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e9174d1e SL |
1 | //! See docs in build/expr/mod.rs |
2 | ||
9fa01778 XL |
3 | use crate::build::expr::category::Category; |
4 | use crate::build::ForGuard::{OutsideGuard, RefWithinGuard}; | |
f2b60f7d | 5 | use crate::build::{BlockAnd, BlockAndExtension, Builder, Capture, CaptureMap}; |
064997fb | 6 | use rustc_hir::def_id::LocalDefId; |
923072b8 | 7 | use rustc_middle::hir::place::Projection as HirProjection; |
fc512014 | 8 | use rustc_middle::hir::place::ProjectionKind as HirProjectionKind; |
5869c6ff | 9 | use rustc_middle::middle::region; |
ba9703b0 XL |
10 | use rustc_middle::mir::AssertKind::BoundsCheck; |
11 | use rustc_middle::mir::*; | |
17df50a5 | 12 | use rustc_middle::thir::*; |
6a06907d | 13 | use rustc_middle::ty::AdtDef; |
ba9703b0 | 14 | use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt, Variance}; |
dfeec247 | 15 | use rustc_span::Span; |
fc512014 | 16 | use rustc_target::abi::VariantIdx; |
e9174d1e | 17 | |
e74abb32 XL |
18 | use rustc_index::vec::Idx; |
19 | ||
cdc7bbd5 XL |
20 | use std::iter; |
21 | ||
fc512014 | 22 | /// The "outermost" place that holds this value. |
6a06907d | 23 | #[derive(Copy, Clone, Debug, PartialEq)] |
923072b8 | 24 | pub(crate) enum PlaceBase { |
fc512014 XL |
25 | /// Denotes the start of a `Place`. |
26 | Local(Local), | |
27 | ||
28 | /// When building place for an expression within a closure, the place might start off a | |
29 | /// captured path. When `capture_disjoint_fields` is enabled, we might not know the capture | |
30 | /// index (within the desugared closure) of the captured path until most of the projections | |
31 | /// are applied. We use `PlaceBase::Upvar` to keep track of the root variable off of which the | |
32 | /// captured path starts, the closure the capture belongs to and the trait the closure | |
33 | /// implements. | |
34 | /// | |
35 | /// Once we have figured out the capture index, we can convert the place builder to start from | |
36 | /// `PlaceBase::Local`. | |
37 | /// | |
38 | /// Consider the following example | |
39 | /// ```rust | |
04454e1e | 40 | /// let t = (((10, 10), 10), 10); |
fc512014 XL |
41 | /// |
42 | /// let c = || { | |
43 | /// println!("{}", t.0.0.0); | |
44 | /// }; | |
45 | /// ``` | |
46 | /// Here the THIR expression for `t.0.0.0` will be something like | |
47 | /// | |
04454e1e | 48 | /// ```ignore (illustrative) |
fc512014 XL |
49 | /// * Field(0) |
50 | /// * Field(0) | |
51 | /// * Field(0) | |
52 | /// * UpvarRef(t) | |
53 | /// ``` | |
54 | /// | |
55 | /// When `capture_disjoint_fields` is enabled, `t.0.0.0` is captured and we won't be able to | |
56 | /// figure out that it is captured until all the `Field` projections are applied. | |
57 | Upvar { | |
58 | /// HirId of the upvar | |
923072b8 | 59 | var_hir_id: LocalVarId, |
fc512014 | 60 | /// DefId of the closure |
064997fb | 61 | closure_def_id: LocalDefId, |
5869c6ff | 62 | }, |
fc512014 XL |
63 | } |
64 | ||
e74abb32 XL |
65 | /// `PlaceBuilder` is used to create places during MIR construction. It allows you to "build up" a |
66 | /// place by pushing more and more projections onto the end, and then convert the final set into a | |
67 | /// place using the `into_place` method. | |
68 | /// | |
69 | /// This is used internally when building a place for an expression like `a.b.c`. The fields `b` | |
70 | /// and `c` can be progressively pushed onto the place builder that is created when converting `a`. | |
6a06907d | 71 | #[derive(Clone, Debug, PartialEq)] |
923072b8 | 72 | pub(crate) struct PlaceBuilder<'tcx> { |
fc512014 | 73 | base: PlaceBase, |
e74abb32 XL |
74 | projection: Vec<PlaceElem<'tcx>>, |
75 | } | |
76 | ||
fc512014 XL |
77 | /// Given a list of MIR projections, convert them to list of HIR ProjectionKind. |
78 | /// The projections are truncated to represent a path that might be captured by a | |
79 | /// closure/generator. This implies the vector returned from this function doesn't contain | |
80 | /// ProjectionElems `Downcast`, `ConstantIndex`, `Index`, or `Subslice` because those will never be | |
cdc7bbd5 | 81 | /// part of a path that is captured by a closure. We stop applying projections once we see the first |
fc512014 XL |
