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Commit | Line | Data |
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ff7c6d11 XL |
1 | //! This query borrow-checks the MIR to (further) ensure it is not broken. |
2 | ||
532ac7d7 | 3 | use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
0bf4aa26 | 4 | use rustc_data_structures::graph::dominators::Dominators; |
ba9703b0 | 5 | use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorReported}; |
dfeec247 | 6 | use rustc_hir as hir; |
f9f354fc | 7 | use rustc_hir::def_id::LocalDefId; |
5869c6ff | 8 | use rustc_hir::Node; |
dfeec247 | 9 | use rustc_index::bit_set::BitSet; |
e74abb32 | 10 | use rustc_index::vec::IndexVec; |
74b04a01 | 11 | use rustc_infer::infer::{InferCtxt, TyCtxtInferExt}; |
ba9703b0 | 12 | use rustc_middle::mir::{ |
f9f354fc | 13 | traversal, Body, ClearCrossCrate, Local, Location, Mutability, Operand, Place, PlaceElem, |
fc512014 | 14 | PlaceRef, VarDebugInfoContents, |
ba9703b0 XL |
15 | }; |
16 | use rustc_middle::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind}; | |
17 | use rustc_middle::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKind}; | |
f9f354fc | 18 | use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind}; |
ba9703b0 | 19 | use rustc_middle::ty::query::Providers; |
5869c6ff | 20 | use rustc_middle::ty::{self, CapturedPlace, ParamEnv, RegionVid, TyCtxt}; |
ba9703b0 | 21 | use rustc_session::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT, UNUSED_MUT}; |
f9f354fc | 22 | use rustc_span::{Span, Symbol, DUMMY_SP}; |
ff7c6d11 | 23 | |
74b04a01 | 24 | use either::Either; |
dfeec247 XL |
25 | use smallvec::SmallVec; |
26 | use std::cell::RefCell; | |
0bf4aa26 | 27 | use std::collections::BTreeMap; |
cdc7bbd5 | 28 | use std::iter; |
532ac7d7 XL |
29 | use std::mem; |
30 | use std::rc::Rc; | |
ff7c6d11 | 31 | |
74b04a01 | 32 | use crate::dataflow; |
f9f354fc XL |
33 | use crate::dataflow::impls::{ |
34 | Borrows, EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces, | |
35 | }; | |
9fa01778 | 36 | use crate::dataflow::indexes::{BorrowIndex, InitIndex, MoveOutIndex, MovePathIndex}; |
74b04a01 | 37 | use crate::dataflow::move_paths::{InitLocation, LookupResult, MoveData, MoveError}; |
9fa01778 | 38 | use crate::dataflow::MoveDataParamEnv; |
ba9703b0 | 39 | use crate::dataflow::{Analysis, BorrowckFlowState as Flows, BorrowckResults}; |
ff7c6d11 | 40 | |
dfeec247 | 41 | use self::diagnostics::{AccessKind, RegionName}; |
83c7162d | 42 | use self::location::LocationTable; |
ff7c6d11 XL |
43 | use self::prefixes::PrefixSet; |
44 | use self::MutateMode::{JustWrite, WriteAndRead}; | |
45 | ||
94b46f34 XL |
46 | use self::path_utils::*; |
47 | ||
dfeec247 XL |
48 | mod borrow_set; |
49 | mod constraint_generation; | |
50 | mod constraints; | |
f9f354fc | 51 | mod def_use; |
60c5eb7d | 52 | mod diagnostics; |
dfeec247 | 53 | mod facts; |
dfeec247 | 54 | mod invalidation; |
83c7162d | 55 | mod location; |
dfeec247 XL |
56 | mod member_constraints; |
57 | mod nll; | |
8faf50e0 | 58 | mod path_utils; |
dfeec247 XL |
59 | mod place_ext; |
60 | mod places_conflict; | |
ff7c6d11 | 61 | mod prefixes; |
dfeec247 | 62 | mod region_infer; |
60c5eb7d | 63 | mod renumber; |
60c5eb7d | 64 | mod type_check; |
dfeec247 XL |
65 | mod universal_regions; |
66 | mod used_muts; | |
60c5eb7d | 67 | |
dfeec247 | 68 | crate use borrow_set::{BorrowData, BorrowSet}; |
74b04a01 | 69 | crate use nll::{PoloniusOutput, ToRegionVid}; |
dfeec247 XL |
70 | crate use place_ext::PlaceExt; |
71 | crate use places_conflict::{places_conflict, PlaceConflictBias}; | |
72 | crate use region_infer::RegionInferenceContext; | |
ff7c6d11 | 73 | |
48663c56 XL |
74 | // FIXME(eddyb) perhaps move this somewhere more centrally. |
75 | #[derive(Debug)] | |
5869c6ff | 76 | crate struct Upvar<'tcx> { |
5869c6ff | 77 | place: CapturedPlace<'tcx>, |
48663c56 XL |
78 | |
79 | /// If true, the capture is behind a reference. | |
80 | by_ref: bool, | |
48663c56 XL |
81 | } |
82 | ||
74b04a01 XL |
83 | const DEREF_PROJECTION: &[PlaceElem<'_>; 1] = &[ProjectionElem::Deref]; |
84 | ||
f035d41b | 85 | pub fn provide(providers: &mut Providers) { |
3dfed10e XL |
86 | *providers = Providers { |
87 | mir_borrowck: |tcx, did| { | |
88 | if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) { | |
89 | tcx.mir_borrowck_const_arg(def) | |
90 | } else { | |
91 | mir_borrowck(tcx, ty::WithOptConstParam::unknown(did)) | |
92 | } | |
93 | }, | |
94 | mir_borrowck_const_arg: |tcx, (did, param_did)| { | |
95 | mir_borrowck(tcx, ty::WithOptConstParam { did, const_param_did: Some(param_did) }) | |
96 | }, | |
97 | ..*providers | |
98 | }; | |
ff7c6d11 XL |
99 | } |
100 | ||
3dfed10e XL |
101 | fn mir_borrowck<'tcx>( |
102 | tcx: TyCtxt<'tcx>, | |
103 | def: ty::WithOptConstParam<LocalDefId>, | |
104 | ) -> &'tcx BorrowCheckResult<'tcx> { | |
105 | let (input_body, promoted) = tcx.mir_promoted(def); | |
106 | debug!("run query mir_borrowck: {}", tcx.def_path_str(def.did.to_def_id())); | |
ff7c6d11 | 107 | |
ff7c6d11 | 108 | let opt_closure_req = tcx.infer_ctxt().enter(|infcx| { |
dc9dc135 | 109 | let input_body: &Body<'_> = &input_body.borrow(); |
e1599b0c | 110 | let promoted: &IndexVec<_, _> = &promoted.borrow(); |
29967ef6 | 111 | do_mir_borrowck(&infcx, input_body, promoted) |
ff7c6d11 XL |
112 | }); |
113 | debug!("mir_borrowck done"); | |
114 | ||
3dfed10e | 115 | tcx.arena.alloc(opt_closure_req) |
ff7c6d11 XL |
116 | } |
117 | ||
dc9dc135 XL |
118 | fn do_mir_borrowck<'a, 'tcx>( |
119 | infcx: &InferCtxt<'a, 'tcx>, | |
120 | input_body: &Body<'tcx>, | |
f9f354fc | 121 | input_promoted: &IndexVec<Promoted, Body<'tcx>>, |
dc9dc135 | 122 | ) -> BorrowCheckResult<'tcx> { |
29967ef6 XL |
123 | let def = input_body.source.with_opt_param().as_local().unwrap(); |
124 | ||
3dfed10e | 125 | debug!("do_mir_borrowck(def = {:?})", def); |
8faf50e0 | 126 | |
ff7c6d11 | 127 | let tcx = infcx.tcx; |
3dfed10e XL |
128 | let param_env = tcx.param_env(def.did); |
129 | let id = tcx.hir().local_def_id_to_hir_id(def.did); | |
ff7c6d11 | 130 | |
60c5eb7d XL |
131 | let mut local_names = IndexVec::from_elem(None, &input_body.local_decls); |
132 | for var_debug_info in &input_body.var_debug_info { | |
fc512014 XL |
133 | if let VarDebugInfoContents::Place(place) = var_debug_info.value { |
134 | if let Some(local) = place.as_local() { | |
135 | if let Some(prev_name) = local_names[local] { | |
136 | if var_debug_info.name != prev_name { | |
137 | span_bug!( | |
138 | var_debug_info.source_info.span, | |
139 | "local {:?} has many names (`{}` vs `{}`)", | |
140 | local, | |
141 | prev_name, | |
142 | var_debug_info.name | |
143 | ); | |
144 | } | |
60c5eb7d | 145 | } |
fc512014 | 146 | local_names[local] = Some(var_debug_info.name); |
60c5eb7d | 147 | } |
60c5eb7d XL |
148 | } |
149 | } | |
150 | ||
48663c56 | 151 | // Gather the upvars of a closure, if any. |
3dfed10e | 152 | let tables = tcx.typeck_opt_const_arg(def); |
ba9703b0 | 153 | if let Some(ErrorReported) = tables.tainted_by_errors { |
74b04a01 XL |
154 | infcx.set_tainted_by_errors(); |
155 | } | |
48663c56 | 156 | let upvars: Vec<_> = tables |
fc512014 XL |
157 | .closure_min_captures_flattened(def.did.to_def_id()) |
158 | .map(|captured_place| { | |
fc512014 | 159 | let capture = captured_place.info.capture_kind; |
48663c56 | 160 | let by_ref = match capture { |
1b1a35ee | 161 | ty::UpvarCapture::ByValue(_) => false, |
48663c56 XL |
162 | ty::UpvarCapture::ByRef(..) => true, |
163 | }; | |
17df50a5 | 164 | Upvar { place: captured_place.clone(), by_ref } |
48663c56 XL |
165 | }) |
166 | .collect(); | |
167 | ||
83c7162d XL |
168 | // Replace all regions with fresh inference variables. This |
169 | // requires first making our own copy of the MIR. This copy will | |
170 | // be modified (in place) to contain non-lexical lifetimes. It | |
171 | // will have a lifetime tied to the inference context. | |
f9f354fc | 172 | let mut body = input_body.clone(); |
60c5eb7d | 173 | let mut promoted = input_promoted.clone(); |
29967ef6 | 174 | let free_regions = nll::replace_regions_in_mir(infcx, param_env, &mut body, &mut promoted); |
f9f354fc | 175 | let body = &body; // no further changes |
60c5eb7d XL |
176 | |
177 | let location_table = &LocationTable::new(&body); | |
ff7c6d11 | 178 | |
8faf50e0 | 179 | let mut errors_buffer = Vec::new(); |
f9f354fc | 180 | let (move_data, move_errors): (MoveData<'tcx>, Vec<(Place<'tcx>, MoveError<'tcx>)>) = |
60c5eb7d | 181 | match MoveData::gather_moves(&body, tcx, param_env) { |
f9f354fc XL |
182 | Ok(move_data) => (move_data, Vec::new()), |
183 | Err((move_data, move_errors)) => (move_data, move_errors), | |
8faf50e0 | 184 | }; |
f9f354fc XL |
185 | let promoted_errors = promoted |
186 | .iter_enumerated() | |
187 | .map(|(idx, body)| (idx, MoveData::gather_moves(&body, tcx, param_env))); | |
ff7c6d11 | 188 | |
dfeec247 | 189 | let mdpe = MoveDataParamEnv { move_data, param_env }; |
ff7c6d11 | 190 | |
74b04a01 | 191 | let mut flow_inits = MaybeInitializedPlaces::new(tcx, &body, &mdpe) |
29967ef6 | 192 | .into_engine(tcx, &body) |
1b1a35ee | 193 | .pass_name("borrowck") |
74b04a01 XL |
194 | .iterate_to_fixpoint() |
195 | .into_results_cursor(&body); | |
ff7c6d11 | 196 | |
dc9dc135 | 197 | let locals_are_invalidated_at_exit = tcx.hir().body_owner_kind(id).is_fn_or_closure(); |
dfeec247 XL |
198 | let borrow_set = |
199 | Rc::new(BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &mdpe.move_data)); | |
200 | ||
201 | // Compute non-lexical lifetimes. | |
74b04a01 XL |
202 | let nll::NllOutput { |
203 | regioncx, | |
204 | opaque_type_values, | |
205 | polonius_output, | |
206 | opt_closure_req, | |
207 | nll_errors, | |
208 | } = nll::compute_regions( | |
209 | infcx, | |
74b04a01 XL |
210 | free_regions, |
211 | body, | |
212 | &promoted, | |
213 | location_table, | |
214 | param_env, | |
215 | &mut flow_inits, | |
216 | &mdpe.move_data, | |
217 | &borrow_set, | |
f035d41b | 218 | &upvars, |
74b04a01 | 219 | ); |
83c7162d | 220 | |
dfeec247 XL |
221 | // Dump MIR results into a file, if that is enabled. This let us |
222 | // write unit-tests, as well as helping with debugging. | |
29967ef6 | 223 | nll::dump_mir_results(infcx, &body, ®ioncx, &opt_closure_req); |
dfeec247 | 224 | |
74b04a01 | 225 | // We also have a `#[rustc_regions]` annotation that causes us to dump |
dfeec247 | 226 | // information. |
74b04a01 XL |
227 | nll::dump_annotation( |
228 | infcx, | |
229 | &body, | |
74b04a01 XL |
230 | ®ioncx, |
231 | &opt_closure_req, | |
232 | &opaque_type_values, | |
233 | &mut errors_buffer, | |
234 | ); | |
b7449926 XL |
235 | |
236 | // The various `flow_*` structures can be large. We drop `flow_inits` here | |
237 | // so it doesn't overlap with the others below. This reduces peak memory | |
238 | // usage significantly on some benchmarks. | |
239 | drop(flow_inits); | |
240 | ||
83c7162d | 241 | let regioncx = Rc::new(regioncx); |
ff7c6d11 | 242 | |
6a06907d | 243 | let flow_borrows = Borrows::new(tcx, &body, ®ioncx, &borrow_set) |
29967ef6 | 244 | .into_engine(tcx, &body) |
1b1a35ee | 245 | .pass_name("borrowck") |
74b04a01 XL |
246 | .iterate_to_fixpoint(); |
247 | let flow_uninits = MaybeUninitializedPlaces::new(tcx, &body, &mdpe) | |
29967ef6 | 248 | .into_engine(tcx, &body) |
1b1a35ee | 249 | .pass_name("borrowck") |
74b04a01 XL |
250 | .iterate_to_fixpoint(); |
251 | let flow_ever_inits = EverInitializedPlaces::new(tcx, &body, &mdpe) | |
29967ef6 | 252 | .into_engine(tcx, &body) |
1b1a35ee | 253 | .pass_name("borrowck") |
74b04a01 | 254 | .iterate_to_fixpoint(); |
0531ce1d | 255 | |
dc9dc135 | 256 | let movable_generator = match tcx.hir().get(id) { |
b7449926 | 257 | Node::Expr(&hir::Expr { |
60c5eb7d | 258 | kind: hir::ExprKind::Closure(.., Some(hir::Movability::Static)), |
2c00a5a8 | 259 | .. |
83c7162d XL |
260 | }) => false, |
261 | _ => true, | |
2c00a5a8 XL |
262 | }; |
263 | ||
f9f354fc XL |
264 | for (idx, move_data_results) in promoted_errors { |
265 | let promoted_body = &promoted[idx]; | |
f9f354fc XL |
266 | |
267 | if let Err((move_data, move_errors)) = move_data_results { | |
268 | let mut promoted_mbcx = MirBorrowckCtxt { | |
269 | infcx, | |
1b1a35ee | 270 | param_env, |
f9f354fc | 271 | body: promoted_body, |
f9f354fc | 272 | move_data: &move_data, |
6a06907d | 273 | location_table, // no need to create a real one for the promoted, it is not used |
f9f354fc | 274 | movable_generator, |
f035d41b | 275 | fn_self_span_reported: Default::default(), |
f9f354fc XL |
276 | locals_are_invalidated_at_exit, |
277 | access_place_error_reported: Default::default(), | |
278 | reservation_error_reported: Default::default(), | |
279 | reservation_warnings: Default::default(), | |
