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9fa01778 | 1 | //! A different sort of visitor for walking fn bodies. Unlike the |
1a4d82fc JJ |
2 | //! normal visitor, which just walks the entire body in one shot, the |
3 | //! `ExprUseVisitor` determines how expressions are being used. | |
4 | ||
064997fb FG |
5 | use std::slice::from_ref; |
6 | ||
94222f64 | 7 | use hir::def::DefKind; |
064997fb | 8 | use hir::Expr; |
60c5eb7d | 9 | // Export these here so that Clippy can use them. |
6a06907d | 10 | pub use rustc_middle::hir::place::{Place, PlaceBase, PlaceWithHirId, Projection}; |
60c5eb7d | 11 | |
6a06907d | 12 | use rustc_data_structures::fx::FxIndexMap; |
dfeec247 XL |
13 | use rustc_hir as hir; |
14 | use rustc_hir::def::Res; | |
f9f354fc | 15 | use rustc_hir::def_id::LocalDefId; |
dfeec247 | 16 | use rustc_hir::PatKind; |
3dfed10e | 17 | use rustc_index::vec::Idx; |
74b04a01 | 18 | use rustc_infer::infer::InferCtxt; |
3dfed10e | 19 | use rustc_middle::hir::place::ProjectionKind; |
6a06907d | 20 | use rustc_middle::mir::FakeReadCause; |
94222f64 | 21 | use rustc_middle::ty::{self, adjustment, AdtKind, Ty, TyCtxt}; |
3dfed10e | 22 | use rustc_target::abi::VariantIdx; |
923072b8 | 23 | use ty::BorrowKind::ImmBorrow; |
60c5eb7d XL |
24 | |
25 | use crate::mem_categorization as mc; | |
1a4d82fc | 26 | |
1a4d82fc JJ |
27 | /// This trait defines the callbacks you can expect to receive when |
28 | /// employing the ExprUseVisitor. | |
29 | pub trait Delegate<'tcx> { | |
94222f64 XL |
30 | /// The value found at `place` is moved, depending |
31 | /// on `mode`. Where `diag_expr_id` is the id used for diagnostics for `place`. | |
32 | /// | |
33 | /// Use of a `Copy` type in a ByValue context is considered a use | |
34 | /// by `ImmBorrow` and `borrow` is called instead. This is because | |
35 | /// a shared borrow is the "minimum access" that would be needed | |
36 | /// to perform a copy. | |
37 | /// | |
38 | /// | |
39 | /// The parameter `diag_expr_id` indicates the HIR id that ought to be used for | |
40 | /// diagnostics. Around pattern matching such as `let pat = expr`, the diagnostic | |
41 | /// id will be the id of the expression `expr` but the place itself will have | |
42 | /// the id of the binding in the pattern `pat`. | |
136023e0 | 43 | fn consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId); |
1a4d82fc | 44 | |
94222f64 XL |
45 | /// The value found at `place` is being borrowed with kind `bk`. |
46 | /// `diag_expr_id` is the id used for diagnostics (see `consume` for more details). | |
29967ef6 XL |
47 | fn borrow( |
48 | &mut self, | |
49 | place_with_id: &PlaceWithHirId<'tcx>, | |
50 | diag_expr_id: hir::HirId, | |
51 | bk: ty::BorrowKind, | |
52 | ); | |
53 | ||
5e7ed085 FG |
54 | /// The value found at `place` is being copied. |
55 | /// `diag_expr_id` is the id used for diagnostics (see `consume` for more details). | |
56 | fn copy(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) { | |
57 | // In most cases, copying data from `x` is equivalent to doing `*&x`, so by default | |
58 | // we treat a copy of `x` as a borrow of `x`. | |
59 | self.borrow(place_with_id, diag_expr_id, ty::BorrowKind::ImmBorrow) | |
60 | } | |
61 | ||
94222f64 XL |
62 | /// The path at `assignee_place` is being assigned to. |
63 | /// `diag_expr_id` is the id used for diagnostics (see `consume` for more details). | |
29967ef6 | 64 | fn mutate(&mut self, assignee_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId); |
6a06907d | 65 | |
5e7ed085 FG |
66 | /// The path at `binding_place` is a binding that is being initialized. |
67 | /// | |
68 | /// This covers cases such as `let x = 42;` | |
69 | fn bind(&mut self, binding_place: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) { | |
70 | // Bindings can normally be treated as a regular assignment, so by default we | |
71 | // forward this to the mutate callback. | |
72 | self.mutate(binding_place, diag_expr_id) | |
73 | } | |
74 | ||
94222f64 | 75 | /// The `place` should be a fake read because of specified `cause`. |
923072b8 FG |
76 | fn fake_read( |
77 | &mut self, | |
78 | place_with_id: &PlaceWithHirId<'tcx>, | |
79 | cause: FakeReadCause, | |
80 | diag_expr_id: hir::HirId, | |
81 | ); | |
1a4d82fc JJ |
82 | } |
83 | ||
c34b1796 | 84 | #[derive(Copy, Clone, PartialEq, Debug)] |
136023e0 | 85 | enum ConsumeMode { |
94222f64 XL |
86 | /// reference to x where x has a type that copies |
87 | Copy, | |
88 | /// reference to x where x has a type that moves | |
89 | Move, | |
1a4d82fc JJ |
90 | } |
91 | ||
94222f64 XL |
92 | /// The ExprUseVisitor type |
93 | /// | |
94 | /// This is the code that actually walks the tree. | |
dc9dc135 XL |
95 | pub struct ExprUseVisitor<'a, 'tcx> { |
96 | mc: mc::MemCategorizationContext<'a, 'tcx>, | |
fc512014 | 97 | body_owner: LocalDefId, |
0531ce1d | 98 | delegate: &'a mut dyn Delegate<'tcx>, |
1a4d82fc JJ |
99 | } |
100 | ||
94222f64 XL |