82 | /// projection that isn't captured by a closure. |
83 | fn convert_to_hir_projections_and_truncate_for_capture<'tcx>( | |
5869c6ff | 84 | mir_projections: &[PlaceElem<'tcx>], |
fc512014 | 85 | ) -> Vec<HirProjectionKind> { |
5869c6ff | 86 | let mut hir_projections = Vec::new(); |
6a06907d | 87 | let mut variant = None; |
fc512014 XL |
88 | |
89 | for mir_projection in mir_projections { | |
90 | let hir_projection = match mir_projection { | |
91 | ProjectionElem::Deref => HirProjectionKind::Deref, | |
92 | ProjectionElem::Field(field, _) => { | |
6a06907d XL |
93 | let variant = variant.unwrap_or(VariantIdx::new(0)); |
94 | HirProjectionKind::Field(field.index() as u32, variant) | |
5869c6ff | 95 | } |
6a06907d XL |
96 | ProjectionElem::Downcast(.., idx) => { |
97 | // We don't expect to see multi-variant enums here, as earlier | |
98 | // phases will have truncated them already. However, there can | |
99 | // still be downcasts, thanks to single-variant enums. | |
100 | // We keep track of VariantIdx so we can use this information | |
101 | // if the next ProjectionElem is a Field. | |
102 | variant = Some(*idx); | |
103 | continue; | |
5869c6ff | 104 | } |
fc512014 XL |
105 | ProjectionElem::Index(..) |
106 | | ProjectionElem::ConstantIndex { .. } | |
107 | | ProjectionElem::Subslice { .. } => { | |
108 | // We don't capture array-access projections. | |
109 | // We can stop here as arrays are captured completely. | |
5869c6ff XL |
110 | break; |
111 | } | |
fc512014 | 112 | }; |
6a06907d | 113 | variant = None; |
fc512014 XL |
114 | hir_projections.push(hir_projection); |
115 | } | |
116 | ||
117 | hir_projections | |
118 | } | |
119 | ||
120 | /// Return true if the `proj_possible_ancestor` represents an ancestor path | |
121 | /// to `proj_capture` or `proj_possible_ancestor` is same as `proj_capture`, | |
122 | /// assuming they both start off of the same root variable. | |
123 | /// | |
124 | /// **Note:** It's the caller's responsibility to ensure that both lists of projections | |
125 | /// start off of the same root variable. | |
126 | /// | |
127 | /// Eg: 1. `foo.x` which is represented using `projections=[Field(x)]` is an ancestor of | |
128 | /// `foo.x.y` which is represented using `projections=[Field(x), Field(y)]`. | |
129 | /// Note both `foo.x` and `foo.x.y` start off of the same root variable `foo`. | |
130 | /// 2. Since we only look at the projections here function will return `bar.x` as an a valid | |
131 | /// ancestor of `foo.x.y`. It's the caller's responsibility to ensure that both projections | |
132 | /// list are being applied to the same root variable. | |
133 | fn is_ancestor_or_same_capture( | |
923072b8 | 134 | proj_possible_ancestor: &[HirProjectionKind], |
5869c6ff | 135 | proj_capture: &[HirProjectionKind], |
fc512014 XL |
136 | ) -> bool { |
137 | // We want to make sure `is_ancestor_or_same_capture("x.0.0", "x.0")` to return false. | |
138 | // Therefore we can't just check if all projections are same in the zipped iterator below. | |
139 | if proj_possible_ancestor.len() > proj_capture.len() { | |
140 | return false; | |
141 | } | |
142 | ||
cdc7bbd5 | 143 | iter::zip(proj_possible_ancestor, proj_capture).all(|(a, b)| a == b) |
fc512014 XL |
144 | } |
145 | ||
fc512014 XL |
146 | /// Given a closure, returns the index of a capture within the desugared closure struct and the |
147 | /// `ty::CapturedPlace` which is the ancestor of the Place represented using the `var_hir_id` | |
148 | /// and `projection`. | |
149 | /// | |
150 | /// Note there will be at most one ancestor for any given Place. | |
151 | /// | |
152 | /// Returns None, when the ancestor is not found. | |
153 | fn find_capture_matching_projections<'a, 'tcx>( | |
f2b60f7d | 154 | upvars: &'a CaptureMap<'tcx>, |
923072b8 | 155 | var_hir_id: LocalVarId, |
5869c6ff | 156 | projections: &[PlaceElem<'tcx>], |
f2b60f7d | 157 | ) -> Option<(usize, &'a Capture<'tcx>)> { |
fc512014 XL |
158 | let hir_projections = convert_to_hir_projections_and_truncate_for_capture(projections); |
159 | ||
f2b60f7d | 160 | upvars.get_by_key_enumerated(var_hir_id.0).find(|(_, capture)| { |
923072b8 | 161 | let possible_ancestor_proj_kinds: Vec<_> = |
