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Commit | Line | Data |
---|---|---|
dfeec247 | 1 | use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs}; |
416331ca | 2 | |
74b04a01 XL |
3 | use rustc_ast::attr; |
4 | use rustc_ast::ptr::P as AstP; | |
3dfed10e | 5 | use rustc_ast::*; |
f9f354fc | 6 | use rustc_data_structures::stack::ensure_sufficient_stack; |
416331ca | 7 | use rustc_data_structures::thin_vec::ThinVec; |
dfeec247 XL |
8 | use rustc_errors::struct_span_err; |
9 | use rustc_hir as hir; | |
10 | use rustc_hir::def::Res; | |
6a06907d | 11 | use rustc_hir::definitions::DefPathData; |
6a06907d | 12 | use rustc_span::hygiene::ExpnId; |
3dfed10e | 13 | use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned}; |
f9f354fc | 14 | use rustc_span::symbol::{sym, Ident, Symbol}; |
3c0e092e | 15 | use rustc_span::DUMMY_SP; |
416331ca | 16 | |
dfeec247 XL |
17 | impl<'hir> LoweringContext<'_, 'hir> { |
18 | fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] { | |
19 | self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x))) | |
20 | } | |
60c5eb7d | 21 | |
dfeec247 XL |
22 | pub(super) fn lower_expr(&mut self, e: &Expr) -> &'hir hir::Expr<'hir> { |
23 | self.arena.alloc(self.lower_expr_mut(e)) | |
416331ca XL |
24 | } |
25 | ||
dfeec247 | 26 | pub(super) fn lower_expr_mut(&mut self, e: &Expr) -> hir::Expr<'hir> { |
f9f354fc XL |
27 | ensure_sufficient_stack(|| { |
28 | let kind = match e.kind { | |
29 | ExprKind::Box(ref inner) => hir::ExprKind::Box(self.lower_expr(inner)), | |
30 | ExprKind::Array(ref exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)), | |
29967ef6 XL |
31 | ExprKind::ConstBlock(ref anon_const) => { |
32 | let anon_const = self.lower_anon_const(anon_const); | |
33 | hir::ExprKind::ConstBlock(anon_const) | |
34 | } | |
f9f354fc XL |
35 | ExprKind::Repeat(ref expr, ref count) => { |
36 | let expr = self.lower_expr(expr); | |
a2a8927a | 37 | let count = self.lower_array_length(count); |
f9f354fc XL |
38 | hir::ExprKind::Repeat(expr, count) |
39 | } | |
40 | ExprKind::Tup(ref elts) => hir::ExprKind::Tup(self.lower_exprs(elts)), | |
41 | ExprKind::Call(ref f, ref args) => { | |
6a06907d XL |
42 | if let Some(legacy_args) = self.resolver.legacy_const_generic_args(f) { |
43 | self.lower_legacy_const_generics((**f).clone(), args.clone(), &legacy_args) | |
44 | } else { | |
45 | let f = self.lower_expr(f); | |
46 | hir::ExprKind::Call(f, self.lower_exprs(args)) | |
47 | } | |
f9f354fc | 48 | } |
f035d41b | 49 | ExprKind::MethodCall(ref seg, ref args, span) => { |
f9f354fc XL |
50 | let hir_seg = self.arena.alloc(self.lower_path_segment( |
51 | e.span, | |
52 | seg, | |
53 | ParamMode::Optional, | |
54 | 0, | |
55 | ParenthesizedGenericArgs::Err, | |
56 | ImplTraitContext::disallowed(), | |
f9f354fc XL |
57 | )); |
58 | let args = self.lower_exprs(args); | |
94222f64 XL |
59 | hir::ExprKind::MethodCall( |
60 | hir_seg, | |
61 | self.lower_span(seg.ident.span), | |
62 | args, | |
63 | self.lower_span(span), | |
64 | ) | |
f9f354fc XL |
65 | } |
66 | ExprKind::Binary(binop, ref lhs, ref rhs) => { | |
67 | let binop = self.lower_binop(binop); | |
68 | let lhs = self.lower_expr(lhs); | |
69 | let rhs = self.lower_expr(rhs); | |
70 | hir::ExprKind::Binary(binop, lhs, rhs) | |
71 | } | |
72 | ExprKind::Unary(op, ref ohs) => { | |
73 | let op = self.lower_unop(op); | |
74 | let ohs = self.lower_expr(ohs); | |
75 | hir::ExprKind::Unary(op, ohs) | |
76 | } | |
94222f64 XL |
77 | ExprKind::Lit(ref l) => { |
78 | hir::ExprKind::Lit(respan(self.lower_span(l.span), l.kind.clone())) | |
79 | } | |
f9f354fc XL |
80 | ExprKind::Cast(ref expr, ref ty) => { |
81 | let expr = self.lower_expr(expr); | |
82 | let ty = self.lower_ty(ty, ImplTraitContext::disallowed()); | |
83 | hir::ExprKind::Cast(expr, ty) | |
84 | } | |
85 | ExprKind::Type(ref expr, ref ty) => { | |
86 | let expr = self.lower_expr(expr); | |
87 | let ty = self.lower_ty(ty, ImplTraitContext::disallowed()); | |
88 | hir::ExprKind::Type(expr, ty) | |
89 | } | |
90 | ExprKind::AddrOf(k, m, ref ohs) => { | |
91 | let ohs = self.lower_expr(ohs); | |
92 | hir::ExprKind::AddrOf(k, m, ohs) | |
93 | } | |
a2a8927a XL |
94 | ExprKind::Let(ref pat, ref scrutinee, span) => { |
95 | hir::ExprKind::Let(self.arena.alloc(hir::Let { | |
96 | hir_id: self.next_id(), | |
97 | span: self.lower_span(span), | |
98 | pat: self.lower_pat(pat), | |
99 | ty: None, | |
100 | init: self.lower_expr(scrutinee), | |
101 | })) | |
102 | } | |
94222f64 XL |
103 | ExprKind::If(ref cond, ref then, ref else_opt) => { |
104 | self.lower_expr_if(cond, then, else_opt.as_deref()) | |
f9f354fc | 105 | } |
c295e0f8 XL |
106 | ExprKind::While(ref cond, ref body, opt_label) => { |
107 | self.with_loop_scope(e.id, |this| { | |
108 | let span = | |
109 | this.mark_span_with_reason(DesugaringKind::WhileLoop, e.span, None); | |
110 | this.lower_expr_while_in_loop_scope(span, cond, body, opt_label) | |
111 | }) | |
112 | } | |
f9f354fc XL |
113 | ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| { |
114 | hir::ExprKind::Loop( | |
115 | this.lower_block(body, false), | |
94222f64 | 116 | this.lower_label(opt_label), |
f9f354fc | 117 | hir::LoopSource::Loop, |
5869c6ff | 118 | DUMMY_SP, |
dfeec247 | 119 | ) |
f9f354fc XL |
120 | }), |
121 | ExprKind::TryBlock(ref body) => self.lower_expr_try_block(body), | |
122 | ExprKind::Match(ref expr, ref arms) => hir::ExprKind::Match( | |
123 | self.lower_expr(expr), | |
124 | self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))), | |
125 | hir::MatchSource::Normal, | |
126 | ), | |
127 | ExprKind::Async(capture_clause, closure_node_id, ref block) => self | |
128 | .make_async_expr( | |
129 | capture_clause, | |
130 | closure_node_id, | |
131 | None, | |
132 | block.span, | |
133 | hir::AsyncGeneratorKind::Block, | |
134 | |this| this.with_new_scopes(|this| this.lower_block_expr(block)), | |
135 | ), | |
a2a8927a XL |
136 | ExprKind::Await(ref expr) => { |
137 | let span = if expr.span.hi() < e.span.hi() { | |
138 | expr.span.shrink_to_hi().with_hi(e.span.hi()) | |
139 | } else { | |
140 | // this is a recovered `await expr` | |
141 | e.span | |
142 | }; | |
143 | self.lower_expr_await(span, expr) | |
144 | } | |
f9f354fc XL |
145 | ExprKind::Closure( |
146 | capture_clause, | |
147 | asyncness, | |
148 | movability, | |
149 | ref decl, | |
150 | ref body, | |
151 | fn_decl_span, | |
152 | ) => { | |
153 | if let Async::Yes { closure_id, .. } = asyncness { | |
154 | self.lower_expr_async_closure( | |
155 | capture_clause, | |
156 | closure_id, | |
157 | decl, | |
158 | body, | |
159 | fn_decl_span, | |
160 | ) | |
161 | } else { | |
162 | self.lower_expr_closure( | |
163 | capture_clause, | |
164 | movability, | |
165 | decl, | |
166 | body, | |
167 | fn_decl_span, | |
168 | ) | |
169 | } | |
dfeec247 | 170 | } |
f9f354fc | 171 | ExprKind::Block(ref blk, opt_label) => { |
94222f64 | 172 | let opt_label = self.lower_label(opt_label); |
f9f354fc XL |
173 | hir::ExprKind::Block(self.lower_block(blk, opt_label.is_some()), opt_label) |
174 | } | |
175 | ExprKind::Assign(ref el, ref er, span) => { | |
29967ef6 | 176 | self.lower_expr_assign(el, er, span, e.span) |
f9f354fc XL |
177 | } |
178 | ExprKind::AssignOp(op, ref el, ref er) => hir::ExprKind::AssignOp( | |
179 | self.lower_binop(op), | |
180 | self.lower_expr(el), | |
181 | self.lower_expr(er), | |
182 | ), | |
94222f64 XL |
183 | ExprKind::Field(ref el, ident) => { |
184 | hir::ExprKind::Field(self.lower_expr(el), self.lower_ident(ident)) | |
185 | } | |
f9f354fc XL |
186 | ExprKind::Index(ref el, ref er) => { |
187 | hir::ExprKind::Index(self.lower_expr(el), self.lower_expr(er)) | |
188 | } | |
189 | ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => { | |
190 | self.lower_expr_range_closed(e.span, e1, e2) | |
191 | } | |
192 | ExprKind::Range(ref e1, ref e2, lims) => { | |
193 | self.lower_expr_range(e.span, e1.as_deref(), e2.as_deref(), lims) | |
194 | } | |
fc512014 XL |
195 | ExprKind::Underscore => { |
196 | self.sess | |
197 | .struct_span_err( | |
198 | e.span, | |
199 | "in expressions, `_` can only be used on the left-hand side of an assignment", | |
200 | ) | |
201 | .span_label(e.span, "`_` not allowed here") | |
202 | .emit(); | |
203 | hir::ExprKind::Err | |
204 | } | |
f9f354fc XL |
205 | ExprKind::Path(ref qself, ref path) => { |
206 | let qpath = self.lower_qpath( | |
dfeec247 | 207 | e.id, |
f9f354fc | 208 | qself, |
dfeec247 XL |
209 | path, |
210 | ParamMode::Optional, | |
211 | ImplTraitContext::disallowed(), | |
f9f354fc XL |
212 | ); |
213 | hir::ExprKind::Path(qpath) | |
214 | } | |
215 | ExprKind::Break(opt_label, ref opt_expr) => { | |
216 | let opt_expr = opt_expr.as_ref().map(|x| self.lower_expr(x)); | |
217 | hir::ExprKind::Break(self.lower_jump_destination(e.id, opt_label), opt_expr) | |
218 | } | |
219 | ExprKind::Continue(opt_label) => { | |
220 | hir::ExprKind::Continue(self.lower_jump_destination(e.id, opt_label)) | |
221 | } | |
222 | ExprKind::Ret(ref e) => { | |
223 | let e = e.as_ref().map(|x| self.lower_expr(x)); | |
224 | hir::ExprKind::Ret(e) | |
225 | } | |
