaitee = self.expr_ident(span, awaitee_ident, awaitee_pat_hid);
916 let ref_mut_awaitee = self.expr_mut_addr_of(span, awaitee);
917
918 let Some(task_context_hid) = self.task_context else {
919 unreachable!("use of `await` outside of an async context.");
920 };
921
922 let task_context = self.expr_ident_mut(span, task_context_ident, task_context_hid);
923
924 let new_unchecked = self.expr_call_lang_item_fn_mut(
925 span,
926 hir::LangItem::PinNewUnchecked,
927 arena_vec![self; ref_mut_awaitee],
928 );
929 let get_context = self.expr_call_lang_item_fn_mut(
930 gen_future_span,
931 hir::LangItem::GetContext,
932 arena_vec![self; task_context],
933 );
934 let call = match await_kind {
935 FutureKind::Future => self.expr_call_lang_item_fn(
936 span,
937 hir::LangItem::FuturePoll,
938 arena_vec![self; new_unchecked, get_context],
939 ),
940 FutureKind::AsyncIterator => self.expr_call_lang_item_fn(
941 span,
942 hir::LangItem::AsyncIteratorPollNext,
943 arena_vec![self; new_unchecked, get_context],
944 ),
945 };
946 self.arena.alloc(self.expr_unsafe(call))
947 };
948
949 let loop_node_id = self.next_node_id();
951 let loop_hir_id = self.lower_node_id(loop_node_id);
952 let ready_arm = {
953 let x_ident = Ident::with_dummy_span(sym::result);
954 let (x_pat, x_pat_hid) = self.pat_ident(gen_future_span, x_ident);
955 let x_expr = self.expr_ident(gen_future_span, x_ident, x_pat_hid);
956 let ready_field = self.single_pat_field(gen_future_span, x_pat);
957 let ready_pat = self.pat_lang_item_variant(span, hir::LangItem::PollReady, ready_field);
958 let break_x = self.with_loop_scope(loop_hir_id, move |this| {
959 let expr_break =
960 hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr));
961 this.arena.alloc(this.expr(gen_future_span, expr_break))
962 });
963 self.arm(ready_pat, break_x)
964 };
965
966 let pending_arm = {
968 let pending_pat = self.pat_lang_item_variant(span, hir::LangItem::PollPending, &[]);
969 let empty_block = self.expr_block_empty(span);
970 self.arm(pending_pat, empty_block)
971 };
972
973 let inner_match_stmt = {
974 let match_expr = self.expr_match(
975 span,
976 poll_expr,
977 arena_vec![self; ready_arm, pending_arm],
978 hir::MatchSource::AwaitDesugar,
979 );
980 self.stmt_expr(span, match_expr)
981 };
982
983 let yield_stmt = {
987 let yielded = if is_async_gen {
988 self.arena.alloc(self.expr_lang_item_path(span, hir::LangItem::AsyncGenPending))
989 } else {
990 self.expr_unit(span)
991 };
992
993 let yield_expr = self.expr(
994 span,
995 hir::ExprKind::Yield(yielded, hir::YieldSource::Await { expr: Some(expr_hir_id) }),
996 );
997 let yield_expr = self.arena.alloc(yield_expr);
998
999 let Some(task_context_hid) = self.task_context else {
1000 unreachable!("use of `await` outside of an async context.");
1001 };
1002
1003 let lhs = self.expr_ident(span, task_context_ident, task_context_hid);
1004 let assign =
1005 self.expr(span, hir::ExprKind::Assign(lhs, yield_expr, self.lower_span(span)));
1006 self.stmt_expr(span, assign)
1007 };
1008
1009 let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None);
1010
1011 let loop_expr = self.arena.alloc(hir::Expr {
1013 hir_id: loop_hir_id,
1014 kind: hir::ExprKind::Loop(
1015 loop_block,
1016 None,
1017 hir::LoopSource::Loop,
1018 self.lower_span(span),
1019 ),
1020 span: self.lower_span(span),
1021 });
1022
1023 let awaitee_arm = self.arm(awaitee_pat, loop_expr);
1025
1026 let into_future_expr = match await_kind {
1028 FutureKind::Future => self.expr_call_lang_item_fn(
1029 span,
1030 hir::LangItem::IntoFutureIntoFuture,
1031 arena_vec![self; *expr],
1032 ),
1033 FutureKind::AsyncIterator => expr,
1036 };
1037
1038 hir::ExprKind::Match(
1042 into_future_expr,
1043 arena_vec![self; awaitee_arm],
1044 hir::MatchSource::AwaitDesugar,
1045 )
1046 }
1047
1048 fn lower_expr_use(&mut self, use_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
1049 hir::ExprKind::Use(self.lower_expr(expr), self.lower_span(use_kw_span))
1050 }
1051
1052 fn lower_expr_closure(
1053 &mut self,
1054 attrs: &[rustc_hir::Attribute],
1055 binder: &ClosureBinder,
1056 capture_clause: CaptureBy,
1057 closure_id: NodeId,
1058 constness: Const,
1059 movability: Movability,
1060 decl: &FnDecl,
1061 body: &Expr,
1062 fn_decl_span: Span,
1063 fn_arg_span: Span,
1064 ) -> hir::ExprKind<'hir> {
1065 let closure_def_id = self.local_def_id(closure_id);
1066 let (binder_clause, generic_params) = self.lower_closure_binder(binder);
1067
1068 let (body_id, closure_kind) = self.with_new_scopes(fn_decl_span, move |this| {
1069
1070 let mut coroutine_kind = find_attr!(attrs, AttributeKind::Coroutine(_) => hir::CoroutineKind::Coroutine(Movability::Movable));
1071
1072 let body_id = this.lower_fn_body(decl, None, |this| {
1074 this.coroutine_kind = coroutine_kind;