280 | move_error_reported: BTreeMap::new(), | |
281 | uninitialized_error_reported: Default::default(), | |
282 | errors_buffer, | |
283 | regioncx: regioncx.clone(), | |
284 | used_mut: Default::default(), | |
285 | used_mut_upvars: SmallVec::new(), | |
6a06907d XL |
286 | borrow_set: Rc::clone(&borrow_set), |
287 | dominators: Dominators::dummy(), // not used | |
f9f354fc XL |
288 | upvars: Vec::new(), |
289 | local_names: IndexVec::from_elem(None, &promoted_body.local_decls), | |
290 | region_names: RefCell::default(), | |
291 | next_region_name: RefCell::new(1), | |
292 | polonius_output: None, | |
293 | }; | |
294 | promoted_mbcx.report_move_errors(move_errors); | |
295 | errors_buffer = promoted_mbcx.errors_buffer; | |
296 | }; | |
297 | } | |
298 | ||
dc9dc135 | 299 | let dominators = body.dominators(); |
83c7162d | 300 | |
ff7c6d11 | 301 | let mut mbcx = MirBorrowckCtxt { |
0bf4aa26 | 302 | infcx, |
1b1a35ee | 303 | param_env, |
dc9dc135 | 304 | body, |
ff7c6d11 | 305 | move_data: &mdpe.move_data, |
8faf50e0 | 306 | location_table, |
2c00a5a8 | 307 | movable_generator, |
b7449926 | 308 | locals_are_invalidated_at_exit, |
f035d41b | 309 | fn_self_span_reported: Default::default(), |
0bf4aa26 XL |
310 | access_place_error_reported: Default::default(), |
311 | reservation_error_reported: Default::default(), | |
532ac7d7 | 312 | reservation_warnings: Default::default(), |
0bf4aa26 XL |
313 | move_error_reported: BTreeMap::new(), |
314 | uninitialized_error_reported: Default::default(), | |
8faf50e0 | 315 | errors_buffer, |
6a06907d | 316 | regioncx: Rc::clone(®ioncx), |
0bf4aa26 | 317 | used_mut: Default::default(), |
83c7162d | 318 | used_mut_upvars: SmallVec::new(), |
6a06907d | 319 | borrow_set: Rc::clone(&borrow_set), |
83c7162d | 320 | dominators, |
48663c56 | 321 | upvars, |
60c5eb7d | 322 | local_names, |
dfeec247 XL |
323 | region_names: RefCell::default(), |
324 | next_region_name: RefCell::new(1), | |
74b04a01 | 325 | polonius_output, |
ff7c6d11 XL |
326 | }; |
327 | ||
dfeec247 XL |
328 | // Compute and report region errors, if any. |
329 | mbcx.report_region_errors(nll_errors); | |
330 | ||
74b04a01 XL |
331 | let results = BorrowckResults { |
332 | ever_inits: flow_ever_inits, | |
333 | uninits: flow_uninits, | |
334 | borrows: flow_borrows, | |
335 | }; | |
ff7c6d11 | 336 | |
f9f354fc | 337 | mbcx.report_move_errors(move_errors); |
74b04a01 | 338 | |
ba9703b0 XL |
339 | dataflow::visit_results( |
340 | &body, | |
341 | traversal::reverse_postorder(&body).map(|(bb, _)| bb), | |
74b04a01 XL |
342 | &results, |
343 | &mut mbcx, | |
344 | ); | |
ff7c6d11 | 345 | |
532ac7d7 | 346 | // Convert any reservation warnings into lints. |
416331ca | 347 | let reservation_warnings = mem::take(&mut mbcx.reservation_warnings); |
48663c56 | 348 | for (_, (place, span, location, bk, borrow)) in reservation_warnings { |
ba9703b0 | 349 | let mut initial_diag = mbcx.report_conflicting_borrow(location, (place, span), bk, &borrow); |
532ac7d7 | 350 | |
60c5eb7d XL |
351 | let scope = mbcx.body.source_info(location).scope; |
352 | let lint_root = match &mbcx.body.source_scopes[scope].local_data { | |
353 | ClearCrossCrate::Set(data) => data.lint_root, | |
354 | _ => id, | |
532ac7d7 XL |
355 | }; |
356 | ||
357 | // Span and message don't matter; we overwrite them below anyway | |
74b04a01 | 358 | mbcx.infcx.tcx.struct_span_lint_hir( |
dfeec247 XL |
359 | MUTABLE_BORROW_RESERVATION_CONFLICT, |
360 | lint_root, | |
361 | DUMMY_SP, | |
74b04a01 XL |
362 | |lint| { |
363 | let mut diag = lint.build(""); | |
532ac7d7 | 364 | |
74b04a01 XL |
365 | diag.message = initial_diag.styled_message().clone(); |
366 | diag.span = initial_diag.span.clone(); | |
532ac7d7 | 367 | |
74b04a01 XL |
368 | diag.buffer(&mut mbcx.errors_buffer); |
369 | }, | |
370 | ); | |
532ac7d7 | 371 | initial_diag.cancel(); |
532ac7d7 XL |
372 | } |
373 | ||
83c7162d XL |
374 | // For each non-user used mutable variable, check if it's been assigned from |
375 | // a user-declared local. If so, then put that local into the used_mut set. | |
376 | // Note that this set is expected to be small - only upvars from closures | |
377 | // would have a chance of erroneously adding non-user-defined mutable vars | |
378 | // to the set. | |
dfeec247 XL |
379 | let temporary_used_locals: FxHashSet<Local> = mbcx |
380 | .used_mut | |
381 | .iter() | |
60c5eb7d | 382 | .filter(|&local| !mbcx.body.local_decls[*local].is_user_variable()) |
8faf50e0 XL |
383 | .cloned() |
384 | .collect(); | |
a1dfa0c6 XL |
385 | // For the remaining unused locals that are marked as mutable, we avoid linting any that |
386 | // were never initialized. These locals may have been removed as unreachable code; or will be | |
387 | // linted as unused variables. | |
dfeec247 XL |
388 | let unused_mut_locals = |
389 | mbcx.body.mut_vars_iter().filter(|local| !mbcx.used_mut.contains(local)).collect(); | |
a1dfa0c6 | 390 | mbcx.gather_used_muts(temporary_used_locals, unused_mut_locals); |
83c7162d XL |
391 | |
392 | debug!("mbcx.used_mut: {:?}", mbcx.used_mut); | |
8faf50e0 | 393 | let used_mut = mbcx.used_mut; |
dfeec247 | 394 | for local in mbcx.body.mut_vars_and_args_iter().filter(|local| !used_mut.contains(local)) { |
60c5eb7d XL |
395 | let local_decl = &mbcx.body.local_decls[local]; |
396 | let lint_root = match &mbcx.body.source_scopes[local_decl.source_info.scope].local_data { | |
397 | ClearCrossCrate::Set(data) => data.lint_root, | |
398 | _ => continue, | |
399 | }; | |
83c7162d | 400 | |
60c5eb7d XL |
401 | // Skip over locals that begin with an underscore or have no name |
402 | match mbcx.local_names[local] { | |
dfeec247 | 403 | Some(name) => { |
74b04a01 | 404 | if name.as_str().starts_with('_') { |
dfeec247 XL |
405 | continue; |
406 | } | |
407 | } | |
60c5eb7d XL |
408 | None => continue, |
409 | } | |
83c7162d | 410 | |
60c5eb7d XL |
411 | let span = local_decl.source_info.span; |
412 | if span.desugaring_kind().is_some() { | |
413 | // If the `mut` arises as part of a desugaring, we should ignore it. | |
414 | continue; | |
8faf50e0 | 415 | } |
60c5eb7d | 416 | |
74b04a01 XL |
417 | tcx.struct_span_lint_hir(UNUSED_MUT, lint_root, span, |lint| { |
418 | let mut_span = tcx.sess.source_map().span_until_non_whitespace(span); | |
419 | lint.build("variable does not need to be mutable") | |
420 | .span_suggestion_short( | |
421 | mut_span, | |
422 | "remove this `mut`", | |
423 | String::new(), | |
424 | Applicability::MachineApplicable, | |
425 | ) | |
426 | .emit(); | |
427 | }) | |
8faf50e0 XL |
428 | } |
429 | ||
0bf4aa26 XL |
430 | // Buffer any move errors that we collected and de-duplicated. |
431 | for (_, (_, diag)) in mbcx.move_error_reported { | |
432 | diag.buffer(&mut mbcx.errors_buffer); | |
433 | } | |
434 | ||
435 | if !mbcx.errors_buffer.is_empty() { | |
60c5eb7d | 436 | mbcx.errors_buffer.sort_by_key(|diag| diag.sort_span); |
b7449926 | 437 | |
8faf50e0 | 438 | for diag in mbcx.errors_buffer.drain(..) { |
e1599b0c | 439 | mbcx.infcx.tcx.sess.diagnostic().emit_diagnostic(&diag); |
83c7162d XL |
440 | } |
441 | } | |
442 | ||
8faf50e0 | 443 | let result = BorrowCheckResult { |
74b04a01 | 444 | concrete_opaque_types: opaque_type_values, |
83c7162d XL |
445 | closure_requirements: opt_closure_req, |
446 | used_mut_upvars: mbcx.used_mut_upvars, | |
8faf50e0 XL |
447 | }; |
448 | ||
449 | debug!("do_mir_borrowck: result = {:#?}", result); | |
450 | ||
451 | result | |
ff7c6d11 XL |
452 | } |
453 | ||
416331ca XL |
454 | crate struct MirBorrowckCtxt<'cx, 'tcx> { |
455 | crate infcx: &'cx InferCtxt<'cx, 'tcx>, | |
1b1a35ee | 456 | param_env: ParamEnv<'tcx>, |
f9f354fc | 457 | body: &'cx Body<'tcx>, |
ff7c6d11 | 458 | move_data: &'cx MoveData<'tcx>, |
8faf50e0 XL |
459 | |
460 | /// Map from MIR `Location` to `LocationIndex`; created | |
461 | /// when MIR borrowck begins. | |
462 | location_table: &'cx LocationTable, | |
463 | ||
2c00a5a8 | 464 | movable_generator: bool, |
ff7c6d11 XL |
465 | /// This keeps track of whether local variables are free-ed when the function |
466 | /// exits even without a `StorageDead`, which appears to be the case for | |
467 | /// constants. | |
468 | /// | |
469 | /// I'm not sure this is the right approach - @eddyb could you try and | |
470 | /// figure this out? | |
471 | locals_are_invalidated_at_exit: bool, | |
2c00a5a8 XL |
472 | /// This field keeps track of when borrow errors are reported in the access_place function |
473 | /// so that there is no duplicate reporting. This field cannot also be used for the conflicting | |
474 | /// borrow errors that is handled by the `reservation_error_reported` field as the inclusion | |
475 | /// of the `Span` type (while required to mute some errors) stops the muting of the reservation | |
476 | /// errors. | |
477 | access_place_error_reported: FxHashSet<(Place<'tcx>, Span)>, | |
ff7c6d11 XL |
478 | /// This field keeps track of when borrow conflict errors are reported |
479 | /// for reservations, so that we don't report seemingly duplicate | |
9fa01778 XL |
480 | /// errors for corresponding activations. |
481 | // | |
482 | // FIXME: ideally this would be a set of `BorrowIndex`, not `Place`s, | |
483 | // but it is currently inconvenient to track down the `BorrowIndex` | |
484 | // at the time we detect and report a reservation error. | |
ff7c6d11 | 485 | reservation_error_reported: FxHashSet<Place<'tcx>>, |
f035d41b XL |
486 | /// This fields keeps track of the `Span`s that we have |
487 | /// used to report extra information for `FnSelfUse`, to avoid | |
488 | /// unnecessarily verbose errors. | |
489 | fn_self_span_reported: FxHashSet<Span>, | |
532ac7d7 XL |
490 | /// Migration warnings to be reported for #56254. We delay reporting these |
491 | /// so that we can suppress the warning if there's a corresponding error | |
492 | /// for the activation of the borrow. | |
dfeec247 XL |
493 | reservation_warnings: |
494 | FxHashMap<BorrowIndex, (Place<'tcx>, Span, Location, BorrowKind, BorrowData<'tcx>)>, | |
74b04a01 | 495 | /// This field keeps track of move errors that are to be reported for given move indices. |
0bf4aa26 XL |
496 | /// |
497 | /// There are situations where many errors can be reported for a single move out (see #53807) | |
498 | /// and we want only the best of those errors. | |
499 | /// | |
500 | /// The `report_use_of_moved_or_uninitialized` function checks this map and replaces the | |
501 | /// diagnostic (if there is one) if the `Place` of the error being reported is a prefix of the | |
502 | /// `Place` of the previous most diagnostic. This happens instead of buffering the error. Once | |
503 | /// all move errors have been reported, any diagnostics in this map are added to the buffer | |
504 | /// to be emitted. | |
505 | /// | |
506 | /// `BTreeMap` is used to preserve the order of insertions when iterating. This is necessary | |
507 | /// when errors in the map are being re-added to the error buffer so that errors with the | |
508 | /// same primary span come out in a consistent order. | |
74b04a01 | 509 | move_error_reported: BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, DiagnosticBuilder<'cx>)>, |
0bf4aa26 | 510 | /// This field keeps track of errors reported in the checking of uninitialized variables, |
8faf50e0 | 511 | /// so that we don't report seemingly duplicate errors. |
74b04a01 | 512 | uninitialized_error_reported: FxHashSet<PlaceRef<'tcx>>, |
8faf50e0 XL |
513 | /// Errors to be reported buffer |
514 | errors_buffer: Vec<Diagnostic>, | |
83c7162d XL |
515 | /// This field keeps track of all the local variables that are declared mut and are mutated. |
516 | /// Used for the warning issued by an unused mutable local variable. | |
517 | used_mut: FxHashSet<Local>, | |
518 | /// If the function we're checking is a closure, then we'll need to report back the list of | |
519 | /// mutable upvars that have been used. This field keeps track of them. | |
520 | used_mut_upvars: SmallVec<[Field; 8]>, | |
dfeec247 | 521 | /// Region inference context. This contains the results from region inference and lets us e.g. |
ff7c6d11 | 522 | /// find out which CFG points are contained in each borrow region. |
dfeec247 | 523 | regioncx: Rc<RegionInferenceContext<'tcx>>, |
83c7162d XL |
524 | |
525 | /// The set of borrows extracted from the MIR | |
526 | borrow_set: Rc<BorrowSet<'tcx>>, | |
527 | ||
528 | /// Dominators for MIR | |
529 | dominators: Dominators<BasicBlock>, | |
48663c56 XL |
530 | |
531 | /// Information about upvars not necessarily preserved in types or MIR | |
5869c6ff | 532 | upvars: Vec<Upvar<'tcx>>, |
60c5eb7d XL |
533 | |
534 | /// Names of local (user) variables (extracted from `var_debug_info`). | |
f9f354fc | 535 | local_names: IndexVec<Local, Option<Symbol>>, |