17df50a5 XL |
226 | ExprKind::InlineAsm(ref asm) => { |
227 | hir::ExprKind::InlineAsm(self.lower_inline_asm(e.span, asm)) | |
228 | } | |
f9f354fc | 229 | ExprKind::LlvmInlineAsm(ref asm) => self.lower_expr_llvm_asm(asm), |
6a06907d XL |
230 | ExprKind::Struct(ref se) => { |
231 | let rest = match &se.rest { | |
29967ef6 XL |
232 | StructRest::Base(e) => Some(self.lower_expr(e)), |
233 | StructRest::Rest(sp) => { | |
234 | self.sess | |
235 | .struct_span_err(*sp, "base expression required after `..`") | |
236 | .span_label(*sp, "add a base expression here") | |
237 | .emit(); | |
238 | Some(&*self.arena.alloc(self.expr_err(*sp))) | |
239 | } | |
240 | StructRest::None => None, | |
241 | }; | |
f9f354fc XL |
242 | hir::ExprKind::Struct( |
243 | self.arena.alloc(self.lower_qpath( | |
244 | e.id, | |
17df50a5 | 245 | &se.qself, |
6a06907d | 246 | &se.path, |
f9f354fc XL |
247 | ParamMode::Optional, |
248 | ImplTraitContext::disallowed(), | |
249 | )), | |
6a06907d XL |
250 | self.arena |
251 | .alloc_from_iter(se.fields.iter().map(|x| self.lower_expr_field(x))), | |
29967ef6 | 252 | rest, |
f9f354fc XL |
253 | ) |
254 | } | |
255 | ExprKind::Yield(ref opt_expr) => self.lower_expr_yield(e.span, opt_expr.as_deref()), | |
256 | ExprKind::Err => hir::ExprKind::Err, | |
257 | ExprKind::Try(ref sub_expr) => self.lower_expr_try(e.span, sub_expr), | |
258 | ExprKind::Paren(ref ex) => { | |
259 | let mut ex = self.lower_expr_mut(ex); | |
260 | // Include parens in span, but only if it is a super-span. | |
261 | if e.span.contains(ex.span) { | |
94222f64 | 262 | ex.span = self.lower_span(e.span); |
f9f354fc XL |
263 | } |
264 | // Merge attributes into the inner expression. | |
6a06907d | 265 | if !e.attrs.is_empty() { |
3c0e092e XL |
266 | let old_attrs = |
267 | self.attrs.get(&ex.hir_id.local_id).map(|la| *la).unwrap_or(&[]); | |
6a06907d | 268 | self.attrs.insert( |
3c0e092e | 269 | ex.hir_id.local_id, |
6a06907d XL |
270 | &*self.arena.alloc_from_iter( |
271 | e.attrs | |
272 | .iter() | |
273 | .map(|a| self.lower_attr(a)) | |
274 | .chain(old_attrs.iter().cloned()), | |
275 | ), | |
276 | ); | |
277 | } | |
f9f354fc | 278 | return ex; |
416331ca | 279 | } |
416331ca | 280 | |
f9f354fc XL |
281 | // Desugar `ExprForLoop` |
282 | // from: `[opt_ident]: for <pat> in <head> <body>` | |
283 | ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => { | |
284 | return self.lower_expr_for(e, pat, head, body, opt_label); | |
285 | } | |
286 | ExprKind::MacCall(_) => panic!("{:?} shouldn't exist here", e.span), | |
287 | }; | |
416331ca | 288 | |
6a06907d XL |
289 | let hir_id = self.lower_node_id(e.id); |
290 | self.lower_attrs(hir_id, &e.attrs); | |
94222f64 | 291 | hir::Expr { hir_id, kind, span: self.lower_span(e.span) } |
f9f354fc | 292 | }) |
416331ca XL |
293 | } |
294 | ||
295 | fn lower_unop(&mut self, u: UnOp) -> hir::UnOp { | |
296 | match u { | |
6a06907d XL |
297 | UnOp::Deref => hir::UnOp::Deref, |
298 | UnOp::Not => hir::UnOp::Not, | |
299 | UnOp::Neg => hir::UnOp::Neg, | |
416331ca XL |
300 | } |
301 | } | |
302 | ||
303 | fn lower_binop(&mut self, b: BinOp) -> hir::BinOp { | |
304 | Spanned { | |
305 | node: match b.node { | |
306 | BinOpKind::Add => hir::BinOpKind::Add, | |
307 | BinOpKind::Sub => hir::BinOpKind::Sub, | |
308 | BinOpKind::Mul => hir::BinOpKind::Mul, | |
309 | BinOpKind::Div => hir::BinOpKind::Div, | |
310 | BinOpKind::Rem => hir::BinOpKind::Rem, | |
311 | BinOpKind::And => hir::BinOpKind::And, | |
312 | BinOpKind::Or => hir::BinOpKind::Or, | |
313 | BinOpKind::BitXor => hir::BinOpKind::BitXor, | |
314 | BinOpKind::BitAnd => hir::BinOpKind::BitAnd, | |
315 | BinOpKind::BitOr => hir::BinOpKind::BitOr, | |
316 | BinOpKind::Shl => hir::BinOpKind::Shl, | |
317 | BinOpKind::Shr => hir::BinOpKind::Shr, | |
318 | BinOpKind::Eq => hir::BinOpKind::Eq, | |
319 | BinOpKind::Lt => hir::BinOpKind::Lt, | |
320 | BinOpKind::Le => hir::BinOpKind::Le, | |
321 | BinOpKind::Ne => hir::BinOpKind::Ne, | |
322 | BinOpKind::Ge => hir::BinOpKind::Ge, | |
323 | BinOpKind::Gt => hir::BinOpKind::Gt, | |
324 | }, | |
94222f64 | 325 | span: self.lower_span(b.span), |
416331ca XL |
326 | } |
327 | } | |
328 | ||
6a06907d XL |
329 | fn lower_legacy_const_generics( |
330 | &mut self, | |
331 | mut f: Expr, | |
332 | args: Vec<AstP<Expr>>, | |
333 | legacy_args_idx: &[usize], | |
334 | ) -> hir::ExprKind<'hir> { | |
335 | let path = match f.kind { | |
336 | ExprKind::Path(None, ref mut path) => path, | |
337 | _ => unreachable!(), | |
338 | }; | |
339 | ||
340 | // Split the arguments into const generics and normal arguments | |
341 | let mut real_args = vec![]; | |
342 | let mut generic_args = vec![]; | |
343 | for (idx, arg) in args.into_iter().enumerate() { | |
344 | if legacy_args_idx.contains(&idx) { | |
c295e0f8 | 345 | let parent_def_id = self.current_hir_id_owner; |
6a06907d XL |
346 | let node_id = self.resolver.next_node_id(); |
347 | ||
348 | // Add a definition for the in-band const def. | |
349 | self.resolver.create_def( | |
350 | parent_def_id, | |
351 | node_id, | |
352 | DefPathData::AnonConst, | |
353 | ExpnId::root(), | |
354 | arg.span, | |
355 | ); | |
356 | ||
357 | let anon_const = AnonConst { id: node_id, value: arg }; | |
358 | generic_args.push(AngleBracketedArg::Arg(GenericArg::Const(anon_const))); | |
359 | } else { | |
360 | real_args.push(arg); | |
361 | } | |
362 | } | |
363 | ||
364 | // Add generic args to the last element of the path. | |
365 | let last_segment = path.segments.last_mut().unwrap(); | |
366 | assert!(last_segment.args.is_none()); | |
367 | last_segment.args = Some(AstP(GenericArgs::AngleBracketed(AngleBracketedArgs { | |
368 | span: DUMMY_SP, | |
369 | args: generic_args, | |
370 | }))); | |
371 | ||
372 | // Now lower everything as normal. | |
373 | let f = self.lower_expr(&f); | |
374 | hir::ExprKind::Call(f, self.lower_exprs(&real_args)) | |
375 | } | |
376 | ||
416331ca XL |
377 | fn lower_expr_if( |
378 | &mut self, | |
416331ca XL |
379 | cond: &Expr, |
380 | then: &Block, | |
381 | else_opt: Option<&Expr>, | |
5869c6ff | 382 | ) -> hir::ExprKind<'hir> { |
94222f64 XL |
383 | let lowered_cond = self.lower_expr(cond); |
384 | let new_cond = self.manage_let_cond(lowered_cond); | |
385 | let then_expr = self.lower_block_expr(then); | |
5869c6ff | 386 | if let Some(rslt) = else_opt { |
94222f64 | 387 | hir::ExprKind::If(new_cond, self.arena.alloc(then_expr), Some(self.lower_expr(rslt))) |
5869c6ff | 388 | } else { |
94222f64 | 389 | hir::ExprKind::If(new_cond, self.arena.alloc(then_expr), None) |
5869c6ff XL |
390 | } |
391 | } | |
392 | ||
94222f64 XL |
393 | // If `cond` kind is `let`, returns `let`. Otherwise, wraps and returns `cond` |
394 | // in a temporary block. | |
395 | fn manage_let_cond(&mut self, cond: &'hir hir::Expr<'hir>) -> &'hir hir::Expr<'hir> { | |
396 | match cond.kind { | |
397 | hir::ExprKind::Let(..) => cond, | |
398 | _ => { | |
399 | let span_block = | |
400 | self.mark_span_with_reason(DesugaringKind::CondTemporary, cond.span, None); | |
401 | self.expr_drop_temps(span_block, cond, AttrVec::new()) | |
402 | } | |
403 | } | |
416331ca XL |
404 | } |
405 | ||
94222f64 XL |
406 | // We desugar: `'label: while $cond $body` into: |
407 | // | |
408 | // ``` | |
409 | // 'label: loop { | |
410 | // if { let _t = $cond; _t } { | |
411 | // $body | |
412 | // } | |
413 | // else { | |
414 | // break; | |
415 | // } | |
416 | // } | |
417 | // ``` | |
418 | // | |
419 | // Wrap in a construct equivalent to `{ let _t = $cond; _t }` | |
420 | // to preserve drop semantics since `while $cond { ... }` does not | |
421 | // let temporaries live outside of `cond`. | |
416331ca XL |
422 | fn lower_expr_while_in_loop_scope( |
423 | &mut self, | |
424 | span: Span, | |
425 | cond: &Expr, | |
426 | body: &Block, | |
dfeec247 XL |
427 | opt_label: Option<Label>, |
428 | ) -> hir::ExprKind<'hir> { | |
94222f64 XL |
429 | let lowered_cond = self.with_loop_condition_scope(|t| t.lower_expr(cond)); |
430 | let new_cond = self.manage_let_cond(lowered_cond); | |
431 | let then = self.lower_block_expr(body); | |
432 | let expr_break = self.expr_break(span, ThinVec::new()); | |
433 | let stmt_break = self.stmt_expr(span, expr_break); | |
434 | let else_blk = self.block_all(span, arena_vec![self; stmt_break], None); | |
435 | let else_expr = self.arena.alloc(self.expr_block(else_blk, ThinVec::new())); | |
436 | let if_kind = hir::ExprKind::If(new_cond, self.arena.alloc(then), Some(else_expr)); | |
437 | let if_expr = self.expr(span, if_kind, ThinVec::new()); | |
438 | let block = self.block_expr(self.arena.alloc(if_expr)); | |
c295e0f8 XL |
439 | let span = self.lower_span(span.with_hi(cond.span.hi())); |
440 | let opt_label = self.lower_label(opt_label); | |
441 | hir::ExprKind::Loop(block, opt_label, hir::LoopSource::While, span) | |
416331ca XL |
442 | } |
443 | ||
17df50a5 XL |
444 | /// Desugar `try { <stmts>; <expr> }` into `{ <stmts>; ::std::ops::Try::from_output(<expr>) }`, |
445 | /// `try { <stmts>; }` into `{ <stmts>; ::std::ops::Try::from_output(()) }` | |