1075 let e = this.lower_expr_mut(body);
1076 coroutine_kind = this.coroutine_kind;
1077 e
1078 });
1079 let coroutine_option =
1080 this.closure_movability_for_fn(decl, fn_decl_span, coroutine_kind, movability);
1081 (body_id, coroutine_option)
1082 });
1083
1084 let bound_generic_params = self.lower_lifetime_binder(closure_id, generic_params);
1085 let fn_decl = self.lower_fn_decl(decl, closure_id, fn_decl_span, FnDeclKind::Closure, None);
1087
1088 let c = self.arena.alloc(hir::Closure {
1089 def_id: closure_def_id,
1090 binder: binder_clause,
1091 capture_clause: self.lower_capture_clause(capture_clause),
1092 bound_generic_params,
1093 fn_decl,
1094 body: body_id,
1095 fn_decl_span: self.lower_span(fn_decl_span),
1096 fn_arg_span: Some(self.lower_span(fn_arg_span)),
1097 kind: closure_kind,
1098 constness: self.lower_constness(constness),
1099 });
1100
1101 hir::ExprKind::Closure(c)
1102 }
1103
1104 fn closure_movability_for_fn(
1105 &mut self,
1106 decl: &FnDecl,
1107 fn_decl_span: Span,
1108 coroutine_kind: Option<hir::CoroutineKind>,
1109 movability: Movability,
1110 ) -> hir::ClosureKind {
1111 match coroutine_kind {
1112 Some(hir::CoroutineKind::Coroutine(_)) => {
1113 if decl.inputs.len() > 1 {
1114 self.dcx().emit_err(CoroutineTooManyParameters { fn_decl_span });
1115 }
1116 hir::ClosureKind::Coroutine(hir::CoroutineKind::Coroutine(movability))
1117 }
1118 Some(
1119 hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)
1120 | hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)
1121 | hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _),
1122 ) => {
1123 panic!("non-`async`/`gen` closure body turned `async`/`gen` during lowering");
1124 }
1125 None => {
1126 if movability == Movability::Static {
1127 self.dcx().emit_err(ClosureCannotBeStatic { fn_decl_span });
1128 }
1129 hir::ClosureKind::Closure
1130 }
1131 }
1132 }
1133
1134 fn lower_closure_binder<'c>(
1135 &mut self,
1136 binder: &'c ClosureBinder,
1137 ) -> (hir::ClosureBinder, &'c [GenericParam]) {
1138 let (binder, params) = match binder {
1139 ClosureBinder::NotPresent => (hir::ClosureBinder::Default, &[][..]),
1140 ClosureBinder::For { span, generic_params } => {
1141 let span = self.lower_span(*span);
1142 (hir::ClosureBinder::For { span }, &**generic_params)
1143 }
1144 };
1145
1146 (binder, params)
1147 }
1148
1149 fn lower_expr_coroutine_closure(
1150 &mut self,
1151 binder: &ClosureBinder,
1152 capture_clause: CaptureBy,
1153 closure_id: NodeId,
1154 closure_hir_id: HirId,
1155 coroutine_kind: CoroutineKind,
1156 decl: &FnDecl,
1157 body: &Expr,
1158 fn_decl_span: Span,
1159 fn_arg_span: Span,
1160 ) -> hir::ExprKind<'hir> {
1161 let closure_def_id = self.local_def_id(closure_id);
1162 let (binder_clause, generic_params) = self.lower_closure_binder(binder);
1163
1164 let coroutine_desugaring = match coroutine_kind {
1165 CoroutineKind::Async { .. } => hir::CoroutineDesugaring::Async,
1166 CoroutineKind::Gen { .. } => hir::CoroutineDesugaring::Gen,
1167 CoroutineKind::AsyncGen { span, .. } => {
1168 span_bug!(span, "only async closures and `iter!` closures are supported currently")
1169 }
1170 };
1171
1172 let body = self.with_new_scopes(fn_decl_span, |this| {
1173 let inner_decl =
1174 FnDecl { inputs: decl.inputs.clone(), output: FnRetTy::Default(fn_decl_span) };
1175
1176 let body_id = this.lower_body(|this| {
1179 let (parameters, expr) = this.lower_coroutine_body_with_moved_arguments(
1180 &inner_decl,
1181 |this| this.with_new_scopes(fn_decl_span, |this| this.lower_expr_mut(body)),
1182 fn_decl_span,
1183 body.span,
1184 coroutine_kind,
1185 hir::CoroutineSource::Closure,
1186 );
1187
1188 this.maybe_forward_track_caller(body.span, closure_hir_id, expr.hir_id);
1189
1190 (parameters, expr)
1191 });
1192 body_id
1193 });
1194
1195 let bound_generic_params = self.lower_lifetime_binder(closure_id, generic_params);
1196 let fn_decl =
1200 self.lower_fn_decl(&decl, closure_id, fn_decl_span, FnDeclKind::Closure, None);
1201
1202 let c = self.arena.alloc(hir::Closure {
1203 def_id: closure_def_id,
1204 binder: binder_clause,
1205 capture_clause: self.lower_capture_clause(capture_clause),
1206 bound_generic_params,
1207 fn_decl,
1208 body,
1209 fn_decl_span: self.lower_span(fn_decl_span),
1210 fn_arg_span: Some(self.lower_span(fn_arg_span)),
1211 kind: hir::ClosureKind::CoroutineClosure(coroutine_desugaring),
1215 constness: hir::Constness::NotConst,
1216 });
1217 hir::ExprKind::Closure(c)
1218 }
1219
1220 fn lower_expr_assign(
1223 &mut self,
1224 lhs: &Expr,
1225 rhs: &Expr,
1226 eq_sign_span: Span,
1227 whole_span: Span,
1228 ) -> hir::ExprKind<'hir> {
1229 fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool {
1231 match &lhs.kind {
1232 ExprKind::Array(..)
1233 | ExprKind::Struct(..)
1234 | ExprKind::Tup(..)