dfeec247 XL |
536 | |
537 | /// Record the region names generated for each region in the given | |
538 | /// MIR def so that we can reuse them later in help/error messages. | |
539 | region_names: RefCell<FxHashMap<RegionVid, RegionName>>, | |
540 | ||
541 | /// The counter for generating new region names. | |
542 | next_region_name: RefCell<usize>, | |
74b04a01 XL |
543 | |
544 | /// Results of Polonius analysis. | |
545 | polonius_output: Option<Rc<PoloniusOutput>>, | |
ff7c6d11 XL |
546 | } |
547 | ||
548 | // Check that: | |
549 | // 1. assignments are always made to mutable locations (FIXME: does that still really go here?) | |
550 | // 2. loans made in overlapping scopes do not conflict | |
551 | // 3. assignments do not affect things loaned out as immutable | |
552 | // 4. moves do not affect things loaned out in any way | |
ba9703b0 | 553 | impl<'cx, 'tcx> dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tcx> { |
dc9dc135 | 554 | type FlowState = Flows<'cx, 'tcx>; |
ff7c6d11 | 555 | |
f9f354fc | 556 | fn visit_statement_before_primary_effect( |
ff7c6d11 | 557 | &mut self, |
74b04a01 | 558 | flow_state: &Flows<'cx, 'tcx>, |
416331ca | 559 | stmt: &'cx Statement<'tcx>, |
74b04a01 | 560 | location: Location, |
ff7c6d11 | 561 | ) { |
74b04a01 | 562 | debug!("MirBorrowckCtxt::process_statement({:?}, {:?}): {:?}", location, stmt, flow_state); |
ff7c6d11 XL |
563 | let span = stmt.source_info.span; |
564 | ||
565 | self.check_activations(location, span, flow_state); | |
566 | ||
ba9703b0 XL |
567 | match &stmt.kind { |
568 | StatementKind::Assign(box (lhs, ref rhs)) => { | |
dfeec247 | 569 | self.consume_rvalue(location, (rhs, span), flow_state); |
2c00a5a8 | 570 | |
ba9703b0 | 571 | self.mutate_place(location, (*lhs, span), Shallow(None), JustWrite, flow_state); |
ff7c6d11 | 572 | } |
cdc7bbd5 | 573 | StatementKind::FakeRead(box (_, ref place)) => { |
0bf4aa26 XL |
574 | // Read for match doesn't access any memory and is used to |
575 | // assert that a place is safe and live. So we don't have to | |
576 | // do any checks here. | |
577 | // | |
578 | // FIXME: Remove check that the place is initialized. This is | |
579 | // needed for now because matches don't have never patterns yet. | |
580 | // So this is the only place we prevent | |
581 | // let x: !; | |
582 | // match x {}; | |
583 | // from compiling. | |
584 | self.check_if_path_or_subpath_is_moved( | |
48663c56 | 585 | location, |
0bf4aa26 | 586 | InitializationRequiringAction::Use, |
416331ca | 587 | (place.as_ref(), span), |
8faf50e0 XL |
588 | flow_state, |
589 | ); | |
94b46f34 | 590 | } |
ba9703b0 XL |
591 | StatementKind::SetDiscriminant { place, variant_index: _ } => { |
592 | self.mutate_place(location, (**place, span), Shallow(None), JustWrite, flow_state); | |
ff7c6d11 | 593 | } |
ba9703b0 | 594 | StatementKind::LlvmInlineAsm(ref asm) => { |
cdc7bbd5 | 595 | for (o, output) in iter::zip(&asm.asm.outputs, &*asm.outputs) { |
ff7c6d11 XL |
596 | if o.is_indirect { |
597 | // FIXME(eddyb) indirect inline asm outputs should | |
532ac7d7 | 598 | // be encoded through MIR place derefs instead. |
ff7c6d11 | 599 | self.access_place( |
48663c56 | 600 | location, |
ba9703b0 | 601 | (*output, o.span), |
ff7c6d11 XL |
602 | (Deep, Read(ReadKind::Copy)), |
603 | LocalMutationIsAllowed::No, | |
604 | flow_state, | |
605 | ); | |
83c7162d | 606 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 607 | location, |
ff7c6d11 | 608 | InitializationRequiringAction::Use, |
416331ca | 609 | (output.as_ref(), o.span), |
ff7c6d11 XL |
610 | flow_state, |
611 | ); | |
612 | } else { | |
613 | self.mutate_place( | |
48663c56 | 614 | location, |
ba9703b0 | 615 | (*output, o.span), |
ff7c6d11 XL |
616 | if o.is_rw { Deep } else { Shallow(None) }, |
617 | if o.is_rw { WriteAndRead } else { JustWrite }, | |
618 | flow_state, | |
619 | ); | |
620 | } | |
621 | } | |
532ac7d7 | 622 | for (_, input) in asm.inputs.iter() { |
48663c56 | 623 | self.consume_operand(location, (input, span), flow_state); |
ff7c6d11 XL |
624 | } |
625 | } | |
6a06907d XL |
626 | |
627 | StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping { | |
628 | .. | |
629 | }) => { | |
630 | span_bug!( | |
631 | span, | |
632 | "Unexpected CopyNonOverlapping, should only appear after lower_intrinsics", | |
633 | ) | |
634 | } | |
8faf50e0 | 635 | StatementKind::Nop |
3dfed10e | 636 | | StatementKind::Coverage(..) |
b7449926 | 637 | | StatementKind::AscribeUserType(..) |
a1dfa0c6 | 638 | | StatementKind::Retag { .. } |
8faf50e0 | 639 | | StatementKind::StorageLive(..) => { |
a1dfa0c6 | 640 | // `Nop`, `AscribeUserType`, `Retag`, and `StorageLive` are irrelevant |
ff7c6d11 XL |
641 | // to borrow check. |
642 | } | |
ff7c6d11 XL |
643 | StatementKind::StorageDead(local) => { |
644 | self.access_place( | |
48663c56 | 645 | location, |
ba9703b0 | 646 | (Place::from(*local), span), |
ff7c6d11 XL |
647 | (Shallow(None), Write(WriteKind::StorageDeadOrDrop)), |
648 | LocalMutationIsAllowed::Yes, | |
649 | flow_state, | |
650 | ); | |
651 | } | |
652 | } | |
653 | } | |
654 | ||
f9f354fc | 655 | fn visit_terminator_before_primary_effect( |
ff7c6d11 | 656 | &mut self, |
74b04a01 | 657 | flow_state: &Flows<'cx, 'tcx>, |
416331ca | 658 | term: &'cx Terminator<'tcx>, |
74b04a01 | 659 | loc: Location, |
ff7c6d11 | 660 | ) { |
74b04a01 | 661 | debug!("MirBorrowckCtxt::process_terminator({:?}, {:?}): {:?}", loc, term, flow_state); |
ff7c6d11 XL |
662 | let span = term.source_info.span; |
663 | ||
74b04a01 | 664 | self.check_activations(loc, span, flow_state); |
ff7c6d11 XL |
665 | |
666 | match term.kind { | |
29967ef6 | 667 | TerminatorKind::SwitchInt { ref discr, switch_ty: _, targets: _ } => { |
48663c56 | 668 | self.consume_operand(loc, (discr, span), flow_state); |
ff7c6d11 | 669 | } |
29967ef6 | 670 | TerminatorKind::Drop { place, target: _, unwind: _ } => { |
dfeec247 XL |
671 | debug!( |
672 | "visit_terminator_drop \ | |
29967ef6 XL |
673 | loc: {:?} term: {:?} place: {:?} span: {:?}", |
674 | loc, term, place, span | |
dfeec247 | 675 | ); |
b7449926 | 676 | |
0bf4aa26 | 677 | self.access_place( |
48663c56 | 678 | loc, |
29967ef6 | 679 | (place, span), |
0bf4aa26 XL |
680 | (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)), |
681 | LocalMutationIsAllowed::Yes, | |
682 | flow_state, | |
683 | ); | |
ff7c6d11 XL |
684 | } |
685 | TerminatorKind::DropAndReplace { | |
f035d41b | 686 | place: drop_place, |
ff7c6d11 XL |
687 | value: ref new_value, |
688 | target: _, | |
689 | unwind: _, | |
690 | } => { | |
dfeec247 XL |
691 | self.mutate_place(loc, (drop_place, span), Deep, JustWrite, flow_state); |
692 | self.consume_operand(loc, (new_value, span), flow_state); | |
ff7c6d11 XL |
693 | } |
694 | TerminatorKind::Call { | |
695 | ref func, | |
696 | ref args, | |
697 | ref destination, | |
698 | cleanup: _, | |
0bf4aa26 | 699 | from_hir_call: _, |
f035d41b | 700 | fn_span: _, |
ff7c6d11 | 701 | } => { |
48663c56 | 702 | self.consume_operand(loc, (func, span), flow_state); |
ff7c6d11 | 703 | for arg in args { |
dfeec247 | 704 | self.consume_operand(loc, (arg, span), flow_state); |
ff7c6d11 | 705 | } |
ba9703b0 | 706 | if let Some((dest, _ /*bb*/)) = *destination { |
dfeec247 | 707 | self.mutate_place(loc, (dest, span), Deep, JustWrite, flow_state); |
ff7c6d11 XL |
708 | } |
709 | } | |
dfeec247 | 710 | TerminatorKind::Assert { ref cond, expected: _, ref msg, target: _, cleanup: _ } => { |
48663c56 | 711 | self.consume_operand(loc, (cond, span), flow_state); |
ba9703b0 | 712 | use rustc_middle::mir::AssertKind; |
74b04a01 | 713 | if let AssertKind::BoundsCheck { ref len, ref index } = *msg { |
48663c56 XL |
714 | self.consume_operand(loc, (len, span), flow_state); |
715 | self.consume_operand(loc, (index, span), flow_state); | |
ff7c6d11 XL |
716 | } |
717 | } | |
718 | ||
ba9703b0 | 719 | TerminatorKind::Yield { ref value, resume: _, resume_arg, drop: _ } => { |
48663c56 | 720 | self.consume_operand(loc, (value, span), flow_state); |
74b04a01 XL |
721 | self.mutate_place(loc, (resume_arg, span), Deep, JustWrite, flow_state); |
722 | } | |
2c00a5a8 | 723 | |
f9f354fc XL |
724 | TerminatorKind::InlineAsm { |
725 | template: _, | |
726 | ref operands, | |
727 | options: _, | |
728 | line_spans: _, | |
729 | destination: _, | |
730 | } => { | |
731 | for op in operands { | |
732 | match *op { | |
cdc7bbd5 | 733 | InlineAsmOperand::In { reg: _, ref value } => { |
f9f354fc XL |
734 | self.consume_operand(loc, (value, span), flow_state); |
735 | } | |
736 | InlineAsmOperand::Out { reg: _, late: _, place, .. } => { | |
737 | if let Some(place) = place { | |
738 | self.mutate_place( | |
739 | loc, | |
740 | (place, span), | |
741 | Shallow(None), | |
742 | JustWrite, | |
743 | flow_state, | |
744 | ); | |
745 | } | |
746 | } | |
747 | InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => { | |
748 | self.consume_operand(loc, (in_value, span), flow_state); | |
749 | if let Some(out_place) = out_place { | |
750 | self.mutate_place( | |
751 | loc, | |
752 | (out_place, span), | |
753 | Shallow(None), | |
754 | JustWrite, | |
755 | flow_state, | |
756 | ); | |
757 | } | |
758 | } | |
cdc7bbd5 XL |
759 | InlineAsmOperand::Const { value: _ } |
760 | | InlineAsmOperand::SymFn { value: _ } | |
f035d41b | 761 | | InlineAsmOperand::SymStatic { def_id: _ } => {} |
f9f354fc XL |
762 | } |
763 | } | |
764 | } | |
765 | ||
74b04a01 XL |
766 | TerminatorKind::Goto { target: _ } |
767 | | TerminatorKind::Abort | |
768 | | TerminatorKind::Unreachable | |
769 | | TerminatorKind::Resume | |
770 | | TerminatorKind::Return | |
771 | | TerminatorKind::GeneratorDrop | |
f035d41b | 772 | | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ } |
74b04a01 XL |
773 | | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => { |
774 | // no data used, thus irrelevant to borrowck | |
775 | } | |
776 | } | |
777 | } | |
778 | ||
f9f354fc | 779 | fn visit_terminator_after_primary_effect( |
74b04a01 XL |
780 | &mut self, |
781 | flow_state: &Flows<'cx, 'tcx>, | |
782 | term: &'cx Terminator<'tcx>, | |
783 | loc: Location, | |
784 | ) { | |
785 | let span = term.source_info.span; | |
786 | ||
787 | match term.kind { | |
788 | TerminatorKind::Yield { value: _, resume: _, resume_arg: _, drop: _ } => { | |
2c00a5a8 XL |
789 | if self.movable_generator { |
790 | // Look for any active borrows to locals | |
83c7162d | 791 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
792 | for i in flow_state.borrows.iter() { |
793 | let borrow = &borrow_set[i]; | |
794 | self.check_for_local_borrow(borrow, span); | |
795 | } | |
2c00a5a8 | 796 | } |
ff7c6d11 XL |
797 | } |
798 | ||
799 | TerminatorKind::Resume | TerminatorKind::Return | TerminatorKind::GeneratorDrop => { | |
800 | // Returning from the function implicitly kills storage for all locals and statics. | |
801 | // Often, the storage will already have been killed by an explicit | |
802 | // StorageDead, but we don't always emit those (notably on unwind paths), | |
803 | // so this "extra check" serves as a kind of backup. | |
83c7162d | 804 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
805 | for i in flow_state.borrows.iter() { |
806 | let borrow = &borrow_set[i]; | |
807 | self.check_for_invalidation_at_exit(loc, borrow, span); | |
808 | } | |
ff7c6d11 | 809 | } |
74b04a01 XL |
810 | |
811 | TerminatorKind::Abort | |
812 | | TerminatorKind::Assert { .. } | |
813 | | TerminatorKind::Call { .. } | |
814 | | TerminatorKind::Drop { .. } | |
815 | | TerminatorKind::DropAndReplace { .. } | |
f035d41b | 816 | | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ } |
74b04a01 XL |
817 | | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } |
818 | | TerminatorKind::Goto { .. } | |
819 | | TerminatorKind::SwitchInt { .. } | |
f9f354fc XL |
820 | | TerminatorKind::Unreachable |
821 | | TerminatorKind::InlineAsm { .. } => {} | |
ff7c6d11 XL |
822 | } |
823 | } | |
824 | } | |
825 | ||
826 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
827 | enum MutateMode { | |
828 | JustWrite, | |
829 | WriteAndRead, | |
830 | } | |
831 | ||
0bf4aa26 | 832 | use self::AccessDepth::{Deep, Shallow}; |
dfeec247 | 833 | use self::ReadOrWrite::{Activation, Read, Reservation, Write}; |
ff7c6d11 XL |
834 | |
835 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
836 | enum ArtificialField { | |
ff7c6d11 | 837 | ArrayLength, |
0bf4aa26 | 838 | ShallowBorrow, |
ff7c6d11 XL |
839 | } |
840 | ||
841 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
0bf4aa26 | 842 | enum AccessDepth { |
ff7c6d11 | 843 | /// From the RFC: "A *shallow* access means that the immediate |
2c00a5a8 | 844 | /// fields reached at P are accessed, but references or pointers |
ff7c6d11 XL |
