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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 | ||
c295e0f8 XL |
3 | #![feature(bool_to_option)] |
4 | #![feature(box_patterns)] | |
c295e0f8 | 5 | #![feature(crate_visibility_modifier)] |
3c0e092e | 6 | #![feature(let_else)] |
c295e0f8 XL |
7 | #![feature(min_specialization)] |
8 | #![feature(stmt_expr_attributes)] | |
9 | #![feature(trusted_step)] | |
10 | #![feature(try_blocks)] | |
11 | #![recursion_limit = "256"] | |
5099ac24 | 12 | #![cfg_attr(not(bootstrap), allow(rustc::potential_query_instability))] |
c295e0f8 XL |
13 | |
14 | #[macro_use] | |
15 | extern crate rustc_middle; | |
16 | #[macro_use] | |
17 | extern crate tracing; | |
18 | ||
532ac7d7 | 19 | use rustc_data_structures::fx::{FxHashMap, FxHashSet}; |
0bf4aa26 | 20 | use rustc_data_structures::graph::dominators::Dominators; |
ba9703b0 | 21 | use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorReported}; |
dfeec247 | 22 | use rustc_hir as hir; |
f9f354fc | 23 | use rustc_hir::def_id::LocalDefId; |
5869c6ff | 24 | use rustc_hir::Node; |
dfeec247 | 25 | use rustc_index::bit_set::BitSet; |
e74abb32 | 26 | use rustc_index::vec::IndexVec; |
74b04a01 | 27 | use rustc_infer::infer::{InferCtxt, TyCtxtInferExt}; |
ba9703b0 | 28 | use rustc_middle::mir::{ |
f9f354fc | 29 | traversal, Body, ClearCrossCrate, Local, Location, Mutability, Operand, Place, PlaceElem, |
fc512014 | 30 | PlaceRef, VarDebugInfoContents, |
ba9703b0 XL |
31 | }; |
32 | use rustc_middle::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind}; | |
33 | use rustc_middle::mir::{Field, ProjectionElem, Promoted, Rvalue, Statement, StatementKind}; | |
f9f354fc | 34 | use rustc_middle::mir::{InlineAsmOperand, Terminator, TerminatorKind}; |
ba9703b0 | 35 | use rustc_middle::ty::query::Providers; |
5869c6ff | 36 | use rustc_middle::ty::{self, CapturedPlace, ParamEnv, RegionVid, TyCtxt}; |
ba9703b0 | 37 | use rustc_session::lint::builtin::{MUTABLE_BORROW_RESERVATION_CONFLICT, UNUSED_MUT}; |
f9f354fc | 38 | use rustc_span::{Span, Symbol, DUMMY_SP}; |
ff7c6d11 | 39 | |
74b04a01 | 40 | use either::Either; |
dfeec247 XL |
41 | use smallvec::SmallVec; |
42 | use std::cell::RefCell; | |
0bf4aa26 | 43 | use std::collections::BTreeMap; |
532ac7d7 XL |
44 | use std::mem; |
45 | use std::rc::Rc; | |
ff7c6d11 | 46 | |
c295e0f8 XL |
47 | use rustc_mir_dataflow::impls::{ |
48 | EverInitializedPlaces, MaybeInitializedPlaces, MaybeUninitializedPlaces, | |
f9f354fc | 49 | }; |
c295e0f8 XL |
50 | use rustc_mir_dataflow::move_paths::{InitIndex, MoveOutIndex, MovePathIndex}; |
51 | use rustc_mir_dataflow::move_paths::{InitLocation, LookupResult, MoveData, MoveError}; | |
52 | use rustc_mir_dataflow::Analysis; | |
53 | use rustc_mir_dataflow::MoveDataParamEnv; | |
ff7c6d11 | 54 | |
dfeec247 | 55 | use self::diagnostics::{AccessKind, RegionName}; |
83c7162d | 56 | use self::location::LocationTable; |
ff7c6d11 | 57 | use self::prefixes::PrefixSet; |
94222f64 | 58 | use facts::AllFacts; |
ff7c6d11 | 59 | |
94b46f34 XL |
60 | use self::path_utils::*; |
61 | ||
3c0e092e | 62 | pub mod borrow_set; |
c295e0f8 | 63 | mod borrowck_errors; |
dfeec247 XL |
64 | mod constraint_generation; |
65 | mod constraints; | |
c295e0f8 | 66 | mod dataflow; |
f9f354fc | 67 | mod def_use; |
60c5eb7d | 68 | mod diagnostics; |
dfeec247 | 69 | mod facts; |
dfeec247 | 70 | mod invalidation; |
83c7162d | 71 | mod location; |
dfeec247 XL |
72 | mod member_constraints; |
73 | mod nll; | |
8faf50e0 | 74 | mod path_utils; |
dfeec247 XL |
75 | mod place_ext; |
76 | mod places_conflict; | |
ff7c6d11 | 77 | mod prefixes; |
dfeec247 | 78 | mod region_infer; |
60c5eb7d | 79 | mod renumber; |
60c5eb7d | 80 | mod type_check; |
dfeec247 XL |
81 | mod universal_regions; |
82 | mod used_muts; | |
60c5eb7d | 83 | |
c295e0f8 XL |
84 | // A public API provided for the Rust compiler consumers. |
85 | pub mod consumers; | |
86 | ||
87 | use borrow_set::{BorrowData, BorrowSet}; | |
88 | use dataflow::{BorrowIndex, BorrowckFlowState as Flows, BorrowckResults, Borrows}; | |
89 | use nll::{PoloniusOutput, ToRegionVid}; | |
90 | use place_ext::PlaceExt; | |
91 | use places_conflict::{places_conflict, PlaceConflictBias}; | |
92 | use region_infer::RegionInferenceContext; | |
ff7c6d11 | 93 | |
48663c56 XL |
94 | // FIXME(eddyb) perhaps move this somewhere more centrally. |
95 | #[derive(Debug)] | |
c295e0f8 | 96 | struct Upvar<'tcx> { |
5869c6ff | 97 | place: CapturedPlace<'tcx>, |
48663c56 XL |
98 | |
99 | /// If true, the capture is behind a reference. | |
100 | by_ref: bool, | |
48663c56 XL |
101 | } |
102 | ||
74b04a01 XL |
103 | const DEREF_PROJECTION: &[PlaceElem<'_>; 1] = &[ProjectionElem::Deref]; |
104 | ||
f035d41b | 105 | pub fn provide(providers: &mut Providers) { |
3dfed10e XL |
106 | *providers = Providers { |
107 | mir_borrowck: |tcx, did| { | |
108 | if let Some(def) = ty::WithOptConstParam::try_lookup(did, tcx) { | |
109 | tcx.mir_borrowck_const_arg(def) | |
110 | } else { | |
111 | mir_borrowck(tcx, ty::WithOptConstParam::unknown(did)) | |
112 | } | |
113 | }, | |
114 | mir_borrowck_const_arg: |tcx, (did, param_did)| { | |
115 | mir_borrowck(tcx, ty::WithOptConstParam { did, const_param_did: Some(param_did) }) | |
116 | }, | |
117 | ..*providers | |
118 | }; | |
ff7c6d11 XL |
119 | } |
120 | ||
3dfed10e XL |
121 | fn mir_borrowck<'tcx>( |
122 | tcx: TyCtxt<'tcx>, | |
123 | def: ty::WithOptConstParam<LocalDefId>, | |
124 | ) -> &'tcx BorrowCheckResult<'tcx> { | |