1235 | ExprKind::Underscore => false,
1236 ExprKind::Path(..) => lower_ctx.extract_unit_struct_path(lhs).is_none(),
1238 ExprKind::Call(callee, ..) => lower_ctx.extract_tuple_struct_path(callee).is_none(),
1240 ExprKind::Paren(e) => {
1241 match e.kind {
1242 ExprKind::Range(None, None, RangeLimits::HalfOpen) => false,
1244 _ => is_ordinary(lower_ctx, e),
1245 }
1246 }
1247 _ => true,
1248 }
1249 }
1250 if is_ordinary(self, lhs) {
1251 return hir::ExprKind::Assign(
1252 self.lower_expr(lhs),
1253 self.lower_expr(rhs),
1254 self.lower_span(eq_sign_span),
1255 );
1256 }
1257
1258 let mut assignments = vec![];
1259
1260 let pat = self.destructure_assign(lhs, eq_sign_span, &mut assignments);
1262 let rhs = self.lower_expr(rhs);
1263
1264 let destructure_let = self.stmt_let_pat(
1266 None,
1267 whole_span,
1268 Some(rhs),
1269 pat,
1270 hir::LocalSource::AssignDesugar(self.lower_span(eq_sign_span)),
1271 );
1272
1273 let stmts = self.arena.alloc_from_iter(std::iter::once(destructure_let).chain(assignments));
1275
1276 hir::ExprKind::Block(self.block_all(whole_span, stmts, None), None)
1278 }
1279
1280 fn extract_tuple_struct_path<'a>(
1285 &mut self,
1286 expr: &'a Expr,
1287 ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
1288 if let ExprKind::Path(qself, path) = &expr.kind {
1289 if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
1291 if let Some(res) = partial_res.full_res()
1292 && !res.expected_in_tuple_struct_pat()
1293 {
1294 return None;
1295 }
1296 }
1297 return Some((qself, path));
1298 }
1299 None
1300 }
1301
1302 fn extract_unit_struct_path<'a>(
1307 &mut self,
1308 expr: &'a Expr,
1309 ) -> Option<(&'a Option<Box<QSelf>>, &'a Path)> {
1310 if let ExprKind::Path(qself, path) = &expr.kind {
1311 if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
1313 if let Some(res) = partial_res.full_res()
1314 && !res.expected_in_unit_struct_pat()
1315 {
1316 return None;
1317 }
1318 }
1319 return Some((qself, path));
1320 }
1321 None
1322 }
1323
1324 fn destructure_assign(
1327 &mut self,
1328 lhs: &Expr,
1329 eq_sign_span: Span,
1330 assignments: &mut Vec<hir::Stmt<'hir>>,
1331 ) -> &'hir hir::Pat<'hir> {
1332 self.arena.alloc(self.destructure_assign_mut(lhs, eq_sign_span, assignments))
1333 }
1334
1335 fn destructure_assign_mut(
1336 &mut self,
1337 lhs: &Expr,
1338 eq_sign_span: Span,
1339 assignments: &mut Vec<hir::Stmt<'hir>>,
1340 ) -> hir::Pat<'hir> {
1341 match &lhs.kind {
1342 ExprKind::Underscore => {
1344 return self.pat_without_dbm(lhs.span, hir::PatKind::Wild);
1345 }
1346 ExprKind::Array(elements) => {
1348 let (pats, rest) =
1349 self.destructure_sequence(elements, "slice", eq_sign_span, assignments);
1350 let slice_pat = if let Some((i, span)) = rest {
1351 let (before, after) = pats.split_at(i);
1352 hir::PatKind::Slice(
1353 before,
1354 Some(self.arena.alloc(self.pat_without_dbm(span, hir::PatKind::Wild))),
1355 after,
1356 )
1357 } else {
1358 hir::PatKind::Slice(pats, None, &[])
1359 };
1360 return self.pat_without_dbm(lhs.span, slice_pat);
1361 }
1362 ExprKind::Call(callee, args) => {
1364 if let Some((qself, path)) = self.extract_tuple_struct_path(callee) {
1365 let (pats, rest) = self.destructure_sequence(
1366 args,
1367 "tuple struct or variant",
1368 eq_sign_span,
1369 assignments,
1370 );
1371 let qpath = self.lower_qpath(
1372 callee.id,
1373 qself,
1374 path,
1375 ParamMode::Optional,
1376 AllowReturnTypeNotation::No,
1377 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1378 None,
1379 );
1380 let tuple_struct_pat = hir::PatKind::TupleStruct(
1382 qpath,
1383 pats,
1384 hir::DotDotPos::new(rest.map(|r| r.0)),
1385 );
1386 return self.pat_without_dbm(lhs.span, tuple_struct_pat);
1387 }
1388 }
1389 ExprKind::Path(..) => {
1391 if let Some((qself, path)) = self.extract_unit_struct_path(lhs) {
1392 let qpath = self.lower_qpath(
1393 lhs.id,
1394 qself,
1395 path,
1396 ParamMode::Optional,
1397 AllowReturnTypeNotation::No,
1398 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1399 None,
1400 );
1401 let unit_struct_pat = hir::PatKind::Expr(self.arena.alloc(hir::PatExpr {
1403 kind: hir::PatExprKind::Path(qpath),
1404 hir_id: self.next_id(),
1405 span: self.lower_span(lhs.span),
1406 }));
1407 return self.pat_without_dbm(lhs.span, unit_struct_pat);
1408 }
1409 }
1410 ExprKind::Struct(se) => {
1412 let field_pats = self.arena.alloc_from_iter(se.fields.iter().map(|f| {
1413 let pat = self.destructure_assign(&f.expr, eq_sign_span, assignments);
1414 hir::PatField {
1415 hir_id: self.next_id(),
1416 ident: self.lower_ident(f.ident),
1417 pat,
1418 is_shorthand: f.is_shorthand,
1419 span: self.lower_span(f.span),
1420 }
1421 }));
1422 let qpath = self.lower_qpath(
1423 lhs.id,
1424 &se.qself,
1425 &se.path,
1426 ParamMode::Optional,
1427 AllowReturnTypeNotation::No,
1428 ImplTraitContext::Disallowed(ImplTraitPosition::Path),