101 | /// If the MC results in an error, it's because the type check |
102 | /// failed (or will fail, when the error is uncovered and reported | |
103 | /// during writeback). In this case, we just ignore this part of the | |
104 | /// code. | |
105 | /// | |
106 | /// Note that this macro appears similar to try!(), but, unlike try!(), | |
107 | /// it does not propagate the error. | |
1a4d82fc | 108 | macro_rules! return_if_err { |
dfeec247 | 109 | ($inp: expr) => { |
1a4d82fc JJ |
110 | match $inp { |
111 | Ok(v) => v, | |
c1a9b12d SL |
112 | Err(()) => { |
113 | debug!("mc reported err"); | |
dfeec247 | 114 | return; |
c1a9b12d | 115 | } |
1a4d82fc | 116 | } |
dfeec247 | 117 | }; |
1a4d82fc JJ |
118 | } |
119 | ||
dc9dc135 | 120 | impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> { |
abe05a73 XL |
121 | /// Creates the ExprUseVisitor, configuring it with the various options provided: |
122 | /// | |
123 | /// - `delegate` -- who receives the callbacks | |
124 | /// - `param_env` --- parameter environment for trait lookups (esp. pertaining to `Copy`) | |
3dfed10e | 125 | /// - `typeck_results` --- typeck results for the code being analyzed |
dc9dc135 | 126 | pub fn new( |
dc9dc135 | 127 | delegate: &'a mut (dyn Delegate<'tcx> + 'a), |
2b03887a | 128 | infcx: &'a InferCtxt<'tcx>, |
f9f354fc | 129 | body_owner: LocalDefId, |
dc9dc135 | 130 | param_env: ty::ParamEnv<'tcx>, |
3dfed10e | 131 | typeck_results: &'a ty::TypeckResults<'tcx>, |
dc9dc135 | 132 | ) -> Self { |
a7813a04 | 133 | ExprUseVisitor { |
3dfed10e | 134 | mc: mc::MemCategorizationContext::new(infcx, param_env, body_owner, typeck_results), |
fc512014 | 135 | body_owner, |
7cac9316 | 136 | delegate, |
a7813a04 | 137 | } |
1a4d82fc JJ |
138 | } |
139 | ||
94222f64 | 140 | #[instrument(skip(self), level = "debug")] |
dfeec247 | 141 | pub fn consume_body(&mut self, body: &hir::Body<'_>) { |
dfeec247 | 142 | for param in body.params { |
c295e0f8 | 143 | let param_ty = return_if_err!(self.mc.pat_ty_adjusted(param.pat)); |
e1599b0c | 144 | debug!("consume_body: param_ty = {:?}", param_ty); |
1a4d82fc | 145 | |
60c5eb7d | 146 | let param_place = self.mc.cat_rvalue(param.hir_id, param.pat.span, param_ty); |
1a4d82fc | 147 | |
c295e0f8 | 148 | self.walk_irrefutable_pat(¶m_place, param.pat); |
1a4d82fc | 149 | } |
32a655c1 SL |
150 | |
151 | self.consume_expr(&body.value); | |
1a4d82fc JJ |
152 | } |
153 | ||
dc9dc135 | 154 | fn tcx(&self) -> TyCtxt<'tcx> { |
60c5eb7d | 155 | self.mc.tcx() |
1a4d82fc JJ |
156 | } |
157 | ||
29967ef6 | 158 | fn delegate_consume(&mut self, place_with_id: &PlaceWithHirId<'tcx>, diag_expr_id: hir::HirId) { |
136023e0 | 159 | delegate_consume(&self.mc, self.delegate, place_with_id, diag_expr_id) |
1a4d82fc JJ |
160 | } |
161 | ||
dfeec247 | 162 | fn consume_exprs(&mut self, exprs: &[hir::Expr<'_>]) { |
85aaf69f | 163 | for expr in exprs { |
c295e0f8 | 164 | self.consume_expr(expr); |
1a4d82fc JJ |
165 | } |
166 | } | |
167 | ||
dfeec247 | 168 | pub fn consume_expr(&mut self, expr: &hir::Expr<'_>) { |
62682a34 | 169 | debug!("consume_expr(expr={:?})", expr); |
1a4d82fc | 170 | |
f035d41b | 171 | let place_with_id = return_if_err!(self.mc.cat_expr(expr)); |
29967ef6 | 172 | self.delegate_consume(&place_with_id, place_with_id.hir_id); |
1a4d82fc JJ |
173 | self.walk_expr(expr); |
174 | } | |
175 | ||
dfeec247 | 176 | fn mutate_expr(&mut self, expr: &hir::Expr<'_>) { |
f035d41b | 177 | let place_with_id = return_if_err!(self.mc.cat_expr(expr)); |
29967ef6 | 178 | self.delegate.mutate(&place_with_id, place_with_id.hir_id); |
1a4d82fc JJ |
179 | self.walk_expr(expr); |
180 | } | |
181 | ||
dfeec247 | 182 | fn borrow_expr(&mut self, expr: &hir::Expr<'_>, bk: ty::BorrowKind) { |
e74abb32 | 183 | debug!("borrow_expr(expr={:?}, bk={:?})", expr, bk); |
1a4d82fc | 184 | |
f035d41b | 185 | let place_with_id = return_if_err!(self.mc.cat_expr(expr)); |
29967ef6 | 186 | self.delegate.borrow(&place_with_id, place_with_id.hir_id, bk); |
1a4d82fc | 187 | |
1a4d82fc JJ |
188 | self.walk_expr(expr) |
189 | } | |
190 | ||
dfeec247 | 191 | fn select_from_expr(&mut self, expr: &hir::Expr<'_>) { |
1a4d82fc JJ |
192 | self.walk_expr(expr) |
193 | } | |
194 | ||
dfeec247 | 195 | pub fn walk_expr(&mut self, expr: &hir::Expr<'_>) { |
62682a34 | 196 | debug!("walk_expr(expr={:?})", expr); |
1a4d82fc JJ |
197 | |
198 | self.walk_adjustment(expr); | |
199 | ||
e74abb32 | 200 | match expr.kind { |
dfeec247 | 201 | hir::ExprKind::Path(_) => {} |
1a4d82fc | 202 | |
c295e0f8 | 203 | hir::ExprKind::Type(subexpr, _) => self.walk_expr(subexpr), |
9cc50fc6 | 204 | |
c295e0f8 | 205 | hir::ExprKind::Unary(hir::UnOp::Deref, base) => { |
dfeec247 | 206 | // *base |
e74abb32 | 207 | self.select_from_expr(base); |
1a4d82fc JJ |
208 | } |
209 | ||
c295e0f8 | 210 | hir::ExprKind::Field(base, _) => { |
dfeec247 | 211 | // base.f |
e74abb32 | 212 | self.select_from_expr(base); |
1a4d82fc JJ |
213 | } |
214 | ||
c295e0f8 | 215 | hir::ExprKind::Index(lhs, rhs) => { |