125 | let (input_body, promoted) = tcx.mir_promoted(def); | |
126 | debug!("run query mir_borrowck: {}", tcx.def_path_str(def.did.to_def_id())); | |
ff7c6d11 | 127 | |
94222f64 | 128 | let opt_closure_req = tcx.infer_ctxt().with_opaque_type_inference(def.did).enter(|infcx| { |
dc9dc135 | 129 | let input_body: &Body<'_> = &input_body.borrow(); |
e1599b0c | 130 | let promoted: &IndexVec<_, _> = &promoted.borrow(); |
94222f64 | 131 | do_mir_borrowck(&infcx, input_body, promoted, false).0 |
ff7c6d11 XL |
132 | }); |
133 | debug!("mir_borrowck done"); | |
134 | ||
3dfed10e | 135 | tcx.arena.alloc(opt_closure_req) |
ff7c6d11 XL |
136 | } |
137 | ||
94222f64 XL |
138 | /// Perform the actual borrow checking. |
139 | /// | |
140 | /// If `return_body_with_facts` is true, then return the body with non-erased | |
141 | /// region ids on which the borrow checking was performed together with Polonius | |
142 | /// facts. | |
c295e0f8 | 143 | #[instrument(skip(infcx, input_body, input_promoted), level = "debug")] |
dc9dc135 XL |
144 | fn do_mir_borrowck<'a, 'tcx>( |
145 | infcx: &InferCtxt<'a, 'tcx>, | |
146 | input_body: &Body<'tcx>, | |
f9f354fc | 147 | input_promoted: &IndexVec<Promoted, Body<'tcx>>, |
94222f64 XL |
148 | return_body_with_facts: bool, |
149 | ) -> (BorrowCheckResult<'tcx>, Option<Box<BodyWithBorrowckFacts<'tcx>>>) { | |
29967ef6 XL |
150 | let def = input_body.source.with_opt_param().as_local().unwrap(); |
151 | ||
c295e0f8 | 152 | debug!(?def); |
94222f64 | 153 | |
ff7c6d11 | 154 | let tcx = infcx.tcx; |
3dfed10e XL |
155 | let param_env = tcx.param_env(def.did); |
156 | let id = tcx.hir().local_def_id_to_hir_id(def.did); | |
ff7c6d11 | 157 | |
60c5eb7d XL |
158 | let mut local_names = IndexVec::from_elem(None, &input_body.local_decls); |
159 | for var_debug_info in &input_body.var_debug_info { | |
fc512014 XL |
160 | if let VarDebugInfoContents::Place(place) = var_debug_info.value { |
161 | if let Some(local) = place.as_local() { | |
162 | if let Some(prev_name) = local_names[local] { | |
163 | if var_debug_info.name != prev_name { | |
164 | span_bug!( | |
165 | var_debug_info.source_info.span, | |
166 | "local {:?} has many names (`{}` vs `{}`)", | |
167 | local, | |
168 | prev_name, | |
169 | var_debug_info.name | |
170 | ); | |
171 | } | |
60c5eb7d | 172 | } |
fc512014 | 173 | local_names[local] = Some(var_debug_info.name); |
60c5eb7d | 174 | } |
60c5eb7d XL |
175 | } |
176 | } | |
177 | ||
5099ac24 FG |
178 | let mut errors = error::BorrowckErrors::new(); |
179 | ||
48663c56 | 180 | // Gather the upvars of a closure, if any. |
3dfed10e | 181 | let tables = tcx.typeck_opt_const_arg(def); |
ba9703b0 | 182 | if let Some(ErrorReported) = tables.tainted_by_errors { |
74b04a01 | 183 | infcx.set_tainted_by_errors(); |
5099ac24 | 184 | errors.set_tainted_by_errors(); |
74b04a01 | 185 | } |
48663c56 | 186 | let upvars: Vec<_> = tables |
fc512014 XL |
187 | .closure_min_captures_flattened(def.did.to_def_id()) |
188 | .map(|captured_place| { | |
fc512014 | 189 | let capture = captured_place.info.capture_kind; |
48663c56 | 190 | let by_ref = match capture { |
5099ac24 | 191 | ty::UpvarCapture::ByValue => false, |
48663c56 XL |
192 | ty::UpvarCapture::ByRef(..) => true, |
193 | }; | |
17df50a5 | 194 | Upvar { place: captured_place.clone(), by_ref } |
48663c56 XL |
195 | }) |
196 | .collect(); | |
197 | ||
83c7162d XL |
198 | // Replace all regions with fresh inference variables. This |
199 | // requires first making our own copy of the MIR. This copy will | |
200 | // be modified (in place) to contain non-lexical lifetimes. It | |
201 | // will have a lifetime tied to the inference context. | |
94222f64 | 202 | let mut body_owned = input_body.clone(); |
60c5eb7d | 203 | let mut promoted = input_promoted.clone(); |
94222f64 XL |
204 | let free_regions = |
205 | nll::replace_regions_in_mir(infcx, param_env, &mut body_owned, &mut promoted); | |
206 | let body = &body_owned; // no further changes | |
60c5eb7d | 207 | |
94222f64 XL |
208 | let location_table_owned = LocationTable::new(body); |
209 | let location_table = &location_table_owned; | |
ff7c6d11 | 210 | |
f9f354fc | 211 | let (move_data, move_errors): (MoveData<'tcx>, Vec<(Place<'tcx>, MoveError<'tcx>)>) = |
60c5eb7d | 212 | match MoveData::gather_moves(&body, tcx, param_env) { |
f9f354fc XL |
213 | Ok(move_data) => (move_data, Vec::new()), |
214 | Err((move_data, move_errors)) => (move_data, move_errors), | |
8faf50e0 | 215 | }; |
f9f354fc XL |
216 | let promoted_errors = promoted |
217 | .iter_enumerated() | |
218 | .map(|(idx, body)| (idx, MoveData::gather_moves(&body, tcx, param_env))); | |
ff7c6d11 | 219 | |
dfeec247 | 220 | let mdpe = MoveDataParamEnv { move_data, param_env }; |
ff7c6d11 | 221 | |
74b04a01 | 222 | let mut flow_inits = MaybeInitializedPlaces::new(tcx, &body, &mdpe) |
29967ef6 | 223 | .into_engine(tcx, &body) |
1b1a35ee | 224 | .pass_name("borrowck") |
74b04a01 XL |
225 | .iterate_to_fixpoint() |
226 | .into_results_cursor(&body); | |
ff7c6d11 | 227 | |
dc9dc135 | 228 | let locals_are_invalidated_at_exit = tcx.hir().body_owner_kind(id).is_fn_or_closure(); |
dfeec247 XL |
229 | let borrow_set = |
230 | Rc::new(BorrowSet::build(tcx, body, locals_are_invalidated_at_exit, &mdpe.move_data)); | |
231 | ||
c295e0f8 XL |
232 | let use_polonius = return_body_with_facts || infcx.tcx.sess.opts.debugging_opts.polonius; |
233 | ||
dfeec247 | 234 | // Compute non-lexical lifetimes. |