f2b60f7d | 162 | capture.captured_place.place.projections.iter().map(|proj| proj.kind).collect(); |
5869c6ff | 163 | is_ancestor_or_same_capture(&possible_ancestor_proj_kinds, &hir_projections) |
f2b60f7d | 164 | }) |
fc512014 XL |
165 | } |
166 | ||
167 | /// Takes a PlaceBuilder and resolves the upvar (if any) within it, so that the | |
168 | /// `PlaceBuilder` now starts from `PlaceBase::Local`. | |
169 | /// | |
6a06907d | 170 | /// Returns a Result with the error being the PlaceBuilder (`from_builder`) that was not found. |
fc512014 XL |
171 | fn to_upvars_resolved_place_builder<'a, 'tcx>( |
172 | from_builder: PlaceBuilder<'tcx>, | |
173 | tcx: TyCtxt<'tcx>, | |
f2b60f7d | 174 | upvars: &'a CaptureMap<'tcx>, |
6a06907d | 175 | ) -> Result<PlaceBuilder<'tcx>, PlaceBuilder<'tcx>> { |
fc512014 XL |
176 | match from_builder.base { |
177 | PlaceBase::Local(_) => Ok(from_builder), | |
f2b60f7d | 178 | PlaceBase::Upvar { var_hir_id, closure_def_id } => { |
3c0e092e | 179 | let Some((capture_index, capture)) = |
5869c6ff | 180 | find_capture_matching_projections( |
f2b60f7d | 181 | upvars, |
fc512014 | 182 | var_hir_id, |
fc512014 | 183 | &from_builder.projection, |
3c0e092e | 184 | ) else { |
5099ac24 | 185 | let closure_span = tcx.def_span(closure_def_id); |
136023e0 | 186 | if !enable_precise_capture(tcx, closure_span) { |
5869c6ff XL |
187 | bug!( |
188 | "No associated capture found for {:?}[{:#?}] even though \ | |
fc512014 | 189 | capture_disjoint_fields isn't enabled", |
5869c6ff XL |
190 | var_hir_id, |
191 | from_builder.projection | |
192 | ) | |
193 | } else { | |
5869c6ff XL |
194 | debug!( |
195 | "No associated capture found for {:?}[{:#?}]", | |
196 | var_hir_id, from_builder.projection, | |
197 | ); | |
198 | } | |
6a06907d | 199 | return Err(from_builder); |
5869c6ff | 200 | }; |
fc512014 | 201 | |
fc512014 | 202 | // Access the capture by accessing the field within the Closure struct. |
f2b60f7d FG |
203 | let capture_info = &upvars[capture_index]; |
204 | ||
205 | let mut upvar_resolved_place_builder = PlaceBuilder::from(capture_info.use_place); | |
fc512014 | 206 | |
fc512014 XL |
207 | // We used some of the projections to build the capture itself, |
208 | // now we apply the remaining to the upvar resolved place. | |
923072b8 | 209 | let remaining_projections = strip_prefix( |
f2b60f7d | 210 | capture.captured_place.place.base_ty, |
923072b8 | 211 | from_builder.projection, |
f2b60f7d | 212 | &capture.captured_place.place.projections, |
923072b8 FG |
213 | ); |
214 | upvar_resolved_place_builder.projection.extend(remaining_projections); | |
fc512014 XL |
215 | |
216 | Ok(upvar_resolved_place_builder) | |
217 | } | |
218 | } | |
219 | } | |
220 | ||
923072b8 FG |
221 | /// Returns projections remaining after stripping an initial prefix of HIR |
222 | /// projections. | |
223 | /// | |
224 | /// Supports only HIR projection kinds that represent a path that might be | |
225 | /// captured by a closure or a generator, i.e., an `Index` or a `Subslice` | |
226 | /// projection kinds are unsupported. | |
227 | fn strip_prefix<'tcx>( | |
228 | mut base_ty: Ty<'tcx>, | |
229 | projections: Vec<PlaceElem<'tcx>>, | |
230 | prefix_projections: &[HirProjection<'tcx>], | |
231 | ) -> impl Iterator<Item = PlaceElem<'tcx>> { | |
232 | let mut iter = projections.into_iter(); | |
233 | for projection in prefix_projections { | |
234 | match projection.kind { | |
235 | HirProjectionKind::Deref => { | |
236 | assert!(matches!(iter.next(), Some(ProjectionElem::Deref))); | |
237 | } | |
238 | HirProjectionKind::Field(..) => { | |
239 | if base_ty.is_enum() { | |
240 | assert!(matches!(iter.next(), Some(ProjectionElem::Downcast(..)))); | |
241 | } | |
242 | assert!(matches!(iter.next(), Some(ProjectionElem::Field(..)))); | |
243 | } | |
244 | HirProjectionKind::Index | HirProjectionKind::Subslice => { | |
245 | bug!("unexpected projection kind: {:?}", projection); | |
246 | } | |
247 | } | |
248 | base_ty = projection.ty; | |
249 | } | |
250 | iter | |
251 | } | |
252 | ||
dfeec247 | 253 | impl<'tcx> PlaceBuilder<'tcx> { |
f2b60f7d | 254 | pub(in crate::build) fn into_place<'a>( |
fc512014 XL |
255 | self, |
256 | tcx: TyCtxt<'tcx>, | |
f2b60f7d | 257 | upvars: &'a CaptureMap<'tcx>, |
fc512014 XL |
258 | ) -> Place<'tcx> { |