845 | /// found within are not dereferenced. Right now, the only access |
846 | /// that is shallow is an assignment like `x = ...;`, which would | |
847 | /// be a *shallow write* of `x`." | |
848 | Shallow(Option<ArtificialField>), | |
849 | ||
850 | /// From the RFC: "A *deep* access means that all data reachable | |
851 | /// through the given place may be invalidated or accesses by | |
852 | /// this action." | |
853 | Deep, | |
0bf4aa26 XL |
854 | |
855 | /// Access is Deep only when there is a Drop implementation that | |
856 | /// can reach the data behind the reference. | |
857 | Drop, | |
ff7c6d11 XL |
858 | } |
859 | ||
860 | /// Kind of access to a value: read or write | |
861 | /// (For informational purposes only) | |
862 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
863 | enum ReadOrWrite { | |
864 | /// From the RFC: "A *read* means that the existing data may be | |
865 | /// read, but will not be changed." | |
866 | Read(ReadKind), | |
867 | ||
868 | /// From the RFC: "A *write* means that the data may be mutated to | |
869 | /// new values or otherwise invalidated (for example, it could be | |
870 | /// de-initialized, as in a move operation). | |
871 | Write(WriteKind), | |
872 | ||
873 | /// For two-phase borrows, we distinguish a reservation (which is treated | |
874 | /// like a Read) from an activation (which is treated like a write), and | |
875 | /// each of those is furthermore distinguished from Reads/Writes above. | |
876 | Reservation(WriteKind), | |
877 | Activation(WriteKind, BorrowIndex), | |
878 | } | |
879 | ||
880 | /// Kind of read access to a value | |
881 | /// (For informational purposes only) | |
882 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
883 | enum ReadKind { | |
884 | Borrow(BorrowKind), | |
885 | Copy, | |
886 | } | |
887 | ||
888 | /// Kind of write access to a value | |
889 | /// (For informational purposes only) | |
890 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
891 | enum WriteKind { | |
892 | StorageDeadOrDrop, | |
893 | MutableBorrow(BorrowKind), | |
894 | Mutate, | |
895 | Move, | |
896 | } | |
897 | ||
898 | /// When checking permissions for a place access, this flag is used to indicate that an immutable | |
899 | /// local place can be mutated. | |
9fa01778 XL |
900 | // |
901 | // FIXME: @nikomatsakis suggested that this flag could be removed with the following modifications: | |
902 | // - Merge `check_access_permissions()` and `check_if_reassignment_to_immutable_state()`. | |
903 | // - Split `is_mutable()` into `is_assignable()` (can be directly assigned) and | |
904 | // `is_declared_mutable()`. | |
905 | // - Take flow state into consideration in `is_assignable()` for local variables. | |
ff7c6d11 XL |
906 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
907 | enum LocalMutationIsAllowed { | |
908 | Yes, | |
909 | /// We want use of immutable upvars to cause a "write to immutable upvar" | |
910 | /// error, not an "reassignment" error. | |
911 | ExceptUpvars, | |
912 | No, | |
913 | } | |
914 | ||
0bf4aa26 | 915 | #[derive(Copy, Clone, Debug)] |
ff7c6d11 XL |
916 | enum InitializationRequiringAction { |
917 | Update, | |
918 | Borrow, | |
0bf4aa26 | 919 | MatchOn, |
ff7c6d11 XL |
920 | Use, |
921 | Assignment, | |
0bf4aa26 | 922 | PartialAssignment, |
ff7c6d11 XL |
923 | } |
924 | ||
74b04a01 XL |
925 | struct RootPlace<'tcx> { |
926 | place_local: Local, | |
927 | place_projection: &'tcx [PlaceElem<'tcx>], | |
83c7162d XL |
928 | is_local_mutation_allowed: LocalMutationIsAllowed, |
929 | } | |
930 | ||
ff7c6d11 XL |
931 | impl InitializationRequiringAction { |
932 | fn as_noun(self) -> &'static str { | |
933 | match self { | |
934 | InitializationRequiringAction::Update => "update", | |
935 | InitializationRequiringAction::Borrow => "borrow", | |
0bf4aa26 | 936 | InitializationRequiringAction::MatchOn => "use", // no good noun |
ff7c6d11 XL |
937 | InitializationRequiringAction::Use => "use", |
938 | InitializationRequiringAction::Assignment => "assign", | |
0bf4aa26 | 939 | InitializationRequiringAction::PartialAssignment => "assign to part", |
ff7c6d11 XL |
940 | } |
941 | } | |
942 | ||
943 | fn as_verb_in_past_tense(self) -> &'static str { | |
944 | match self { | |
945 | InitializationRequiringAction::Update => "updated", | |
946 | InitializationRequiringAction::Borrow => "borrowed", | |
0bf4aa26 | 947 | InitializationRequiringAction::MatchOn => "matched on", |
ff7c6d11 XL |
948 | InitializationRequiringAction::Use => "used", |
949 | InitializationRequiringAction::Assignment => "assigned", | |
0bf4aa26 | 950 | InitializationRequiringAction::PartialAssignment => "partially assigned", |
b7449926 XL |
951 | } |
952 | } | |
953 | } | |
954 | ||
dc9dc135 | 955 | impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
74b04a01 | 956 | fn body(&self) -> &'cx Body<'tcx> { |
f9f354fc | 957 | self.body |
74b04a01 XL |
958 | } |
959 | ||
ff7c6d11 XL |
960 | /// Checks an access to the given place to see if it is allowed. Examines the set of borrows |
961 | /// that are in scope, as well as which paths have been initialized, to ensure that (a) the | |
962 | /// place is initialized and (b) it is not borrowed in some way that would prevent this | |
963 | /// access. | |
964 | /// | |
9fa01778 | 965 | /// Returns `true` if an error is reported. |
ff7c6d11 XL |
966 | fn access_place( |
967 | &mut self, | |
48663c56 | 968 | location: Location, |
ba9703b0 | 969 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 970 | kind: (AccessDepth, ReadOrWrite), |
ff7c6d11 | 971 | is_local_mutation_allowed: LocalMutationIsAllowed, |
dc9dc135 | 972 | flow_state: &Flows<'cx, 'tcx>, |
b7449926 | 973 | ) { |
ff7c6d11 XL |
974 | let (sd, rw) = kind; |
975 | ||
976 | if let Activation(_, borrow_index) = rw { | |
977 | if self.reservation_error_reported.contains(&place_span.0) { | |
0531ce1d XL |
978 | debug!( |
979 | "skipping access_place for activation of invalid reservation \ | |
980 | place: {:?} borrow_index: {:?}", | |
981 | place_span.0, borrow_index | |
982 | ); | |
b7449926 | 983 | return; |
ff7c6d11 XL |
984 | } |
985 | } | |
986 | ||
b7449926 XL |
987 | // Check is_empty() first because it's the common case, and doing that |
988 | // way we avoid the clone() call. | |
dfeec247 | 989 | if !self.access_place_error_reported.is_empty() |
ba9703b0 | 990 | && self.access_place_error_reported.contains(&(place_span.0, place_span.1)) |
0531ce1d XL |
991 | { |
992 | debug!( | |
993 | "access_place: suppressing error place_span=`{:?}` kind=`{:?}`", | |
994 | place_span, kind | |
995 | ); | |
b7449926 | 996 | return; |
2c00a5a8 XL |
997 | } |
998 | ||
dfeec247 XL |
999 | let mutability_error = self.check_access_permissions( |
1000 | place_span, | |
1001 | rw, | |
1002 | is_local_mutation_allowed, | |
1003 | flow_state, | |
1004 | location, | |
1005 | ); | |
ff7c6d11 | 1006 | let conflict_error = |
48663c56 | 1007 | self.check_access_for_conflict(location, place_span, sd, rw, flow_state); |
ff7c6d11 | 1008 | |
532ac7d7 | 1009 | if let (Activation(_, borrow_idx), true) = (kind.1, conflict_error) { |
60c5eb7d | 1010 | // Suppress this warning when there's an error being emitted for the |
532ac7d7 XL |
1011 | // same borrow: fixing the error is likely to fix the warning. |
1012 | self.reservation_warnings.remove(&borrow_idx); | |
1013 | } | |
1014 | ||
2c00a5a8 | 1015 | if conflict_error || mutability_error { |
dfeec247 | 1016 | debug!("access_place: logging error place_span=`{:?}` kind=`{:?}`", place_span, kind); |
532ac7d7 | 1017 | |
ba9703b0 | 1018 | self.access_place_error_reported.insert((place_span.0, place_span.1)); |
2c00a5a8 | 1019 | } |
ff7c6d11 XL |
1020 | } |
1021 | ||
1022 | fn check_access_for_conflict( | |
1023 | &mut self, | |
48663c56 | 1024 | location: Location, |
ba9703b0 | 1025 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 1026 | sd: AccessDepth, |
ff7c6d11 | 1027 | rw: ReadOrWrite, |
dc9dc135 | 1028 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1029 | ) -> bool { |
83c7162d | 1030 | debug!( |
48663c56 XL |
1031 | "check_access_for_conflict(location={:?}, place_span={:?}, sd={:?}, rw={:?})", |
1032 | location, place_span, sd, rw, | |
83c7162d XL |
1033 | ); |
1034 | ||
ff7c6d11 | 1035 | let mut error_reported = false; |
0bf4aa26 | 1036 | let tcx = self.infcx.tcx; |
dc9dc135 | 1037 | let body = self.body; |
94b46f34 | 1038 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
1039 | |
1040 | // Use polonius output if it has been enabled. | |
1041 | let polonius_output = self.polonius_output.clone(); | |
1042 | let borrows_in_scope = if let Some(polonius) = &polonius_output { | |
1043 | let location = self.location_table.start_index(location); | |
1044 | Either::Left(polonius.errors_at(location).iter().copied()) | |
1045 | } else { | |
1046 | Either::Right(flow_state.borrows.iter()) | |
1047 | }; | |
1048 | ||
94b46f34 XL |
1049 | each_borrow_involving_path( |
1050 | self, | |
1051 | tcx, | |
dc9dc135 | 1052 | body, |
48663c56 | 1053 | location, |
ff7c6d11 | 1054 | (sd, place_span.0), |
94b46f34 | 1055 | &borrow_set, |
74b04a01 | 1056 | borrows_in_scope, |
8faf50e0 | 1057 | |this, borrow_index, borrow| match (rw, borrow.kind) { |
ff7c6d11 XL |
1058 | // Obviously an activation is compatible with its own |
1059 | // reservation (or even prior activating uses of same | |
1060 | // borrow); so don't check if they interfere. | |
1061 | // | |
1062 | // NOTE: *reservations* do conflict with themselves; | |
1063 | // thus aren't injecting unsoundenss w/ this check.) | |
83c7162d | 1064 | (Activation(_, activating), _) if activating == borrow_index => { |
ff7c6d11 XL |
1065 | debug!( |
1066 | "check_access_for_conflict place_span: {:?} sd: {:?} rw: {:?} \ | |
83c7162d | 1067 | skipping {:?} b/c activation of same borrow_index", |
ff7c6d11 XL |
1068 | place_span, |
1069 | sd, | |
1070 | rw, | |
83c7162d | 1071 | (borrow_index, borrow), |
ff7c6d11 XL |
1072 | ); |
1073 | Control::Continue | |
1074 | } | |
1075 | ||
ba9703b0 XL |
1076 | (Read(_), BorrowKind::Shared | BorrowKind::Shallow) |
1077 | | ( | |
1078 | Read(ReadKind::Borrow(BorrowKind::Shallow)), | |
1079 | BorrowKind::Unique | BorrowKind::Mut { .. }, | |
1080 | ) => Control::Continue, | |
0bf4aa26 XL |
1081 | |
1082 | (Write(WriteKind::Move), BorrowKind::Shallow) => { | |
1083 | // Handled by initialization checks. | |
ff7c6d11 XL |
1084 | Control::Continue |
1085 | } | |
1086 | ||
ba9703b0 | 1087 | (Read(kind), BorrowKind::Unique | BorrowKind::Mut { .. }) => { |
ff7c6d11 | 1088 | // Reading from mere reservations of mutable-borrows is OK. |
48663c56 XL |
1089 | if !is_active(&this.dominators, borrow, location) { |
1090 | assert!(allow_two_phase_borrow(borrow.kind)); | |
ff7c6d11 XL |
1091 | return Control::Continue; |
1092 | } | |
1093 | ||
0bf4aa26 | 1094 | error_reported = true; |
ff7c6d11 | 1095 | match kind { |
dfeec247 | 1096 | ReadKind::Copy => { |
48663c56 | 1097 | this.report_use_while_mutably_borrowed(location, place_span, borrow) |
532ac7d7 | 1098 | .buffer(&mut this.errors_buffer); |
ff7c6d11 XL |
1099 | } |
1100 | ReadKind::Borrow(bk) => { | |
48663c56 | 1101 | this.report_conflicting_borrow(location, place_span, bk, borrow) |
532ac7d7 | 1102 | .buffer(&mut this.errors_buffer); |
ff7c6d11 XL |
1103 | } |
1104 | } | |
1105 | Control::Break | |
1106 | } | |
1107 | ||
ba9703b0 XL |
1108 | ( |
1109 | Reservation(WriteKind::MutableBorrow(bk)), | |
1110 | BorrowKind::Shallow | BorrowKind::Shared, | |
3dfed10e XL |
1111 | ) if { tcx.migrate_borrowck() && this.borrow_set.contains(&location) } => { |
1112 | let bi = this.borrow_set.get_index_of(&location).unwrap(); | |
532ac7d7 XL |
1113 | debug!( |
1114 | "recording invalid reservation of place: {:?} with \ | |
1115 | borrow index {:?} as warning", | |
dfeec247 | 1116 | place_span.0, bi, |
532ac7d7 XL |
1117 | ); |
1118 | // rust-lang/rust#56254 - This was previously permitted on | |
1119 | // the 2018 edition so we emit it as a warning. We buffer | |
1120 | // these sepately so that we only emit a warning if borrow | |
1121 | // checking was otherwise successful. | |
dfeec247 | 1122 | this.reservation_warnings |
ba9703b0 | 1123 | .insert(bi, (place_span.0, place_span.1, location, bk, borrow.clone())); |
532ac7d7 XL |
1124 | |
1125 | // Don't suppress actual errors. | |
1126 | Control::Continue | |
1127 | } | |
1128 | ||
ba9703b0 | 1129 | (Reservation(kind) | Activation(kind, _) | Write(kind), _) => { |
ff7c6d11 | 1130 | match rw { |
532ac7d7 | 1131 | Reservation(..) => { |
ff7c6d11 XL |
1132 | debug!( |
1133 | "recording invalid reservation of \ | |
1134 | place: {:?}", | |
1135 | place_span.0 | |
1136 | ); | |
ba9703b0 | 1137 | this.reservation_error_reported.insert(place_span.0); |
0531ce1d | 1138 | } |
ff7c6d11 XL |
1139 | Activation(_, activating) => { |