dfeec247 | 216 | // lhs[rhs] |
e74abb32 XL |
217 | self.select_from_expr(lhs); |
218 | self.consume_expr(rhs); | |
1a4d82fc JJ |
219 | } |
220 | ||
c295e0f8 | 221 | hir::ExprKind::Call(callee, args) => { |
dfeec247 XL |
222 | // callee(args) |
223 | self.consume_expr(callee); | |
1a4d82fc JJ |
224 | self.consume_exprs(args); |
225 | } | |
226 | ||
f2b60f7d | 227 | hir::ExprKind::MethodCall(.., receiver, args, _) => { |
dfeec247 | 228 | // callee.m(args) |
f2b60f7d | 229 | self.consume_expr(receiver); |
1a4d82fc JJ |
230 | self.consume_exprs(args); |
231 | } | |
232 | ||
c295e0f8 | 233 | hir::ExprKind::Struct(_, fields, ref opt_with) => { |
9e0c209e | 234 | self.walk_struct_expr(fields, opt_with); |
1a4d82fc JJ |
235 | } |
236 | ||
c295e0f8 | 237 | hir::ExprKind::Tup(exprs) => { |
1a4d82fc JJ |
238 | self.consume_exprs(exprs); |
239 | } | |
240 | ||
5869c6ff | 241 | hir::ExprKind::If(ref cond_expr, ref then_expr, ref opt_else_expr) => { |
c295e0f8 XL |
242 | self.consume_expr(cond_expr); |
243 | self.consume_expr(then_expr); | |
5869c6ff | 244 | if let Some(ref else_expr) = *opt_else_expr { |
c295e0f8 | 245 | self.consume_expr(else_expr); |
5869c6ff XL |
246 | } |
247 | } | |
248 | ||
a2a8927a | 249 | hir::ExprKind::Let(hir::Let { pat, init, .. }) => { |
064997fb | 250 | self.walk_local(init, pat, None, |t| t.borrow_expr(init, ty::ImmBorrow)) |
94222f64 XL |
251 | } |
252 | ||
dfeec247 | 253 | hir::ExprKind::Match(ref discr, arms, _) => { |
c295e0f8 | 254 | let discr_place = return_if_err!(self.mc.cat_expr(discr)); |
487cf647 | 255 | return_if_err!(self.maybe_read_scrutinee( |
064997fb FG |
256 | discr, |
257 | discr_place.clone(), | |
258 | arms.iter().map(|arm| arm.pat), | |
487cf647 | 259 | )); |
1a4d82fc JJ |
260 | |
261 | // treatment of the discriminant is handled while walking the arms. | |
85aaf69f | 262 | for arm in arms { |
60c5eb7d | 263 | self.walk_arm(&discr_place, arm); |
1a4d82fc JJ |
264 | } |
265 | } | |
266 | ||
c295e0f8 | 267 | hir::ExprKind::Array(exprs) => { |
1a4d82fc JJ |
268 | self.consume_exprs(exprs); |
269 | } | |
270 | ||
dfeec247 XL |
271 | hir::ExprKind::AddrOf(_, m, ref base) => { |
272 | // &base | |
1a4d82fc JJ |
273 | // make sure that the thing we are pointing out stays valid |
274 | // for the lifetime `scope_r` of the resulting ptr: | |
e74abb32 | 275 | let bk = ty::BorrowKind::from_mutbl(m); |
c295e0f8 | 276 | self.borrow_expr(base, bk); |
1a4d82fc JJ |
277 | } |
278 | ||
c295e0f8 | 279 | hir::ExprKind::InlineAsm(asm) => { |
fc512014 | 280 | for (op, _op_sp) in asm.operands { |
f9f354fc | 281 | match op { |
04454e1e | 282 | hir::InlineAsmOperand::In { expr, .. } => self.consume_expr(expr), |
94222f64 XL |
283 | hir::InlineAsmOperand::Out { expr: Some(expr), .. } |
284 | | hir::InlineAsmOperand::InOut { expr, .. } => { | |
f9f354fc XL |
285 | self.mutate_expr(expr); |
286 | } | |
287 | hir::InlineAsmOperand::SplitInOut { in_expr, out_expr, .. } => { | |
288 | self.consume_expr(in_expr); | |
289 | if let Some(out_expr) = out_expr { | |
290 | self.mutate_expr(out_expr); | |
291 | } | |
292 | } | |
94222f64 | 293 | hir::InlineAsmOperand::Out { expr: None, .. } |
04454e1e FG |
294 | | hir::InlineAsmOperand::Const { .. } |
295 | | hir::InlineAsmOperand::SymFn { .. } | |
296 | | hir::InlineAsmOperand::SymStatic { .. } => {} | |
f9f354fc XL |
297 | } |
298 | } | |
299 | } | |
300 | ||
29967ef6 XL |
301 | hir::ExprKind::Continue(..) |
302 | | hir::ExprKind::Lit(..) | |
303 | | hir::ExprKind::ConstBlock(..) | |
304 | | hir::ExprKind::Err => {} | |
1a4d82fc | 305 | |
c295e0f8 | 306 | hir::ExprKind::Loop(blk, ..) => { |
e74abb32 | 307 | self.walk_block(blk); |
1a4d82fc JJ |
308 | } |
309 | ||
c295e0f8 | 310 | hir::ExprKind::Unary(_, lhs) => { |
e74abb32 | 311 | self.consume_expr(lhs); |
1a4d82fc JJ |
312 | } |
313 | ||
c295e0f8 | 314 | hir::ExprKind::Binary(_, lhs, rhs) => { |
e74abb32 XL |
315 | self.consume_expr(lhs); |
316 | self.consume_expr(rhs); | |
1a4d82fc JJ |
317 | } |
318 | ||
c295e0f8 | 319 | hir::ExprKind::Block(blk, _) => { |
e74abb32 | 320 | self.walk_block(blk); |
1a4d82fc JJ |
321 | } |
322 | ||
8faf50e0 | 323 | hir::ExprKind::Break(_, ref opt_expr) | hir::ExprKind::Ret(ref opt_expr) => { |
c295e0f8 | 324 | if let Some(expr) = *opt_expr { |
e74abb32 | 325 | self.consume_expr(expr); |
1a4d82fc JJ |
326 | } |
327 | } | |
328 | ||
c295e0f8 | 329 | hir::ExprKind::Assign(lhs, rhs, _) => { |
e74abb32 XL |
330 | self.mutate_expr(lhs); |
331 | self.consume_expr(rhs); | |
1a4d82fc JJ |
332 | } |
333 | ||
c295e0f8 | 334 | hir::ExprKind::Cast(base, _) => { |
e74abb32 | 335 | self.consume_expr(base); |
1a4d82fc JJ |
336 | } |
337 | ||
c295e0f8 | 338 | hir::ExprKind::DropTemps(expr) => { |
e74abb32 | 339 | self.consume_expr(expr); |
48663c56 XL |
340 | } |
341 | ||
c295e0f8 | 342 | hir::ExprKind::AssignOp(_, lhs, rhs) => { |
3dfed10e | 343 | if self.mc.typeck_results.is_method_call(expr) { |
7cac9316 XL |