74b04a01 XL |
235 | let nll::NllOutput { |
236 | regioncx, | |
237 | opaque_type_values, | |
94222f64 | 238 | polonius_input, |
74b04a01 XL |
239 | polonius_output, |
240 | opt_closure_req, | |
241 | nll_errors, | |
242 | } = nll::compute_regions( | |
243 | infcx, | |
74b04a01 XL |
244 | free_regions, |
245 | body, | |
246 | &promoted, | |
247 | location_table, | |
248 | param_env, | |
249 | &mut flow_inits, | |
250 | &mdpe.move_data, | |
251 | &borrow_set, | |
f035d41b | 252 | &upvars, |
c295e0f8 | 253 | use_polonius, |
74b04a01 | 254 | ); |
83c7162d | 255 | |
dfeec247 XL |
256 | // Dump MIR results into a file, if that is enabled. This let us |
257 | // write unit-tests, as well as helping with debugging. | |
29967ef6 | 258 | nll::dump_mir_results(infcx, &body, ®ioncx, &opt_closure_req); |
dfeec247 | 259 | |
74b04a01 | 260 | // We also have a `#[rustc_regions]` annotation that causes us to dump |
dfeec247 | 261 | // information. |
74b04a01 XL |
262 | nll::dump_annotation( |
263 | infcx, | |
264 | &body, | |
74b04a01 XL |
265 | ®ioncx, |
266 | &opt_closure_req, | |
267 | &opaque_type_values, | |
5099ac24 | 268 | &mut errors, |
74b04a01 | 269 | ); |
b7449926 XL |
270 | |
271 | // The various `flow_*` structures can be large. We drop `flow_inits` here | |
272 | // so it doesn't overlap with the others below. This reduces peak memory | |
273 | // usage significantly on some benchmarks. | |
274 | drop(flow_inits); | |
275 | ||
83c7162d | 276 | let regioncx = Rc::new(regioncx); |
ff7c6d11 | 277 | |
c295e0f8 XL |
278 | let flow_borrows = Borrows::new(tcx, body, ®ioncx, &borrow_set) |
279 | .into_engine(tcx, body) | |
1b1a35ee | 280 | .pass_name("borrowck") |
74b04a01 | 281 | .iterate_to_fixpoint(); |
c295e0f8 XL |
282 | let flow_uninits = MaybeUninitializedPlaces::new(tcx, body, &mdpe) |
283 | .into_engine(tcx, body) | |
1b1a35ee | 284 | .pass_name("borrowck") |
74b04a01 | 285 | .iterate_to_fixpoint(); |
c295e0f8 XL |
286 | let flow_ever_inits = EverInitializedPlaces::new(tcx, body, &mdpe) |
287 | .into_engine(tcx, body) | |
1b1a35ee | 288 | .pass_name("borrowck") |
74b04a01 | 289 | .iterate_to_fixpoint(); |
0531ce1d | 290 | |
c295e0f8 XL |
291 | let movable_generator = !matches!( |
292 | tcx.hir().get(id), | |
b7449926 | 293 | Node::Expr(&hir::Expr { |
60c5eb7d | 294 | kind: hir::ExprKind::Closure(.., Some(hir::Movability::Static)), |
2c00a5a8 | 295 | .. |
c295e0f8 XL |
296 | }) |
297 | ); | |
2c00a5a8 | 298 | |
f9f354fc XL |
299 | for (idx, move_data_results) in promoted_errors { |
300 | let promoted_body = &promoted[idx]; | |
f9f354fc XL |
301 | |
302 | if let Err((move_data, move_errors)) = move_data_results { | |
303 | let mut promoted_mbcx = MirBorrowckCtxt { | |
304 | infcx, | |
1b1a35ee | 305 | param_env, |
f9f354fc | 306 | body: promoted_body, |
f9f354fc | 307 | move_data: &move_data, |
6a06907d | 308 | location_table, // no need to create a real one for the promoted, it is not used |
f9f354fc | 309 | movable_generator, |
f035d41b | 310 | fn_self_span_reported: Default::default(), |
f9f354fc XL |
311 | locals_are_invalidated_at_exit, |
312 | access_place_error_reported: Default::default(), | |
313 | reservation_error_reported: Default::default(), | |
314 | reservation_warnings: Default::default(), | |
f9f354fc | 315 | uninitialized_error_reported: Default::default(), |
f9f354fc XL |
316 | regioncx: regioncx.clone(), |
317 | used_mut: Default::default(), | |
318 | used_mut_upvars: SmallVec::new(), | |
6a06907d XL |
319 | borrow_set: Rc::clone(&borrow_set), |
320 | dominators: Dominators::dummy(), // not used | |
f9f354fc XL |
321 | upvars: Vec::new(), |
322 | local_names: IndexVec::from_elem(None, &promoted_body.local_decls), | |
323 | region_names: RefCell::default(), | |
324 | next_region_name: RefCell::new(1), | |
325 | polonius_output: None, | |
5099ac24 | 326 | errors, |
f9f354fc XL |
327 | }; |
328 | promoted_mbcx.report_move_errors(move_errors); | |
5099ac24 | 329 | errors = promoted_mbcx.errors; |
f9f354fc XL |
330 | }; |
331 | } | |
332 | ||
dc9dc135 | 333 | let dominators = body.dominators(); |
83c7162d | 334 | |
ff7c6d11 | 335 | let mut mbcx = MirBorrowckCtxt { |
0bf4aa26 | 336 | infcx, |
1b1a35ee | 337 | param_env, |
dc9dc135 | 338 | body, |
ff7c6d11 | 339 | move_data: &mdpe.move_data, |
8faf50e0 | 340 | location_table, |
2c00a5a8 | 341 | movable_generator, |
b7449926 | 342 | locals_are_invalidated_at_exit, |
f035d41b | 343 | fn_self_span_reported: Default::default(), |
0bf4aa26 XL |
344 | access_place_error_reported: Default::default(), |
345 | reservation_error_reported: Default::default(), | |
532ac7d7 | 346 | reservation_warnings: Default::default(), |
0bf4aa26 | 347 | uninitialized_error_reported: Default::default(), |
6a06907d | 348 | regioncx: Rc::clone(®ioncx), |
0bf4aa26 | 349 | used_mut: Default::default(), |
83c7162d | 350 | used_mut_upvars: SmallVec::new(), |
6a06907d | 351 | borrow_set: Rc::clone(&borrow_set), |
83c7162d | 352 | dominators, |
48663c56 | 353 | upvars, |
60c5eb7d | 354 | local_names, |
dfeec247 XL |
355 | region_names: RefCell::default(), |
356 | next_region_name: RefCell::new(1), | |
74b04a01 | 357 | polonius_output, |
5099ac24 | 358 | errors, |
ff7c6d11 XL |
359 | }; |
360 | ||
dfeec247 XL |
361 | // Compute and report region errors, if any. |
362 | mbcx.report_region_errors(nll_errors); | |
363 | ||
74b04a01 XL |
364 | let results = BorrowckResults { |
365 | ever_inits: flow_ever_inits, | |
366 | uninits: flow_uninits, | |