1140 | debug!( | |
1141 | "observing check_place for activation of \ | |
1142 | borrow_index: {:?}", | |
1143 | activating | |
1144 | ); | |
0531ce1d XL |
1145 | } |
1146 | Read(..) | Write(..) => {} | |
ff7c6d11 XL |
1147 | } |
1148 | ||
0bf4aa26 | 1149 | error_reported = true; |
ff7c6d11 XL |
1150 | match kind { |
1151 | WriteKind::MutableBorrow(bk) => { | |
48663c56 | 1152 | this.report_conflicting_borrow(location, place_span, bk, borrow) |
532ac7d7 | 1153 | .buffer(&mut this.errors_buffer); |
ff7c6d11 | 1154 | } |
dfeec247 XL |
1155 | WriteKind::StorageDeadOrDrop => this |
1156 | .report_borrowed_value_does_not_live_long_enough( | |
48663c56 | 1157 | location, |
ff7c6d11 | 1158 | borrow, |
94b46f34 | 1159 | place_span, |
dfeec247 XL |
1160 | Some(kind), |
1161 | ), | |
ff7c6d11 | 1162 | WriteKind::Mutate => { |
48663c56 | 1163 | this.report_illegal_mutation_of_borrowed(location, place_span, borrow) |
ff7c6d11 XL |
1164 | } |
1165 | WriteKind::Move => { | |
48663c56 | 1166 | this.report_move_out_while_borrowed(location, place_span, borrow) |
ff7c6d11 XL |
1167 | } |
1168 | } | |
1169 | Control::Break | |
1170 | } | |
1171 | }, | |
1172 | ); | |
1173 | ||
1174 | error_reported | |
1175 | } | |
1176 | ||
1177 | fn mutate_place( | |
1178 | &mut self, | |
48663c56 | 1179 | location: Location, |
ba9703b0 | 1180 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 1181 | kind: AccessDepth, |
ff7c6d11 | 1182 | mode: MutateMode, |
dc9dc135 | 1183 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 XL |
1184 | ) { |
1185 | // Write of P[i] or *P, or WriteAndRead of any P, requires P init'd. | |
1186 | match mode { | |
1187 | MutateMode::WriteAndRead => { | |
83c7162d | 1188 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1189 | location, |
ff7c6d11 | 1190 | InitializationRequiringAction::Update, |
416331ca | 1191 | (place_span.0.as_ref(), place_span.1), |
ff7c6d11 XL |
1192 | flow_state, |
1193 | ); | |
1194 | } | |
1195 | MutateMode::JustWrite => { | |
48663c56 | 1196 | self.check_if_assigned_path_is_moved(location, place_span, flow_state); |
ff7c6d11 XL |
1197 | } |
1198 | } | |
1199 | ||
b7449926 XL |
1200 | // Special case: you can assign a immutable local variable |
1201 | // (e.g., `x = ...`) so long as it has never been initialized | |
1202 | // before (at this point in the flow). | |
e74abb32 XL |
1203 | if let Some(local) = place_span.0.as_local() { |
1204 | if let Mutability::Not = self.body.local_decls[local].mutability { | |
b7449926 XL |
1205 | // check for reassignments to immutable local variables |
1206 | self.check_if_reassignment_to_immutable_state( | |
dfeec247 | 1207 | location, local, place_span, flow_state, |
b7449926 XL |
1208 | ); |
1209 | return; | |
1210 | } | |
1211 | } | |
1212 | ||
1213 | // Otherwise, use the normal access permission rules. | |
1214 | self.access_place( | |
48663c56 | 1215 | location, |
ff7c6d11 XL |
1216 | place_span, |
1217 | (kind, Write(WriteKind::Mutate)), | |
b7449926 | 1218 | LocalMutationIsAllowed::No, |
ff7c6d11 XL |
1219 | flow_state, |
1220 | ); | |
ff7c6d11 XL |
1221 | } |
1222 | ||
1223 | fn consume_rvalue( | |
1224 | &mut self, | |
48663c56 | 1225 | location: Location, |
416331ca | 1226 | (rvalue, span): (&'cx Rvalue<'tcx>, Span), |
dc9dc135 | 1227 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 XL |
1228 | ) { |
1229 | match *rvalue { | |
ba9703b0 | 1230 | Rvalue::Ref(_ /*rgn*/, bk, place) => { |
ff7c6d11 | 1231 | let access_kind = match bk { |
0bf4aa26 XL |
1232 | BorrowKind::Shallow => { |
1233 | (Shallow(Some(ArtificialField::ShallowBorrow)), Read(ReadKind::Borrow(bk))) | |
dfeec247 | 1234 | } |
ff7c6d11 | 1235 | BorrowKind::Shared => (Deep, Read(ReadKind::Borrow(bk))), |
2c00a5a8 | 1236 | BorrowKind::Unique | BorrowKind::Mut { .. } => { |
ff7c6d11 | 1237 | let wk = WriteKind::MutableBorrow(bk); |
48663c56 | 1238 | if allow_two_phase_borrow(bk) { |
ff7c6d11 XL |
1239 | (Deep, Reservation(wk)) |
1240 | } else { | |
1241 | (Deep, Write(wk)) | |
1242 | } | |
1243 | } | |
1244 | }; | |
1245 | ||
1246 | self.access_place( | |
48663c56 | 1247 | location, |
ff7c6d11 XL |
1248 | (place, span), |
1249 | access_kind, | |
1250 | LocalMutationIsAllowed::No, | |
1251 | flow_state, | |
1252 | ); | |
1253 | ||
0bf4aa26 XL |
1254 | let action = if bk == BorrowKind::Shallow { |
1255 | InitializationRequiringAction::MatchOn | |
1256 | } else { | |
1257 | InitializationRequiringAction::Borrow | |
1258 | }; | |
1259 | ||
83c7162d | 1260 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1261 | location, |
0bf4aa26 | 1262 | action, |
416331ca | 1263 | (place.as_ref(), span), |
ff7c6d11 XL |
1264 | flow_state, |
1265 | ); | |
1266 | } | |
1267 | ||
ba9703b0 | 1268 | Rvalue::AddressOf(mutability, place) => { |
dfeec247 XL |
1269 | let access_kind = match mutability { |
1270 | Mutability::Mut => ( | |
1271 | Deep, | |
1272 | Write(WriteKind::MutableBorrow(BorrowKind::Mut { | |
1273 | allow_two_phase_borrow: false, | |
1274 | })), | |
1275 | ), | |
1276 | Mutability::Not => (Deep, Read(ReadKind::Borrow(BorrowKind::Shared))), | |
1277 | }; | |
1278 | ||
1279 | self.access_place( | |
1280 | location, | |
1281 | (place, span), | |
1282 | access_kind, | |
1283 | LocalMutationIsAllowed::No, | |
1284 | flow_state, | |
1285 | ); | |
1286 | ||
1287 | self.check_if_path_or_subpath_is_moved( | |
1288 | location, | |
1289 | InitializationRequiringAction::Borrow, | |
1290 | (place.as_ref(), span), | |
1291 | flow_state, | |
1292 | ); | |
1293 | } | |
1294 | ||
f9f354fc XL |
1295 | Rvalue::ThreadLocalRef(_) => {} |
1296 | ||
ff7c6d11 XL |
1297 | Rvalue::Use(ref operand) |
1298 | | Rvalue::Repeat(ref operand, _) | |
1299 | | Rvalue::UnaryOp(_ /*un_op*/, ref operand) | |
1300 | | Rvalue::Cast(_ /*cast_kind*/, ref operand, _ /*ty*/) => { | |
48663c56 | 1301 | self.consume_operand(location, (operand, span), flow_state) |
ff7c6d11 XL |
1302 | } |
1303 | ||
ba9703b0 | 1304 | Rvalue::Len(place) | Rvalue::Discriminant(place) => { |
ff7c6d11 | 1305 | let af = match *rvalue { |
0731742a XL |
1306 | Rvalue::Len(..) => Some(ArtificialField::ArrayLength), |
1307 | Rvalue::Discriminant(..) => None, | |
ff7c6d11 XL |
1308 | _ => unreachable!(), |
1309 | }; | |
1310 | self.access_place( | |
48663c56 | 1311 | location, |
ff7c6d11 | 1312 | (place, span), |
0731742a | 1313 | (Shallow(af), Read(ReadKind::Copy)), |
ff7c6d11 XL |
1314 | LocalMutationIsAllowed::No, |
1315 | flow_state, | |
1316 | ); | |
83c7162d | 1317 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1318 | location, |
ff7c6d11 | 1319 | InitializationRequiringAction::Use, |
416331ca | 1320 | (place.as_ref(), span), |
ff7c6d11 XL |
1321 | flow_state, |
1322 | ); | |
1323 | } | |
1324 | ||
6a06907d XL |
1325 | Rvalue::BinaryOp(_bin_op, box (ref operand1, ref operand2)) |
1326 | | Rvalue::CheckedBinaryOp(_bin_op, box (ref operand1, ref operand2)) => { | |
48663c56 XL |
1327 | self.consume_operand(location, (operand1, span), flow_state); |
1328 | self.consume_operand(location, (operand2, span), flow_state); | |
ff7c6d11 XL |
1329 | } |
1330 | ||
1331 | Rvalue::NullaryOp(_op, _ty) => { | |
1332 | // nullary ops take no dynamic input; no borrowck effect. | |
1333 | // | |
1334 | // FIXME: is above actually true? Do we want to track | |
1335 | // the fact that uninitialized data can be created via | |
1336 | // `NullOp::Box`? | |
1337 | } | |
1338 | ||
83c7162d XL |
1339 | Rvalue::Aggregate(ref aggregate_kind, ref operands) => { |
1340 | // We need to report back the list of mutable upvars that were | |
1341 | // moved into the closure and subsequently used by the closure, | |
1342 | // in order to populate our used_mut set. | |
8faf50e0 | 1343 | match **aggregate_kind { |
dfeec247 XL |
1344 | AggregateKind::Closure(def_id, _) | AggregateKind::Generator(def_id, _, _) => { |
1345 | let BorrowCheckResult { used_mut_upvars, .. } = | |
f9f354fc | 1346 | self.infcx.tcx.mir_borrowck(def_id.expect_local()); |
8faf50e0 XL |
1347 | debug!("{:?} used_mut_upvars={:?}", def_id, used_mut_upvars); |
1348 | for field in used_mut_upvars { | |
48663c56 | 1349 | self.propagate_closure_used_mut_upvar(&operands[field.index()]); |
83c7162d XL |
1350 | } |
1351 | } | |
8faf50e0 XL |
1352 | AggregateKind::Adt(..) |
1353 | | AggregateKind::Array(..) | |
1354 | | AggregateKind::Tuple { .. } => (), | |
83c7162d XL |
1355 | } |
1356 | ||
1357 | for operand in operands { | |
48663c56 XL |
1358 | self.consume_operand(location, (operand, span), flow_state); |
1359 | } | |
1360 | } | |
1361 | } | |
1362 | } | |
1363 | ||
1364 | fn propagate_closure_used_mut_upvar(&mut self, operand: &Operand<'tcx>) { | |
ba9703b0 | 1365 | let propagate_closure_used_mut_place = |this: &mut Self, place: Place<'tcx>| { |
5869c6ff XL |
1366 | // We have three possibilities here: |
1367 | // a. We are modifying something through a mut-ref | |
1368 | // b. We are modifying something that is local to our parent | |
1369 | // c. Current body is a nested closure, and we are modifying path starting from | |
1370 | // a Place captured by our parent closure. | |
1371 | ||
1372 | // Handle (c), the path being modified is exactly the path captured by our parent | |
1373 | if let Some(field) = this.is_upvar_field_projection(place.as_ref()) { | |
1374 | this.used_mut_upvars.push(field); | |
1375 | return; | |
1376 | } | |
1377 | ||
1378 | for (place_ref, proj) in place.iter_projections().rev() { | |
1379 | // Handle (a) | |
1380 | if proj == ProjectionElem::Deref { | |
1381 | match place_ref.ty(this.body(), this.infcx.tcx).ty.kind() { | |
1382 | // We aren't modifying a variable directly | |
1383 | ty::Ref(_, _, hir::Mutability::Mut) => return, | |
1384 | ||
1385 | _ => {} | |
1386 | } | |
1387 | } | |
1388 | ||
1389 | // Handle (c) | |
1390 | if let Some(field) = this.is_upvar_field_projection(place_ref) { | |
416331ca | 1391 | this.used_mut_upvars.push(field); |
5869c6ff | 1392 | return; |
48663c56 | 1393 | } |
48663c56 | 1394 | } |
5869c6ff XL |
1395 | |
1396 | // Handle(b) | |
1397 | this.used_mut.insert(place.local); | |
48663c56 XL |
1398 | }; |
1399 | ||
1400 | // This relies on the current way that by-value | |
1401 | // captures of a closure are copied/moved directly | |
1402 | // when generating MIR. | |
1403 | match *operand { | |
ba9703b0 | 1404 | Operand::Move(place) | Operand::Copy(place) => { |
e74abb32 | 1405 | match place.as_local() { |
60c5eb7d | 1406 | Some(local) if !self.body.local_decls[local].is_user_variable() => { |
e74abb32 XL |
1407 | if self.body.local_decls[local].ty.is_mutable_ptr() { |
1408 | // The variable will be marked as mutable by the borrow. | |
1409 | return; | |
1410 | } | |
1411 | // This is an edge case where we have a `move` closure | |
1412 | // inside a non-move closure, and the inner closure | |
1413 | // contains a mutation: | |
1414 | // | |
1415 | // let mut i = 0; | |
1416 | // || { move || { i += 1; }; }; | |
1417 | // | |
1418 | // In this case our usual strategy of assuming that the | |
1419 | // variable will be captured by mutable reference is | |
1420 | // wrong, since `i` can be copied into the inner | |
1421 | // closure from a shared reference. | |
1422 | // | |
1423 | // As such we have to search for the local that this | |
1424 | // capture comes from and mark it as being used as mut. | |
1425 | ||
1426 | let temp_mpi = self.move_data.rev_lookup.find_local(local); | |
1427 | let init = if let [init_index] = *self.move_data.init_path_map[temp_mpi] { | |
1428 | &self.move_data.inits[init_index] | |
1429 | } else { | |
1430 | bug!("temporary should be initialized exactly once") | |
1431 | }; | |
48663c56 | 1432 | |
e74abb32 XL |
1433 | let loc = match init.location { |
1434 | InitLocation::Statement(stmt) => stmt, | |
1435 | _ => bug!("temporary initialized in arguments"), | |
1436 | }; | |
48663c56 | 1437 | |
60c5eb7d XL |
1438 | let body = self.body; |
1439 | let bbd = &body[loc.block]; | |
e74abb32 XL |
1440 | let stmt = &bbd.statements[loc.statement_index]; |
1441 | debug!("temporary assigned in: stmt={:?}", stmt); | |
48663c56 | 1442 | |
ba9703b0 | 1443 | if let StatementKind::Assign(box (_, Rvalue::Ref(_, _, source))) = stmt.kind |
e74abb32 XL |
1444 | { |
1445 | propagate_closure_used_mut_place(self, source); | |
1446 | } else { | |
1447 | bug!( | |
1448 | "closures should only capture user variables \ | |
1449 | or references to user variables" | |
1450 | ); | |
1451 | } | |
1452 | } | |
1453 | _ => propagate_closure_used_mut_place(self, place), | |
83c7162d XL |
1454 | } |
1455 | } | |
48663c56 | 1456 | Operand::Constant(..) => {} |
ff7c6d11 XL |
1457 | } |
1458 | } | |
1459 | ||
1460 | fn consume_operand( | |
1461 | &mut self, | |
48663c56 | 1462 | location: Location, |
416331ca | 1463 | (operand, span): (&'cx Operand<'tcx>, Span), |