259 | if let PlaceBase::Local(local) = self.base { | |
260 | Place { local, projection: tcx.intern_place_elems(&self.projection) } | |
261 | } else { | |
f2b60f7d | 262 | self.expect_upvars_resolved(tcx, upvars).into_place(tcx, upvars) |
fc512014 XL |
263 | } |
264 | } | |
265 | ||
266 | fn expect_upvars_resolved<'a>( | |
267 | self, | |
268 | tcx: TyCtxt<'tcx>, | |
f2b60f7d | 269 | upvars: &'a CaptureMap<'tcx>, |
fc512014 | 270 | ) -> PlaceBuilder<'tcx> { |
f2b60f7d | 271 | to_upvars_resolved_place_builder(self, tcx, upvars).unwrap() |
fc512014 XL |
272 | } |
273 | ||
6a06907d XL |
274 | /// Attempts to resolve the `PlaceBuilder`. |
275 | /// On success, it will return the resolved `PlaceBuilder`. | |
276 | /// On failure, it will return itself. | |
277 | /// | |
278 | /// Upvars resolve may fail for a `PlaceBuilder` when attempting to | |
279 | /// resolve a disjoint field whose root variable is not captured | |
280 | /// (destructured assignments) or when attempting to resolve a root | |
281 | /// variable (discriminant matching with only wildcard arm) that is | |
282 | /// not captured. This can happen because the final mir that will be | |
283 | /// generated doesn't require a read for this place. Failures will only | |
284 | /// happen inside closures. | |
f2b60f7d | 285 | pub(in crate::build) fn try_upvars_resolved<'a>( |
6a06907d XL |
286 | self, |
287 | tcx: TyCtxt<'tcx>, | |
f2b60f7d | 288 | upvars: &'a CaptureMap<'tcx>, |
6a06907d | 289 | ) -> Result<PlaceBuilder<'tcx>, PlaceBuilder<'tcx>> { |
f2b60f7d | 290 | to_upvars_resolved_place_builder(self, tcx, upvars) |
6a06907d XL |
291 | } |
292 | ||
923072b8 | 293 | pub(crate) fn base(&self) -> PlaceBase { |
fc512014 | 294 | self.base |
e74abb32 XL |
295 | } |
296 | ||
923072b8 | 297 | pub(crate) fn field(self, f: Field, ty: Ty<'tcx>) -> Self { |
e74abb32 XL |
298 | self.project(PlaceElem::Field(f, ty)) |
299 | } | |
300 | ||
923072b8 | 301 | pub(crate) fn deref(self) -> Self { |
e74abb32 XL |
302 | self.project(PlaceElem::Deref) |
303 | } | |
304 | ||
923072b8 | 305 | pub(crate) fn downcast(self, adt_def: AdtDef<'tcx>, variant_index: VariantIdx) -> Self { |
5e7ed085 | 306 | self.project(PlaceElem::Downcast(Some(adt_def.variant(variant_index).name), variant_index)) |
6a06907d XL |
307 | } |
308 | ||
e74abb32 XL |
309 | fn index(self, index: Local) -> Self { |
310 | self.project(PlaceElem::Index(index)) | |
311 | } | |
312 | ||
923072b8 | 313 | pub(crate) fn project(mut self, elem: PlaceElem<'tcx>) -> Self { |
e74abb32 XL |
314 | self.projection.push(elem); |
315 | self | |
316 | } | |
317 | } | |
318 | ||
dfeec247 | 319 | impl<'tcx> From<Local> for PlaceBuilder<'tcx> { |
e74abb32 | 320 | fn from(local: Local) -> Self { |
fc512014 XL |
321 | Self { base: PlaceBase::Local(local), projection: Vec::new() } |
322 | } | |
323 | } | |
324 | ||
325 | impl<'tcx> From<PlaceBase> for PlaceBuilder<'tcx> { | |
326 | fn from(base: PlaceBase) -> Self { | |
327 | Self { base, projection: Vec::new() } | |
e74abb32 XL |
328 | } |
329 | } | |
3157f602 | 330 | |
f2b60f7d FG |
331 | impl<'tcx> From<Place<'tcx>> for PlaceBuilder<'tcx> { |
332 | fn from(p: Place<'tcx>) -> Self { | |
333 | Self { base: PlaceBase::Local(p.local), projection: p.projection.to_vec() } | |
334 | } | |
335 | } | |
336 | ||
dc9dc135 | 337 | impl<'a, 'tcx> Builder<'a, 'tcx> { |
ff7c6d11 | 338 | /// Compile `expr`, yielding a place that we can move from etc. |
60c5eb7d XL |
339 | /// |
340 | /// WARNING: Any user code might: | |
341 | /// * Invalidate any slice bounds checks performed. | |
342 | /// * Change the address that this `Place` refers to. | |
343 | /// * Modify the memory that this place refers to. | |
344 | /// * Invalidate the memory that this place refers to, this will be caught | |
345 | /// by borrow checking. | |
346 | /// | |
347 | /// Extra care is needed if any user code is allowed to run between calling | |
348 | /// this method and using it, as is the case for `match` and index | |
349 | /// expressions. | |
923072b8 | 350 | pub(crate) fn as_place( |
6a06907d XL |
351 | &mut self, |
352 | mut block: BasicBlock, | |
17df50a5 | 353 | expr: &Expr<'tcx>, |
6a06907d | 354 | ) -> BlockAnd<Place<'tcx>> { |