344 | self.consume_expr(lhs); |
345 | } else { | |
e74abb32 | 346 | self.mutate_expr(lhs); |
b039eaaf | 347 | } |
e74abb32 | 348 | self.consume_expr(rhs); |
1a4d82fc JJ |
349 | } |
350 | ||
c295e0f8 | 351 | hir::ExprKind::Repeat(base, _) => { |
e74abb32 | 352 | self.consume_expr(base); |
1a4d82fc JJ |
353 | } |
354 | ||
487cf647 FG |
355 | hir::ExprKind::Closure(closure) => { |
356 | self.walk_captures(closure); | |
1a4d82fc JJ |
357 | } |
358 | ||
8faf50e0 | 359 | hir::ExprKind::Box(ref base) => { |
e74abb32 | 360 | self.consume_expr(base); |
1a4d82fc | 361 | } |
ea8adc8c | 362 | |
c295e0f8 | 363 | hir::ExprKind::Yield(value, _) => { |
e74abb32 | 364 | self.consume_expr(value); |
ea8adc8c | 365 | } |
1a4d82fc JJ |
366 | } |
367 | } | |
368 | ||
dfeec247 | 369 | fn walk_stmt(&mut self, stmt: &hir::Stmt<'_>) { |
e74abb32 | 370 | match stmt.kind { |
064997fb FG |
371 | hir::StmtKind::Local(hir::Local { pat, init: Some(expr), els, .. }) => { |
372 | self.walk_local(expr, pat, *els, |_| {}) | |
9fa01778 | 373 | } |
1a4d82fc | 374 | |
94222f64 XL |
375 | hir::StmtKind::Local(_) => {} |
376 | ||
9fa01778 | 377 | hir::StmtKind::Item(_) => { |
e1599b0c | 378 | // We don't visit nested items in this visitor, |
9fa01778 | 379 | // only the fn body we were given. |
1a4d82fc JJ |
380 | } |
381 | ||
dfeec247 | 382 | hir::StmtKind::Expr(ref expr) | hir::StmtKind::Semi(ref expr) => { |
c295e0f8 | 383 | self.consume_expr(expr); |
1a4d82fc | 384 | } |
1a4d82fc JJ |
385 | } |
386 | } | |
387 | ||
064997fb FG |
388 | fn maybe_read_scrutinee<'t>( |
389 | &mut self, | |
390 | discr: &Expr<'_>, | |
391 | discr_place: PlaceWithHirId<'tcx>, | |
392 | pats: impl Iterator<Item = &'t hir::Pat<'t>>, | |
487cf647 | 393 | ) -> Result<(), ()> { |
064997fb FG |
394 | // Matching should not always be considered a use of the place, hence |
395 | // discr does not necessarily need to be borrowed. | |
396 | // We only want to borrow discr if the pattern contain something other | |
397 | // than wildcards. | |
398 | let ExprUseVisitor { ref mc, body_owner: _, delegate: _ } = *self; | |
399 | let mut needs_to_be_read = false; | |
400 | for pat in pats { | |
487cf647 | 401 | mc.cat_pattern(discr_place.clone(), pat, |place, pat| { |
064997fb FG |
402 | match &pat.kind { |
403 | PatKind::Binding(.., opt_sub_pat) => { | |
404 | // If the opt_sub_pat is None, than the binding does not count as | |
405 | // a wildcard for the purpose of borrowing discr. | |
406 | if opt_sub_pat.is_none() { | |
407 | needs_to_be_read = true; | |
408 | } | |
409 | } | |
410 | PatKind::Path(qpath) => { | |
411 | // A `Path` pattern is just a name like `Foo`. This is either a | |
412 | // named constant or else it refers to an ADT variant | |
413 | ||
414 | let res = self.mc.typeck_results.qpath_res(qpath, pat.hir_id); | |
415 | match res { | |
416 | Res::Def(DefKind::Const, _) | Res::Def(DefKind::AssocConst, _) => { | |
417 | // Named constants have to be equated with the value | |
418 | // being matched, so that's a read of the value being matched. | |
419 | // | |
420 | // FIXME: We don't actually reads for ZSTs. | |
421 | needs_to_be_read = true; | |
422 | } | |
423 | _ => { | |
424 | // Otherwise, this is a struct/enum variant, and so it's | |
425 | // only a read if we need to read the discriminant. | |
426 | needs_to_be_read |= is_multivariant_adt(place.place.ty()); | |
427 | } | |
428 | } | |
429 | } | |
430 | PatKind::TupleStruct(..) | PatKind::Struct(..) | PatKind::Tuple(..) => { | |
431 | // For `Foo(..)`, `Foo { ... }` and `(...)` patterns, check if we are matching | |
432 | // against a multivariant enum or struct. In that case, we have to read | |
433 | // the discriminant. Otherwise this kind of pattern doesn't actually | |
434 | // read anything (we'll get invoked for the `...`, which may indeed | |
435 | // perform some reads). | |
436 | ||
437 | let place_ty = place.place.ty(); | |
438 | needs_to_be_read |= is_multivariant_adt(place_ty); | |
439 | } | |
440 | PatKind::Lit(_) | PatKind::Range(..) => { | |
441 | // If the PatKind is a Lit or a Range then we want | |
442 | // to borrow discr. | |
443 | needs_to_be_read = true; | |
444 | } | |
445 | PatKind::Or(_) | |
446 | | PatKind::Box(_) | |
447 | | PatKind::Slice(..) | |
448 | | PatKind::Ref(..) | |
449 | | PatKind::Wild => { | |
450 | // If the PatKind is Or, Box, Slice or Ref, the decision is made later | |
451 | // as these patterns contains subpatterns | |
452 | // If the PatKind is Wild, the decision is made based on the other patterns being | |
453 | // examined | |
454 | } | |
455 | } | |
487cf647 | 456 | })? |
064997fb FG |
457 | } |
458 | ||
459 | if needs_to_be_read { | |
460 | self.borrow_expr(discr, ty::ImmBorrow); | |
461 | } else { | |
462 | let closure_def_id = match discr_place.place.base { | |
463 | PlaceBase::Upvar(upvar_id) => Some(upvar_id.closure_expr_id), | |
464 | _ => None, | |
465 | }; | |
466 | ||
467 | self.delegate.fake_read( | |
468 | &discr_place, | |