dc9dc135 | 1464 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 XL |
1465 | ) { |
1466 | match *operand { | |
ba9703b0 | 1467 | Operand::Copy(place) => { |
ff7c6d11 XL |
1468 | // copy of place: check if this is "copy of frozen path" |
1469 | // (FIXME: see check_loans.rs) | |
1470 | self.access_place( | |
48663c56 | 1471 | location, |
ff7c6d11 XL |
1472 | (place, span), |
1473 | (Deep, Read(ReadKind::Copy)), | |
1474 | LocalMutationIsAllowed::No, | |
1475 | flow_state, | |
1476 | ); | |
1477 | ||
1478 | // Finally, check if path was already moved. | |
83c7162d | 1479 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1480 | location, |
ff7c6d11 | 1481 | InitializationRequiringAction::Use, |
416331ca | 1482 | (place.as_ref(), span), |
ff7c6d11 XL |
1483 | flow_state, |
1484 | ); | |
1485 | } | |
ba9703b0 | 1486 | Operand::Move(place) => { |
ff7c6d11 XL |
1487 | // move of place: check if this is move of already borrowed path |
1488 | self.access_place( | |
48663c56 | 1489 | location, |
ff7c6d11 XL |
1490 | (place, span), |
1491 | (Deep, Write(WriteKind::Move)), | |
1492 | LocalMutationIsAllowed::Yes, | |
1493 | flow_state, | |
1494 | ); | |
1495 | ||
1496 | // Finally, check if path was already moved. | |
83c7162d | 1497 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1498 | location, |
ff7c6d11 | 1499 | InitializationRequiringAction::Use, |
416331ca | 1500 | (place.as_ref(), span), |
ff7c6d11 XL |
1501 | flow_state, |
1502 | ); | |
1503 | } | |
1504 | Operand::Constant(_) => {} | |
1505 | } | |
1506 | } | |
1507 | ||
0bf4aa26 | 1508 | /// Checks whether a borrow of this place is invalidated when the function |
ff7c6d11 XL |
1509 | /// exits |
1510 | fn check_for_invalidation_at_exit( | |
1511 | &mut self, | |
48663c56 | 1512 | location: Location, |
ff7c6d11 XL |
1513 | borrow: &BorrowData<'tcx>, |
1514 | span: Span, | |
ff7c6d11 XL |
1515 | ) { |
1516 | debug!("check_for_invalidation_at_exit({:?})", borrow); | |
ba9703b0 | 1517 | let place = borrow.borrowed_place; |
74b04a01 | 1518 | let mut root_place = PlaceRef { local: place.local, projection: &[] }; |
ff7c6d11 XL |
1519 | |
1520 | // FIXME(nll-rfc#40): do more precise destructor tracking here. For now | |
1521 | // we just know that all locals are dropped at function exit (otherwise | |
1522 | // we'll have a memory leak) and assume that all statics have a destructor. | |
1523 | // | |
1524 | // FIXME: allow thread-locals to borrow other thread locals? | |
416331ca | 1525 | |
dfeec247 | 1526 | let (might_be_alive, will_be_dropped) = |
74b04a01 | 1527 | if self.body.local_decls[root_place.local].is_ref_to_thread_local() { |
dfeec247 XL |
1528 | // Thread-locals might be dropped after the function exits |
1529 | // We have to dereference the outer reference because | |
1530 | // borrows don't conflict behind shared references. | |
74b04a01 | 1531 | root_place.projection = DEREF_PROJECTION; |
dfeec247 XL |
1532 | (true, true) |
1533 | } else { | |
1534 | (false, self.locals_are_invalidated_at_exit) | |
1535 | }; | |
ff7c6d11 XL |
1536 | |
1537 | if !will_be_dropped { | |
dfeec247 | 1538 | debug!("place_is_invalidated_at_exit({:?}) - won't be dropped", place); |
ff7c6d11 XL |
1539 | return; |
1540 | } | |
1541 | ||
ff7c6d11 XL |
1542 | let sd = if might_be_alive { Deep } else { Shallow(None) }; |
1543 | ||
0bf4aa26 XL |
1544 | if places_conflict::borrow_conflicts_with_place( |
1545 | self.infcx.tcx, | |
60c5eb7d | 1546 | &self.body, |
0bf4aa26 XL |
1547 | place, |
1548 | borrow.kind, | |
1549 | root_place, | |
0731742a XL |
1550 | sd, |
1551 | places_conflict::PlaceConflictBias::Overlap, | |
0bf4aa26 | 1552 | ) { |
ff7c6d11 XL |
1553 | debug!("check_for_invalidation_at_exit({:?}): INVALID", place); |
1554 | // FIXME: should be talking about the region lifetime instead | |
1555 | // of just a span here. | |
0bf4aa26 | 1556 | let span = self.infcx.tcx.sess.source_map().end_point(span); |
ff7c6d11 | 1557 | self.report_borrowed_value_does_not_live_long_enough( |
48663c56 | 1558 | location, |
ff7c6d11 | 1559 | borrow, |
94b46f34 XL |
1560 | (place, span), |
1561 | None, | |
ff7c6d11 XL |
1562 | ) |
1563 | } | |
1564 | } | |
1565 | ||
2c00a5a8 | 1566 | /// Reports an error if this is a borrow of local data. |
dfeec247 | 1567 | /// This is called for all Yield expressions on movable generators |
0531ce1d | 1568 | fn check_for_local_borrow(&mut self, borrow: &BorrowData<'tcx>, yield_span: Span) { |
2c00a5a8 XL |
1569 | debug!("check_for_local_borrow({:?})", borrow); |
1570 | ||
ba9703b0 | 1571 | if borrow_of_local_data(borrow.borrowed_place) { |
416331ca | 1572 | let err = self.cannot_borrow_across_generator_yield( |
dfeec247 XL |
1573 | self.retrieve_borrow_spans(borrow).var_or_use(), |
1574 | yield_span, | |
1575 | ); | |
8faf50e0 XL |
1576 | |
1577 | err.buffer(&mut self.errors_buffer); | |
2c00a5a8 XL |
1578 | } |
1579 | } | |
1580 | ||
dc9dc135 | 1581 | fn check_activations(&mut self, location: Location, span: Span, flow_state: &Flows<'cx, 'tcx>) { |
ff7c6d11 XL |
1582 | // Two-phase borrow support: For each activation that is newly |
1583 | // generated at this statement, check if it interferes with | |
1584 | // another borrow. | |
83c7162d XL |
1585 | let borrow_set = self.borrow_set.clone(); |
1586 | for &borrow_index in borrow_set.activations_at_location(location) { | |
1587 | let borrow = &borrow_set[borrow_index]; | |
1588 | ||
1589 | // only mutable borrows should be 2-phase | |
1590 | assert!(match borrow.kind { | |
0bf4aa26 | 1591 | BorrowKind::Shared | BorrowKind::Shallow => false, |
83c7162d XL |
1592 | BorrowKind::Unique | BorrowKind::Mut { .. } => true, |
1593 | }); | |
1594 | ||
1595 | self.access_place( | |
48663c56 | 1596 | location, |
ba9703b0 | 1597 | (borrow.borrowed_place, span), |
dfeec247 | 1598 | (Deep, Activation(WriteKind::MutableBorrow(borrow.kind), borrow_index)), |
83c7162d XL |
1599 | LocalMutationIsAllowed::No, |
1600 | flow_state, | |
1601 | ); | |
1602 | // We do not need to call `check_if_path_or_subpath_is_moved` | |
1603 | // again, as we already called it when we made the | |
1604 | // initial reservation. | |
1605 | } | |
ff7c6d11 | 1606 | } |
ff7c6d11 | 1607 | |
ff7c6d11 XL |
1608 | fn check_if_reassignment_to_immutable_state( |
1609 | &mut self, | |
48663c56 | 1610 | location: Location, |
b7449926 | 1611 | local: Local, |
ba9703b0 | 1612 | place_span: (Place<'tcx>, Span), |
dc9dc135 | 1613 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1614 | ) { |
b7449926 XL |
1615 | debug!("check_if_reassignment_to_immutable_state({:?})", local); |
1616 | ||
1617 | // Check if any of the initializiations of `local` have happened yet: | |
0bf4aa26 | 1618 | if let Some(init_index) = self.is_local_ever_initialized(local, flow_state) { |
b7449926 XL |
1619 | // And, if so, report an error. |
1620 | let init = &self.move_data.inits[init_index]; | |
dc9dc135 | 1621 | let span = init.span(&self.body); |
dfeec247 | 1622 | self.report_illegal_reassignment(location, place_span, span, place_span.0); |
ff7c6d11 XL |
1623 | } |
1624 | } | |
1625 | ||
83c7162d | 1626 | fn check_if_full_path_is_moved( |
ff7c6d11 | 1627 | &mut self, |
48663c56 | 1628 | location: Location, |
ff7c6d11 | 1629 | desired_action: InitializationRequiringAction, |
74b04a01 | 1630 | place_span: (PlaceRef<'tcx>, Span), |
dc9dc135 | 1631 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1632 | ) { |
ff7c6d11 | 1633 | let maybe_uninits = &flow_state.uninits; |
ff7c6d11 XL |
1634 | |
1635 | // Bad scenarios: | |
1636 | // | |
1637 | // 1. Move of `a.b.c`, use of `a.b.c` | |
1638 | // 2. Move of `a.b.c`, use of `a.b.c.d` (without first reinitializing `a.b.c.d`) | |
83c7162d | 1639 | // 3. Uninitialized `(a.b.c: &_)`, use of `*a.b.c`; note that with |
ff7c6d11 XL |
1640 | // partial initialization support, one might have `a.x` |
1641 | // initialized but not `a.b`. | |
1642 | // | |
1643 | // OK scenarios: | |
1644 | // | |
83c7162d XL |
1645 | // 4. Move of `a.b.c`, use of `a.b.d` |
1646 | // 5. Uninitialized `a.x`, initialized `a.b`, use of `a.b` | |
1647 | // 6. Copied `(a.b: &_)`, use of `*(a.b).c`; note that `a.b` | |
ff7c6d11 | 1648 | // must have been initialized for the use to be sound. |
83c7162d | 1649 | // 7. Move of `a.b.c` then reinit of `a.b.c.d`, use of `a.b.c.d` |
ff7c6d11 XL |
1650 | |
1651 | // The dataflow tracks shallow prefixes distinctly (that is, | |
1652 | // field-accesses on P distinctly from P itself), in order to | |
1653 | // track substructure initialization separately from the whole | |
1654 | // structure. | |
1655 | // | |
1656 | // E.g., when looking at (*a.b.c).d, if the closest prefix for | |
1657 | // which we have a MovePath is `a.b`, then that means that the | |
1658 | // initialization state of `a.b` is all we need to inspect to | |
1659 | // know if `a.b.c` is valid (and from that we infer that the | |
1660 | // dereference and `.d` access is also valid, since we assume | |
1661 | // `a.b.c` is assigned a reference to a initialized and | |
1662 | // well-formed record structure.) | |
1663 | ||
1664 | // Therefore, if we seek out the *closest* prefix for which we | |
1665 | // have a MovePath, that should capture the initialization | |
1666 | // state for the place scenario. | |
1667 | // | |
83c7162d | 1668 | // This code covers scenarios 1, 2, and 3. |
ff7c6d11 | 1669 | |
b7449926 | 1670 | debug!("check_if_full_path_is_moved place: {:?}", place_span.0); |
dfeec247 XL |
1671 | let (prefix, mpi) = self.move_path_closest_to(place_span.0); |
1672 | if maybe_uninits.contains(mpi) { | |
1673 | self.report_use_of_moved_or_uninitialized( | |
1674 | location, | |
1675 | desired_action, | |
1676 | (prefix, place_span.0, place_span.1), | |
1677 | mpi, | |
1678 | ); | |
1679 | } // Only query longest prefix with a MovePath, not further | |
1680 | // ancestors; dataflow recurs on children when parents | |
1681 | // move (to support partial (re)inits). | |
1682 | // | |
1683 | // (I.e., querying parents breaks scenario 7; but may want | |
1684 | // to do such a query based on partial-init feature-gate.) | |
83c7162d XL |
1685 | } |
1686 | ||
60c5eb7d XL |
1687 | /// Subslices correspond to multiple move paths, so we iterate through the |
1688 | /// elements of the base array. For each element we check | |
1689 | /// | |
1690 | /// * Does this element overlap with our slice. | |
1691 | /// * Is any part of it uninitialized. | |
1692 | fn check_if_subslice_element_is_moved( | |
1693 | &mut self, | |
1694 | location: Location, | |
1695 | desired_action: InitializationRequiringAction, | |
74b04a01 XL |
1696 | place_span: (PlaceRef<'tcx>, Span), |
1697 | maybe_uninits: &BitSet<MovePathIndex>, | |
1b1a35ee XL |
1698 | from: u64, |
1699 | to: u64, | |
60c5eb7d XL |
1700 | ) { |
1701 | if let Some(mpi) = self.move_path_for_place(place_span.0) { | |
74b04a01 XL |
1702 | let move_paths = &self.move_data.move_paths; |
1703 | ||
1704 | let root_path = &move_paths[mpi]; | |
1705 | for (child_mpi, child_move_path) in root_path.children(move_paths) { | |
1706 | let last_proj = child_move_path.place.projection.last().unwrap(); | |
60c5eb7d XL |
1707 | if let ProjectionElem::ConstantIndex { offset, from_end, .. } = last_proj { |
1708 | debug_assert!(!from_end, "Array constant indexing shouldn't be `from_end`."); | |
1709 | ||
1710 | if (from..to).contains(offset) { | |
74b04a01 XL |
1711 | let uninit_child = |
1712 | self.move_data.find_in_move_path_or_its_descendants(child_mpi, |mpi| { | |
1713 | maybe_uninits.contains(mpi) | |
1714 | }); | |
1715 | ||
1716 | if let Some(uninit_child) = uninit_child { | |
60c5eb7d XL |
1717 | self.report_use_of_moved_or_uninitialized( |
1718 | location, | |
1719 | desired_action, | |
1720 | (place_span.0, place_span.0, place_span.1), | |
1721 | uninit_child, | |
1722 | ); | |
1723 | return; // don't bother finding other problems. | |
1724 | } | |
1725 | } | |
1726 | } | |
60c5eb7d XL |
1727 | } |
1728 | } | |
1729 | } | |
1730 | ||
83c7162d XL |
1731 | fn check_if_path_or_subpath_is_moved( |
1732 | &mut self, | |
48663c56 | 1733 | location: Location, |
83c7162d | 1734 | desired_action: InitializationRequiringAction, |
74b04a01 | 1735 | place_span: (PlaceRef<'tcx>, Span), |
dc9dc135 | 1736 | flow_state: &Flows<'cx, 'tcx>, |
83c7162d | 1737 | ) { |
83c7162d | 1738 | let maybe_uninits = &flow_state.uninits; |
83c7162d XL |
1739 | |
1740 | // Bad scenarios: | |
1741 | // | |
1742 | // 1. Move of `a.b.c`, use of `a` or `a.b` | |
1743 | // partial initialization support, one might have `a.x` | |
1744 | // initialized but not `a.b`. | |
1745 | // 2. All bad scenarios from `check_if_full_path_is_moved` | |
1746 | // | |
1747 | // OK scenarios: | |
1748 | // | |
1749 | // 3. Move of `a.b.c`, use of `a.b.d` | |