e74abb32 | 355 | let place_builder = unpack!(block = self.as_place_builder(block, expr)); |
f2b60f7d | 356 | block.and(place_builder.into_place(self.tcx, &self.upvars)) |
e74abb32 XL |
357 | } |
358 | ||
359 | /// This is used when constructing a compound `Place`, so that we can avoid creating | |
360 | /// intermediate `Place` values until we know the full set of projections. | |
923072b8 | 361 | pub(crate) fn as_place_builder( |
5869c6ff XL |
362 | &mut self, |
363 | block: BasicBlock, | |
17df50a5 | 364 | expr: &Expr<'tcx>, |
6a06907d | 365 | ) -> BlockAnd<PlaceBuilder<'tcx>> { |
60c5eb7d | 366 | self.expr_as_place(block, expr, Mutability::Mut, None) |
e9174d1e SL |
367 | } |
368 | ||
b7449926 XL |
369 | /// Compile `expr`, yielding a place that we can move from etc. |
370 | /// Mutability note: The caller of this method promises only to read from the resulting | |
371 | /// place. The place itself may or may not be mutable: | |
372 | /// * If this expr is a place expr like a.b, then we will return that place. | |
373 | /// * Otherwise, a temporary is created: in that event, it will be an immutable temporary. | |
923072b8 | 374 | pub(crate) fn as_read_only_place( |
dfeec247 XL |
375 | &mut self, |
376 | mut block: BasicBlock, | |
17df50a5 | 377 | expr: &Expr<'tcx>, |
6a06907d | 378 | ) -> BlockAnd<Place<'tcx>> { |
e74abb32 | 379 | let place_builder = unpack!(block = self.as_read_only_place_builder(block, expr)); |
f2b60f7d | 380 | block.and(place_builder.into_place(self.tcx, &self.upvars)) |
e74abb32 XL |
381 | } |
382 | ||
383 | /// This is used when constructing a compound `Place`, so that we can avoid creating | |
384 | /// intermediate `Place` values until we know the full set of projections. | |
385 | /// Mutability note: The caller of this method promises only to read from the resulting | |
386 | /// place. The place itself may or may not be mutable: | |
387 | /// * If this expr is a place expr like a.b, then we will return that place. | |
388 | /// * Otherwise, a temporary is created: in that event, it will be an immutable temporary. | |
6a06907d | 389 | fn as_read_only_place_builder( |
e74abb32 XL |
390 | &mut self, |
391 | block: BasicBlock, | |
17df50a5 | 392 | expr: &Expr<'tcx>, |
6a06907d | 393 | ) -> BlockAnd<PlaceBuilder<'tcx>> { |
60c5eb7d | 394 | self.expr_as_place(block, expr, Mutability::Not, None) |
b7449926 XL |
395 | } |
396 | ||
397 | fn expr_as_place( | |
398 | &mut self, | |
399 | mut block: BasicBlock, | |
17df50a5 | 400 | expr: &Expr<'tcx>, |
b7449926 | 401 | mutability: Mutability, |
60c5eb7d | 402 | fake_borrow_temps: Option<&mut Vec<Local>>, |
e74abb32 | 403 | ) -> BlockAnd<PlaceBuilder<'tcx>> { |
dfeec247 | 404 | debug!("expr_as_place(block={:?}, expr={:?}, mutability={:?})", block, expr, mutability); |
e9174d1e SL |
405 | |
406 | let this = self; | |
407 | let expr_span = expr.span; | |
3157f602 | 408 | let source_info = this.source_info(expr_span); |
e9174d1e | 409 | match expr.kind { |
dfeec247 XL |
410 | ExprKind::Scope { region_scope, lint_level, value } => { |
411 | this.in_scope((region_scope, source_info), lint_level, |this| { | |
17df50a5 | 412 | this.expr_as_place(block, &this.thir[value], mutability, fake_borrow_temps) |
dfeec247 XL |
413 | }) |
414 | } | |
923072b8 FG |
415 | ExprKind::Field { lhs, variant_index, name } => { |
416 | let lhs = &this.thir[lhs]; | |
417 | let mut place_builder = | |
418 | unpack!(block = this.expr_as_place(block, lhs, mutability, fake_borrow_temps,)); | |
419 | if let ty::Adt(adt_def, _) = lhs.ty.kind() { | |
420 | if adt_def.is_enum() { | |
421 | place_builder = place_builder.downcast(*adt_def, variant_index); | |
422 | } | |
423 | } | |
e74abb32 | 424 | block.and(place_builder.field(name, expr.ty)) |
e9174d1e SL |
425 | } |
426 | ExprKind::Deref { arg } => { | |
17df50a5 XL |
427 | let place_builder = unpack!( |
428 | block = | |
429 | this.expr_as_place(block, &this.thir[arg], mutability, fake_borrow_temps,) | |
430 | ); | |
e74abb32 | 431 | block.and(place_builder.deref()) |
e9174d1e | 432 | } |
dfeec247 XL |
433 | ExprKind::Index { lhs, index } => this.lower_index_expression( |
434 | block, | |
17df50a5 XL |
435 | &this.thir[lhs], |
436 | &this.thir[index], | |
dfeec247 XL |
437 | mutability, |
438 | fake_borrow_temps, | |