e74abb32 | 446 | /// and save the block id to use it as a break target for desugaring of the `?` operator. |
dfeec247 | 447 | fn lower_expr_try_block(&mut self, body: &Block) -> hir::ExprKind<'hir> { |
416331ca | 448 | self.with_catch_scope(body.id, |this| { |
dfeec247 | 449 | let mut block = this.lower_block_noalloc(body, true); |
e74abb32 | 450 | |
e74abb32 | 451 | // Final expression of the block (if present) or `()` with span at the end of block |
29967ef6 XL |
452 | let (try_span, tail_expr) = if let Some(expr) = block.expr.take() { |
453 | ( | |
454 | this.mark_span_with_reason( | |
455 | DesugaringKind::TryBlock, | |
456 | expr.span, | |
457 | this.allow_try_trait.clone(), | |
458 | ), | |
459 | expr, | |
460 | ) | |
461 | } else { | |
462 | let try_span = this.mark_span_with_reason( | |
463 | DesugaringKind::TryBlock, | |
464 | this.sess.source_map().end_point(body.span), | |
465 | this.allow_try_trait.clone(), | |
466 | ); | |
467 | ||
468 | (try_span, this.expr_unit(try_span)) | |
469 | }; | |
e74abb32 | 470 | |
dfeec247 XL |
471 | let ok_wrapped_span = |
472 | this.mark_span_with_reason(DesugaringKind::TryBlock, tail_expr.span, None); | |
e74abb32 | 473 | |
17df50a5 | 474 | // `::std::ops::Try::from_output($tail_expr)` |
e74abb32 | 475 | block.expr = Some(this.wrap_in_try_constructor( |
17df50a5 | 476 | hir::LangItem::TryTraitFromOutput, |
dfeec247 XL |
477 | try_span, |
478 | tail_expr, | |
479 | ok_wrapped_span, | |
480 | )); | |
e74abb32 | 481 | |
dfeec247 | 482 | hir::ExprKind::Block(this.arena.alloc(block), None) |
416331ca XL |
483 | }) |
484 | } | |
485 | ||
486 | fn wrap_in_try_constructor( | |
487 | &mut self, | |
3dfed10e | 488 | lang_item: hir::LangItem, |
e74abb32 | 489 | method_span: Span, |
dfeec247 | 490 | expr: &'hir hir::Expr<'hir>, |
e74abb32 | 491 | overall_span: Span, |
dfeec247 | 492 | ) -> &'hir hir::Expr<'hir> { |
a2a8927a XL |
493 | let constructor = self.arena.alloc(self.expr_lang_item_path( |
494 | method_span, | |
495 | lang_item, | |
496 | ThinVec::new(), | |
497 | None, | |
498 | )); | |
dfeec247 | 499 | self.expr_call(overall_span, constructor, std::slice::from_ref(expr)) |
416331ca XL |
500 | } |
501 | ||
dfeec247 | 502 | fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> { |
fc512014 XL |
503 | let pat = self.lower_pat(&arm.pat); |
504 | let guard = arm.guard.as_ref().map(|cond| { | |
94222f64 | 505 | if let ExprKind::Let(ref pat, ref scrutinee, _) = cond.kind { |
fc512014 XL |
506 | hir::Guard::IfLet(self.lower_pat(pat), self.lower_expr(scrutinee)) |
507 | } else { | |
508 | hir::Guard::If(self.lower_expr(cond)) | |
509 | } | |
510 | }); | |
6a06907d XL |
511 | let hir_id = self.next_id(); |
512 | self.lower_attrs(hir_id, &arm.attrs); | |
94222f64 XL |
513 | hir::Arm { |
514 | hir_id, | |
515 | pat, | |
516 | guard, | |
517 | body: self.lower_expr(&arm.body), | |
518 | span: self.lower_span(arm.span), | |
519 | } | |
416331ca XL |
520 | } |
521 | ||
ba9703b0 XL |
522 | /// Lower an `async` construct to a generator that is then wrapped so it implements `Future`. |
523 | /// | |
524 | /// This results in: | |
525 | /// | |
526 | /// ```text | |
527 | /// std::future::from_generator(static move? |_task_context| -> <ret_ty> { | |
528 | /// <body> | |
529 | /// }) | |
530 | /// ``` | |
416331ca XL |
531 | pub(super) fn make_async_expr( |
532 | &mut self, | |
533 | capture_clause: CaptureBy, | |
534 | closure_node_id: NodeId, | |
535 | ret_ty: Option<AstP<Ty>>, | |
536 | span: Span, | |
e74abb32 | 537 | async_gen_kind: hir::AsyncGeneratorKind, |
dfeec247 XL |
538 | body: impl FnOnce(&mut Self) -> hir::Expr<'hir>, |
539 | ) -> hir::ExprKind<'hir> { | |
416331ca | 540 | let output = match ret_ty { |
ba9703b0 | 541 | Some(ty) => hir::FnRetTy::Return(self.lower_ty(&ty, ImplTraitContext::disallowed())), |
94222f64 | 542 | None => hir::FnRetTy::DefaultReturn(self.lower_span(span)), |
416331ca | 543 | }; |
ba9703b0 XL |
544 | |
545 | // Resume argument type. We let the compiler infer this to simplify the lowering. It is | |
546 | // fully constrained by `future::from_generator`. | |
94222f64 XL |
547 | let input_ty = hir::Ty { |
548 | hir_id: self.next_id(), | |
549 | kind: hir::TyKind::Infer, | |
550 | span: self.lower_span(span), | |
551 | }; | |
ba9703b0 XL |
552 | |
553 | // The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`. | |
554 | let decl = self.arena.alloc(hir::FnDecl { | |
555 | inputs: arena_vec![self; input_ty], | |
556 | output, | |
557 | c_variadic: false, | |
558 | implicit_self: hir::ImplicitSelfKind::None, | |
559 | }); | |
560 | ||
561 | // Lower the argument pattern/ident. The ident is used again in the `.await` lowering. | |
562 | let (pat, task_context_hid) = self.pat_ident_binding_mode( | |
563 | span, | |
564 | Ident::with_dummy_span(sym::_task_context), | |
565 | hir::BindingAnnotation::Mutable, | |
566 | ); | |
94222f64 XL |
567 | let param = hir::Param { |
568 | hir_id: self.next_id(), | |
569 | pat, | |
570 | ty_span: self.lower_span(span), | |
571 | span: self.lower_span(span), | |
572 | }; | |
ba9703b0 XL |
573 | let params = arena_vec![self; param]; |
574 | ||
575 | let body_id = self.lower_body(move |this| { | |
e74abb32 | 576 | this.generator_kind = Some(hir::GeneratorKind::Async(async_gen_kind)); |
ba9703b0 XL |
577 | |
578 | let old_ctx = this.task_context; | |
579 | this.task_context = Some(task_context_hid); | |
580 | let res = body(this); | |
581 | this.task_context = old_ctx; | |
582 | (params, res) | |
416331ca XL |
583 | }); |
584 | ||
ba9703b0 | 585 | // `static |_task_context| -> <ret_ty> { body }`: |
e74abb32 | 586 | let generator_kind = hir::ExprKind::Closure( |
416331ca XL |
587 | capture_clause, |
588 | decl, | |
589 | body_id, | |
94222f64 | 590 | self.lower_span(span), |
dfeec247 | 591 | Some(hir::Movability::Static), |
416331ca | 592 | ); |
94222f64 XL |
593 | let generator = hir::Expr { |
594 | hir_id: self.lower_node_id(closure_node_id), | |
595 | kind: generator_kind, | |
596 | span: self.lower_span(span), | |
597 | }; | |
416331ca XL |
598 | |
599 | // `future::from_generator`: | |
dfeec247 XL |
600 | let unstable_span = |
601 | self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone()); | |
a2a8927a XL |
602 | let gen_future = self.expr_lang_item_path( |
603 | unstable_span, | |
604 | hir::LangItem::FromGenerator, | |
605 | ThinVec::new(), | |
606 | None, | |
607 | ); | |
416331ca XL |
608 | |
609 | // `future::from_generator(generator)`: | |
dfeec247 | 610 | hir::ExprKind::Call(self.arena.alloc(gen_future), arena_vec![self; generator]) |
416331ca XL |
611 | } |
612 | ||
613 | /// Desugar `<expr>.await` into: | |
614 | /// ```rust | |
a2a8927a | 615 | /// match ::std::future::IntoFuture::into_future(<expr>) { |
e1599b0c | 616 | /// mut pinned => loop { |
ba9703b0 XL |
617 | /// match unsafe { ::std::future::Future::poll( |
618 | /// <::std::pin::Pin>::new_unchecked(&mut pinned), | |
619 | /// ::std::future::get_context(task_context), | |
620 | /// ) } { | |
416331ca | 621 | /// ::std::task::Poll::Ready(result) => break result, |
e1599b0c | 622 | /// ::std::task::Poll::Pending => {} |
416331ca | 623 | /// } |
ba9703b0 | 624 | /// task_context = yield (); |
416331ca XL |
625 | /// } |
626 | /// } | |
627 | /// ``` | |
dfeec247 | 628 | fn lower_expr_await(&mut self, await_span: Span, expr: &Expr) -> hir::ExprKind<'hir> { |
a2a8927a | 629 | let dot_await_span = expr.span.shrink_to_hi().to(await_span); |
416331ca | 630 | match self.generator_kind { |
dfeec247 XL |
631 | Some(hir::GeneratorKind::Async(_)) => {} |
632 | Some(hir::GeneratorKind::Gen) | None => { | |
416331ca XL |
633 | let mut err = struct_span_err!( |
634 | self.sess, | |
635 | await_span, | |
636 | E0728, | |
637 | "`await` is only allowed inside `async` functions and blocks" | |
638 | ); | |
639 | err.span_label(await_span, "only allowed inside `async` functions and blocks"); | |
640 | if let Some(item_sp) = self.current_item { | |
641 | err.span_label(item_sp, "this is not `async`"); | |
642 | } | |
643 | err.emit(); | |
644 | } | |
645 | } | |
a2a8927a | 646 | let span = self.mark_span_with_reason(DesugaringKind::Await, dot_await_span, None); |
416331ca XL |
647 | let gen_future_span = self.mark_span_with_reason( |
648 | DesugaringKind::Await, | |
649 | await_span, | |
650 | self.allow_gen_future.clone(), | |
651 | ); | |
a2a8927a XL |
652 | let expr = self.lower_expr_mut(expr); |
653 | let expr_hir_id = expr.hir_id; | |
416331ca | 654 | |
e1599b0c | 655 | let pinned_ident = Ident::with_dummy_span(sym::pinned); |
dfeec247 XL |
656 | let (pinned_pat, pinned_pat_hid) = |
657 | self.pat_ident_binding_mode(span, pinned_ident, hir::BindingAnnotation::Mutable); | |
416331ca | 658 | |
ba9703b0 XL |
659 | let task_context_ident = Ident::with_dummy_span(sym::_task_context); |
660 | ||
661 | // unsafe { | |
662 | // ::std::future::Future::poll( | |
663 | // ::std::pin::Pin::new_unchecked(&mut pinned), | |
664 | // ::std::future::get_context(task_context), | |
665 | // ) | |
666 | // } | |
416331ca | 667 | let poll_expr = { |
dfeec247 | 668 | let pinned = self.expr_ident(span, pinned_ident, pinned_pat_hid); |