367 | borrows: flow_borrows, | |
368 | }; | |
ff7c6d11 | 369 | |
f9f354fc | 370 | mbcx.report_move_errors(move_errors); |
74b04a01 | 371 | |
c295e0f8 XL |
372 | rustc_mir_dataflow::visit_results( |
373 | body, | |
374 | traversal::reverse_postorder(body).map(|(bb, _)| bb), | |
74b04a01 XL |
375 | &results, |
376 | &mut mbcx, | |
377 | ); | |
ff7c6d11 | 378 | |
532ac7d7 | 379 | // Convert any reservation warnings into lints. |
416331ca | 380 | let reservation_warnings = mem::take(&mut mbcx.reservation_warnings); |
48663c56 | 381 | for (_, (place, span, location, bk, borrow)) in reservation_warnings { |
ba9703b0 | 382 | let mut initial_diag = mbcx.report_conflicting_borrow(location, (place, span), bk, &borrow); |
532ac7d7 | 383 | |
60c5eb7d XL |
384 | let scope = mbcx.body.source_info(location).scope; |
385 | let lint_root = match &mbcx.body.source_scopes[scope].local_data { | |
386 | ClearCrossCrate::Set(data) => data.lint_root, | |
387 | _ => id, | |
532ac7d7 XL |
388 | }; |
389 | ||
390 | // Span and message don't matter; we overwrite them below anyway | |
74b04a01 | 391 | mbcx.infcx.tcx.struct_span_lint_hir( |
dfeec247 XL |
392 | MUTABLE_BORROW_RESERVATION_CONFLICT, |
393 | lint_root, | |
394 | DUMMY_SP, | |
74b04a01 XL |
395 | |lint| { |
396 | let mut diag = lint.build(""); | |
532ac7d7 | 397 | |
74b04a01 XL |
398 | diag.message = initial_diag.styled_message().clone(); |
399 | diag.span = initial_diag.span.clone(); | |
532ac7d7 | 400 | |
5099ac24 | 401 | mbcx.buffer_non_error_diag(diag); |
74b04a01 XL |
402 | }, |
403 | ); | |
532ac7d7 | 404 | initial_diag.cancel(); |
532ac7d7 XL |
405 | } |
406 | ||
83c7162d XL |
407 | // For each non-user used mutable variable, check if it's been assigned from |
408 | // a user-declared local. If so, then put that local into the used_mut set. | |
409 | // Note that this set is expected to be small - only upvars from closures | |
410 | // would have a chance of erroneously adding non-user-defined mutable vars | |
411 | // to the set. | |
dfeec247 XL |
412 | let temporary_used_locals: FxHashSet<Local> = mbcx |
413 | .used_mut | |
414 | .iter() | |
60c5eb7d | 415 | .filter(|&local| !mbcx.body.local_decls[*local].is_user_variable()) |
8faf50e0 XL |
416 | .cloned() |
417 | .collect(); | |
a1dfa0c6 XL |
418 | // For the remaining unused locals that are marked as mutable, we avoid linting any that |
419 | // were never initialized. These locals may have been removed as unreachable code; or will be | |
420 | // linted as unused variables. | |
dfeec247 XL |
421 | let unused_mut_locals = |
422 | mbcx.body.mut_vars_iter().filter(|local| !mbcx.used_mut.contains(local)).collect(); | |
a1dfa0c6 | 423 | mbcx.gather_used_muts(temporary_used_locals, unused_mut_locals); |
83c7162d XL |
424 | |
425 | debug!("mbcx.used_mut: {:?}", mbcx.used_mut); | |
5099ac24 | 426 | let used_mut = std::mem::take(&mut mbcx.used_mut); |
dfeec247 | 427 | for local in mbcx.body.mut_vars_and_args_iter().filter(|local| !used_mut.contains(local)) { |
60c5eb7d XL |
428 | let local_decl = &mbcx.body.local_decls[local]; |
429 | let lint_root = match &mbcx.body.source_scopes[local_decl.source_info.scope].local_data { | |
430 | ClearCrossCrate::Set(data) => data.lint_root, | |
431 | _ => continue, | |
432 | }; | |
83c7162d | 433 | |
60c5eb7d XL |
434 | // Skip over locals that begin with an underscore or have no name |
435 | match mbcx.local_names[local] { | |
dfeec247 | 436 | Some(name) => { |
74b04a01 | 437 | if name.as_str().starts_with('_') { |
dfeec247 XL |
438 | continue; |
439 | } | |
440 | } | |
60c5eb7d XL |
441 | None => continue, |
442 | } | |
83c7162d | 443 | |
60c5eb7d XL |
444 | let span = local_decl.source_info.span; |
445 | if span.desugaring_kind().is_some() { | |
446 | // If the `mut` arises as part of a desugaring, we should ignore it. | |
447 | continue; | |
8faf50e0 | 448 | } |
60c5eb7d | 449 | |
74b04a01 XL |
450 | tcx.struct_span_lint_hir(UNUSED_MUT, lint_root, span, |lint| { |
451 | let mut_span = tcx.sess.source_map().span_until_non_whitespace(span); | |
452 | lint.build("variable does not need to be mutable") | |
453 | .span_suggestion_short( | |
454 | mut_span, | |
455 | "remove this `mut`", | |
456 | String::new(), | |
457 | Applicability::MachineApplicable, | |
458 | ) | |
459 | .emit(); | |
460 | }) | |
8faf50e0 XL |
461 | } |
462 | ||
5099ac24 | 463 | let tainted_by_errors = mbcx.emit_errors(); |
83c7162d | 464 | |
8faf50e0 | 465 | let result = BorrowCheckResult { |
74b04a01 | 466 | concrete_opaque_types: opaque_type_values, |
83c7162d XL |
467 | closure_requirements: opt_closure_req, |
468 | used_mut_upvars: mbcx.used_mut_upvars, | |
5099ac24 | 469 | tainted_by_errors, |
8faf50e0 XL |
470 | }; |
471 | ||
94222f64 XL |
472 | let body_with_facts = if return_body_with_facts { |
473 | let output_facts = mbcx.polonius_output.expect("Polonius output was not computed"); | |
474 | Some(Box::new(BodyWithBorrowckFacts { | |
475 | body: body_owned, | |
476 | input_facts: *polonius_input.expect("Polonius input facts were not generated"), | |
477 | output_facts, | |
478 | location_table: location_table_owned, | |
479 | })) | |
480 | } else { | |
481 | None | |
482 | }; | |
483 | ||
8faf50e0 XL |
484 | debug!("do_mir_borrowck: result = {:#?}", result); |
485 | ||
94222f64 XL |
486 | (result, body_with_facts) |
487 | } | |
488 | ||
489 | /// A `Body` with information computed by the borrow checker. This struct is | |
490 | /// intended to be consumed by compiler consumers. | |