1750 | // 4. Uninitialized `a.x`, initialized `a.b`, use of `a.b` | |
1751 | // 5. Copied `(a.b: &_)`, use of `*(a.b).c`; note that `a.b` | |
1752 | // must have been initialized for the use to be sound. | |
1753 | // 6. Move of `a.b.c` then reinit of `a.b.c.d`, use of `a.b.c.d` | |
1754 | ||
48663c56 | 1755 | self.check_if_full_path_is_moved(location, desired_action, place_span, flow_state); |
ff7c6d11 | 1756 | |
5869c6ff XL |
1757 | if let Some((place_base, ProjectionElem::Subslice { from, to, from_end: false })) = |
1758 | place_span.0.last_projection() | |
dfeec247 | 1759 | { |
5869c6ff | 1760 | let place_ty = place_base.ty(self.body(), self.infcx.tcx); |
1b1a35ee | 1761 | if let ty::Array(..) = place_ty.ty.kind() { |
60c5eb7d XL |
1762 | self.check_if_subslice_element_is_moved( |
1763 | location, | |
1764 | desired_action, | |
5869c6ff | 1765 | (place_base, place_span.1), |
60c5eb7d | 1766 | maybe_uninits, |
5869c6ff XL |
1767 | from, |
1768 | to, | |
60c5eb7d XL |
1769 | ); |
1770 | return; | |
1771 | } | |
1772 | } | |
1773 | ||
ff7c6d11 XL |
1774 | // A move of any shallow suffix of `place` also interferes |
1775 | // with an attempt to use `place`. This is scenario 3 above. | |
1776 | // | |
1777 | // (Distinct from handling of scenarios 1+2+4 above because | |
1778 | // `place` does not interfere with suffixes of its prefixes, | |
0731742a | 1779 | // e.g., `a.b.c` does not interfere with `a.b.d`) |
83c7162d XL |
1780 | // |
1781 | // This code covers scenario 1. | |
ff7c6d11 | 1782 | |
b7449926 XL |
1783 | debug!("check_if_path_or_subpath_is_moved place: {:?}", place_span.0); |
1784 | if let Some(mpi) = self.move_path_for_place(place_span.0) { | |
74b04a01 XL |
1785 | let uninit_mpi = self |
1786 | .move_data | |
1787 | .find_in_move_path_or_its_descendants(mpi, |mpi| maybe_uninits.contains(mpi)); | |
1788 | ||
1789 | if let Some(uninit_mpi) = uninit_mpi { | |
ff7c6d11 | 1790 | self.report_use_of_moved_or_uninitialized( |
48663c56 | 1791 | location, |
ff7c6d11 | 1792 | desired_action, |
0bf4aa26 | 1793 | (place_span.0, place_span.0, place_span.1), |
74b04a01 | 1794 | uninit_mpi, |
ff7c6d11 XL |
1795 | ); |
1796 | return; // don't bother finding other problems. | |
1797 | } | |
1798 | } | |
1799 | } | |
1800 | ||
1801 | /// Currently MoveData does not store entries for all places in | |
1802 | /// the input MIR. For example it will currently filter out | |
1803 | /// places that are Copy; thus we do not track places of shared | |
1804 | /// reference type. This routine will walk up a place along its | |
1805 | /// prefixes, searching for a foundational place that *is* | |
1806 | /// tracked in the MoveData. | |
1807 | /// | |
1808 | /// An Err result includes a tag indicated why the search failed. | |
0531ce1d | 1809 | /// Currently this can only occur if the place is built off of a |
ff7c6d11 | 1810 | /// static variable, as we do not track those in the MoveData. |
74b04a01 | 1811 | fn move_path_closest_to(&mut self, place: PlaceRef<'tcx>) -> (PlaceRef<'tcx>, MovePathIndex) { |
60c5eb7d | 1812 | match self.move_data.rev_lookup.find(place) { |
dfeec247 XL |
1813 | LookupResult::Parent(Some(mpi)) | LookupResult::Exact(mpi) => { |
1814 | (self.move_data.move_paths[mpi].place.as_ref(), mpi) | |
1815 | } | |
1816 | LookupResult::Parent(None) => panic!("should have move path for every Local"), | |
ff7c6d11 XL |
1817 | } |
1818 | } | |
1819 | ||
74b04a01 | 1820 | fn move_path_for_place(&mut self, place: PlaceRef<'tcx>) -> Option<MovePathIndex> { |
ff7c6d11 XL |
1821 | // If returns None, then there is no move path corresponding |
1822 | // to a direct owner of `place` (which means there is nothing | |
1823 | // that borrowck tracks for its analysis). | |
1824 | ||
1825 | match self.move_data.rev_lookup.find(place) { | |
1826 | LookupResult::Parent(_) => None, | |
1827 | LookupResult::Exact(mpi) => Some(mpi), | |
1828 | } | |
1829 | } | |
1830 | ||
1831 | fn check_if_assigned_path_is_moved( | |
1832 | &mut self, | |
48663c56 | 1833 | location: Location, |
ba9703b0 | 1834 | (place, span): (Place<'tcx>, Span), |
dc9dc135 | 1835 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1836 | ) { |
83c7162d | 1837 | debug!("check_if_assigned_path_is_moved place: {:?}", place); |
416331ca XL |
1838 | |
1839 | // None case => assigning to `x` does not require `x` be initialized. | |
5869c6ff | 1840 | for (place_base, elem) in place.iter_projections().rev() { |
e1599b0c | 1841 | match elem { |
416331ca XL |
1842 | ProjectionElem::Index(_/*operand*/) | |
1843 | ProjectionElem::ConstantIndex { .. } | | |
1844 | // assigning to P[i] requires P to be valid. | |
1845 | ProjectionElem::Downcast(_/*adt_def*/, _/*variant_idx*/) => | |
1846 | // assigning to (P->variant) is okay if assigning to `P` is okay | |
1847 | // | |
1848 | // FIXME: is this true even if P is a adt with a dtor? | |
1849 | { } | |
1850 | ||
1851 | // assigning to (*P) requires P to be initialized | |
1852 | ProjectionElem::Deref => { | |
1853 | self.check_if_full_path_is_moved( | |
1854 | location, InitializationRequiringAction::Use, | |
5869c6ff | 1855 | (place_base, span), flow_state); |
416331ca XL |
1856 | // (base initialized; no need to |
1857 | // recur further) | |
ff7c6d11 XL |
1858 | break; |
1859 | } | |
416331ca XL |
1860 | |
1861 | ProjectionElem::Subslice { .. } => { | |
1862 | panic!("we don't allow assignments to subslices, location: {:?}", | |
1863 | location); | |
1864 | } | |
1865 | ||
1866 | ProjectionElem::Field(..) => { | |
1867 | // if type of `P` has a dtor, then | |
1868 | // assigning to `P.f` requires `P` itself | |
1869 | // be already initialized | |
1870 | let tcx = self.infcx.tcx; | |
5869c6ff | 1871 | let base_ty = place_base.ty(self.body(), tcx).ty; |
1b1a35ee | 1872 | match base_ty.kind() { |
416331ca XL |
1873 | ty::Adt(def, _) if def.has_dtor(tcx) => { |
1874 | self.check_if_path_or_subpath_is_moved( | |
1875 | location, InitializationRequiringAction::Assignment, | |
5869c6ff | 1876 | (place_base, span), flow_state); |
416331ca | 1877 | |
83c7162d XL |
1878 | // (base initialized; no need to |
1879 | // recur further) | |
1880 | break; | |
1881 | } | |
1882 | ||
416331ca XL |
1883 | // Once `let s; s.x = V; read(s.x);`, |
1884 | // is allowed, remove this match arm. | |
1885 | ty::Adt(..) | ty::Tuple(..) => { | |
5869c6ff | 1886 | check_parent_of_field(self, location, place_base, span, flow_state); |
416331ca | 1887 | |
dfeec247 XL |
1888 | // rust-lang/rust#21232, #54499, #54986: during period where we reject |
1889 | // partial initialization, do not complain about unnecessary `mut` on | |
1890 | // an attempt to do a partial initialization. | |
1891 | self.used_mut.insert(place.local); | |
ff7c6d11 | 1892 | } |
ff7c6d11 | 1893 | |
416331ca XL |
1894 | _ => {} |
1895 | } | |
ff7c6d11 XL |
1896 | } |
1897 | } | |
1898 | } | |
ff7c6d11 | 1899 | |
dc9dc135 XL |
1900 | fn check_parent_of_field<'cx, 'tcx>( |
1901 | this: &mut MirBorrowckCtxt<'cx, 'tcx>, | |
48663c56 | 1902 | location: Location, |
74b04a01 | 1903 | base: PlaceRef<'tcx>, |
a1dfa0c6 | 1904 | span: Span, |
dc9dc135 | 1905 | flow_state: &Flows<'cx, 'tcx>, |
a1dfa0c6 | 1906 | ) { |
0bf4aa26 XL |
1907 | // rust-lang/rust#21232: Until Rust allows reads from the |
1908 | // initialized parts of partially initialized structs, we | |
1909 | // will, starting with the 2018 edition, reject attempts | |
1910 | // to write to structs that are not fully initialized. | |
1911 | // | |
1912 | // In other words, *until* we allow this: | |
1913 | // | |
1914 | // 1. `let mut s; s.x = Val; read(s.x);` | |
1915 | // | |
1916 | // we will for now disallow this: | |
1917 | // | |
1918 | // 2. `let mut s; s.x = Val;` | |
1919 | // | |
1920 | // and also this: | |
1921 | // | |
1922 | // 3. `let mut s = ...; drop(s); s.x=Val;` | |
1923 | // | |
1924 | // This does not use check_if_path_or_subpath_is_moved, | |
1925 | // because we want to *allow* reinitializations of fields: | |
0731742a | 1926 | // e.g., want to allow |
0bf4aa26 XL |
1927 | // |
1928 | // `let mut s = ...; drop(s.x); s.x=Val;` | |
1929 | // | |
1930 | // This does not use check_if_full_path_is_moved on | |
1931 | // `base`, because that would report an error about the | |
1932 | // `base` as a whole, but in this scenario we *really* | |
1933 | // want to report an error about the actual thing that was | |
1934 | // moved, which may be some prefix of `base`. | |
1935 | ||
1936 | // Shallow so that we'll stop at any dereference; we'll | |
1937 | // report errors about issues with such bases elsewhere. | |
1938 | let maybe_uninits = &flow_state.uninits; | |
1939 | ||
1940 | // Find the shortest uninitialized prefix you can reach | |
1941 | // without going over a Deref. | |
1942 | let mut shortest_uninit_seen = None; | |
1943 | for prefix in this.prefixes(base, PrefixSet::Shallow) { | |
1944 | let mpi = match this.move_path_for_place(prefix) { | |
dfeec247 XL |
1945 | Some(mpi) => mpi, |
1946 | None => continue, | |
0bf4aa26 XL |
1947 | }; |
1948 | ||
1949 | if maybe_uninits.contains(mpi) { | |
dfeec247 XL |
1950 | debug!( |
1951 | "check_parent_of_field updating shortest_uninit_seen from {:?} to {:?}", | |
1952 | shortest_uninit_seen, | |
1953 | Some((prefix, mpi)) | |
1954 | ); | |
0bf4aa26 XL |
1955 | shortest_uninit_seen = Some((prefix, mpi)); |
1956 | } else { | |
1957 | debug!("check_parent_of_field {:?} is definitely initialized", (prefix, mpi)); | |
1958 | } | |
1959 | } | |
1960 | ||
1961 | if let Some((prefix, mpi)) = shortest_uninit_seen { | |
a1dfa0c6 XL |
1962 | // Check for a reassignment into a uninitialized field of a union (for example, |
1963 | // after a move out). In this case, do not report a error here. There is an | |
1964 | // exception, if this is the first assignment into the union (that is, there is | |
1965 | // no move out from an earlier location) then this is an attempt at initialization | |
1966 | // of the union - we should error in that case. | |
1967 | let tcx = this.infcx.tcx; | |
17df50a5 XL |
1968 | if base.ty(this.body(), tcx).ty.is_union() { |
1969 | if this.move_data.path_map[mpi].iter().any(|moi| { | |
1970 | this.move_data.moves[*moi].source.is_predecessor_of(location, this.body) | |
1971 | }) { | |
1972 | return; | |
a1dfa0c6 XL |
1973 | } |
1974 | } | |
1975 | ||
0bf4aa26 | 1976 | this.report_use_of_moved_or_uninitialized( |
48663c56 | 1977 | location, |
0bf4aa26 XL |
1978 | InitializationRequiringAction::PartialAssignment, |
1979 | (prefix, base, span), | |
1980 | mpi, | |
1981 | ); | |
1982 | } | |
1983 | } | |
1984 | } | |
8faf50e0 | 1985 | |
9fa01778 | 1986 | /// Checks the permissions for the given place and read or write kind |
ff7c6d11 | 1987 | /// |
9fa01778 | 1988 | /// Returns `true` if an error is reported. |
ff7c6d11 | 1989 | fn check_access_permissions( |
83c7162d | 1990 | &mut self, |
ba9703b0 | 1991 | (place, span): (Place<'tcx>, Span), |
ff7c6d11 XL |
1992 | kind: ReadOrWrite, |
1993 | is_local_mutation_allowed: LocalMutationIsAllowed, | |
dc9dc135 | 1994 | flow_state: &Flows<'cx, 'tcx>, |
8faf50e0 | 1995 | location: Location, |
ff7c6d11 XL |
1996 | ) -> bool { |
1997 | debug!( | |
0bf4aa26 | 1998 | "check_access_permissions({:?}, {:?}, is_local_mutation_allowed: {:?})", |
0531ce1d | 1999 | place, kind, is_local_mutation_allowed |
ff7c6d11 | 2000 | ); |
94b46f34 | 2001 | |
94b46f34 XL |
2002 | let error_access; |
2003 | let the_place_err; | |
2004 | ||
ff7c6d11 | 2005 | match kind { |
ba9703b0 XL |
2006 | Reservation(WriteKind::MutableBorrow( |
2007 | borrow_kind @ (BorrowKind::Unique | BorrowKind::Mut { .. }), | |
2008 | )) | |
2009 | | Write(WriteKind::MutableBorrow( | |
2010 | borrow_kind @ (BorrowKind::Unique | BorrowKind::Mut { .. }), | |
2011 | )) => { | |
94b46f34 XL |
2012 | let is_local_mutation_allowed = match borrow_kind { |
2013 | BorrowKind::Unique => LocalMutationIsAllowed::Yes, | |
2014 | BorrowKind::Mut { .. } => is_local_mutation_allowed, | |
0bf4aa26 | 2015 | BorrowKind::Shared | BorrowKind::Shallow => unreachable!(), |
94b46f34 | 2016 | }; |
416331ca | 2017 | match self.is_mutable(place.as_ref(), is_local_mutation_allowed) { |
94b46f34 XL |
2018 | Ok(root_place) => { |
2019 | self.add_used_mut(root_place, flow_state); | |
2020 | return false; | |
2021 | } | |
83c7162d | 2022 | Err(place_err) => { |
94b46f34 XL |
2023 | error_access = AccessKind::MutableBorrow; |
2024 | the_place_err = place_err; | |
ff7c6d11 XL |
2025 | } |
2026 | } | |
83c7162d | 2027 | } |
ff7c6d11 | 2028 | Reservation(WriteKind::Mutate) | Write(WriteKind::Mutate) => { |
416331ca | 2029 | match self.is_mutable(place.as_ref(), is_local_mutation_allowed) { |
94b46f34 XL |
2030 | Ok(root_place) => { |
2031 | self.add_used_mut(root_place, flow_state); | |
2032 | return false; | |
2033 | } | |