416331ca | 669 | let ref_mut_pinned = self.expr_mut_addr_of(span, pinned); |
ba9703b0 XL |
670 | let task_context = if let Some(task_context_hid) = self.task_context { |
671 | self.expr_ident_mut(span, task_context_ident, task_context_hid) | |
672 | } else { | |
673 | // Use of `await` outside of an async context, we cannot use `task_context` here. | |
674 | self.expr_err(span) | |
675 | }; | |
3dfed10e | 676 | let new_unchecked = self.expr_call_lang_item_fn_mut( |
416331ca | 677 | span, |
3dfed10e | 678 | hir::LangItem::PinNewUnchecked, |
dfeec247 | 679 | arena_vec![self; ref_mut_pinned], |
a2a8927a | 680 | Some(expr_hir_id), |
416331ca | 681 | ); |
3dfed10e | 682 | let get_context = self.expr_call_lang_item_fn_mut( |
416331ca | 683 | gen_future_span, |
3dfed10e | 684 | hir::LangItem::GetContext, |
ba9703b0 | 685 | arena_vec![self; task_context], |
a2a8927a | 686 | Some(expr_hir_id), |
ba9703b0 | 687 | ); |
3dfed10e | 688 | let call = self.expr_call_lang_item_fn( |
ba9703b0 | 689 | span, |
3dfed10e | 690 | hir::LangItem::FuturePoll, |
ba9703b0 | 691 | arena_vec![self; new_unchecked, get_context], |
a2a8927a | 692 | Some(expr_hir_id), |
ba9703b0 XL |
693 | ); |
694 | self.arena.alloc(self.expr_unsafe(call)) | |
416331ca XL |
695 | }; |
696 | ||
697 | // `::std::task::Poll::Ready(result) => break result` | |
60c5eb7d | 698 | let loop_node_id = self.resolver.next_node_id(); |
416331ca XL |
699 | let loop_hir_id = self.lower_node_id(loop_node_id); |
700 | let ready_arm = { | |
e1599b0c | 701 | let x_ident = Ident::with_dummy_span(sym::result); |
416331ca | 702 | let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident); |
dfeec247 | 703 | let x_expr = self.expr_ident(span, x_ident, x_pat_hid); |
3dfed10e | 704 | let ready_field = self.single_pat_field(span, x_pat); |
a2a8927a XL |
705 | let ready_pat = self.pat_lang_item_variant( |
706 | span, | |
707 | hir::LangItem::PollReady, | |
708 | ready_field, | |
709 | Some(expr_hir_id), | |
710 | ); | |
dfeec247 XL |
711 | let break_x = self.with_loop_scope(loop_node_id, move |this| { |
712 | let expr_break = | |
713 | hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr)); | |
a2a8927a | 714 | this.arena.alloc(this.expr(span, expr_break, ThinVec::new())) |
416331ca | 715 | }); |
e74abb32 | 716 | self.arm(ready_pat, break_x) |
416331ca XL |
717 | }; |
718 | ||
719 | // `::std::task::Poll::Pending => {}` | |
720 | let pending_arm = { | |
a2a8927a XL |
721 | let pending_pat = self.pat_lang_item_variant( |
722 | span, | |
723 | hir::LangItem::PollPending, | |
724 | &[], | |
725 | Some(expr_hir_id), | |
726 | ); | |
dfeec247 | 727 | let empty_block = self.expr_block_empty(span); |
e74abb32 | 728 | self.arm(pending_pat, empty_block) |
416331ca XL |
729 | }; |
730 | ||
e1599b0c | 731 | let inner_match_stmt = { |
416331ca XL |
732 | let match_expr = self.expr_match( |
733 | span, | |
734 | poll_expr, | |
dfeec247 | 735 | arena_vec![self; ready_arm, pending_arm], |
416331ca XL |
736 | hir::MatchSource::AwaitDesugar, |
737 | ); | |
738 | self.stmt_expr(span, match_expr) | |
739 | }; | |
740 | ||
ba9703b0 | 741 | // task_context = yield (); |
416331ca XL |
742 | let yield_stmt = { |
743 | let unit = self.expr_unit(span); | |
744 | let yield_expr = self.expr( | |
745 | span, | |
a2a8927a | 746 | hir::ExprKind::Yield(unit, hir::YieldSource::Await { expr: Some(expr_hir_id) }), |
416331ca XL |
747 | ThinVec::new(), |
748 | ); | |
ba9703b0 XL |
749 | let yield_expr = self.arena.alloc(yield_expr); |
750 | ||
751 | if let Some(task_context_hid) = self.task_context { | |
752 | let lhs = self.expr_ident(span, task_context_ident, task_context_hid); | |
94222f64 XL |
753 | let assign = self.expr( |
754 | span, | |
755 | hir::ExprKind::Assign(lhs, yield_expr, self.lower_span(span)), | |
756 | AttrVec::new(), | |
757 | ); | |
ba9703b0 XL |
758 | self.stmt_expr(span, assign) |
759 | } else { | |
760 | // Use of `await` outside of an async context. Return `yield_expr` so that we can | |
761 | // proceed with type checking. | |
762 | self.stmt(span, hir::StmtKind::Semi(yield_expr)) | |
763 | } | |
416331ca XL |
764 | }; |
765 | ||
dfeec247 | 766 | let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None); |
416331ca | 767 | |
e1599b0c | 768 | // loop { .. } |
dfeec247 | 769 | let loop_expr = self.arena.alloc(hir::Expr { |
416331ca | 770 | hir_id: loop_hir_id, |
94222f64 XL |
771 | kind: hir::ExprKind::Loop( |
772 | loop_block, | |
773 | None, | |
774 | hir::LoopSource::Loop, | |
775 | self.lower_span(span), | |
776 | ), | |
777 | span: self.lower_span(span), | |
416331ca XL |
778 | }); |
779 | ||
e1599b0c | 780 | // mut pinned => loop { ... } |
e74abb32 | 781 | let pinned_arm = self.arm(pinned_pat, loop_expr); |
e1599b0c | 782 | |
a2a8927a XL |
783 | // `match ::std::future::IntoFuture::into_future(<expr>) { ... }` |
784 | let into_future_span = self.mark_span_with_reason( | |
785 | DesugaringKind::Await, | |
786 | await_span, | |
787 | self.allow_into_future.clone(), | |
788 | ); | |
789 | let into_future_expr = self.expr_call_lang_item_fn( | |
790 | into_future_span, | |
791 | hir::LangItem::IntoFutureIntoFuture, | |
792 | arena_vec![self; expr], | |
793 | Some(expr_hir_id), | |
794 | ); | |
795 | ||
796 | // match <into_future_expr> { | |
e1599b0c XL |
797 | // mut pinned => loop { .. } |
798 | // } | |
a2a8927a XL |
799 | hir::ExprKind::Match( |
800 | into_future_expr, | |
801 | arena_vec![self; pinned_arm], | |
802 | hir::MatchSource::AwaitDesugar, | |
803 | ) | |
416331ca XL |
804 | } |
805 | ||
806 | fn lower_expr_closure( | |
807 | &mut self, | |
808 | capture_clause: CaptureBy, | |
809 | movability: Movability, | |
810 | decl: &FnDecl, | |
811 | body: &Expr, | |
812 | fn_decl_span: Span, | |
dfeec247 | 813 | ) -> hir::ExprKind<'hir> { |
5869c6ff | 814 | let (body_id, generator_option) = self.with_new_scopes(move |this| { |
e1599b0c | 815 | let prev = this.current_item; |
416331ca XL |
816 | this.current_item = Some(fn_decl_span); |
817 | let mut generator_kind = None; | |
818 | let body_id = this.lower_fn_body(decl, |this| { | |
dfeec247 | 819 | let e = this.lower_expr_mut(body); |
416331ca XL |
820 | generator_kind = this.generator_kind; |
821 | e | |
822 | }); | |
dfeec247 XL |
823 | let generator_option = |
824 | this.generator_movability_for_fn(&decl, fn_decl_span, generator_kind, movability); | |
e1599b0c | 825 | this.current_item = prev; |
5869c6ff XL |
826 | (body_id, generator_option) |
827 | }); | |
828 | ||
829 | // Lower outside new scope to preserve `is_in_loop_condition`. | |
830 | let fn_decl = self.lower_fn_decl(decl, None, false, None); | |
831 | ||
94222f64 XL |
832 | hir::ExprKind::Closure( |
833 | capture_clause, | |
834 | fn_decl, | |
835 | body_id, | |
836 | self.lower_span(fn_decl_span), | |
837 | generator_option, | |
838 | ) | |
416331ca XL |
839 | } |
840 | ||
416331ca XL |
841 | fn generator_movability_for_fn( |
842 | &mut self, | |
843 | decl: &FnDecl, | |
844 | fn_decl_span: Span, | |
845 | generator_kind: Option<hir::GeneratorKind>, | |
846 | movability: Movability, | |
60c5eb7d | 847 | ) -> Option<hir::Movability> { |
416331ca | 848 | match generator_kind { |
dfeec247 | 849 | Some(hir::GeneratorKind::Gen) => { |
74b04a01 | 850 | if decl.inputs.len() > 1 { |
dfeec247 | 851 | struct_span_err!( |
416331ca XL |
852 | self.sess, |
853 | fn_decl_span, | |
854 | E0628, | |
74b04a01 | 855 | "too many parameters for a generator (expected 0 or 1 parameters)" |
dfeec247 XL |
856 | ) |
857 | .emit(); | |
416331ca | 858 | } |
60c5eb7d | 859 | Some(movability) |
dfeec247 | 860 | } |
e74abb32 | 861 | Some(hir::GeneratorKind::Async(_)) => { |
ba9703b0 | 862 | panic!("non-`async` closure body turned `async` during lowering"); |
dfeec247 | 863 | } |
416331ca XL |
864 | None => { |
865 | if movability == Movability::Static { | |
dfeec247 XL |
866 | struct_span_err!(self.sess, fn_decl_span, E0697, "closures cannot be static") |
867 | .emit(); | |
416331ca XL |
868 | } |
869 | None | |
dfeec247 | 870 | } |
416331ca XL |
871 | } |
872 | } | |
873 | ||
874 | fn lower_expr_async_closure( | |
875 | &mut self, | |
876 | capture_clause: CaptureBy, | |
877 | closure_id: NodeId, | |
878 | decl: &FnDecl, | |
879 | body: &Expr, | |
880 | fn_decl_span: Span, | |
dfeec247 XL |
881 | ) -> hir::ExprKind<'hir> { |
882 | let outer_decl = | |
74b04a01 | 883 | FnDecl { inputs: decl.inputs.clone(), output: FnRetTy::Default(fn_decl_span) }; |
416331ca | 884 | |
5869c6ff | 885 | let body_id = self.with_new_scopes(|this| { |
416331ca XL |
886 | // FIXME(cramertj): allow `async` non-`move` closures with arguments. |
887 | if capture_clause == CaptureBy::Ref && !decl.inputs.is_empty() { | |
888 | struct_span_err!( | |
889 | this.sess, | |
890 | fn_decl_span, | |
891 | E0708, | |
e1599b0c | 892 | "`async` non-`move` closures with parameters are not currently supported", |
416331ca XL |
893 | ) |
894 | .help( | |
895 | "consider using `let` statements to manually capture \ | |
dfeec247 | 896 | variables by reference before entering an `async move` closure", |
416331ca XL |
897 | ) |
898 | .emit(); | |
899 | } | |
900 | ||