491 | /// | |
492 | /// We need to include the MIR body here because the region identifiers must | |
493 | /// match the ones in the Polonius facts. | |
494 | pub struct BodyWithBorrowckFacts<'tcx> { | |
495 | /// A mir body that contains region identifiers. | |
496 | pub body: Body<'tcx>, | |
497 | /// Polonius input facts. | |
498 | pub input_facts: AllFacts, | |
499 | /// Polonius output facts. | |
500 | pub output_facts: Rc<self::nll::PoloniusOutput>, | |
501 | /// The table that maps Polonius points to locations in the table. | |
502 | pub location_table: LocationTable, | |
ff7c6d11 XL |
503 | } |
504 | ||
c295e0f8 XL |
505 | struct MirBorrowckCtxt<'cx, 'tcx> { |
506 | infcx: &'cx InferCtxt<'cx, 'tcx>, | |
1b1a35ee | 507 | param_env: ParamEnv<'tcx>, |
f9f354fc | 508 | body: &'cx Body<'tcx>, |
ff7c6d11 | 509 | move_data: &'cx MoveData<'tcx>, |
8faf50e0 XL |
510 | |
511 | /// Map from MIR `Location` to `LocationIndex`; created | |
512 | /// when MIR borrowck begins. | |
513 | location_table: &'cx LocationTable, | |
514 | ||
2c00a5a8 | 515 | movable_generator: bool, |
ff7c6d11 XL |
516 | /// This keeps track of whether local variables are free-ed when the function |
517 | /// exits even without a `StorageDead`, which appears to be the case for | |
518 | /// constants. | |
519 | /// | |
520 | /// I'm not sure this is the right approach - @eddyb could you try and | |
521 | /// figure this out? | |
522 | locals_are_invalidated_at_exit: bool, | |
2c00a5a8 XL |
523 | /// This field keeps track of when borrow errors are reported in the access_place function |
524 | /// so that there is no duplicate reporting. This field cannot also be used for the conflicting | |
525 | /// borrow errors that is handled by the `reservation_error_reported` field as the inclusion | |
526 | /// of the `Span` type (while required to mute some errors) stops the muting of the reservation | |
527 | /// errors. | |
528 | access_place_error_reported: FxHashSet<(Place<'tcx>, Span)>, | |
ff7c6d11 XL |
529 | /// This field keeps track of when borrow conflict errors are reported |
530 | /// for reservations, so that we don't report seemingly duplicate | |
9fa01778 XL |
531 | /// errors for corresponding activations. |
532 | // | |
533 | // FIXME: ideally this would be a set of `BorrowIndex`, not `Place`s, | |
534 | // but it is currently inconvenient to track down the `BorrowIndex` | |
535 | // at the time we detect and report a reservation error. | |
ff7c6d11 | 536 | reservation_error_reported: FxHashSet<Place<'tcx>>, |
f035d41b XL |
537 | /// This fields keeps track of the `Span`s that we have |
538 | /// used to report extra information for `FnSelfUse`, to avoid | |
539 | /// unnecessarily verbose errors. | |
540 | fn_self_span_reported: FxHashSet<Span>, | |
532ac7d7 XL |
541 | /// Migration warnings to be reported for #56254. We delay reporting these |
542 | /// so that we can suppress the warning if there's a corresponding error | |
543 | /// for the activation of the borrow. | |
dfeec247 XL |
544 | reservation_warnings: |
545 | FxHashMap<BorrowIndex, (Place<'tcx>, Span, Location, BorrowKind, BorrowData<'tcx>)>, | |
0bf4aa26 | 546 | /// This field keeps track of errors reported in the checking of uninitialized variables, |
8faf50e0 | 547 | /// so that we don't report seemingly duplicate errors. |
74b04a01 | 548 | uninitialized_error_reported: FxHashSet<PlaceRef<'tcx>>, |
83c7162d XL |
549 | /// This field keeps track of all the local variables that are declared mut and are mutated. |
550 | /// Used for the warning issued by an unused mutable local variable. | |
551 | used_mut: FxHashSet<Local>, | |
552 | /// If the function we're checking is a closure, then we'll need to report back the list of | |
553 | /// mutable upvars that have been used. This field keeps track of them. | |
554 | used_mut_upvars: SmallVec<[Field; 8]>, | |
dfeec247 | 555 | /// Region inference context. This contains the results from region inference and lets us e.g. |
ff7c6d11 | 556 | /// find out which CFG points are contained in each borrow region. |
dfeec247 | 557 | regioncx: Rc<RegionInferenceContext<'tcx>>, |
83c7162d XL |
558 | |
559 | /// The set of borrows extracted from the MIR | |
560 | borrow_set: Rc<BorrowSet<'tcx>>, | |
561 | ||
562 | /// Dominators for MIR | |
563 | dominators: Dominators<BasicBlock>, | |
48663c56 XL |
564 | |
565 | /// Information about upvars not necessarily preserved in types or MIR | |
5869c6ff | 566 | upvars: Vec<Upvar<'tcx>>, |
60c5eb7d XL |
567 | |
568 | /// Names of local (user) variables (extracted from `var_debug_info`). | |
f9f354fc | 569 | local_names: IndexVec<Local, Option<Symbol>>, |
dfeec247 XL |
570 | |
571 | /// Record the region names generated for each region in the given | |
572 | /// MIR def so that we can reuse them later in help/error messages. | |
573 | region_names: RefCell<FxHashMap<RegionVid, RegionName>>, | |
574 | ||
575 | /// The counter for generating new region names. | |
576 | next_region_name: RefCell<usize>, | |
74b04a01 XL |
577 | |
578 | /// Results of Polonius analysis. | |
579 | polonius_output: Option<Rc<PoloniusOutput>>, | |
5099ac24 FG |
580 | |
581 | errors: error::BorrowckErrors<'tcx>, | |
ff7c6d11 XL |
582 | } |
583 | ||
584 | // Check that: | |
585 | // 1. assignments are always made to mutable locations (FIXME: does that still really go here?) | |
586 | // 2. loans made in overlapping scopes do not conflict | |