1429 None,
1430 );
1431 let fields_omitted = match &se.rest {
1432 StructRest::Base(e) => {
1433 self.dcx().emit_err(FunctionalRecordUpdateDestructuringAssignment {
1434 span: e.span,
1435 });
1436 true
1437 }
1438 StructRest::Rest(_) => true,
1439 StructRest::None => false,
1440 };
1441 let struct_pat = hir::PatKind::Struct(qpath, field_pats, fields_omitted);
1442 return self.pat_without_dbm(lhs.span, struct_pat);
1443 }
1444 ExprKind::Tup(elements) => {
1446 let (pats, rest) =
1447 self.destructure_sequence(elements, "tuple", eq_sign_span, assignments);
1448 let tuple_pat = hir::PatKind::Tuple(pats, hir::DotDotPos::new(rest.map(|r| r.0)));
1449 return self.pat_without_dbm(lhs.span, tuple_pat);
1450 }
1451 ExprKind::Paren(e) => {
1452 if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
1454 let tuple_pat = hir::PatKind::Tuple(&[], hir::DotDotPos::new(Some(0)));
1455 return self.pat_without_dbm(lhs.span, tuple_pat);
1456 } else {
1457 return self.destructure_assign_mut(e, eq_sign_span, assignments);
1458 }
1459 }
1460 _ => {}
1461 }
1462 let ident = Ident::new(sym::lhs, self.lower_span(lhs.span));
1464 let (pat, binding) = self.pat_ident_mut(lhs.span, ident);
1465 let ident = self.expr_ident(lhs.span, ident, binding);
1466 let assign =
1467 hir::ExprKind::Assign(self.lower_expr(lhs), ident, self.lower_span(eq_sign_span));
1468 let expr = self.expr(lhs.span, assign);
1469 assignments.push(self.stmt_expr(lhs.span, expr));
1470 pat
1471 }
1472
1473 fn destructure_sequence(
1479 &mut self,
1480 elements: &[Box<Expr>],
1481 ctx: &str,
1482 eq_sign_span: Span,
1483 assignments: &mut Vec<hir::Stmt<'hir>>,
1484 ) -> (&'hir [hir::Pat<'hir>], Option<(usize, Span)>) {
1485 let mut rest = None;
1486 let elements =
1487 self.arena.alloc_from_iter(elements.iter().enumerate().filter_map(|(i, e)| {
1488 if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
1490 if let Some((_, prev_span)) = rest {
1491 self.ban_extra_rest_pat(e.span, prev_span, ctx);
1492 } else {
1493 rest = Some((i, e.span));
1494 }
1495 None
1496 } else {
1497 Some(self.destructure_assign_mut(e, eq_sign_span, assignments))
1498 }
1499 }));
1500 (elements, rest)
1501 }
1502
1503 fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> {
1505 let e1 = self.lower_expr_mut(e1);
1506 let e2 = self.lower_expr_mut(e2);
1507 let fn_path = hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span));
1508 let fn_expr = self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path)));
1509 hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2])
1510 }
1511
1512 fn lower_expr_range(
1513 &mut self,
1514 span: Span,
1515 e1: Option<&Expr>,
1516 e2: Option<&Expr>,
1517 lims: RangeLimits,
1518 ) -> hir::ExprKind<'hir> {
1519 use rustc_ast::RangeLimits::*;
1520
1521 let lang_item = match (e1, e2, lims) {
1522 (None, None, HalfOpen) => hir::LangItem::RangeFull,
1523 (Some(..), None, HalfOpen) => {
1524 if self.tcx.features().new_range() {
1525 hir::LangItem::RangeFromCopy
1526 } else {
1527 hir::LangItem::RangeFrom
1528 }
1529 }
1530 (None, Some(..), HalfOpen) => hir::LangItem::RangeTo,
1531 (Some(..), Some(..), HalfOpen) => {
1532 if self.tcx.features().new_range() {
1533 hir::LangItem::RangeCopy
1534 } else {
1535 hir::LangItem::Range
1536 }
1537 }
1538 (None, Some(..), Closed) => hir::LangItem::RangeToInclusive,
1539 (Some(e1), Some(e2), Closed) => {
1540 if self.tcx.features().new_range() {
1541 hir::LangItem::RangeInclusiveCopy
1542 } else {
1543 return self.lower_expr_range_closed(span, e1, e2);
1544 }
1545 }
1546 (start, None, Closed) => {
1547 self.dcx().emit_err(InclusiveRangeWithNoEnd { span });
1548 match start {
1549 Some(..) => {
1550 if self.tcx.features().new_range() {
1551 hir::LangItem::RangeFromCopy
1552 } else {
1553 hir::LangItem::RangeFrom
1554 }
1555 }
1556 None => hir::LangItem::RangeFull,
1557 }
1558 }
1559 };
1560
1561 let fields = self.arena.alloc_from_iter(
1562 e1.iter().map(|e| (sym::start, e)).chain(e2.iter().map(|e| (sym::end, e))).map(
1563 |(s, e)| {
1564 let expr = self.lower_expr(e);
1565 let ident = Ident::new(s, self.lower_span(e.span));
1566 self.expr_field(ident, expr, e.span)
1567 },
1568 ),
1569 );
1570
1571 hir::ExprKind::Struct(
1572 self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span))),
1573 fields,
1574 hir::StructTailExpr::None,
1575 )
1576 }
1577
1578 fn lower_label(
1581 &mut self,
1582 opt_label: Option<Label>,
1583 dest_id: NodeId,
1584 dest_hir_id: hir::HirId,
1585 ) -> Option<Label> {
1586 let label = opt_label?;
1587 self.ident_and_label_to_local_id.insert(dest_id, dest_hir_id.local_id);
1588 Some(Label { ident: self.lower_ident(label.ident) })
1589 }
1590
1591 fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
1592 let target_id = match destination {
1593 Some((id, _)) => {
1594 if let Some(loop_id) = self.resolver.get_label_res(id) {