901 | // Transform `async |x: u8| -> X { ... }` into | |
902 | // `|x: u8| future_from_generator(|| -> X { ... })`. | |
903 | let body_id = this.lower_fn_body(&outer_decl, |this| { | |
dfeec247 | 904 | let async_ret_ty = |
74b04a01 | 905 | if let FnRetTy::Ty(ty) = &decl.output { Some(ty.clone()) } else { None }; |
416331ca | 906 | let async_body = this.make_async_expr( |
e74abb32 XL |
907 | capture_clause, |
908 | closure_id, | |
909 | async_ret_ty, | |
910 | body.span, | |
911 | hir::AsyncGeneratorKind::Closure, | |
dfeec247 | 912 | |this| this.with_new_scopes(|this| this.lower_expr_mut(body)), |
416331ca XL |
913 | ); |
914 | this.expr(fn_decl_span, async_body, ThinVec::new()) | |
915 | }); | |
5869c6ff XL |
916 | body_id |
917 | }); | |
918 | ||
919 | // We need to lower the declaration outside the new scope, because we | |
920 | // have to conserve the state of being inside a loop condition for the | |
921 | // closure argument types. | |
922 | let fn_decl = self.lower_fn_decl(&outer_decl, None, false, None); | |
923 | ||
94222f64 XL |
924 | hir::ExprKind::Closure( |
925 | capture_clause, | |
926 | fn_decl, | |
927 | body_id, | |
928 | self.lower_span(fn_decl_span), | |
929 | None, | |
930 | ) | |
416331ca XL |
931 | } |
932 | ||
29967ef6 XL |
933 | /// Destructure the LHS of complex assignments. |
934 | /// For instance, lower `(a, b) = t` to `{ let (lhs1, lhs2) = t; a = lhs1; b = lhs2; }`. | |
935 | fn lower_expr_assign( | |
936 | &mut self, | |
937 | lhs: &Expr, | |
938 | rhs: &Expr, | |
939 | eq_sign_span: Span, | |
940 | whole_span: Span, | |
941 | ) -> hir::ExprKind<'hir> { | |
942 | // Return early in case of an ordinary assignment. | |
943 | fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool { | |
944 | match &lhs.kind { | |
fc512014 XL |
945 | ExprKind::Array(..) |
946 | | ExprKind::Struct(..) | |
947 | | ExprKind::Tup(..) | |
948 | | ExprKind::Underscore => false, | |
29967ef6 XL |
949 | // Check for tuple struct constructor. |
950 | ExprKind::Call(callee, ..) => lower_ctx.extract_tuple_struct_path(callee).is_none(), | |
951 | ExprKind::Paren(e) => { | |
952 | match e.kind { | |
953 | // We special-case `(..)` for consistency with patterns. | |
954 | ExprKind::Range(None, None, RangeLimits::HalfOpen) => false, | |
955 | _ => is_ordinary(lower_ctx, e), | |
956 | } | |
957 | } | |
958 | _ => true, | |
959 | } | |
960 | } | |
961 | if is_ordinary(self, lhs) { | |
94222f64 XL |
962 | return hir::ExprKind::Assign( |
963 | self.lower_expr(lhs), | |
964 | self.lower_expr(rhs), | |
965 | self.lower_span(eq_sign_span), | |
966 | ); | |
29967ef6 | 967 | } |
29967ef6 XL |
968 | |
969 | let mut assignments = vec![]; | |
970 | ||
971 | // The LHS becomes a pattern: `(lhs1, lhs2)`. | |
972 | let pat = self.destructure_assign(lhs, eq_sign_span, &mut assignments); | |
973 | let rhs = self.lower_expr(rhs); | |
974 | ||
975 | // Introduce a `let` for destructuring: `let (lhs1, lhs2) = t`. | |
976 | let destructure_let = self.stmt_let_pat( | |
6a06907d | 977 | None, |
29967ef6 XL |
978 | whole_span, |
979 | Some(rhs), | |
980 | pat, | |
94222f64 | 981 | hir::LocalSource::AssignDesugar(self.lower_span(eq_sign_span)), |
29967ef6 XL |
982 | ); |
983 | ||
984 | // `a = lhs1; b = lhs2;`. | |
985 | let stmts = self | |
986 | .arena | |
987 | .alloc_from_iter(std::iter::once(destructure_let).chain(assignments.into_iter())); | |
988 | ||
989 | // Wrap everything in a block. | |
990 | hir::ExprKind::Block(&self.block_all(whole_span, stmts, None), None) | |
991 | } | |
992 | ||
993 | /// If the given expression is a path to a tuple struct, returns that path. | |
994 | /// It is not a complete check, but just tries to reject most paths early | |
995 | /// if they are not tuple structs. | |
996 | /// Type checking will take care of the full validation later. | |
17df50a5 XL |
997 | fn extract_tuple_struct_path<'a>( |
998 | &mut self, | |
999 | expr: &'a Expr, | |
1000 | ) -> Option<(&'a Option<QSelf>, &'a Path)> { | |
1001 | if let ExprKind::Path(qself, path) = &expr.kind { | |
1002 | // Does the path resolve to something disallowed in a tuple struct/variant pattern? | |
29967ef6 XL |
1003 | if let Some(partial_res) = self.resolver.get_partial_res(expr.id) { |
1004 | if partial_res.unresolved_segments() == 0 | |
1005 | && !partial_res.base_res().expected_in_tuple_struct_pat() | |
1006 | { | |
1007 | return None; | |
1008 | } | |
1009 | } | |
17df50a5 | 1010 | return Some((qself, path)); |
29967ef6 XL |
1011 | } |
1012 | None | |
1013 | } | |
1014 | ||
1015 | /// Convert the LHS of a destructuring assignment to a pattern. | |
1016 | /// Each sub-assignment is recorded in `assignments`. | |
1017 | fn destructure_assign( | |
1018 | &mut self, | |
1019 | lhs: &Expr, | |
1020 | eq_sign_span: Span, | |
1021 | assignments: &mut Vec<hir::Stmt<'hir>>, | |
1022 | ) -> &'hir hir::Pat<'hir> { | |
136023e0 XL |
1023 | self.arena.alloc(self.destructure_assign_mut(lhs, eq_sign_span, assignments)) |
1024 | } | |
1025 | ||
1026 | fn destructure_assign_mut( | |
1027 | &mut self, | |
1028 | lhs: &Expr, | |
1029 | eq_sign_span: Span, | |
1030 | assignments: &mut Vec<hir::Stmt<'hir>>, | |
1031 | ) -> hir::Pat<'hir> { | |
29967ef6 | 1032 | match &lhs.kind { |
fc512014 XL |
1033 | // Underscore pattern. |
1034 | ExprKind::Underscore => { | |
1035 | return self.pat_without_dbm(lhs.span, hir::PatKind::Wild); | |
1036 | } | |
29967ef6 XL |
1037 | // Slice patterns. |
1038 | ExprKind::Array(elements) => { | |
1039 | let (pats, rest) = | |
1040 | self.destructure_sequence(elements, "slice", eq_sign_span, assignments); | |
1041 | let slice_pat = if let Some((i, span)) = rest { | |
1042 | let (before, after) = pats.split_at(i); | |
1043 | hir::PatKind::Slice( | |
1044 | before, | |
136023e0 | 1045 | Some(self.arena.alloc(self.pat_without_dbm(span, hir::PatKind::Wild))), |
29967ef6 XL |
1046 | after, |
1047 | ) | |
1048 | } else { | |
1049 | hir::PatKind::Slice(pats, None, &[]) | |
1050 | }; | |
1051 | return self.pat_without_dbm(lhs.span, slice_pat); | |
1052 | } | |
1053 | // Tuple structs. | |
1054 | ExprKind::Call(callee, args) => { | |
17df50a5 | 1055 | if let Some((qself, path)) = self.extract_tuple_struct_path(callee) { |
29967ef6 XL |
1056 | let (pats, rest) = self.destructure_sequence( |
1057 | args, | |
1058 | "tuple struct or variant", | |
1059 | eq_sign_span, | |
1060 | assignments, | |
1061 | ); | |
1062 | let qpath = self.lower_qpath( | |
1063 | callee.id, | |
17df50a5 | 1064 | qself, |
29967ef6 XL |
1065 | path, |
1066 | ParamMode::Optional, | |
1067 | ImplTraitContext::disallowed(), | |
1068 | ); | |
1069 | // Destructure like a tuple struct. | |
1070 | let tuple_struct_pat = | |
1071 | hir::PatKind::TupleStruct(qpath, pats, rest.map(|r| r.0)); | |
1072 | return self.pat_without_dbm(lhs.span, tuple_struct_pat); | |
1073 | } | |
1074 | } | |
1075 | // Structs. | |
6a06907d XL |
1076 | ExprKind::Struct(se) => { |
1077 | let field_pats = self.arena.alloc_from_iter(se.fields.iter().map(|f| { | |
29967ef6 | 1078 | let pat = self.destructure_assign(&f.expr, eq_sign_span, assignments); |
6a06907d | 1079 | hir::PatField { |
29967ef6 | 1080 | hir_id: self.next_id(), |
94222f64 | 1081 | ident: self.lower_ident(f.ident), |
29967ef6 XL |
1082 | pat, |
1083 | is_shorthand: f.is_shorthand, | |
94222f64 | 1084 | span: self.lower_span(f.span), |
29967ef6 XL |
1085 | } |
1086 | })); | |
1087 | let qpath = self.lower_qpath( | |
1088 | lhs.id, | |
17df50a5 | 1089 | &se.qself, |
6a06907d | 1090 | &se.path, |
29967ef6 XL |
1091 | ParamMode::Optional, |
1092 | ImplTraitContext::disallowed(), | |
1093 | ); | |
6a06907d | 1094 | let fields_omitted = match &se.rest { |
29967ef6 XL |
1095 | StructRest::Base(e) => { |
1096 | self.sess | |
1097 | .struct_span_err( | |
1098 | e.span, | |
1099 | "functional record updates are not allowed in destructuring \ | |
1100 | assignments", | |
1101 | ) | |
1102 | .span_suggestion( | |
1103 | e.span, | |
1104 | "consider removing the trailing pattern", | |
1105 | String::new(), | |
1106 | rustc_errors::Applicability::MachineApplicable, | |
1107 | ) | |
1108 | .emit(); | |
1109 | true | |
1110 | } | |
1111 | StructRest::Rest(_) => true, | |
1112 | StructRest::None => false, | |
1113 | }; | |
1114 | let struct_pat = hir::PatKind::Struct(qpath, field_pats, fields_omitted); | |
1115 | return self.pat_without_dbm(lhs.span, struct_pat); | |
1116 | } | |
1117 | // Tuples. | |
1118 | ExprKind::Tup(elements) => { | |
1119 | let (pats, rest) = | |
1120 | self.destructure_sequence(elements, "tuple", eq_sign_span, assignments); | |
1121 | let tuple_pat = hir::PatKind::Tuple(pats, rest.map(|r| r.0)); | |
1122 | return self.pat_without_dbm(lhs.span, tuple_pat); | |
1123 | } | |
1124 | ExprKind::Paren(e) => { | |
1125 | // We special-case `(..)` for consistency with patterns. | |
1126 | if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind { | |
1127 | let tuple_pat = hir::PatKind::Tuple(&[], Some(0)); | |
1128 | return self.pat_without_dbm(lhs.span, tuple_pat); | |
1129 | } else { | |
136023e0 | 1130 | return self.destructure_assign_mut(e, eq_sign_span, assignments); |