587 | // 3. assignments do not affect things loaned out as immutable | |
588 | // 4. moves do not affect things loaned out in any way | |
c295e0f8 | 589 | impl<'cx, 'tcx> rustc_mir_dataflow::ResultsVisitor<'cx, 'tcx> for MirBorrowckCtxt<'cx, 'tcx> { |
dc9dc135 | 590 | type FlowState = Flows<'cx, 'tcx>; |
ff7c6d11 | 591 | |
f9f354fc | 592 | fn visit_statement_before_primary_effect( |
ff7c6d11 | 593 | &mut self, |
74b04a01 | 594 | flow_state: &Flows<'cx, 'tcx>, |
416331ca | 595 | stmt: &'cx Statement<'tcx>, |
74b04a01 | 596 | location: Location, |
ff7c6d11 | 597 | ) { |
74b04a01 | 598 | debug!("MirBorrowckCtxt::process_statement({:?}, {:?}): {:?}", location, stmt, flow_state); |
ff7c6d11 XL |
599 | let span = stmt.source_info.span; |
600 | ||
601 | self.check_activations(location, span, flow_state); | |
602 | ||
ba9703b0 XL |
603 | match &stmt.kind { |
604 | StatementKind::Assign(box (lhs, ref rhs)) => { | |
dfeec247 | 605 | self.consume_rvalue(location, (rhs, span), flow_state); |
2c00a5a8 | 606 | |
5099ac24 | 607 | self.mutate_place(location, (*lhs, span), Shallow(None), flow_state); |
ff7c6d11 | 608 | } |
cdc7bbd5 | 609 | StatementKind::FakeRead(box (_, ref place)) => { |
0bf4aa26 XL |
610 | // Read for match doesn't access any memory and is used to |
611 | // assert that a place is safe and live. So we don't have to | |
612 | // do any checks here. | |
613 | // | |
614 | // FIXME: Remove check that the place is initialized. This is | |
615 | // needed for now because matches don't have never patterns yet. | |
616 | // So this is the only place we prevent | |
617 | // let x: !; | |
618 | // match x {}; | |
619 | // from compiling. | |
620 | self.check_if_path_or_subpath_is_moved( | |
48663c56 | 621 | location, |
0bf4aa26 | 622 | InitializationRequiringAction::Use, |
416331ca | 623 | (place.as_ref(), span), |
8faf50e0 XL |
624 | flow_state, |
625 | ); | |
94b46f34 | 626 | } |
ba9703b0 | 627 | StatementKind::SetDiscriminant { place, variant_index: _ } => { |
5099ac24 | 628 | self.mutate_place(location, (**place, span), Shallow(None), flow_state); |
ff7c6d11 | 629 | } |
6a06907d XL |
630 | StatementKind::CopyNonOverlapping(box rustc_middle::mir::CopyNonOverlapping { |
631 | .. | |
632 | }) => { | |
633 | span_bug!( | |
634 | span, | |
635 | "Unexpected CopyNonOverlapping, should only appear after lower_intrinsics", | |
636 | ) | |
637 | } | |
8faf50e0 | 638 | StatementKind::Nop |
3dfed10e | 639 | | StatementKind::Coverage(..) |
b7449926 | 640 | | StatementKind::AscribeUserType(..) |
a1dfa0c6 | 641 | | StatementKind::Retag { .. } |
8faf50e0 | 642 | | StatementKind::StorageLive(..) => { |
a1dfa0c6 | 643 | // `Nop`, `AscribeUserType`, `Retag`, and `StorageLive` are irrelevant |
ff7c6d11 XL |
644 | // to borrow check. |
645 | } | |
ff7c6d11 XL |
646 | StatementKind::StorageDead(local) => { |
647 | self.access_place( | |
48663c56 | 648 | location, |
ba9703b0 | 649 | (Place::from(*local), span), |
ff7c6d11 XL |
650 | (Shallow(None), Write(WriteKind::StorageDeadOrDrop)), |
651 | LocalMutationIsAllowed::Yes, | |
652 | flow_state, | |
653 | ); | |
654 | } | |
655 | } | |
656 | } | |
657 | ||
f9f354fc | 658 | fn visit_terminator_before_primary_effect( |
ff7c6d11 | 659 | &mut self, |
74b04a01 | 660 | flow_state: &Flows<'cx, 'tcx>, |
416331ca | 661 | term: &'cx Terminator<'tcx>, |
74b04a01 | 662 | loc: Location, |
ff7c6d11 | 663 | ) { |
74b04a01 | 664 | debug!("MirBorrowckCtxt::process_terminator({:?}, {:?}): {:?}", loc, term, flow_state); |
ff7c6d11 XL |
665 | let span = term.source_info.span; |
666 | ||
74b04a01 | 667 | self.check_activations(loc, span, flow_state); |
ff7c6d11 XL |
668 | |
669 | match term.kind { | |
29967ef6 | 670 | TerminatorKind::SwitchInt { ref discr, switch_ty: _, targets: _ } => { |
48663c56 | 671 | self.consume_operand(loc, (discr, span), flow_state); |
ff7c6d11 | 672 | } |
29967ef6 | 673 | TerminatorKind::Drop { place, target: _, unwind: _ } => { |
dfeec247 XL |
674 | debug!( |
675 | "visit_terminator_drop \ | |
29967ef6 XL |
676 | loc: {:?} term: {:?} place: {:?} span: {:?}", |
677 | loc, term, place, span | |
dfeec247 | 678 | ); |
b7449926 | 679 | |
0bf4aa26 | 680 | self.access_place( |
48663c56 | 681 | loc, |
29967ef6 | 682 | (place, span), |
0bf4aa26 XL |
683 | (AccessDepth::Drop, Write(WriteKind::StorageDeadOrDrop)), |
684 | LocalMutationIsAllowed::Yes, | |
685 | flow_state, | |
686 | ); | |
ff7c6d11 XL |
687 | } |
688 | TerminatorKind::DropAndReplace { | |
f035d41b | 689 | place: drop_place, |
ff7c6d11 XL |
690 | value: ref new_value, |
691 | target: _, | |
692 | unwind: _, | |
693 | } => { | |
5099ac24 | 694 | self.mutate_place(loc, (drop_place, span), Deep, flow_state); |
dfeec247 | 695 | self.consume_operand(loc, (new_value, span), flow_state); |
ff7c6d11 XL |
696 | } |
697 | TerminatorKind::Call { | |
698 | ref func, | |
699 | ref args, | |
700 | ref destination, | |
701 | cleanup: _, | |
0bf4aa26 | 702 | from_hir_call: _, |
f035d41b | 703 | fn_span: _, |
ff7c6d11 | 704 | } => { |
48663c56 | 705 | self.consume_operand(loc, (func, span), flow_state); |
ff7c6d11 | 706 | for arg in args { |
dfeec247 | 707 | self.consume_operand(loc, (arg, span), flow_state); |
ff7c6d11 | 708 | } |
ba9703b0 | 709 | if let Some((dest, _ /*bb*/)) = *destination { |
5099ac24 | 710 | self.mutate_place(loc, (dest, span), Deep, flow_state); |
ff7c6d11 XL |
711 | } |
712 | } | |
dfeec247 | 713 | TerminatorKind::Assert { ref cond, expected: _, ref msg, target: _, cleanup: _ } => { |