1595 let local_id = self.ident_and_label_to_local_id[&loop_id];
1596 let loop_hir_id = HirId { owner: self.current_hir_id_owner, local_id };
1597 Ok(loop_hir_id)
1598 } else {
1599 Err(hir::LoopIdError::UnresolvedLabel)
1600 }
1601 }
1602 None => {
1603 self.loop_scope.map(|id| Ok(id)).unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
1604 }
1605 };
1606 let label = destination
1607 .map(|(_, label)| label)
1608 .map(|label| Label { ident: self.lower_ident(label.ident) });
1609 hir::Destination { label, target_id }
1610 }
1611
1612 fn lower_jump_destination(&mut self, id: NodeId, opt_label: Option<Label>) -> hir::Destination {
1613 if self.is_in_loop_condition && opt_label.is_none() {
1614 hir::Destination {
1615 label: None,
1616 target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition),
1617 }
1618 } else {
1619 self.lower_loop_destination(opt_label.map(|label| (id, label)))
1620 }
1621 }
1622
1623 fn with_catch_scope<T>(&mut self, catch_id: hir::HirId, f: impl FnOnce(&mut Self) -> T) -> T {
1624 let old_scope = self.catch_scope.replace(catch_id);
1625 let result = f(self);
1626 self.catch_scope = old_scope;
1627 result
1628 }
1629
1630 fn with_loop_scope<T>(&mut self, loop_id: hir::HirId, f: impl FnOnce(&mut Self) -> T) -> T {
1631 let was_in_loop_condition = self.is_in_loop_condition;
1633 self.is_in_loop_condition = false;
1634
1635 let old_scope = self.loop_scope.replace(loop_id);
1636 let result = f(self);
1637 self.loop_scope = old_scope;
1638
1639 self.is_in_loop_condition = was_in_loop_condition;
1640
1641 result
1642 }
1643
1644 fn with_loop_condition_scope<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
1645 let was_in_loop_condition = self.is_in_loop_condition;
1646 self.is_in_loop_condition = true;
1647
1648 let result = f(self);
1649
1650 self.is_in_loop_condition = was_in_loop_condition;
1651
1652 result
1653 }
1654
1655 fn lower_expr_field(&mut self, f: &ExprField) -> hir::ExprField<'hir> {
1656 let hir_id = self.lower_node_id(f.id);
1657 self.lower_attrs(hir_id, &f.attrs, f.span);
1658 hir::ExprField {
1659 hir_id,
1660 ident: self.lower_ident(f.ident),
1661 expr: self.lower_expr(&f.expr),
1662 span: self.lower_span(f.span),
1663 is_shorthand: f.is_shorthand,
1664 }
1665 }
1666
1667 fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
1668 let yielded =
1669 opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span));
1670
1671 if !self.tcx.features().yield_expr()
1672 && !self.tcx.features().coroutines()
1673 && !self.tcx.features().gen_blocks()
1674 {
1675 rustc_session::parse::feature_err(
1676 &self.tcx.sess,
1677 sym::yield_expr,
1678 span,
1679 fluent_generated::ast_lowering_yield,
1680 )
1681 .emit();
1682 }
1683
1684 let is_async_gen = match self.coroutine_kind {
1685 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Gen, _)) => false,
1686 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::AsyncGen, _)) => true,
1687 Some(hir::CoroutineKind::Desugared(hir::CoroutineDesugaring::Async, _)) => {
1688 let stmt_id = self.next_id();
1691 let expr_err = self.expr(
1692 yielded.span,
1693 hir::ExprKind::Err(self.dcx().emit_err(AsyncCoroutinesNotSupported { span })),
1694 );
1695 return hir::ExprKind::Block(
1696 self.block_all(
1697 yielded.span,
1698 arena_vec![self; hir::Stmt {
1699 hir_id: stmt_id,
1700 kind: hir::StmtKind::Semi(yielded),
1701 span: yielded.span,
1702 }],
1703 Some(self.arena.alloc(expr_err)),
1704 ),
1705 None,
1706 );
1707 }
1708 Some(hir::CoroutineKind::Coroutine(_)) => false,
1709 None => {
1710 let suggestion = self.current_item.map(|s| s.shrink_to_lo());
1711 self.dcx().emit_err(YieldInClosure { span, suggestion });
1712 self.coroutine_kind = Some(hir::CoroutineKind::Coroutine(Movability::Movable));
1713
1714 false
1715 }
1716 };
1717
1718 if is_async_gen {
1719 let wrapped_yielded = self.expr_call_lang_item_fn(
1723 span,
1724 hir::LangItem::AsyncGenReady,
1725 std::slice::from_ref(yielded),
1726 );
1727 let yield_expr = self.arena.alloc(
1728 self.expr(span, hir::ExprKind::Yield(wrapped_yielded, hir::YieldSource::Yield)),
1729 );
1730
1731 let Some(task_context_hid) = self.task_context else {
1732 unreachable!("use of `await` outside of an async context.");
1733 };
1734 let task_context_ident = Ident::with_dummy_span(sym::_task_context);
1735 let lhs = self.expr_ident(span, task_context_ident, task_context_hid);
1736
1737 hir::ExprKind::Assign(lhs, yield_expr, self.lower_span(span))
1738 } else {
1739 hir::ExprKind::Yield(yielded, hir::YieldSource::Yield)
1740 }
1741 }
1742
1743 fn lower_expr_for(
1760 &mut self,
1761 e: &Expr,
1762 pat: &Pat,
1763 head: &Expr,
1764 body: &Block,
1765 opt_label: Option<Label>,
1766 loop_kind: ForLoopKind,
1767 ) -> hir::Expr<'hir> {
1768 let head = self.lower_expr_mut(head);
1769 let pat = self.lower_pat(pat);
1770 let for_span =