29967ef6 XL |
1131 | } |
1132 | } | |
1133 | _ => {} | |
1134 | } | |
1135 | // Treat all other cases as normal lvalue. | |
94222f64 | 1136 | let ident = Ident::new(sym::lhs, self.lower_span(lhs.span)); |
136023e0 | 1137 | let (pat, binding) = self.pat_ident_mut(lhs.span, ident); |
29967ef6 | 1138 | let ident = self.expr_ident(lhs.span, ident, binding); |
94222f64 XL |
1139 | let assign = |
1140 | hir::ExprKind::Assign(self.lower_expr(lhs), ident, self.lower_span(eq_sign_span)); | |
29967ef6 XL |
1141 | let expr = self.expr(lhs.span, assign, ThinVec::new()); |
1142 | assignments.push(self.stmt_expr(lhs.span, expr)); | |
1143 | pat | |
1144 | } | |
1145 | ||
1146 | /// Destructure a sequence of expressions occurring on the LHS of an assignment. | |
1147 | /// Such a sequence occurs in a tuple (struct)/slice. | |
1148 | /// Return a sequence of corresponding patterns, and the index and the span of `..` if it | |
1149 | /// exists. | |
1150 | /// Each sub-assignment is recorded in `assignments`. | |
1151 | fn destructure_sequence( | |
1152 | &mut self, | |
1153 | elements: &[AstP<Expr>], | |
1154 | ctx: &str, | |
1155 | eq_sign_span: Span, | |
1156 | assignments: &mut Vec<hir::Stmt<'hir>>, | |
136023e0 | 1157 | ) -> (&'hir [hir::Pat<'hir>], Option<(usize, Span)>) { |
29967ef6 XL |
1158 | let mut rest = None; |
1159 | let elements = | |
1160 | self.arena.alloc_from_iter(elements.iter().enumerate().filter_map(|(i, e)| { | |
1161 | // Check for `..` pattern. | |
1162 | if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind { | |
1163 | if let Some((_, prev_span)) = rest { | |
1164 | self.ban_extra_rest_pat(e.span, prev_span, ctx); | |
1165 | } else { | |
1166 | rest = Some((i, e.span)); | |
1167 | } | |
1168 | None | |
1169 | } else { | |
136023e0 | 1170 | Some(self.destructure_assign_mut(e, eq_sign_span, assignments)) |
29967ef6 XL |
1171 | } |
1172 | })); | |
1173 | (elements, rest) | |
1174 | } | |
1175 | ||
416331ca | 1176 | /// Desugar `<start>..=<end>` into `std::ops::RangeInclusive::new(<start>, <end>)`. |
dfeec247 | 1177 | fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> { |
dfeec247 XL |
1178 | let e1 = self.lower_expr_mut(e1); |
1179 | let e2 = self.lower_expr_mut(e2); | |
a2a8927a XL |
1180 | let fn_path = |
1181 | hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, self.lower_span(span), None); | |
3dfed10e XL |
1182 | let fn_expr = |
1183 | self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path), ThinVec::new())); | |
1184 | hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2]) | |
416331ca XL |
1185 | } |
1186 | ||
1187 | fn lower_expr_range( | |
1188 | &mut self, | |
1189 | span: Span, | |
1190 | e1: Option<&Expr>, | |
1191 | e2: Option<&Expr>, | |
1192 | lims: RangeLimits, | |
dfeec247 | 1193 | ) -> hir::ExprKind<'hir> { |
3dfed10e XL |
1194 | use rustc_ast::RangeLimits::*; |
1195 | ||
1196 | let lang_item = match (e1, e2, lims) { | |
1197 | (None, None, HalfOpen) => hir::LangItem::RangeFull, | |
1198 | (Some(..), None, HalfOpen) => hir::LangItem::RangeFrom, | |
1199 | (None, Some(..), HalfOpen) => hir::LangItem::RangeTo, | |
1200 | (Some(..), Some(..), HalfOpen) => hir::LangItem::Range, | |
1201 | (None, Some(..), Closed) => hir::LangItem::RangeToInclusive, | |
416331ca | 1202 | (Some(..), Some(..), Closed) => unreachable!(), |
17df50a5 | 1203 | (_, None, Closed) => self.diagnostic().span_fatal(span, "inclusive range with no end"), |
416331ca XL |
1204 | }; |
1205 | ||
dfeec247 XL |
1206 | let fields = self.arena.alloc_from_iter( |
1207 | e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e))).map(|(s, e)| { | |
1208 | let expr = self.lower_expr(&e); | |
94222f64 | 1209 | let ident = Ident::new(Symbol::intern(s), self.lower_span(e.span)); |
6a06907d | 1210 | self.expr_field(ident, expr, e.span) |
dfeec247 XL |
1211 | }), |
1212 | ); | |
416331ca | 1213 | |
94222f64 | 1214 | hir::ExprKind::Struct( |
a2a8927a | 1215 | self.arena.alloc(hir::QPath::LangItem(lang_item, self.lower_span(span), None)), |
94222f64 XL |
1216 | fields, |
1217 | None, | |
1218 | ) | |
1219 | } | |
1220 | ||
1221 | fn lower_label(&self, opt_label: Option<Label>) -> Option<Label> { | |
1222 | let label = opt_label?; | |
1223 | Some(Label { ident: self.lower_ident(label.ident) }) | |
416331ca XL |
1224 | } |
1225 | ||
416331ca XL |
1226 | fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination { |
1227 | let target_id = match destination { | |
1228 | Some((id, _)) => { | |
1229 | if let Some(loop_id) = self.resolver.get_label_res(id) { | |
1230 | Ok(self.lower_node_id(loop_id)) | |
1231 | } else { | |
1232 | Err(hir::LoopIdError::UnresolvedLabel) | |
1233 | } | |
1234 | } | |
dfeec247 | 1235 | None => self |
c295e0f8 | 1236 | .loop_scope |
dfeec247 | 1237 | .map(|id| Ok(self.lower_node_id(id))) |
74b04a01 | 1238 | .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope)), |
416331ca | 1239 | }; |
94222f64 XL |
1240 | let label = self.lower_label(destination.map(|(_, label)| label)); |
1241 | hir::Destination { label, target_id } | |
416331ca XL |
1242 | } |
1243 | ||
1244 | fn lower_jump_destination(&mut self, id: NodeId, opt_label: Option<Label>) -> hir::Destination { | |
1245 | if self.is_in_loop_condition && opt_label.is_none() { | |
1246 | hir::Destination { | |
1247 | label: None, | |
74b04a01 | 1248 | target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition), |
416331ca XL |
1249 | } |
1250 | } else { | |
1251 | self.lower_loop_destination(opt_label.map(|label| (id, label))) | |
1252 | } | |
1253 | } | |
1254 | ||
dfeec247 | 1255 | fn with_catch_scope<T>(&mut self, catch_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { |
c295e0f8 | 1256 | let old_scope = self.catch_scope.replace(catch_id); |
416331ca | 1257 | let result = f(self); |
c295e0f8 | 1258 | self.catch_scope = old_scope; |
416331ca XL |
1259 | result |
1260 | } | |
1261 | ||
dfeec247 | 1262 | fn with_loop_scope<T>(&mut self, loop_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T { |
416331ca XL |
1263 | // We're no longer in the base loop's condition; we're in another loop. |
1264 | let was_in_loop_condition = self.is_in_loop_condition; | |
1265 | self.is_in_loop_condition = false; | |
1266 | ||
c295e0f8 | 1267 | let old_scope = self.loop_scope.replace(loop_id); |
416331ca | 1268 | let result = f(self); |
c295e0f8 | 1269 | self.loop_scope = old_scope; |
416331ca XL |
1270 | |
1271 | self.is_in_loop_condition = was_in_loop_condition; | |
1272 | ||
1273 | result | |
1274 | } | |
1275 | ||
dfeec247 | 1276 | fn with_loop_condition_scope<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T { |
416331ca XL |
1277 | let was_in_loop_condition = self.is_in_loop_condition; |
1278 | self.is_in_loop_condition = true; | |
1279 | ||
1280 | let result = f(self); | |
1281 | ||
1282 | self.is_in_loop_condition = was_in_loop_condition; | |
1283 | ||
1284 | result | |
1285 | } | |
1286 | ||
f9f354fc | 1287 | fn lower_expr_llvm_asm(&mut self, asm: &LlvmInlineAsm) -> hir::ExprKind<'hir> { |
ba9703b0 | 1288 | let inner = hir::LlvmInlineAsmInner { |
dfeec247 XL |
1289 | inputs: asm.inputs.iter().map(|&(c, _)| c).collect(), |
1290 | outputs: asm | |
1291 | .outputs | |
416331ca | 1292 | .iter() |
ba9703b0 | 1293 | .map(|out| hir::LlvmInlineAsmOutput { |
dfeec247 | 1294 | constraint: out.constraint, |
416331ca XL |
1295 | is_rw: out.is_rw, |
1296 | is_indirect: out.is_indirect, | |
94222f64 | 1297 | span: self.lower_span(out.expr.span), |
416331ca XL |
1298 | }) |
1299 | .collect(), | |
dfeec247 | 1300 | asm: asm.asm, |
416331ca | 1301 | asm_str_style: asm.asm_str_style, |
74b04a01 | 1302 | clobbers: asm.clobbers.clone(), |
416331ca XL |
1303 | volatile: asm.volatile, |
1304 | alignstack: asm.alignstack, | |
1305 | dialect: asm.dialect, | |
416331ca | 1306 | }; |
ba9703b0 | 1307 | let hir_asm = hir::LlvmInlineAsm { |
60c5eb7d | 1308 | inner, |
dfeec247 XL |
1309 | inputs_exprs: self.arena.alloc_from_iter( |
1310 | asm.inputs.iter().map(|&(_, ref input)| self.lower_expr_mut(input)), | |
1311 | ), | |
1312 | outputs_exprs: self | |
1313 | .arena | |
1314 | .alloc_from_iter(asm.outputs.iter().map(|out| self.lower_expr_mut(&out.expr))), | |
60c5eb7d | 1315 | }; |
ba9703b0 | 1316 | hir::ExprKind::LlvmInlineAsm(self.arena.alloc(hir_asm)) |
416331ca XL |
1317 | } |
1318 | ||
6a06907d XL |
1319 | fn lower_expr_field(&mut self, f: &ExprField) -> hir::ExprField<'hir> { |
1320 | hir::ExprField { | |
416331ca | 1321 | hir_id: self.next_id(), |
94222f64 | 1322 | ident: self.lower_ident(f.ident), |
dfeec247 | 1323 | expr: self.lower_expr(&f.expr), |
94222f64 | 1324 | span: self.lower_span(f.span), |
416331ca XL |
1325 | is_shorthand: f.is_shorthand, |
1326 | } | |
1327 | } | |
1328 | ||
dfeec247 | 1329 | fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> { |
416331ca | 1330 | match self.generator_kind { |
dfeec247 | 1331 | Some(hir::GeneratorKind::Gen) => {} |
e74abb32 | 1332 | Some(hir::GeneratorKind::Async(_)) => { |
dfeec247 | 1333 | struct_span_err!( |
416331ca XL |
1334 | self.sess, |
1335 | span, | |
1336 | E0727, | |
dfeec247 XL |
1337 | "`async` generators are not yet supported" |