83c7162d | 2034 | Err(place_err) => { |
94b46f34 XL |
2035 | error_access = AccessKind::Mutate; |
2036 | the_place_err = place_err; | |
ff7c6d11 | 2037 | } |
ff7c6d11 XL |
2038 | } |
2039 | } | |
94b46f34 | 2040 | |
ba9703b0 XL |
2041 | Reservation( |
2042 | WriteKind::Move | |
2043 | | WriteKind::StorageDeadOrDrop | |
2044 | | WriteKind::MutableBorrow(BorrowKind::Shared) | |
2045 | | WriteKind::MutableBorrow(BorrowKind::Shallow), | |
2046 | ) | |
2047 | | Write( | |
2048 | WriteKind::Move | |
2049 | | WriteKind::StorageDeadOrDrop | |
2050 | | WriteKind::MutableBorrow(BorrowKind::Shared) | |
2051 | | WriteKind::MutableBorrow(BorrowKind::Shallow), | |
2052 | ) => { | |
e74abb32 | 2053 | if let (Err(_), true) = ( |
416331ca | 2054 | self.is_mutable(place.as_ref(), is_local_mutation_allowed), |
dfeec247 | 2055 | self.errors_buffer.is_empty(), |
a1dfa0c6 | 2056 | ) { |
e74abb32 XL |
2057 | // rust-lang/rust#46908: In pure NLL mode this code path should be |
2058 | // unreachable, but we use `delay_span_bug` because we can hit this when | |
2059 | // dereferencing a non-Copy raw pointer *and* have `-Ztreat-err-as-bug` | |
2060 | // enabled. We don't want to ICE for that case, as other errors will have | |
2061 | // been emitted (#52262). | |
dfeec247 XL |
2062 | self.infcx.tcx.sess.delay_span_bug( |
2063 | span, | |
2064 | &format!( | |
2065 | "Accessing `{:?}` with the kind `{:?}` shouldn't be possible", | |
2066 | place, kind, | |
2067 | ), | |
2068 | ); | |
ff7c6d11 | 2069 | } |
94b46f34 XL |
2070 | return false; |
2071 | } | |
2072 | Activation(..) => { | |
2073 | // permission checks are done at Reservation point. | |
2074 | return false; | |
ff7c6d11 | 2075 | } |
ba9703b0 XL |
2076 | Read( |
2077 | ReadKind::Borrow( | |
2078 | BorrowKind::Unique | |
2079 | | BorrowKind::Mut { .. } | |
2080 | | BorrowKind::Shared | |
2081 | | BorrowKind::Shallow, | |
2082 | ) | |
2083 | | ReadKind::Copy, | |
2084 | ) => { | |
94b46f34 XL |
2085 | // Access authorized |
2086 | return false; | |
2087 | } | |
ff7c6d11 XL |
2088 | } |
2089 | ||
60c5eb7d XL |
2090 | // rust-lang/rust#21232, #54986: during period where we reject |
2091 | // partial initialization, do not complain about mutability | |
2092 | // errors except for actual mutation (as opposed to an attempt | |
2093 | // to do a partial initialization). | |
dfeec247 XL |
2094 | let previously_initialized = |
2095 | self.is_local_ever_initialized(place.local, flow_state).is_some(); | |
60c5eb7d | 2096 | |
94b46f34 | 2097 | // at this point, we have set up the error reporting state. |
60c5eb7d | 2098 | if previously_initialized { |
dfeec247 | 2099 | self.report_mutability_error(place, span, the_place_err, error_access, location); |
0bf4aa26 XL |
2100 | true |
2101 | } else { | |
2102 | false | |
60c5eb7d | 2103 | } |
0bf4aa26 XL |
2104 | } |
2105 | ||
dc9dc135 XL |
2106 | fn is_local_ever_initialized( |
2107 | &self, | |
2108 | local: Local, | |
2109 | flow_state: &Flows<'cx, 'tcx>, | |
2110 | ) -> Option<InitIndex> { | |
0bf4aa26 XL |
2111 | let mpi = self.move_data.rev_lookup.find_local(local); |
2112 | let ii = &self.move_data.init_path_map[mpi]; | |
2113 | for &index in ii { | |
2114 | if flow_state.ever_inits.contains(index) { | |
2115 | return Some(index); | |
2116 | } | |
2117 | } | |
2118 | None | |
ff7c6d11 XL |
2119 | } |
2120 | ||
83c7162d | 2121 | /// Adds the place into the used mutable variables set |
74b04a01 | 2122 | fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'cx, 'tcx>) { |
83c7162d | 2123 | match root_place { |
dfeec247 | 2124 | RootPlace { place_local: local, place_projection: [], is_local_mutation_allowed } => { |
0bf4aa26 XL |
2125 | // If the local may have been initialized, and it is now currently being |
2126 | // mutated, then it is justified to be annotated with the `mut` | |
2127 | // keyword, since the mutation may be a possible reassignment. | |
dfeec247 | 2128 | if is_local_mutation_allowed != LocalMutationIsAllowed::Yes |
74b04a01 | 2129 | && self.is_local_ever_initialized(local, flow_state).is_some() |
0bf4aa26 | 2130 | { |
74b04a01 | 2131 | self.used_mut.insert(local); |
83c7162d XL |
2132 | } |
2133 | } | |
8faf50e0 | 2134 | RootPlace { |
dfeec247 | 2135 | place_local: _, |
416331ca | 2136 | place_projection: _, |
8faf50e0 XL |
2137 | is_local_mutation_allowed: LocalMutationIsAllowed::Yes, |
2138 | } => {} | |
83c7162d | 2139 | RootPlace { |
dfeec247 | 2140 | place_local, |
e1599b0c | 2141 | place_projection: place_projection @ [.., _], |
83c7162d XL |
2142 | is_local_mutation_allowed: _, |
2143 | } => { | |
416331ca | 2144 | if let Some(field) = self.is_upvar_field_projection(PlaceRef { |
dfeec247 XL |
2145 | local: place_local, |
2146 | projection: place_projection, | |
416331ca | 2147 | }) { |
83c7162d XL |
2148 | self.used_mut_upvars.push(field); |
2149 | } | |
2150 | } | |
83c7162d XL |
2151 | } |
2152 | } | |
2153 | ||
0bf4aa26 | 2154 | /// Whether this value can be written or borrowed mutably. |
83c7162d | 2155 | /// Returns the root place if the place passed in is a projection. |
74b04a01 | 2156 | fn is_mutable( |
ff7c6d11 | 2157 | &self, |
74b04a01 | 2158 | place: PlaceRef<'tcx>, |
ff7c6d11 | 2159 | is_local_mutation_allowed: LocalMutationIsAllowed, |
74b04a01 | 2160 | ) -> Result<RootPlace<'tcx>, PlaceRef<'tcx>> { |
5869c6ff XL |
2161 | debug!("is_mutable: place={:?}, is_local...={:?}", place, is_local_mutation_allowed); |
2162 | match place.last_projection() { | |
2163 | None => { | |
2164 | let local = &self.body.local_decls[place.local]; | |
ff7c6d11 XL |
2165 | match local.mutability { |
2166 | Mutability::Not => match is_local_mutation_allowed { | |
8faf50e0 | 2167 | LocalMutationIsAllowed::Yes => Ok(RootPlace { |
dfeec247 | 2168 | place_local: place.local, |
416331ca | 2169 | place_projection: place.projection, |
8faf50e0 XL |
2170 | is_local_mutation_allowed: LocalMutationIsAllowed::Yes, |
2171 | }), | |
2172 | LocalMutationIsAllowed::ExceptUpvars => Ok(RootPlace { | |
dfeec247 | 2173 | place_local: place.local, |
416331ca | 2174 | place_projection: place.projection, |
8faf50e0 XL |
2175 | is_local_mutation_allowed: LocalMutationIsAllowed::ExceptUpvars, |
2176 | }), | |
ff7c6d11 XL |
2177 | LocalMutationIsAllowed::No => Err(place), |
2178 | }, | |
8faf50e0 | 2179 | Mutability::Mut => Ok(RootPlace { |
dfeec247 | 2180 | place_local: place.local, |
416331ca | 2181 | place_projection: place.projection, |
8faf50e0 XL |
2182 | is_local_mutation_allowed, |
2183 | }), | |
ff7c6d11 XL |
2184 | } |
2185 | } | |
5869c6ff | 2186 | Some((place_base, elem)) => { |
e1599b0c | 2187 | match elem { |
ff7c6d11 | 2188 | ProjectionElem::Deref => { |
5869c6ff | 2189 | let base_ty = place_base.ty(self.body(), self.infcx.tcx).ty; |
ff7c6d11 XL |
2190 | |
2191 | // Check the kind of deref to decide | |
1b1a35ee | 2192 | match base_ty.kind() { |
b7449926 | 2193 | ty::Ref(_, _, mutbl) => { |
94b46f34 | 2194 | match mutbl { |
ff7c6d11 | 2195 | // Shared borrowed data is never mutable |
dfeec247 | 2196 | hir::Mutability::Not => Err(place), |
ff7c6d11 XL |
2197 | // Mutably borrowed data is mutable, but only if we have a |
2198 | // unique path to the `&mut` | |
dfeec247 | 2199 | hir::Mutability::Mut => { |
48663c56 | 2200 | let mode = match self.is_upvar_field_projection(place) { |
dfeec247 | 2201 | Some(field) if self.upvars[field.index()].by_ref => { |
ff7c6d11 XL |
2202 | is_local_mutation_allowed |
2203 | } | |
2204 | _ => LocalMutationIsAllowed::Yes, | |
2205 | }; | |
2206 | ||
5869c6ff | 2207 | self.is_mutable(place_base, mode) |
ff7c6d11 XL |
2208 | } |
2209 | } | |
2210 | } | |
b7449926 | 2211 | ty::RawPtr(tnm) => { |
ff7c6d11 XL |
2212 | match tnm.mutbl { |
2213 | // `*const` raw pointers are not mutable | |
dfeec247 | 2214 | hir::Mutability::Not => Err(place), |
83c7162d XL |
2215 | // `*mut` raw pointers are always mutable, regardless of |
2216 | // context. The users have to check by themselves. | |
dfeec247 XL |
2217 | hir::Mutability::Mut => Ok(RootPlace { |
2218 | place_local: place.local, | |
2219 | place_projection: place.projection, | |
2220 | is_local_mutation_allowed, | |
2221 | }), | |
ff7c6d11 XL |
2222 | } |
2223 | } | |
2224 | // `Box<T>` owns its content, so mutable if its location is mutable | |
5869c6ff XL |
2225 | _ if base_ty.is_box() => { |
2226 | self.is_mutable(place_base, is_local_mutation_allowed) | |
2227 | } | |
ff7c6d11 XL |
2228 | // Deref should only be for reference, pointers or boxes |
2229 | _ => bug!("Deref of unexpected type: {:?}", base_ty), | |
2230 | } | |
2231 | } | |
2232 | // All other projections are owned by their base path, so mutable if | |
2233 | // base path is mutable | |
2234 | ProjectionElem::Field(..) | |
2235 | | ProjectionElem::Index(..) | |
2236 | | ProjectionElem::ConstantIndex { .. } | |
2237 | | ProjectionElem::Subslice { .. } | |
2238 | | ProjectionElem::Downcast(..) => { | |
48663c56 | 2239 | let upvar_field_projection = self.is_upvar_field_projection(place); |
8faf50e0 | 2240 | if let Some(field) = upvar_field_projection { |
48663c56 | 2241 | let upvar = &self.upvars[field.index()]; |
ff7c6d11 | 2242 | debug!( |
5869c6ff XL |
2243 | "is_mutable: upvar.mutability={:?} local_mutation_is_allowed={:?} \ |
2244 | place={:?}, place_base={:?}", | |
2245 | upvar, is_local_mutation_allowed, place, place_base | |
ff7c6d11 | 2246 | ); |
5869c6ff | 2247 | match (upvar.place.mutability, is_local_mutation_allowed) { |
ba9703b0 XL |
2248 | ( |
2249 | Mutability::Not, | |
2250 | LocalMutationIsAllowed::No | |
2251 | | LocalMutationIsAllowed::ExceptUpvars, | |
2252 | ) => Err(place), | |
ff7c6d11 XL |
2253 | (Mutability::Not, LocalMutationIsAllowed::Yes) |
2254 | | (Mutability::Mut, _) => { | |
83c7162d XL |
2255 | // Subtle: this is an upvar |
2256 | // reference, so it looks like | |
2257 | // `self.foo` -- we want to double | |
48663c56 | 2258 | // check that the location `*self` |
83c7162d XL |
2259 | // is mutable (i.e., this is not a |
2260 | // `Fn` closure). But if that | |
2261 | // check succeeds, we want to | |
2262 | // *blame* the mutability on | |
2263 | // `place` (that is, | |
2264 | // `self.foo`). This is used to | |
2265 | // propagate the info about | |
2266 | // whether mutability declarations | |
2267 | // are used outwards, so that we register | |
2268 | // the outer variable as mutable. Otherwise a | |
2269 | // test like this fails to record the `mut` | |
2270 | // as needed: | |
2271 | // | |
2272 | // ``` | |
2273 | // fn foo<F: FnOnce()>(_f: F) { } | |
2274 | // fn main() { | |
2275 | // let var = Vec::new(); | |
2276 | // foo(move || { | |
2277 | // var.push(1); | |
2278 | // }); | |
2279 | // } | |
2280 | // ``` | |
5869c6ff XL |
2281 | let _ = |
2282 | self.is_mutable(place_base, is_local_mutation_allowed)?; | |
8faf50e0 | 2283 | Ok(RootPlace { |
dfeec247 | 2284 | place_local: place.local, |
416331ca | 2285 | place_projection: place.projection, |
8faf50e0 XL |
2286 | is_local_mutation_allowed, |
2287 | }) | |
ff7c6d11 XL |
2288 | } |
2289 | } | |
2290 | } else { | |
5869c6ff | 2291 | self.is_mutable(place_base, is_local_mutation_allowed) |
ff7c6d11 XL |
2292 | } |
2293 | } | |
2294 | } | |
2295 | } | |
2296 | } | |
2297 | } | |
48663c56 XL |
2298 | |
2299 | /// If `place` is a field projection, and the field is being projected from a closure type, | |
2300 | /// then returns the index of the field being projected. Note that this closure will always | |
2301 | /// be `self` in the current MIR, because that is the only time we directly access the fields | |
2302 | /// of a closure type. | |
74b04a01 | 2303 | pub fn is_upvar_field_projection(&self, place_ref: PlaceRef<'tcx>) -> Option<Field> { |
f035d41b | 2304 | path_utils::is_upvar_field_projection(self.infcx.tcx, &self.upvars, place_ref, self.body()) |
48663c56 | 2305 | } |
ff7c6d11 XL |
2306 | } |
2307 | ||
ff7c6d11 XL |
2308 | /// The degree of overlap between 2 places for borrow-checking. |
2309 | enum Overlap { | |
2310 | /// The places might partially overlap - in this case, we give | |
2311 | /// up and say that they might conflict. This occurs when | |
2312 | /// different fields of a union are borrowed. For example, | |
2313 | /// if `u` is a union, we have no way of telling how disjoint | |
2314 | /// `u.a.x` and `a.b.y` are. | |
2315 | Arbitrary, | |
2316 | /// The places have the same type, and are either completely disjoint | |
0731742a | 2317 | /// or equal - i.e., they can't "partially" overlap as can occur with |
ff7c6d11 XL |
2318 | /// unions. This is the "base case" on which we recur for extensions |
2319 | /// of the place. | |
2320 | EqualOrDisjoint, | |
2321 | /// The places are disjoint, so we know all extensions of them | |
2322 | /// will also be disjoint. | |
2323 | Disjoint, | |
2324 | } |