1771 self.mark_span_with_reason(DesugaringKind::ForLoop, self.lower_span(e.span), None);
1772 let head_span = self.mark_span_with_reason(DesugaringKind::ForLoop, head.span, None);
1773 let pat_span = self.mark_span_with_reason(DesugaringKind::ForLoop, pat.span, None);
1774
1775 let loop_hir_id = self.lower_node_id(e.id);
1776 let label = self.lower_label(opt_label, e.id, loop_hir_id);
1777
1778 let none_arm = {
1780 let break_expr =
1781 self.with_loop_scope(loop_hir_id, |this| this.expr_break_alloc(for_span));
1782 let pat = self.pat_none(for_span);
1783 self.arm(pat, break_expr)
1784 };
1785
1786 let some_arm = {
1788 let some_pat = self.pat_some(pat_span, pat);
1789 let body_block =
1790 self.with_loop_scope(loop_hir_id, |this| this.lower_block(body, false));
1791 let body_expr = self.arena.alloc(self.expr_block(body_block));
1792 self.arm(some_pat, body_expr)
1793 };
1794
1795 let iter = Ident::with_dummy_span(sym::iter);
1797 let (iter_pat, iter_pat_nid) =
1798 self.pat_ident_binding_mode(head_span, iter, hir::BindingMode::MUT);
1799
1800 let match_expr = {
1801 let iter = self.expr_ident(head_span, iter, iter_pat_nid);
1802 let next_expr = match loop_kind {
1803 ForLoopKind::For => {
1804 let ref_mut_iter = self.expr_mut_addr_of(head_span, iter);
1806 self.expr_call_lang_item_fn(
1807 head_span,
1808 hir::LangItem::IteratorNext,
1809 arena_vec![self; ref_mut_iter],
1810 )
1811 }
1812 ForLoopKind::ForAwait => {
1813 let iter = self.expr_mut_addr_of(head_span, iter);
1820 let iter = self.arena.alloc(self.expr_call_lang_item_fn_mut(
1822 head_span,
1823 hir::LangItem::PinNewUnchecked,
1824 arena_vec![self; iter],
1825 ));
1826 let iter = self.arena.alloc(self.expr_unsafe(iter));
1828 let kind = self.make_lowered_await(head_span, iter, FutureKind::AsyncIterator);
1829 self.arena.alloc(hir::Expr { hir_id: self.next_id(), kind, span: head_span })
1830 }
1831 };
1832 let arms = arena_vec![self; none_arm, some_arm];
1833
1834 self.expr_match(head_span, next_expr, arms, hir::MatchSource::ForLoopDesugar)
1836 };
1837 let match_stmt = self.stmt_expr(for_span, match_expr);
1838
1839 let loop_block = self.block_all(for_span, arena_vec![self; match_stmt], None);
1840
1841 let kind = hir::ExprKind::Loop(
1843 loop_block,
1844 label,
1845 hir::LoopSource::ForLoop,
1846 self.lower_span(for_span.with_hi(head.span.hi())),
1847 );
1848 let loop_expr = self.arena.alloc(hir::Expr { hir_id: loop_hir_id, kind, span: for_span });
1849
1850 let iter_arm = self.arm(iter_pat, loop_expr);
1852
1853 let match_expr = match loop_kind {
1854 ForLoopKind::For => {
1855 let into_iter_expr = self.expr_call_lang_item_fn(
1857 head_span,
1858 hir::LangItem::IntoIterIntoIter,
1859 arena_vec![self; head],
1860 );
1861
1862 self.arena.alloc(self.expr_match(
1863 for_span,
1864 into_iter_expr,
1865 arena_vec![self; iter_arm],
1866 hir::MatchSource::ForLoopDesugar,
1867 ))
1868 }
1869 ForLoopKind::ForAwait => {
1871 let iter_ident = iter;
1872 let (async_iter_pat, async_iter_pat_id) =
1873 self.pat_ident_binding_mode(head_span, iter_ident, hir::BindingMode::REF_MUT);
1874 let iter = self.expr_ident_mut(head_span, iter_ident, async_iter_pat_id);
1875 let iter = self.arena.alloc(self.expr_call_lang_item_fn_mut(
1877 head_span,
1878 hir::LangItem::PinNewUnchecked,
1879 arena_vec![self; iter],
1880 ));
1881 let iter = self.arena.alloc(self.expr_unsafe(iter));
1883 let inner_match_expr = self.arena.alloc(self.expr_match(
1884 for_span,
1885 iter,
1886 arena_vec![self; iter_arm],
1887 hir::MatchSource::ForLoopDesugar,
1888 ));
1889
1890 let iter = self.expr_call_lang_item_fn(
1892 head_span,
1893 hir::LangItem::IntoAsyncIterIntoIter,
1894 arena_vec![self; head],
1895 );
1896 let iter_arm = self.arm(async_iter_pat, inner_match_expr);
1897 self.arena.alloc(self.expr_match(
1898 for_span,
1899 iter,
1900 arena_vec![self; iter_arm],
1901 hir::MatchSource::ForLoopDesugar,
1902 ))
1903 }
1904 };
1905
1906 let expr = self.expr_drop_temps_mut(for_span, match_expr);
1913 self.lower_attrs(expr.hir_id, &e.attrs, e.span);
1914 expr
1915 }
1916
1917 fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> {
1930 let unstable_span = self.mark_span_with_reason(
1931 DesugaringKind::QuestionMark,
1932 span,
1933 Some(Arc::clone(&self.allow_try_trait)),
1934 );
1935 let try_span = self.tcx.sess.source_map().end_point(span);
1936 let try_span = self.mark_span_with_reason(
1937 DesugaringKind::QuestionMark,
1938 try_span,
1939 Some(Arc::clone(&self.allow_try_trait)),
1940 );
1941
1942 let scrutinee = {
1944 let sub_expr = self.lower_expr_mut(sub_expr);
1946
1947 self.expr_call_lang_item_fn(
1948 unstable_span,
1949 hir::LangItem::TryTraitBranch,
1950 arena_vec![self; sub_expr],
1951 )
1952 };
1953
1954 let attr = attr::mk_attr_nested_word(
1956 &self.tcx.sess.psess.attr_id_generator,
1957 AttrStyle::Outer,
1958 Safety::Default,