1338 | ) | |
1339 | .emit(); | |
dfeec247 | 1340 | } |
416331ca XL |
1341 | None => self.generator_kind = Some(hir::GeneratorKind::Gen), |
1342 | } | |
1343 | ||
dfeec247 XL |
1344 | let expr = |
1345 | opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span)); | |
416331ca | 1346 | |
dfeec247 | 1347 | hir::ExprKind::Yield(expr, hir::YieldSource::Yield) |
416331ca XL |
1348 | } |
1349 | ||
1350 | /// Desugar `ExprForLoop` from: `[opt_ident]: for <pat> in <head> <body>` into: | |
1351 | /// ```rust | |
1352 | /// { | |
3c0e092e | 1353 | /// let result = match IntoIterator::into_iter(<head>) { |
416331ca XL |
1354 | /// mut iter => { |
1355 | /// [opt_ident]: loop { | |
3c0e092e XL |
1356 | /// match Iterator::next(&mut iter) { |
1357 | /// None => break, | |
1358 | /// Some(<pat>) => <body>, | |
416331ca | 1359 | /// }; |
416331ca XL |
1360 | /// } |
1361 | /// } | |
1362 | /// }; | |
1363 | /// result | |
1364 | /// } | |
1365 | /// ``` | |
1366 | fn lower_expr_for( | |
1367 | &mut self, | |
1368 | e: &Expr, | |
1369 | pat: &Pat, | |
1370 | head: &Expr, | |
1371 | body: &Block, | |
1372 | opt_label: Option<Label>, | |
dfeec247 | 1373 | ) -> hir::Expr<'hir> { |
3c0e092e XL |
1374 | let head = self.lower_expr_mut(head); |
1375 | let pat = self.lower_pat(pat); | |
1376 | let for_span = | |
1377 | self.mark_span_with_reason(DesugaringKind::ForLoop, self.lower_span(e.span), None); | |
1378 | let head_span = self.mark_span_with_reason(DesugaringKind::ForLoop, head.span, None); | |
1379 | let pat_span = self.mark_span_with_reason(DesugaringKind::ForLoop, pat.span, None); | |
416331ca | 1380 | |
3c0e092e XL |
1381 | // `None => break` |
1382 | let none_arm = { | |
416331ca | 1383 | let break_expr = |
3c0e092e XL |
1384 | self.with_loop_scope(e.id, |this| this.expr_break_alloc(for_span, ThinVec::new())); |
1385 | let pat = self.pat_none(for_span); | |
e74abb32 | 1386 | self.arm(pat, break_expr) |
416331ca XL |
1387 | }; |
1388 | ||
3c0e092e XL |
1389 | // Some(<pat>) => <body>, |
1390 | let some_arm = { | |
1391 | let some_pat = self.pat_some(pat_span, pat); | |
1392 | let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false)); | |
1393 | let body_expr = self.arena.alloc(self.expr_block(body_block, ThinVec::new())); | |
1394 | self.arm(some_pat, body_expr) | |
1395 | }; | |
1396 | ||
416331ca | 1397 | // `mut iter` |
3c0e092e | 1398 | let iter = Ident::with_dummy_span(sym::iter); |
dfeec247 | 1399 | let (iter_pat, iter_pat_nid) = |
3c0e092e | 1400 | self.pat_ident_binding_mode(head_span, iter, hir::BindingAnnotation::Mutable); |
416331ca | 1401 | |
3c0e092e | 1402 | // `match Iterator::next(&mut iter) { ... }` |
416331ca | 1403 | let match_expr = { |
3c0e092e XL |
1404 | let iter = self.expr_ident(head_span, iter, iter_pat_nid); |
1405 | let ref_mut_iter = self.expr_mut_addr_of(head_span, iter); | |
3dfed10e | 1406 | let next_expr = self.expr_call_lang_item_fn( |
3c0e092e | 1407 | head_span, |
3dfed10e XL |
1408 | hir::LangItem::IteratorNext, |
1409 | arena_vec![self; ref_mut_iter], | |
a2a8927a | 1410 | None, |
3dfed10e | 1411 | ); |
3c0e092e | 1412 | let arms = arena_vec![self; none_arm, some_arm]; |
416331ca | 1413 | |
3c0e092e | 1414 | self.expr_match(head_span, next_expr, arms, hir::MatchSource::ForLoopDesugar) |
416331ca | 1415 | }; |
3c0e092e | 1416 | let match_stmt = self.stmt_expr(for_span, match_expr); |
416331ca | 1417 | |
3c0e092e | 1418 | let loop_block = self.block_all(for_span, arena_vec![self; match_stmt], None); |
416331ca XL |
1419 | |
1420 | // `[opt_ident]: loop { ... }` | |
5869c6ff XL |
1421 | let kind = hir::ExprKind::Loop( |
1422 | loop_block, | |
94222f64 | 1423 | self.lower_label(opt_label), |
5869c6ff | 1424 | hir::LoopSource::ForLoop, |
3c0e092e | 1425 | self.lower_span(for_span.with_hi(head.span.hi())), |
5869c6ff | 1426 | ); |
3c0e092e XL |
1427 | let loop_expr = |
1428 | self.arena.alloc(hir::Expr { hir_id: self.lower_node_id(e.id), kind, span: for_span }); | |
416331ca XL |
1429 | |
1430 | // `mut iter => { ... }` | |
e74abb32 | 1431 | let iter_arm = self.arm(iter_pat, loop_expr); |
416331ca XL |
1432 | |
1433 | // `match ::std::iter::IntoIterator::into_iter(<head>) { ... }` | |
1434 | let into_iter_expr = { | |
3dfed10e | 1435 | self.expr_call_lang_item_fn( |
3c0e092e | 1436 | head_span, |
3dfed10e XL |
1437 | hir::LangItem::IntoIterIntoIter, |
1438 | arena_vec![self; head], | |
a2a8927a | 1439 | None, |
3dfed10e | 1440 | ) |
416331ca XL |
1441 | }; |
1442 | ||
dfeec247 | 1443 | let match_expr = self.arena.alloc(self.expr_match( |
3c0e092e | 1444 | for_span, |
416331ca | 1445 | into_iter_expr, |
dfeec247 | 1446 | arena_vec![self; iter_arm], |
416331ca XL |
1447 | hir::MatchSource::ForLoopDesugar, |
1448 | )); | |
1449 | ||
29967ef6 XL |
1450 | let attrs: Vec<_> = e.attrs.iter().map(|a| self.lower_attr(a)).collect(); |
1451 | ||
416331ca XL |
1452 | // This is effectively `{ let _result = ...; _result }`. |
1453 | // The construct was introduced in #21984 and is necessary to make sure that | |
1454 | // temporaries in the `head` expression are dropped and do not leak to the | |
1455 | // surrounding scope of the `match` since the `match` is not a terminating scope. | |
1456 | // | |
1457 | // Also, add the attributes to the outer returned expr node. | |
3c0e092e | 1458 | self.expr_drop_temps_mut(for_span, match_expr, attrs.into()) |
416331ca XL |
1459 | } |
1460 | ||
1461 | /// Desugar `ExprKind::Try` from: `<expr>?` into: | |
1462 | /// ```rust | |
136023e0 XL |
1463 | /// match Try::branch(<expr>) { |
1464 | /// ControlFlow::Continue(val) => #[allow(unreachable_code)] val,, | |
1465 | /// ControlFlow::Break(residual) => | |
1466 | /// #[allow(unreachable_code)] | |
1467 | /// // If there is an enclosing `try {...}`: | |
1468 | /// break 'catch_target Try::from_residual(residual), | |
1469 | /// // Otherwise: | |
1470 | /// return Try::from_residual(residual), | |
416331ca XL |
1471 | /// } |
1472 | /// ``` | |
dfeec247 | 1473 | fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> { |
416331ca XL |
1474 | let unstable_span = self.mark_span_with_reason( |
1475 | DesugaringKind::QuestionMark, | |
1476 | span, | |
1477 | self.allow_try_trait.clone(), | |
1478 | ); | |
1479 | let try_span = self.sess.source_map().end_point(span); | |
1480 | let try_span = self.mark_span_with_reason( | |
1481 | DesugaringKind::QuestionMark, | |
1482 | try_span, | |
1483 | self.allow_try_trait.clone(), | |
1484 | ); | |
1485 | ||
17df50a5 | 1486 | // `Try::branch(<expr>)` |
416331ca XL |
1487 | let scrutinee = { |
1488 | // expand <expr> | |
dfeec247 | 1489 | let sub_expr = self.lower_expr_mut(sub_expr); |
416331ca | 1490 | |
3dfed10e XL |
1491 | self.expr_call_lang_item_fn( |
1492 | unstable_span, | |
17df50a5 | 1493 | hir::LangItem::TryTraitBranch, |
3dfed10e | 1494 | arena_vec![self; sub_expr], |
a2a8927a | 1495 | None, |
3dfed10e | 1496 | ) |
416331ca XL |
1497 | }; |
1498 | ||
1499 | // `#[allow(unreachable_code)]` | |
1500 | let attr = { | |
1501 | // `allow(unreachable_code)` | |
1502 | let allow = { | |
94222f64 XL |
1503 | let allow_ident = Ident::new(sym::allow, self.lower_span(span)); |
1504 | let uc_ident = Ident::new(sym::unreachable_code, self.lower_span(span)); | |
416331ca XL |
1505 | let uc_nested = attr::mk_nested_word_item(uc_ident); |
1506 | attr::mk_list_item(allow_ident, vec![uc_nested]) | |
1507 | }; | |
1508 | attr::mk_attr_outer(allow) | |
1509 | }; | |
1510 | let attrs = vec![attr]; | |
1511 | ||
17df50a5 XL |
1512 | // `ControlFlow::Continue(val) => #[allow(unreachable_code)] val,` |
1513 | let continue_arm = { | |
e1599b0c | 1514 | let val_ident = Ident::with_dummy_span(sym::val); |
416331ca | 1515 | let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident); |
dfeec247 | 1516 | let val_expr = self.arena.alloc(self.expr_ident_with_attrs( |
416331ca XL |
1517 | span, |
1518 | val_ident, | |
1519 | val_pat_nid, | |
1520 | ThinVec::from(attrs.clone()), | |
1521 | )); | |
17df50a5 XL |
1522 | let continue_pat = self.pat_cf_continue(unstable_span, val_pat); |
1523 | self.arm(continue_pat, val_expr) | |
416331ca XL |
1524 | }; |
1525 | ||
17df50a5 XL |
1526 | // `ControlFlow::Break(residual) => |
1527 | // #[allow(unreachable_code)] | |
1528 | // return Try::from_residual(residual),` | |
1529 | let break_arm = { | |
1530 | let residual_ident = Ident::with_dummy_span(sym::residual); | |
1531 | let (residual_local, residual_local_nid) = self.pat_ident(try_span, residual_ident); | |
1532 | let residual_expr = self.expr_ident_mut(try_span, residual_ident, residual_local_nid); | |
1533 | let from_residual_expr = self.wrap_in_try_constructor( | |
1534 | hir::LangItem::TryTraitFromResidual, | |
1535 | try_span, | |
1536 | self.arena.alloc(residual_expr), | |
29967ef6 | 1537 | unstable_span, |
3dfed10e | 1538 | ); |
416331ca | 1539 | let thin_attrs = ThinVec::from(attrs); |
c295e0f8 | 1540 | let ret_expr = if let Some(catch_node) = self.catch_scope { |
416331ca | 1541 | let target_id = Ok(self.lower_node_id(catch_node)); |
dfeec247 | 1542 | self.arena.alloc(self.expr( |
416331ca XL |
1543 | try_span, |