48663c56 | 714 | self.consume_operand(loc, (cond, span), flow_state); |
ba9703b0 | 715 | use rustc_middle::mir::AssertKind; |
74b04a01 | 716 | if let AssertKind::BoundsCheck { ref len, ref index } = *msg { |
48663c56 XL |
717 | self.consume_operand(loc, (len, span), flow_state); |
718 | self.consume_operand(loc, (index, span), flow_state); | |
ff7c6d11 XL |
719 | } |
720 | } | |
721 | ||
ba9703b0 | 722 | TerminatorKind::Yield { ref value, resume: _, resume_arg, drop: _ } => { |
48663c56 | 723 | self.consume_operand(loc, (value, span), flow_state); |
5099ac24 | 724 | self.mutate_place(loc, (resume_arg, span), Deep, flow_state); |
74b04a01 | 725 | } |
2c00a5a8 | 726 | |
f9f354fc XL |
727 | TerminatorKind::InlineAsm { |
728 | template: _, | |
729 | ref operands, | |
730 | options: _, | |
731 | line_spans: _, | |
732 | destination: _, | |
a2a8927a | 733 | cleanup: _, |
f9f354fc XL |
734 | } => { |
735 | for op in operands { | |
736 | match *op { | |
cdc7bbd5 | 737 | InlineAsmOperand::In { reg: _, ref value } => { |
f9f354fc XL |
738 | self.consume_operand(loc, (value, span), flow_state); |
739 | } | |
740 | InlineAsmOperand::Out { reg: _, late: _, place, .. } => { | |
741 | if let Some(place) = place { | |
5099ac24 | 742 | self.mutate_place(loc, (place, span), Shallow(None), flow_state); |
f9f354fc XL |
743 | } |
744 | } | |
745 | InlineAsmOperand::InOut { reg: _, late: _, ref in_value, out_place } => { | |
746 | self.consume_operand(loc, (in_value, span), flow_state); | |
747 | if let Some(out_place) = out_place { | |
748 | self.mutate_place( | |
749 | loc, | |
750 | (out_place, span), | |
751 | Shallow(None), | |
f9f354fc XL |
752 | flow_state, |
753 | ); | |
754 | } | |
755 | } | |
cdc7bbd5 XL |
756 | InlineAsmOperand::Const { value: _ } |
757 | | InlineAsmOperand::SymFn { value: _ } | |
f035d41b | 758 | | InlineAsmOperand::SymStatic { def_id: _ } => {} |
f9f354fc XL |
759 | } |
760 | } | |
761 | } | |
762 | ||
74b04a01 XL |
763 | TerminatorKind::Goto { target: _ } |
764 | | TerminatorKind::Abort | |
765 | | TerminatorKind::Unreachable | |
766 | | TerminatorKind::Resume | |
767 | | TerminatorKind::Return | |
768 | | TerminatorKind::GeneratorDrop | |
f035d41b | 769 | | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ } |
74b04a01 XL |
770 | | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } => { |
771 | // no data used, thus irrelevant to borrowck | |
772 | } | |
773 | } | |
774 | } | |
775 | ||
f9f354fc | 776 | fn visit_terminator_after_primary_effect( |
74b04a01 XL |
777 | &mut self, |
778 | flow_state: &Flows<'cx, 'tcx>, | |
779 | term: &'cx Terminator<'tcx>, | |
780 | loc: Location, | |
781 | ) { | |
782 | let span = term.source_info.span; | |
783 | ||
784 | match term.kind { | |
785 | TerminatorKind::Yield { value: _, resume: _, resume_arg: _, drop: _ } => { | |
2c00a5a8 XL |
786 | if self.movable_generator { |
787 | // Look for any active borrows to locals | |
83c7162d | 788 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
789 | for i in flow_state.borrows.iter() { |
790 | let borrow = &borrow_set[i]; | |
791 | self.check_for_local_borrow(borrow, span); | |
792 | } | |
2c00a5a8 | 793 | } |
ff7c6d11 XL |
794 | } |
795 | ||
796 | TerminatorKind::Resume | TerminatorKind::Return | TerminatorKind::GeneratorDrop => { | |
797 | // Returning from the function implicitly kills storage for all locals and statics. | |
798 | // Often, the storage will already have been killed by an explicit | |
799 | // StorageDead, but we don't always emit those (notably on unwind paths), | |
800 | // so this "extra check" serves as a kind of backup. | |
83c7162d | 801 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
802 | for i in flow_state.borrows.iter() { |
803 | let borrow = &borrow_set[i]; | |
804 | self.check_for_invalidation_at_exit(loc, borrow, span); | |
805 | } | |
ff7c6d11 | 806 | } |
74b04a01 XL |
807 | |
808 | TerminatorKind::Abort | |
809 | | TerminatorKind::Assert { .. } | |
810 | | TerminatorKind::Call { .. } | |
811 | | TerminatorKind::Drop { .. } | |
812 | | TerminatorKind::DropAndReplace { .. } | |
f035d41b | 813 | | TerminatorKind::FalseEdge { real_target: _, imaginary_target: _ } |
74b04a01 XL |
814 | | TerminatorKind::FalseUnwind { real_target: _, unwind: _ } |
815 | | TerminatorKind::Goto { .. } | |
816 | | TerminatorKind::SwitchInt { .. } | |
f9f354fc XL |
817 | | TerminatorKind::Unreachable |
818 | | TerminatorKind::InlineAsm { .. } => {} | |
ff7c6d11 XL |
819 | } |
820 | } | |
821 | } | |
822 | ||
0bf4aa26 | 823 | use self::AccessDepth::{Deep, Shallow}; |
dfeec247 | 824 | use self::ReadOrWrite::{Activation, Read, Reservation, Write}; |
ff7c6d11 XL |
825 | |
826 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
827 | enum ArtificialField { | |
ff7c6d11 | 828 | ArrayLength, |
0bf4aa26 | 829 | ShallowBorrow, |
ff7c6d11 XL |
830 | } |
831 | ||
832 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
0bf4aa26 | 833 | enum AccessDepth { |
ff7c6d11 | 834 | /// From the RFC: "A *shallow* access means that the immediate |
2c00a5a8 | 835 | /// fields reached at P are accessed, but references or pointers |
ff7c6d11 XL |
836 | /// found within are not dereferenced. Right now, the only access |
837 | /// that is shallow is an assignment like `x = ...;`, which would | |
838 | /// be a *shallow write* of `x`." | |
839 | Shallow(Option<ArtificialField>), | |
840 | ||
841 | /// From the RFC: "A *deep* access means that all data reachable | |