439 | expr.temp_lifetime, | |
440 | expr_span, | |
441 | source_info, | |
442 | ), | |
fc512014 | 443 | ExprKind::UpvarRef { closure_def_id, var_hir_id } => { |
923072b8 | 444 | this.lower_captured_upvar(block, closure_def_id.expect_local(), var_hir_id) |
fc512014 XL |
445 | } |
446 | ||
e9174d1e | 447 | ExprKind::VarRef { id } => { |
e74abb32 | 448 | let place_builder = if this.is_bound_var_in_guard(id) { |
8faf50e0 | 449 | let index = this.var_local_id(id, RefWithinGuard); |
e74abb32 | 450 | PlaceBuilder::from(index).deref() |
83c7162d XL |
451 | } else { |
452 | let index = this.var_local_id(id, OutsideGuard); | |
e74abb32 | 453 | PlaceBuilder::from(index) |
83c7162d | 454 | }; |
e74abb32 | 455 | block.and(place_builder) |
e9174d1e | 456 | } |
e9174d1e | 457 | |
f2b60f7d | 458 | ExprKind::PlaceTypeAscription { source, ref user_ty } => { |
dfeec247 | 459 | let place_builder = unpack!( |
17df50a5 XL |
460 | block = this.expr_as_place( |
461 | block, | |
462 | &this.thir[source], | |
463 | mutability, | |
464 | fake_borrow_temps, | |
465 | ) | |
dfeec247 | 466 | ); |
0bf4aa26 | 467 | if let Some(user_ty) = user_ty { |
dfeec247 XL |
468 | let annotation_index = |
469 | this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation { | |
9fa01778 | 470 | span: source_info.span, |
f2b60f7d | 471 | user_ty: user_ty.clone(), |
9fa01778 | 472 | inferred_ty: expr.ty, |
dfeec247 | 473 | }); |
e74abb32 | 474 | |
f2b60f7d | 475 | let place = place_builder.clone().into_place(this.tcx, &this.upvars); |
0bf4aa26 XL |
476 | this.cfg.push( |
477 | block, | |
478 | Statement { | |
479 | source_info, | |
480 | kind: StatementKind::AscribeUserType( | |
94222f64 | 481 | Box::new(( |
e74abb32 | 482 | place, |
dfeec247 | 483 | UserTypeProjection { base: annotation_index, projs: vec![] }, |
94222f64 | 484 | )), |
0bf4aa26 | 485 | Variance::Invariant, |
0bf4aa26 XL |
486 | ), |
487 | }, | |
488 | ); | |
489 | } | |
e74abb32 | 490 | block.and(place_builder) |
0bf4aa26 | 491 | } |
f2b60f7d | 492 | ExprKind::ValueTypeAscription { source, ref user_ty } => { |
17df50a5 | 493 | let source = &this.thir[source]; |
dfeec247 XL |
494 | let temp = |
495 | unpack!(block = this.as_temp(block, source.temp_lifetime, source, mutability)); | |
0bf4aa26 | 496 | if let Some(user_ty) = user_ty { |
dfeec247 XL |
497 | let annotation_index = |
498 | this.canonical_user_type_annotations.push(CanonicalUserTypeAnnotation { | |
9fa01778 | 499 | span: source_info.span, |
f2b60f7d | 500 | user_ty: user_ty.clone(), |
9fa01778 | 501 | inferred_ty: expr.ty, |
dfeec247 | 502 | }); |
0bf4aa26 XL |
503 | this.cfg.push( |
504 | block, | |
505 | Statement { | |
506 | source_info, | |
507 | kind: StatementKind::AscribeUserType( | |
94222f64 | 508 | Box::new(( |
dfeec247 XL |
509 | Place::from(temp), |
510 | UserTypeProjection { base: annotation_index, projs: vec![] }, | |
94222f64 | 511 | )), |
0bf4aa26 | 512 | Variance::Invariant, |
0bf4aa26 XL |
513 | ), |
514 | }, | |
515 | ); | |
516 | } | |
e74abb32 | 517 | block.and(PlaceBuilder::from(temp)) |
0bf4aa26 XL |
518 | } |
519 | ||
b7449926 XL |
520 | ExprKind::Array { .. } |
521 | | ExprKind::Tuple { .. } | |
522 | | ExprKind::Adt { .. } | |
523 | | ExprKind::Closure { .. } | |
524 | | ExprKind::Unary { .. } | |
525 | | ExprKind::Binary { .. } | |
526 | | ExprKind::LogicalOp { .. } | |
527 | | ExprKind::Box { .. } | |
528 | | ExprKind::Cast { .. } | |
529 | | ExprKind::Use { .. } | |
530 | | ExprKind::NeverToAny { .. } | |
48663c56 | 531 | | ExprKind::Pointer { .. } |
b7449926 XL |
532 | | ExprKind::Repeat { .. } |
533 | | ExprKind::Borrow { .. } | |
dfeec247 | 534 | | ExprKind::AddressOf { .. } |
b7449926 | 535 | | ExprKind::Match { .. } |
5869c6ff | 536 | | ExprKind::If { .. } |
b7449926 XL |
537 | | ExprKind::Loop { .. } |
538 | | ExprKind::Block { .. } | |
94222f64 | 539 | | ExprKind::Let { .. } |
b7449926 XL |
540 | | ExprKind::Assign { .. } |
541 | | ExprKind::AssignOp { .. } | |
542 | | ExprKind::Break { .. } | |
543 | | ExprKind::Continue { .. } | |
544 | | ExprKind::Return { .. } | |
545 | | ExprKind::Literal { .. } | |
5e7ed085 FG |
546 | | ExprKind::NamedConst { .. } |
547 | | ExprKind::NonHirLiteral { .. } | |
064997fb | 548 | | ExprKind::ZstLiteral { .. } |