469 | FakeReadCause::ForMatchedPlace(closure_def_id), | |
470 | discr_place.hir_id, | |
471 | ); | |
472 | ||
473 | // We always want to walk the discriminant. We want to make sure, for instance, | |
474 | // that the discriminant has been initialized. | |
475 | self.walk_expr(discr); | |
476 | } | |
487cf647 | 477 | Ok(()) |
064997fb FG |
478 | } |
479 | ||
480 | fn walk_local<F>( | |
481 | &mut self, | |
482 | expr: &hir::Expr<'_>, | |
483 | pat: &hir::Pat<'_>, | |
484 | els: Option<&hir::Block<'_>>, | |
485 | mut f: F, | |
486 | ) where | |
94222f64 XL |
487 | F: FnMut(&mut Self), |
488 | { | |
c295e0f8 XL |
489 | self.walk_expr(expr); |
490 | let expr_place = return_if_err!(self.mc.cat_expr(expr)); | |
94222f64 | 491 | f(self); |
064997fb | 492 | if let Some(els) = els { |
f2b60f7d | 493 | // borrowing because we need to test the discriminant |
487cf647 FG |
494 | return_if_err!(self.maybe_read_scrutinee( |
495 | expr, | |
496 | expr_place.clone(), | |
497 | from_ref(pat).iter() | |
498 | )); | |
064997fb FG |
499 | self.walk_block(els) |
500 | } | |
94222f64 | 501 | self.walk_irrefutable_pat(&expr_place, &pat); |
1a4d82fc JJ |
502 | } |
503 | ||
504 | /// Indicates that the value of `blk` will be consumed, meaning either copied or moved | |
505 | /// depending on its type. | |
dfeec247 | 506 | fn walk_block(&mut self, blk: &hir::Block<'_>) { |
532ac7d7 | 507 | debug!("walk_block(blk.hir_id={})", blk.hir_id); |
1a4d82fc | 508 | |
dfeec247 | 509 | for stmt in blk.stmts { |
92a42be0 | 510 | self.walk_stmt(stmt); |
1a4d82fc JJ |
511 | } |
512 | ||
85aaf69f | 513 | if let Some(ref tail_expr) = blk.expr { |
c295e0f8 | 514 | self.consume_expr(tail_expr); |
1a4d82fc JJ |
515 | } |
516 | } | |
517 | ||
a2a8927a | 518 | fn walk_struct_expr<'hir>( |
dfeec247 | 519 | &mut self, |
6a06907d | 520 | fields: &[hir::ExprField<'_>], |
dfeec247 XL |
521 | opt_with: &Option<&'hir hir::Expr<'_>>, |
522 | ) { | |
1a4d82fc | 523 | // Consume the expressions supplying values for each field. |
85aaf69f | 524 | for field in fields { |
c295e0f8 | 525 | self.consume_expr(field.expr); |
487cf647 FG |
526 | |
527 | // The struct path probably didn't resolve | |
528 | if self.mc.typeck_results.opt_field_index(field.hir_id).is_none() { | |
529 | self.tcx().sess.delay_span_bug(field.span, "couldn't resolve index for field"); | |
530 | } | |
1a4d82fc JJ |
531 | } |
532 | ||
533 | let with_expr = match *opt_with { | |
c295e0f8 | 534 | Some(w) => &*w, |
dfeec247 XL |
535 | None => { |
536 | return; | |
537 | } | |
1a4d82fc JJ |
538 | }; |
539 | ||
c295e0f8 | 540 | let with_place = return_if_err!(self.mc.cat_expr(with_expr)); |
1a4d82fc JJ |
541 | |
542 | // Select just those fields of the `with` | |
543 | // expression that will actually be used | |
1b1a35ee | 544 | match with_place.place.ty().kind() { |
b7449926 | 545 | ty::Adt(adt, substs) if adt.is_struct() => { |
9e0c209e | 546 | // Consume those fields of the with expression that are needed. |
83c7162d | 547 | for (f_index, with_field) in adt.non_enum_variant().fields.iter().enumerate() { |
487cf647 FG |
548 | let is_mentioned = fields |
549 | .iter() | |
550 | .any(|f| self.mc.typeck_results.opt_field_index(f.hir_id) == Some(f_index)); | |
83c7162d | 551 | if !is_mentioned { |
60c5eb7d | 552 | let field_place = self.mc.cat_projection( |
9e0c209e | 553 | &*with_expr, |
60c5eb7d XL |
554 | with_place.clone(), |
555 | with_field.ty(self.tcx(), substs), | |
3dfed10e | 556 | ProjectionKind::Field(f_index as u32, VariantIdx::new(0)), |
9e0c209e | 557 | ); |
29967ef6 | 558 | self.delegate_consume(&field_place, field_place.hir_id); |
9e0c209e | 559 | } |
1a4d82fc | 560 | } |
1a4d82fc | 561 | } |
9e0c209e SL |
562 | _ => { |
563 | // the base expression should always evaluate to a | |
564 | // struct; however, when EUV is run during typeck, it | |
565 | // may not. This will generate an error earlier in typeck, | |
566 | // so we can just ignore it. | |
5e7ed085 | 567 | if !self.tcx().sess.has_errors().is_some() { |
dfeec247 | 568 | span_bug!(with_expr.span, "with expression doesn't evaluate to a struct"); |
9e0c209e | 569 | } |
1a4d82fc | 570 | } |
9e0c209e | 571 | } |
1a4d82fc JJ |
572 | |
573 | // walk the with expression so that complex expressions | |
574 | // are properly handled. | |
575 | self.walk_expr(with_expr); | |
1a4d82fc JJ |
576 | } |
577 | ||
94222f64 XL |
578 | /// Invoke the appropriate delegate calls for anything that gets |
579 | /// consumed or borrowed as part of the automatic adjustment | |
580 | /// process. | |
dfeec247 | 581 | fn walk_adjustment(&mut self, expr: &hir::Expr<'_>) { |
3dfed10e | 582 | let adjustments = self.mc.typeck_results.expr_adjustments(expr); |
f035d41b | 583 | let mut place_with_id = return_if_err!(self.mc.cat_expr_unadjusted(expr)); |
7cac9316 XL |
584 | for adjustment in adjustments { |
585 | debug!("walk_adjustment expr={:?} adj={:?}", expr, adjustment); | |
c30ab7b3 | 586 | match adjustment.kind { |