1959 sym::allow,
1960 sym::unreachable_code,
1961 try_span,
1962 );
1963 let attrs: AttrVec = thin_vec![attr];
1964
1965 let continue_arm = {
1967 let val_ident = Ident::with_dummy_span(sym::val);
1968 let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident);
1969 let val_expr = self.expr_ident(span, val_ident, val_pat_nid);
1970 self.lower_attrs(val_expr.hir_id, &attrs, span);
1971 let continue_pat = self.pat_cf_continue(unstable_span, val_pat);
1972 self.arm(continue_pat, val_expr)
1973 };
1974
1975 let break_arm = {
1979 let residual_ident = Ident::with_dummy_span(sym::residual);
1980 let (residual_local, residual_local_nid) = self.pat_ident(try_span, residual_ident);
1981 let residual_expr = self.expr_ident_mut(try_span, residual_ident, residual_local_nid);
1982 let from_residual_expr = self.wrap_in_try_constructor(
1983 hir::LangItem::TryTraitFromResidual,
1984 try_span,
1985 self.arena.alloc(residual_expr),
1986 unstable_span,
1987 );
1988 let ret_expr = if let Some(catch_id) = self.catch_scope {
1989 let target_id = Ok(catch_id);
1990 self.arena.alloc(self.expr(
1991 try_span,
1992 hir::ExprKind::Break(
1993 hir::Destination { label: None, target_id },
1994 Some(from_residual_expr),
1995 ),
1996 ))
1997 } else {
1998 let ret_expr = self.checked_return(Some(from_residual_expr));
1999 self.arena.alloc(self.expr(try_span, ret_expr))
2000 };
2001 self.lower_attrs(ret_expr.hir_id, &attrs, span);
2002
2003 let break_pat = self.pat_cf_break(try_span, residual_local);
2004 self.arm(break_pat, ret_expr)
2005 };
2006
2007 hir::ExprKind::Match(
2008 scrutinee,
2009 arena_vec![self; break_arm, continue_arm],
2010 hir::MatchSource::TryDesugar(scrutinee.hir_id),
2011 )
2012 }
2013
2014 fn lower_expr_yeet(&mut self, span: Span, sub_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
2024 let (yeeted_span, yeeted_expr) = if let Some(sub_expr) = sub_expr {
2026 (sub_expr.span, self.lower_expr(sub_expr))
2027 } else {
2028 (self.mark_span_with_reason(DesugaringKind::YeetExpr, span, None), self.expr_unit(span))
2029 };
2030
2031 let unstable_span = self.mark_span_with_reason(
2032 DesugaringKind::YeetExpr,
2033 span,
2034 Some(Arc::clone(&self.allow_try_trait)),
2035 );
2036
2037 let from_yeet_expr = self.wrap_in_try_constructor(
2038 hir::LangItem::TryTraitFromYeet,
2039 unstable_span,
2040 yeeted_expr,
2041 yeeted_span,
2042 );
2043
2044 if let Some(catch_id) = self.catch_scope {
2045 let target_id = Ok(catch_id);
2046 hir::ExprKind::Break(hir::Destination { label: None, target_id }, Some(from_yeet_expr))
2047 } else {
2048 self.checked_return(Some(from_yeet_expr))
2049 }
2050 }
2051
2052 pub(super) fn expr_drop_temps(
2064 &mut self,
2065 span: Span,
2066 expr: &'hir hir::Expr<'hir>,
2067 ) -> &'hir hir::Expr<'hir> {
2068 self.arena.alloc(self.expr_drop_temps_mut(span, expr))
2069 }
2070
2071 pub(super) fn expr_drop_temps_mut(
2072 &mut self,
2073 span: Span,
2074 expr: &'hir hir::Expr<'hir>,
2075 ) -> hir::Expr<'hir> {
2076 self.expr(span, hir::ExprKind::DropTemps(expr))
2077 }
2078
2079 pub(super) fn expr_match(
2080 &mut self,
2081 span: Span,
2082 arg: &'hir hir::Expr<'hir>,
2083 arms: &'hir [hir::Arm<'hir>],
2084 source: hir::MatchSource,
2085 ) -> hir::Expr<'hir> {
2086 self.expr(span, hir::ExprKind::Match(arg, arms, source))
2087 }
2088
2089 fn expr_break(&mut self, span: Span) -> hir::Expr<'hir> {
2090 let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None);
2091 self.expr(span, expr_break)
2092 }
2093
2094 fn expr_break_alloc(&mut self, span: Span) -> &'hir hir::Expr<'hir> {
2095 let expr_break = self.expr_break(span);
2096 self.arena.alloc(expr_break)
2097 }
2098
2099 fn expr_mut_addr_of(&mut self, span: Span, e: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
2100 self.expr(span, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, e))
2101 }
2102
2103 fn expr_unit(&mut self, sp: Span) -> &'hir hir::Expr<'hir> {
2104 self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[])))
2105 }
2106
2107 fn expr_uint(&mut self, sp: Span, ty: ast::UintTy, value: u128) -> hir::Expr<'hir> {
2108 let lit = hir::Lit {
2109 span: self.lower_span(sp),
2110 node: ast::LitKind::Int(value.into(), ast::LitIntType::Unsigned(ty)),
2111 };
2112 self.expr(sp, hir::ExprKind::Lit(lit))
2113 }
2114
2115 pub(super) fn expr_usize(&mut self, sp: Span, value: usize) -> hir::Expr<'hir> {
2116 self.expr_uint(sp, ast::UintTy::Usize, value as u128)
2117 }
2118
2119 pub(super) fn expr_u32(&mut self, sp: Span, value: u32) -> hir::Expr<'hir> {
2120 self.expr_uint(sp, ast::UintTy::U32, value as u128)
2121 }
2122
2123 pub(super) fn expr_u16(&mut self, sp: Span, value: u16) -> hir::Expr<'hir> {
2124 self.expr_uint(sp, ast::UintTy::U16, value as u128)
2125 }
2126
2127 pub(super) fn expr_str(&mut self, sp: Span, value: Symbol) -> hir::Expr<'hir> {
2128 let lit = hir::Lit {