5e7ed085 | 549 | | ExprKind::ConstParam { .. } |
29967ef6 | 550 | | ExprKind::ConstBlock { .. } |
60c5eb7d | 551 | | ExprKind::StaticRef { .. } |
f9f354fc | 552 | | ExprKind::InlineAsm { .. } |
b7449926 | 553 | | ExprKind::Yield { .. } |
f9f354fc | 554 | | ExprKind::ThreadLocalRef(_) |
b7449926 | 555 | | ExprKind::Call { .. } => { |
ff7c6d11 | 556 | // these are not places, so we need to make a temporary. |
29967ef6 | 557 | debug_assert!(!matches!(Category::of(&expr.kind), Some(Category::Place))); |
b7449926 XL |
558 | let temp = |
559 | unpack!(block = this.as_temp(block, expr.temp_lifetime, expr, mutability)); | |
e74abb32 | 560 | block.and(PlaceBuilder::from(temp)) |
e9174d1e SL |
561 | } |
562 | } | |
563 | } | |
60c5eb7d | 564 | |
fc512014 XL |
565 | /// Lower a captured upvar. Note we might not know the actual capture index, |
566 | /// so we create a place starting from `PlaceBase::Upvar`, which will be resolved | |
cdc7bbd5 | 567 | /// once all projections that allow us to identify a capture have been applied. |
fc512014 XL |
568 | fn lower_captured_upvar( |
569 | &mut self, | |
570 | block: BasicBlock, | |
064997fb | 571 | closure_def_id: LocalDefId, |
923072b8 | 572 | var_hir_id: LocalVarId, |
fc512014 | 573 | ) -> BlockAnd<PlaceBuilder<'tcx>> { |
f2b60f7d | 574 | block.and(PlaceBuilder::from(PlaceBase::Upvar { var_hir_id, closure_def_id })) |
fc512014 XL |
575 | } |
576 | ||
60c5eb7d XL |
577 | /// Lower an index expression |
578 | /// | |
579 | /// This has two complications; | |
580 | /// | |
581 | /// * We need to do a bounds check. | |
582 | /// * We need to ensure that the bounds check can't be invalidated using an | |
583 | /// expression like `x[1][{x = y; 2}]`. We use fake borrows here to ensure | |
584 | /// that this is the case. | |
585 | fn lower_index_expression( | |
586 | &mut self, | |
587 | mut block: BasicBlock, | |
17df50a5 XL |
588 | base: &Expr<'tcx>, |
589 | index: &Expr<'tcx>, | |
60c5eb7d XL |
590 | mutability: Mutability, |
591 | fake_borrow_temps: Option<&mut Vec<Local>>, | |
592 | temp_lifetime: Option<region::Scope>, | |
593 | expr_span: Span, | |
dfeec247 | 594 | source_info: SourceInfo, |
60c5eb7d | 595 | ) -> BlockAnd<PlaceBuilder<'tcx>> { |
60c5eb7d XL |
596 | let base_fake_borrow_temps = &mut Vec::new(); |
597 | let is_outermost_index = fake_borrow_temps.is_none(); | |
598 | let fake_borrow_temps = fake_borrow_temps.unwrap_or(base_fake_borrow_temps); | |
599 | ||
fc512014 | 600 | let mut base_place = |
6a06907d | 601 | unpack!(block = self.expr_as_place(block, base, mutability, Some(fake_borrow_temps),)); |
60c5eb7d XL |
602 | |
603 | // Making this a *fresh* temporary means we do not have to worry about | |
604 | // the index changing later: Nothing will ever change this temporary. | |
605 | // The "retagging" transformation (for Stacked Borrows) relies on this. | |
dfeec247 | 606 | let idx = unpack!(block = self.as_temp(block, temp_lifetime, index, Mutability::Not,)); |
60c5eb7d | 607 | |
6a06907d | 608 | block = self.bounds_check(block, base_place.clone(), idx, expr_span, source_info); |
60c5eb7d XL |
609 | |
610 | if is_outermost_index { | |
611 | self.read_fake_borrows(block, fake_borrow_temps, source_info) | |
612 | } else { | |
f2b60f7d | 613 | base_place = base_place.expect_upvars_resolved(self.tcx, &self.upvars); |
60c5eb7d XL |
614 | self.add_fake_borrows_of_base( |
615 | &base_place, | |
616 | block, | |
617 | fake_borrow_temps, | |
618 | expr_span, | |
619 | source_info, | |
620 | ); | |
621 | } | |
622 | ||
623 | block.and(base_place.index(idx)) | |
624 | } | |
625 | ||
626 | fn bounds_check( | |
627 | &mut self, | |
628 | block: BasicBlock, | |
6a06907d | 629 | slice: PlaceBuilder<'tcx>, |
60c5eb7d XL |
630 | index: Local, |
631 | expr_span: Span, | |
632 | source_info: SourceInfo, | |
633 | ) -> BasicBlock { | |
6a06907d XL |
634 | let usize_ty = self.tcx.types.usize; |
635 | let bool_ty = self.tcx.types.bool; | |
60c5eb7d XL |
636 | // bounds check: |
637 | let len = self.temp(usize_ty, expr_span); | |
638 | let lt = self.temp(bool_ty, expr_span); | |
639 | ||
640 | // len = len(slice) | |
6a06907d XL |
641 | self.cfg.push_assign( |
642 | block, | |
643 | source_info, | |
644 | len, | |