2b03887a FG |
587 | adjustment::Adjust::NeverToAny |
588 | | adjustment::Adjust::Pointer(_) | |
589 | | adjustment::Adjust::DynStar => { | |
9346a6ac AL |
590 | // Creating a closure/fn-pointer or unsizing consumes |
591 | // the input and stores it into the resulting rvalue. | |
29967ef6 | 592 | self.delegate_consume(&place_with_id, place_with_id.hir_id); |
9346a6ac | 593 | } |
c30ab7b3 | 594 | |
7cac9316 XL |
595 | adjustment::Adjust::Deref(None) => {} |
596 | ||
597 | // Autoderefs for overloaded Deref calls in fact reference | |
598 | // their receiver. That is, if we have `(*x)` where `x` | |
599 | // is of type `Rc<T>`, then this in fact is equivalent to | |
600 | // `x.deref()`. Since `deref()` is declared with `&self`, | |
601 | // this is an autoref of `x`. | |
602 | adjustment::Adjust::Deref(Some(ref deref)) => { | |
603 | let bk = ty::BorrowKind::from_mutbl(deref.mutbl); | |
29967ef6 | 604 | self.delegate.borrow(&place_with_id, place_with_id.hir_id, bk); |
1a4d82fc | 605 | } |
1a4d82fc | 606 | |
7cac9316 | 607 | adjustment::Adjust::Borrow(ref autoref) => { |
f035d41b | 608 | self.walk_autoref(expr, &place_with_id, autoref); |
7cac9316 | 609 | } |
1a4d82fc | 610 | } |
f035d41b | 611 | place_with_id = |
c295e0f8 | 612 | return_if_err!(self.mc.cat_expr_adjusted(expr, place_with_id, adjustment)); |
1a4d82fc JJ |
613 | } |
614 | } | |
615 | ||
7cac9316 | 616 | /// Walks the autoref `autoref` applied to the autoderef'd |
60c5eb7d | 617 | /// `expr`. `base_place` is the mem-categorized form of `expr` |
7cac9316 | 618 | /// after all relevant autoderefs have occurred. |
dfeec247 XL |
619 | fn walk_autoref( |
620 | &mut self, | |
621 | expr: &hir::Expr<'_>, | |
3dfed10e | 622 | base_place: &PlaceWithHirId<'tcx>, |
dfeec247 XL |
623 | autoref: &adjustment::AutoBorrow<'tcx>, |
624 | ) { | |
625 | debug!( | |
626 | "walk_autoref(expr.hir_id={} base_place={:?} autoref={:?})", | |
627 | expr.hir_id, base_place, autoref | |
628 | ); | |
1a4d82fc | 629 | |
9346a6ac | 630 | match *autoref { |
e74abb32 | 631 | adjustment::AutoBorrow::Ref(_, m) => { |
29967ef6 XL |
632 | self.delegate.borrow( |
633 | base_place, | |
634 | base_place.hir_id, | |
635 | ty::BorrowKind::from_mutbl(m.into()), | |
636 | ); | |
1a4d82fc | 637 | } |
9346a6ac | 638 | |
c30ab7b3 | 639 | adjustment::AutoBorrow::RawPtr(m) => { |
dfeec247 | 640 | debug!("walk_autoref: expr.hir_id={} base_place={:?}", expr.hir_id, base_place); |
1a4d82fc | 641 | |
29967ef6 | 642 | self.delegate.borrow(base_place, base_place.hir_id, ty::BorrowKind::from_mutbl(m)); |
e74abb32 | 643 | } |
1a4d82fc | 644 | } |
1a4d82fc JJ |
645 | } |
646 | ||
f035d41b | 647 | fn walk_arm(&mut self, discr_place: &PlaceWithHirId<'tcx>, arm: &hir::Arm<'_>) { |
cdc7bbd5 | 648 | let closure_def_id = match discr_place.place.base { |
064997fb | 649 | PlaceBase::Upvar(upvar_id) => Some(upvar_id.closure_expr_id), |
cdc7bbd5 XL |
650 | _ => None, |
651 | }; | |
652 | ||
6a06907d | 653 | self.delegate.fake_read( |
923072b8 | 654 | discr_place, |
cdc7bbd5 | 655 | FakeReadCause::ForMatchedPlace(closure_def_id), |
6a06907d XL |
656 | discr_place.hir_id, |
657 | ); | |
923072b8 | 658 | self.walk_pat(discr_place, arm.pat, arm.guard.is_some()); |
1a4d82fc | 659 | |
c295e0f8 | 660 | if let Some(hir::Guard::If(e)) = arm.guard { |
0bf4aa26 | 661 | self.consume_expr(e) |
923072b8 FG |
662 | } else if let Some(hir::Guard::IfLet(ref l)) = arm.guard { |
663 | self.consume_expr(l.init) | |
1a4d82fc JJ |
664 | } |
665 | ||
c295e0f8 | 666 | self.consume_expr(arm.body); |
1a4d82fc JJ |
667 | } |
668 | ||
9fa01778 XL |
669 | /// Walks a pat that occurs in isolation (i.e., top-level of fn argument or |
670 | /// let binding, and *not* a match arm or nested pat.) | |
f035d41b | 671 | fn walk_irrefutable_pat(&mut self, discr_place: &PlaceWithHirId<'tcx>, pat: &hir::Pat<'_>) { |
cdc7bbd5 | 672 | let closure_def_id = match discr_place.place.base { |
064997fb | 673 | PlaceBase::Upvar(upvar_id) => Some(upvar_id.closure_expr_id), |
cdc7bbd5 XL |
674 | _ => None, |
675 | }; | |
676 | ||
6a06907d | 677 | self.delegate.fake_read( |
923072b8 | 678 | discr_place, |
cdc7bbd5 | 679 | FakeReadCause::ForLet(closure_def_id), |
6a06907d XL |
680 | discr_place.hir_id, |
681 | ); | |
923072b8 | 682 | self.walk_pat(discr_place, pat, false); |
1a4d82fc JJ |
683 | } |
684 | ||
e74abb32 | 685 | /// The core driver for walking a pattern |
923072b8 FG |
686 | fn walk_pat( |
687 | &mut self, | |
688 | discr_place: &PlaceWithHirId<'tcx>, | |
689 | pat: &hir::Pat<'_>, | |
690 | has_guard: bool, | |
691 | ) { | |
692 | debug!("walk_pat(discr_place={:?}, pat={:?}, has_guard={:?})", discr_place, pat, has_guard); | |
1a4d82fc | 693 | |
8faf50e0 | 694 | let tcx = self.tcx(); |
fc512014 | 695 | let ExprUseVisitor { ref mc, body_owner: _, ref mut delegate } = *self; |
60c5eb7d | 696 | return_if_err!(mc.cat_pattern(discr_place.clone(), pat, |place, pat| { |
e74abb32 | 697 | if let PatKind::Binding(_, canonical_id, ..) = pat.kind { |