2129 span: self.lower_span(sp),
2130 node: ast::LitKind::Str(value, ast::StrStyle::Cooked),
2131 };
2132 self.expr(sp, hir::ExprKind::Lit(lit))
2133 }
2134
2135 pub(super) fn expr_call_mut(
2136 &mut self,
2137 span: Span,
2138 e: &'hir hir::Expr<'hir>,
2139 args: &'hir [hir::Expr<'hir>],
2140 ) -> hir::Expr<'hir> {
2141 self.expr(span, hir::ExprKind::Call(e, args))
2142 }
2143
2144 pub(super) fn expr_call(
2145 &mut self,
2146 span: Span,
2147 e: &'hir hir::Expr<'hir>,
2148 args: &'hir [hir::Expr<'hir>],
2149 ) -> &'hir hir::Expr<'hir> {
2150 self.arena.alloc(self.expr_call_mut(span, e, args))
2151 }
2152
2153 pub(super) fn expr_call_lang_item_fn_mut(
2154 &mut self,
2155 span: Span,
2156 lang_item: hir::LangItem,
2157 args: &'hir [hir::Expr<'hir>],
2158 ) -> hir::Expr<'hir> {
2159 let path = self.arena.alloc(self.expr_lang_item_path(span, lang_item));
2160 self.expr_call_mut(span, path, args)
2161 }
2162
2163 pub(super) fn expr_call_lang_item_fn(
2164 &mut self,
2165 span: Span,
2166 lang_item: hir::LangItem,
2167 args: &'hir [hir::Expr<'hir>],
2168 ) -> &'hir hir::Expr<'hir> {
2169 self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args))
2170 }
2171
2172 fn expr_lang_item_path(&mut self, span: Span, lang_item: hir::LangItem) -> hir::Expr<'hir> {
2173 self.expr(span, hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span))))
2174 }
2175
2176 pub(super) fn expr_lang_item_type_relative(
2178 &mut self,
2179 span: Span,
2180 lang_item: hir::LangItem,
2181 name: Symbol,
2182 ) -> hir::Expr<'hir> {
2183 let qpath = self.make_lang_item_qpath(lang_item, self.lower_span(span), None);
2184 let path = hir::ExprKind::Path(hir::QPath::TypeRelative(
2185 self.arena.alloc(self.ty(span, hir::TyKind::Path(qpath))),
2186 self.arena.alloc(hir::PathSegment::new(
2187 Ident::new(name, self.lower_span(span)),
2188 self.next_id(),
2189 Res::Err,
2190 )),
2191 ));
2192 self.expr(span, path)
2193 }
2194
2195 pub(super) fn expr_ident(
2196 &mut self,
2197 sp: Span,
2198 ident: Ident,
2199 binding: HirId,
2200 ) -> &'hir hir::Expr<'hir> {
2201 self.arena.alloc(self.expr_ident_mut(sp, ident, binding))
2202 }
2203
2204 pub(super) fn expr_ident_mut(
2205 &mut self,
2206 span: Span,
2207 ident: Ident,
2208 binding: HirId,
2209 ) -> hir::Expr<'hir> {
2210 let hir_id = self.next_id();
2211 let res = Res::Local(binding);
2212 let expr_path = hir::ExprKind::Path(hir::QPath::Resolved(
2213 None,
2214 self.arena.alloc(hir::Path {
2215 span: self.lower_span(span),
2216 res,
2217 segments: arena_vec![self; hir::PathSegment::new(self.lower_ident(ident), hir_id, res)],
2218 }),
2219 ));
2220
2221 self.expr(span, expr_path)
2222 }
2223
2224 fn expr_unsafe(&mut self, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
2225 let hir_id = self.next_id();
2226 let span = expr.span;
2227 self.expr(
2228 span,
2229 hir::ExprKind::Block(
2230 self.arena.alloc(hir::Block {
2231 stmts: &[],
2232 expr: Some(expr),
2233 hir_id,
2234 rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated),
2235 span: self.lower_span(span),
2236 targeted_by_break: false,
2237 }),
2238 None,
2239 ),
2240 )
2241 }
2242
2243 fn expr_block_empty(&mut self, span: Span) -> &'hir hir::Expr<'hir> {
2244 let blk = self.block_all(span, &[], None);
2245 let expr = self.expr_block(blk);
2246 self.arena.alloc(expr)
2247 }
2248
2249 pub(super) fn expr_block(&mut self, b: &'hir hir::Block<'hir>) -> hir::Expr<'hir> {
2250 self.expr(b.span, hir::ExprKind::Block(b, None))
2251 }
2252
2253 pub(super) fn expr_array_ref(
2254 &mut self,
2255 span: Span,
2256 elements: &'hir [hir::Expr<'hir>],
2257 ) -> hir::Expr<'hir> {
2258 let array = self.arena.alloc(self.expr(span, hir::ExprKind::Array(elements)));
2259 self.expr_ref(span, array)
2260 }
2261
2262 pub(super) fn expr_ref(&mut self, span: Span, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
2263 self.expr(span, hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Not, expr))
2264 }
2265
2266 pub(super) fn expr(&mut self, span: Span, kind: hir::ExprKind<'hir>) -> hir::Expr<'hir> {
2267 let hir_id = self.next_id();
2268 hir::Expr { hir_id, kind, span: self.lower_span(span) }
2269 }
2270
2271 pub(super) fn expr_field(
2272 &mut self,
2273 ident: Ident,
2274 expr: &'hir hir::Expr<'hir>,
2275 span: Span,
2276 ) -> hir::ExprField<'hir> {
2277 hir::ExprField {
2278 hir_id: self.next_id(),
2279 ident,
2280 span: self.lower_span(span),
2281 expr,
2282 is_shorthand: false,
2283 }
2284 }
2285
2286 pub(super) fn arm(
2287 &mut self,
2288 pat: &'hir hir::Pat<'hir>,
2289 expr: &'hir hir::Expr<'hir>,
2290 ) -> hir::Arm<'hir> {
2291 hir::Arm {
2292 hir_id: self.next_id(),
2293 pat,
2294 guard: None,
2295 span: self.lower_span(expr.span),
2296 body: expr,
2297 }
2298 }
2299}
2300
2301#[derive(Copy, Clone, Debug, PartialEq, Eq)]
2304enum FutureKind {
2305 Future,
2307 AsyncIterator,
2310}