f2b60f7d | 645 | Rvalue::Len(slice.into_place(self.tcx, &self.upvars)), |
6a06907d | 646 | ); |
60c5eb7d XL |
647 | // lt = idx < len |
648 | self.cfg.push_assign( | |
649 | block, | |
650 | source_info, | |
ba9703b0 | 651 | lt, |
6a06907d XL |
652 | Rvalue::BinaryOp( |
653 | BinOp::Lt, | |
94222f64 | 654 | Box::new((Operand::Copy(Place::from(index)), Operand::Copy(len))), |
6a06907d | 655 | ), |
60c5eb7d | 656 | ); |
dfeec247 | 657 | let msg = BoundsCheck { len: Operand::Move(len), index: Operand::Copy(Place::from(index)) }; |
60c5eb7d XL |
658 | // assert!(lt, "...") |
659 | self.assert(block, Operand::Move(lt), true, msg, expr_span) | |
660 | } | |
661 | ||
662 | fn add_fake_borrows_of_base( | |
663 | &mut self, | |
664 | base_place: &PlaceBuilder<'tcx>, | |
665 | block: BasicBlock, | |
666 | fake_borrow_temps: &mut Vec<Local>, | |
667 | expr_span: Span, | |
668 | source_info: SourceInfo, | |
669 | ) { | |
6a06907d | 670 | let tcx = self.tcx; |
fc512014 XL |
671 | let local = match base_place.base { |
672 | PlaceBase::Local(local) => local, | |
5869c6ff | 673 | PlaceBase::Upvar { .. } => bug!("Expected PlacseBase::Local found Upvar"), |
fc512014 XL |
674 | }; |
675 | ||
676 | let place_ty = Place::ty_from(local, &base_place.projection, &self.local_decls, tcx); | |
1b1a35ee | 677 | if let ty::Slice(_) = place_ty.ty.kind() { |
60c5eb7d XL |
678 | // We need to create fake borrows to ensure that the bounds |
679 | // check that we just did stays valid. Since we can't assign to | |
680 | // unsized values, we only need to ensure that none of the | |
681 | // pointers in the base place are modified. | |
682 | for (idx, elem) in base_place.projection.iter().enumerate().rev() { | |
683 | match elem { | |
684 | ProjectionElem::Deref => { | |
685 | let fake_borrow_deref_ty = Place::ty_from( | |
fc512014 | 686 | local, |
60c5eb7d XL |
687 | &base_place.projection[..idx], |
688 | &self.local_decls, | |
689 | tcx, | |
dfeec247 XL |
690 | ) |
691 | .ty; | |
692 | let fake_borrow_ty = | |
693 | tcx.mk_imm_ref(tcx.lifetimes.re_erased, fake_borrow_deref_ty); | |
694 | let fake_borrow_temp = | |
f9f354fc | 695 | self.local_decls.push(LocalDecl::new(fake_borrow_ty, expr_span)); |
60c5eb7d XL |
696 | let projection = tcx.intern_place_elems(&base_place.projection[..idx]); |
697 | self.cfg.push_assign( | |
698 | block, | |
699 | source_info, | |
ba9703b0 | 700 | fake_borrow_temp.into(), |
60c5eb7d XL |
701 | Rvalue::Ref( |
702 | tcx.lifetimes.re_erased, | |
703 | BorrowKind::Shallow, | |
fc512014 | 704 | Place { local, projection }, |
60c5eb7d XL |
705 | ), |
706 | ); | |
707 | fake_borrow_temps.push(fake_borrow_temp); | |
708 | } | |
709 | ProjectionElem::Index(_) => { | |
710 | let index_ty = Place::ty_from( | |
fc512014 | 711 | local, |
60c5eb7d XL |
712 | &base_place.projection[..idx], |
713 | &self.local_decls, | |
714 | tcx, | |
715 | ); | |
1b1a35ee | 716 | match index_ty.ty.kind() { |
60c5eb7d XL |
717 | // The previous index expression has already |
718 | // done any index expressions needed here. | |
719 | ty::Slice(_) => break, | |
720 | ty::Array(..) => (), | |
721 | _ => bug!("unexpected index base"), | |
722 | } | |
723 | } | |
724 | ProjectionElem::Field(..) | |
725 | | ProjectionElem::Downcast(..) | |
726 | | ProjectionElem::ConstantIndex { .. } | |
727 | | ProjectionElem::Subslice { .. } => (), | |
728 | } | |
729 | } | |
730 | } | |
731 | } | |
732 | ||
733 | fn read_fake_borrows( | |
734 | &mut self, | |
735 | bb: BasicBlock, | |
736 | fake_borrow_temps: &mut Vec<Local>, | |
737 | source_info: SourceInfo, | |
738 | ) { | |
739 | // All indexes have been evaluated now, read all of the | |
740 | // fake borrows so that they are live across those index | |
741 | // expressions. | |
742 | for temp in fake_borrow_temps { | |
743 | self.cfg.push_fake_read(bb, source_info, FakeReadCause::ForIndex, Place::from(*temp)); | |
744 | } | |
745 | } | |
e9174d1e | 746 | } |
136023e0 XL |
747 | |
748 | /// Precise capture is enabled if the feature gate `capture_disjoint_fields` is enabled or if | |
749 | /// user is using Rust Edition 2021 or higher. | |
750 | fn enable_precise_capture(tcx: TyCtxt<'_>, closure_span: Span) -> bool { | |
751 | tcx.features().capture_disjoint_fields || closure_span.rust_2021() | |
752 | } |