064997fb | 698 | debug!("walk_pat: binding place={:?} pat={:?}", place, pat); |
3dfed10e XL |
699 | if let Some(bm) = |
700 | mc.typeck_results.extract_binding_mode(tcx.sess, pat.hir_id, pat.span) | |
701 | { | |
8faf50e0 XL |
702 | debug!("walk_pat: pat.hir_id={:?} bm={:?}", pat.hir_id, bm); |
703 | ||
704 | // pat_ty: the type of the binding being produced. | |
705 | let pat_ty = return_if_err!(mc.node_ty(pat.hir_id)); | |
706 | debug!("walk_pat: pat_ty={:?}", pat_ty); | |
707 | ||
48663c56 | 708 | let def = Res::Local(canonical_id); |
60c5eb7d | 709 | if let Ok(ref binding_place) = mc.cat_res(pat.hir_id, pat.span, pat_ty, def) { |
5e7ed085 | 710 | delegate.bind(binding_place, binding_place.hir_id); |
8faf50e0 | 711 | } |
5bcae85e | 712 | |
923072b8 FG |
713 | // Subtle: MIR desugaring introduces immutable borrows for each pattern |
714 | // binding when lowering pattern guards to ensure that the guard does not | |
715 | // modify the scrutinee. | |
716 | if has_guard { | |
717 | delegate.borrow(place, discr_place.hir_id, ImmBorrow); | |
718 | } | |
719 | ||
8faf50e0 | 720 | // It is also a borrow or copy/move of the value being matched. |
29967ef6 XL |
721 | // In a cases of pattern like `let pat = upvar`, don't use the span |
722 | // of the pattern, as this just looks confusing, instead use the span | |
723 | // of the discriminant. | |
8faf50e0 XL |
724 | match bm { |
725 | ty::BindByReference(m) => { | |
e74abb32 | 726 | let bk = ty::BorrowKind::from_mutbl(m); |
29967ef6 | 727 | delegate.borrow(place, discr_place.hir_id, bk); |
8faf50e0 XL |
728 | } |
729 | ty::BindByValue(..) => { | |
8faf50e0 | 730 | debug!("walk_pat binding consuming pat"); |
136023e0 | 731 | delegate_consume(mc, *delegate, place, discr_place.hir_id); |
c1a9b12d | 732 | } |
1a4d82fc | 733 | } |
1a4d82fc JJ |
734 | } |
735 | } | |
736 | })); | |
1a4d82fc JJ |
737 | } |
738 | ||
fc512014 XL |
739 | /// Handle the case where the current body contains a closure. |
740 | /// | |
741 | /// When the current body being handled is a closure, then we must make sure that | |
742 | /// - The parent closure only captures Places from the nested closure that are not local to it. | |
743 | /// | |
94222f64 | 744 | /// In the following example the closures `c` only captures `p.x` even though `incr` |
fc512014 XL |
745 | /// is a capture of the nested closure |
746 | /// | |
04454e1e FG |
747 | /// ``` |
748 | /// struct P { x: i32 } | |
749 | /// let mut p = P { x: 4 }; | |
fc512014 XL |
750 | /// let c = || { |
751 | /// let incr = 10; | |
752 | /// let nested = || p.x += incr; | |
04454e1e | 753 | /// }; |
fc512014 XL |
754 | /// ``` |
755 | /// | |
756 | /// - When reporting the Place back to the Delegate, ensure that the UpvarId uses the enclosing | |
757 | /// closure as the DefId. | |
487cf647 | 758 | fn walk_captures(&mut self, closure_expr: &hir::Closure<'_>) { |
a2a8927a | 759 | fn upvar_is_local_variable<'tcx>( |
6a06907d | 760 | upvars: Option<&'tcx FxIndexMap<hir::HirId, hir::Upvar>>, |
5e7ed085 | 761 | upvar_id: hir::HirId, |
6a06907d XL |
762 | body_owner_is_closure: bool, |
763 | ) -> bool { | |
5e7ed085 | 764 | upvars.map(|upvars| !upvars.contains_key(&upvar_id)).unwrap_or(body_owner_is_closure) |
6a06907d XL |
765 | } |
766 | ||
62682a34 | 767 | debug!("walk_captures({:?})", closure_expr); |
1a4d82fc | 768 | |
a2a8927a | 769 | let tcx = self.tcx(); |
487cf647 | 770 | let closure_def_id = closure_expr.def_id; |
a2a8927a | 771 | let upvars = tcx.upvars_mentioned(self.body_owner); |
fc512014 XL |
772 | |
773 | // For purposes of this function, generator and closures are equivalent. | |
5e7ed085 FG |
774 | let body_owner_is_closure = |
775 | matches!(tcx.hir().body_owner_kind(self.body_owner), hir::BodyOwnerKind::Closure,); | |
fc512014 | 776 | |
6a06907d XL |
777 | // If we have a nested closure, we want to include the fake reads present in the nested closure. |
778 | if let Some(fake_reads) = self.mc.typeck_results.closure_fake_reads.get(&closure_def_id) { | |
779 | for (fake_read, cause, hir_id) in fake_reads.iter() { | |
780 | match fake_read.base { | |
781 | PlaceBase::Upvar(upvar_id) => { | |
782 | if upvar_is_local_variable( | |
783 | upvars, | |
5e7ed085 | 784 | upvar_id.var_path.hir_id, |
6a06907d XL |
785 | body_owner_is_closure, |
786 | ) { | |
787 | // The nested closure might be fake reading the current (enclosing) closure's local variables. | |
788 | // The only places we want to fake read before creating the parent closure are the ones that | |
789 | // are not local to it/ defined by it. | |
790 | // | |
cdc7bbd5 | 791 | // ```rust,ignore(cannot-test-this-because-pseudo-code) |
6a06907d XL |
792 | // let v1 = (0, 1); |
793 | // let c = || { // fake reads: v1 | |
794 | // let v2 = (0, 1); | |
795 | // let e = || { // fake reads: v1, v2 | |
796 | // let (_, t1) = v1; | |
797 | // let (_, t2) = v2; | |
798 | // } | |
799 | // } | |
800 | // ``` | |