1544 | hir::ExprKind::Break( | |
dfeec247 | 1545 | hir::Destination { label: None, target_id }, |
17df50a5 | 1546 | Some(from_residual_expr), |
416331ca XL |
1547 | ), |
1548 | thin_attrs, | |
1549 | )) | |
1550 | } else { | |
dfeec247 XL |
1551 | self.arena.alloc(self.expr( |
1552 | try_span, | |
17df50a5 | 1553 | hir::ExprKind::Ret(Some(from_residual_expr)), |
dfeec247 XL |
1554 | thin_attrs, |
1555 | )) | |
416331ca XL |
1556 | }; |
1557 | ||
17df50a5 XL |
1558 | let break_pat = self.pat_cf_break(try_span, residual_local); |
1559 | self.arm(break_pat, ret_expr) | |
416331ca XL |
1560 | }; |
1561 | ||
1562 | hir::ExprKind::Match( | |
1563 | scrutinee, | |
17df50a5 | 1564 | arena_vec![self; break_arm, continue_arm], |
416331ca XL |
1565 | hir::MatchSource::TryDesugar, |
1566 | ) | |
1567 | } | |
1568 | ||
1569 | // ========================================================================= | |
1570 | // Helper methods for building HIR. | |
1571 | // ========================================================================= | |
1572 | ||
416331ca XL |
1573 | /// Wrap the given `expr` in a terminating scope using `hir::ExprKind::DropTemps`. |
1574 | /// | |
1575 | /// In terms of drop order, it has the same effect as wrapping `expr` in | |
1576 | /// `{ let _t = $expr; _t }` but should provide better compile-time performance. | |
1577 | /// | |
1578 | /// The drop order can be important in e.g. `if expr { .. }`. | |
e1599b0c | 1579 | pub(super) fn expr_drop_temps( |
416331ca XL |
1580 | &mut self, |
1581 | span: Span, | |
dfeec247 XL |
1582 | expr: &'hir hir::Expr<'hir>, |
1583 | attrs: AttrVec, | |
1584 | ) -> &'hir hir::Expr<'hir> { | |
1585 | self.arena.alloc(self.expr_drop_temps_mut(span, expr, attrs)) | |
1586 | } | |
1587 | ||
1588 | pub(super) fn expr_drop_temps_mut( | |
1589 | &mut self, | |
1590 | span: Span, | |
1591 | expr: &'hir hir::Expr<'hir>, | |
1592 | attrs: AttrVec, | |
1593 | ) -> hir::Expr<'hir> { | |
416331ca XL |
1594 | self.expr(span, hir::ExprKind::DropTemps(expr), attrs) |
1595 | } | |
1596 | ||
1597 | fn expr_match( | |
1598 | &mut self, | |
1599 | span: Span, | |
dfeec247 XL |
1600 | arg: &'hir hir::Expr<'hir>, |
1601 | arms: &'hir [hir::Arm<'hir>], | |
416331ca | 1602 | source: hir::MatchSource, |
dfeec247 | 1603 | ) -> hir::Expr<'hir> { |
416331ca XL |
1604 | self.expr(span, hir::ExprKind::Match(arg, arms, source), ThinVec::new()) |
1605 | } | |
1606 | ||
94222f64 | 1607 | fn expr_break(&mut self, span: Span, attrs: AttrVec) -> hir::Expr<'hir> { |
416331ca | 1608 | let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None); |
94222f64 XL |
1609 | self.expr(span, expr_break, attrs) |
1610 | } | |
1611 | ||
1612 | fn expr_break_alloc(&mut self, span: Span, attrs: AttrVec) -> &'hir hir::Expr<'hir> { | |
1613 | let expr_break = self.expr_break(span, attrs); | |
1614 | self.arena.alloc(expr_break) | |
416331ca XL |
1615 | } |
1616 | ||
dfeec247 | 1617 | fn expr_mut_addr_of(&mut self, span: Span, e: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> { |
60c5eb7d XL |
1618 | self.expr( |
1619 | span, | |
dfeec247 | 1620 | hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, e), |
60c5eb7d XL |
1621 | ThinVec::new(), |
1622 | ) | |
416331ca XL |
1623 | } |
1624 | ||
dfeec247 XL |
1625 | fn expr_unit(&mut self, sp: Span) -> &'hir hir::Expr<'hir> { |
1626 | self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[]), ThinVec::new())) | |
416331ca XL |
1627 | } |
1628 | ||
ba9703b0 XL |
1629 | fn expr_call_mut( |
1630 | &mut self, | |
1631 | span: Span, | |
1632 | e: &'hir hir::Expr<'hir>, | |
1633 | args: &'hir [hir::Expr<'hir>], | |
1634 | ) -> hir::Expr<'hir> { | |
1635 | self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new()) | |
1636 | } | |
1637 | ||
416331ca XL |
1638 | fn expr_call( |
1639 | &mut self, | |
1640 | span: Span, | |
dfeec247 XL |
1641 | e: &'hir hir::Expr<'hir>, |
1642 | args: &'hir [hir::Expr<'hir>], | |
1643 | ) -> &'hir hir::Expr<'hir> { | |
ba9703b0 | 1644 | self.arena.alloc(self.expr_call_mut(span, e, args)) |
416331ca XL |
1645 | } |
1646 | ||
3dfed10e | 1647 | fn expr_call_lang_item_fn_mut( |
416331ca XL |
1648 | &mut self, |
1649 | span: Span, | |
3dfed10e | 1650 | lang_item: hir::LangItem, |
dfeec247 | 1651 | args: &'hir [hir::Expr<'hir>], |
a2a8927a | 1652 | hir_id: Option<hir::HirId>, |
ba9703b0 | 1653 | ) -> hir::Expr<'hir> { |
a2a8927a XL |
1654 | let path = |
1655 | self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new(), hir_id)); | |
ba9703b0 XL |
1656 | self.expr_call_mut(span, path, args) |
1657 | } | |
1658 | ||
3dfed10e | 1659 | fn expr_call_lang_item_fn( |
ba9703b0 XL |
1660 | &mut self, |
1661 | span: Span, | |
3dfed10e | 1662 | lang_item: hir::LangItem, |
ba9703b0 | 1663 | args: &'hir [hir::Expr<'hir>], |
a2a8927a | 1664 | hir_id: Option<hir::HirId>, |
ba9703b0 | 1665 | ) -> &'hir hir::Expr<'hir> { |
a2a8927a | 1666 | self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args, hir_id)) |
416331ca XL |
1667 | } |
1668 | ||
3dfed10e | 1669 | fn expr_lang_item_path( |
416331ca XL |
1670 | &mut self, |
1671 | span: Span, | |
3dfed10e | 1672 | lang_item: hir::LangItem, |
dfeec247 | 1673 | attrs: AttrVec, |
a2a8927a | 1674 | hir_id: Option<hir::HirId>, |
dfeec247 | 1675 | ) -> hir::Expr<'hir> { |
94222f64 XL |
1676 | self.expr( |
1677 | span, | |
a2a8927a | 1678 | hir::ExprKind::Path(hir::QPath::LangItem(lang_item, self.lower_span(span), hir_id)), |
94222f64 XL |
1679 | attrs, |
1680 | ) | |
416331ca XL |
1681 | } |
1682 | ||
dfeec247 XL |
1683 | pub(super) fn expr_ident( |
1684 | &mut self, | |
1685 | sp: Span, | |
1686 | ident: Ident, | |
1687 | binding: hir::HirId, | |
1688 | ) -> &'hir hir::Expr<'hir> { | |
1689 | self.arena.alloc(self.expr_ident_mut(sp, ident, binding)) | |
1690 | } | |
1691 | ||
1692 | pub(super) fn expr_ident_mut( | |
1693 | &mut self, | |
1694 | sp: Span, | |
1695 | ident: Ident, | |
1696 | binding: hir::HirId, | |
1697 | ) -> hir::Expr<'hir> { | |
416331ca XL |
1698 | self.expr_ident_with_attrs(sp, ident, binding, ThinVec::new()) |
1699 | } | |
1700 | ||
1701 | fn expr_ident_with_attrs( | |
1702 | &mut self, | |
1703 | span: Span, | |
1704 | ident: Ident, | |
1705 | binding: hir::HirId, | |
dfeec247 XL |
1706 | attrs: AttrVec, |
1707 | ) -> hir::Expr<'hir> { | |
416331ca XL |
1708 | let expr_path = hir::ExprKind::Path(hir::QPath::Resolved( |
1709 | None, | |
dfeec247 | 1710 | self.arena.alloc(hir::Path { |
94222f64 | 1711 | span: self.lower_span(span), |
416331ca | 1712 | res: Res::Local(binding), |
dfeec247 | 1713 | segments: arena_vec![self; hir::PathSegment::from_ident(ident)], |
416331ca XL |
1714 | }), |
1715 | )); | |
1716 | ||
1717 | self.expr(span, expr_path, attrs) | |
1718 | } | |
1719 | ||
dfeec247 | 1720 | fn expr_unsafe(&mut self, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> { |
416331ca XL |
1721 | let hir_id = self.next_id(); |
1722 | let span = expr.span; | |
1723 | self.expr( | |
1724 | span, | |
dfeec247 XL |
1725 | hir::ExprKind::Block( |
1726 | self.arena.alloc(hir::Block { | |
1727 | stmts: &[], | |
1728 | expr: Some(expr), | |
1729 | hir_id, | |
1730 | rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated), | |
94222f64 | 1731 | span: self.lower_span(span), |
dfeec247 XL |
1732 | targeted_by_break: false, |
1733 | }), | |
1734 | None, | |
1735 | ), | |
416331ca XL |
1736 | ThinVec::new(), |
1737 | ) | |
1738 | } | |
1739 | ||
dfeec247 XL |
1740 | fn expr_block_empty(&mut self, span: Span) -> &'hir hir::Expr<'hir> { |
1741 | let blk = self.block_all(span, &[], None); | |
1742 | let expr = self.expr_block(blk, ThinVec::new()); | |
1743 | self.arena.alloc(expr) | |
416331ca XL |
1744 | } |
1745 | ||
dfeec247 XL |
1746 | pub(super) fn expr_block( |
1747 | &mut self, | |
1748 | b: &'hir hir::Block<'hir>, | |
1749 | attrs: AttrVec, | |
1750 | ) -> hir::Expr<'hir> { | |
416331ca XL |
1751 | self.expr(b.span, hir::ExprKind::Block(b, None), attrs) |
1752 | } | |
1753 | ||
1754 | pub(super) fn expr( | |
1755 | &mut self, | |
1756 | span: Span, | |
dfeec247 XL |
1757 | kind: hir::ExprKind<'hir>, |
1758 | attrs: AttrVec, | |
1759 | ) -> hir::Expr<'hir> { | |
6a06907d XL |
1760 | let hir_id = self.next_id(); |
1761 | self.lower_attrs(hir_id, &attrs); | |
94222f64 | 1762 | hir::Expr { hir_id, kind, span: self.lower_span(span) } |
416331ca XL |
1763 | } |
1764 | ||
6a06907d XL |
1765 | fn expr_field( |
1766 | &mut self, | |
1767 | ident: Ident, | |
1768 | expr: &'hir hir::Expr<'hir>, | |
1769 | span: Span, | |
1770 | ) -> hir::ExprField<'hir> { | |
94222f64 XL |
1771 | hir::ExprField { |
1772 | hir_id: self.next_id(), | |
1773 | ident, | |
1774 | span: self.lower_span(span), | |
1775 | expr, | |
1776 | is_shorthand: false, | |
1777 | } | |
416331ca XL |
1778 | } |
1779 | ||
dfeec247 | 1780 | fn arm(&mut self, pat: &'hir hir::Pat<'hir>, expr: &'hir hir::Expr<'hir>) -> hir::Arm<'hir> { |
94222f64 XL |
1781 | hir::Arm { |
1782 | hir_id: self.next_id(), | |
1783 | pat, | |
1784 | guard: None, | |
1785 | span: self.lower_span(expr.span), | |
1786 | body: expr, | |
1787 | } | |
416331ca XL |
1788 | } |
1789 | } |