801 | // This check is performed when visiting the body of the outermost closure (`c`) and ensures | |
802 | // that we don't add a fake read of v2 in c. | |
803 | continue; | |
804 | } | |
805 | } | |
806 | _ => { | |
807 | bug!( | |
808 | "Do not know how to get HirId out of Rvalue and StaticItem {:?}", | |
809 | fake_read.base | |
810 | ); | |
811 | } | |
812 | }; | |
923072b8 FG |
813 | self.delegate.fake_read( |
814 | &PlaceWithHirId { place: fake_read.clone(), hir_id: *hir_id }, | |
815 | *cause, | |
816 | *hir_id, | |
817 | ); | |
6a06907d XL |
818 | } |
819 | } | |
820 | ||
fc512014 XL |
821 | if let Some(min_captures) = self.mc.typeck_results.closure_min_captures.get(&closure_def_id) |
822 | { | |
823 | for (var_hir_id, min_list) in min_captures.iter() { | |
824 | if upvars.map_or(body_owner_is_closure, |upvars| !upvars.contains_key(var_hir_id)) { | |
825 | // The nested closure might be capturing the current (enclosing) closure's local variables. | |
826 | // We check if the root variable is ever mentioned within the enclosing closure, if not | |
827 | // then for the current body (if it's a closure) these aren't captures, we will ignore them. | |
828 | continue; | |
829 | } | |
830 | for captured_place in min_list { | |
831 | let place = &captured_place.place; | |
832 | let capture_info = captured_place.info; | |
833 | ||
834 | let place_base = if body_owner_is_closure { | |
835 | // Mark the place to be captured by the enclosing closure | |
836 | PlaceBase::Upvar(ty::UpvarId::new(*var_hir_id, self.body_owner)) | |
837 | } else { | |
838 | // If the body owner isn't a closure then the variable must | |
839 | // be a local variable | |
840 | PlaceBase::Local(*var_hir_id) | |
841 | }; | |
487cf647 | 842 | let closure_hir_id = tcx.hir().local_def_id_to_hir_id(closure_def_id); |
fc512014 | 843 | let place_with_id = PlaceWithHirId::new( |
487cf647 FG |
844 | capture_info |
845 | .path_expr_id | |
846 | .unwrap_or(capture_info.capture_kind_expr_id.unwrap_or(closure_hir_id)), | |
fc512014 XL |
847 | place.base_ty, |
848 | place_base, | |
849 | place.projections.clone(), | |
850 | ); | |
851 | ||
852 | match capture_info.capture_kind { | |
5099ac24 | 853 | ty::UpvarCapture::ByValue => { |
136023e0 | 854 | self.delegate_consume(&place_with_id, place_with_id.hir_id); |
fc512014 XL |
855 | } |
856 | ty::UpvarCapture::ByRef(upvar_borrow) => { | |
857 | self.delegate.borrow( | |
858 | &place_with_id, | |
859 | place_with_id.hir_id, | |
5099ac24 | 860 | upvar_borrow, |
fc512014 XL |
861 | ); |
862 | } | |
85aaf69f | 863 | } |
1a4d82fc JJ |
864 | } |
865 | } | |
48663c56 | 866 | } |
1a4d82fc | 867 | } |
1a4d82fc JJ |
868 | } |
869 | ||
dc9dc135 XL |
870 | fn copy_or_move<'a, 'tcx>( |
871 | mc: &mc::MemCategorizationContext<'a, 'tcx>, | |
f035d41b | 872 | place_with_id: &PlaceWithHirId<'tcx>, |
dc9dc135 | 873 | ) -> ConsumeMode { |
f035d41b XL |
874 | if !mc.type_is_copy_modulo_regions( |
875 | place_with_id.place.ty(), | |
876 | mc.tcx().hir().span(place_with_id.hir_id), | |
877 | ) { | |
136023e0 | 878 | ConsumeMode::Move |
f035d41b | 879 | } else { |
136023e0 XL |
880 | ConsumeMode::Copy |
881 | } | |
882 | } | |
883 | ||
884 | // - If a place is used in a `ByValue` context then move it if it's not a `Copy` type. | |
94222f64 | 885 | // - If the place that is a `Copy` type consider it an `ImmBorrow`. |
136023e0 XL |
886 | fn delegate_consume<'a, 'tcx>( |
887 | mc: &mc::MemCategorizationContext<'a, 'tcx>, | |
888 | delegate: &mut (dyn Delegate<'tcx> + 'a), | |
889 | place_with_id: &PlaceWithHirId<'tcx>, | |
890 | diag_expr_id: hir::HirId, | |
891 | ) { | |
892 | debug!("delegate_consume(place_with_id={:?})", place_with_id); | |
893 | ||
c295e0f8 | 894 | let mode = copy_or_move(mc, place_with_id); |
136023e0 XL |
895 | |
896 | match mode { | |
897 | ConsumeMode::Move => delegate.consume(place_with_id, diag_expr_id), | |
5e7ed085 | 898 | ConsumeMode::Copy => delegate.copy(place_with_id, diag_expr_id), |
f035d41b | 899 | } |
1a4d82fc | 900 | } |
94222f64 | 901 | |
a2a8927a | 902 | fn is_multivariant_adt(ty: Ty<'_>) -> bool { |
94222f64 XL |
903 | if let ty::Adt(def, _) = ty.kind() { |
904 | // Note that if a non-exhaustive SingleVariant is defined in another crate, we need | |
905 | // to assume that more cases will be added to the variant in the future. This mean | |
906 | // that we should handle non-exhaustive SingleVariant the same way we would handle | |
907 | // a MultiVariant. | |
908 | // If the variant is not local it must be defined in another crate. | |
909 | let is_non_exhaustive = match def.adt_kind() { | |
910 | AdtKind::Struct | AdtKind::Union => { | |
911 | def.non_enum_variant().is_field_list_non_exhaustive() | |
912 | } | |
913 | AdtKind::Enum => def.is_variant_list_non_exhaustive(), | |
914 | }; | |
5e7ed085 | 915 | def.variants().len() > 1 || (!def.did().is_local() && is_non_exhaustive) |
94222f64 XL |
916 | } else { |
917 | false | |
918 | } | |
919 | } |