842 | /// through the given place may be invalidated or accesses by | |
843 | /// this action." | |
844 | Deep, | |
0bf4aa26 XL |
845 | |
846 | /// Access is Deep only when there is a Drop implementation that | |
847 | /// can reach the data behind the reference. | |
848 | Drop, | |
ff7c6d11 XL |
849 | } |
850 | ||
851 | /// Kind of access to a value: read or write | |
852 | /// (For informational purposes only) | |
853 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
854 | enum ReadOrWrite { | |
855 | /// From the RFC: "A *read* means that the existing data may be | |
856 | /// read, but will not be changed." | |
857 | Read(ReadKind), | |
858 | ||
859 | /// From the RFC: "A *write* means that the data may be mutated to | |
860 | /// new values or otherwise invalidated (for example, it could be | |
861 | /// de-initialized, as in a move operation). | |
862 | Write(WriteKind), | |
863 | ||
864 | /// For two-phase borrows, we distinguish a reservation (which is treated | |
865 | /// like a Read) from an activation (which is treated like a write), and | |
866 | /// each of those is furthermore distinguished from Reads/Writes above. | |
867 | Reservation(WriteKind), | |
868 | Activation(WriteKind, BorrowIndex), | |
869 | } | |
870 | ||
871 | /// Kind of read access to a value | |
872 | /// (For informational purposes only) | |
873 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
874 | enum ReadKind { | |
875 | Borrow(BorrowKind), | |
876 | Copy, | |
877 | } | |
878 | ||
879 | /// Kind of write access to a value | |
880 | /// (For informational purposes only) | |
881 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] | |
882 | enum WriteKind { | |
883 | StorageDeadOrDrop, | |
884 | MutableBorrow(BorrowKind), | |
885 | Mutate, | |
886 | Move, | |
887 | } | |
888 | ||
889 | /// When checking permissions for a place access, this flag is used to indicate that an immutable | |
890 | /// local place can be mutated. | |
9fa01778 XL |
891 | // |
892 | // FIXME: @nikomatsakis suggested that this flag could be removed with the following modifications: | |
893 | // - Merge `check_access_permissions()` and `check_if_reassignment_to_immutable_state()`. | |
894 | // - Split `is_mutable()` into `is_assignable()` (can be directly assigned) and | |
895 | // `is_declared_mutable()`. | |
896 | // - Take flow state into consideration in `is_assignable()` for local variables. | |
ff7c6d11 XL |
897 | #[derive(Copy, Clone, PartialEq, Eq, Debug)] |
898 | enum LocalMutationIsAllowed { | |
899 | Yes, | |
900 | /// We want use of immutable upvars to cause a "write to immutable upvar" | |
901 | /// error, not an "reassignment" error. | |
902 | ExceptUpvars, | |
903 | No, | |
904 | } | |
905 | ||
0bf4aa26 | 906 | #[derive(Copy, Clone, Debug)] |
ff7c6d11 | 907 | enum InitializationRequiringAction { |
ff7c6d11 | 908 | Borrow, |
0bf4aa26 | 909 | MatchOn, |
ff7c6d11 XL |
910 | Use, |
911 | Assignment, | |
0bf4aa26 | 912 | PartialAssignment, |
ff7c6d11 XL |
913 | } |
914 | ||
74b04a01 XL |
915 | struct RootPlace<'tcx> { |
916 | place_local: Local, | |
917 | place_projection: &'tcx [PlaceElem<'tcx>], | |
83c7162d XL |
918 | is_local_mutation_allowed: LocalMutationIsAllowed, |
919 | } | |
920 | ||
ff7c6d11 XL |
921 | impl InitializationRequiringAction { |
922 | fn as_noun(self) -> &'static str { | |
923 | match self { | |
ff7c6d11 | 924 | InitializationRequiringAction::Borrow => "borrow", |
0bf4aa26 | 925 | InitializationRequiringAction::MatchOn => "use", // no good noun |
ff7c6d11 XL |
926 | InitializationRequiringAction::Use => "use", |
927 | InitializationRequiringAction::Assignment => "assign", | |
0bf4aa26 | 928 | InitializationRequiringAction::PartialAssignment => "assign to part", |
ff7c6d11 XL |
929 | } |
930 | } | |
931 | ||
932 | fn as_verb_in_past_tense(self) -> &'static str { | |
933 | match self { | |
ff7c6d11 | 934 | InitializationRequiringAction::Borrow => "borrowed", |
0bf4aa26 | 935 | InitializationRequiringAction::MatchOn => "matched on", |
ff7c6d11 XL |
936 | InitializationRequiringAction::Use => "used", |
937 | InitializationRequiringAction::Assignment => "assigned", | |
0bf4aa26 | 938 | InitializationRequiringAction::PartialAssignment => "partially assigned", |
b7449926 XL |
939 | } |
940 | } | |
941 | } | |
942 | ||
dc9dc135 | 943 | impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { |
74b04a01 | 944 | fn body(&self) -> &'cx Body<'tcx> { |
f9f354fc | 945 | self.body |
74b04a01 XL |
946 | } |
947 | ||
ff7c6d11 XL |
948 | /// Checks an access to the given place to see if it is allowed. Examines the set of borrows |
949 | /// that are in scope, as well as which paths have been initialized, to ensure that (a) the | |
950 | /// place is initialized and (b) it is not borrowed in some way that would prevent this | |
951 | /// access. | |
952 | /// | |
9fa01778 | 953 | /// Returns `true` if an error is reported. |
ff7c6d11 XL |
954 | fn access_place( |
955 | &mut self, | |
48663c56 | 956 | location: Location, |
ba9703b0 | 957 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 958 | kind: (AccessDepth, ReadOrWrite), |
ff7c6d11 | 959 | is_local_mutation_allowed: LocalMutationIsAllowed, |
dc9dc135 | 960 | flow_state: &Flows<'cx, 'tcx>, |
b7449926 | 961 | ) { |
ff7c6d11 XL |
962 | let (sd, rw) = kind; |
963 | ||
964 | if let Activation(_, borrow_index) = rw { | |
965 | if self.reservation_error_reported.contains(&place_span.0) { | |
0531ce1d XL |
966 | debug!( |
967 | "skipping access_place for activation of invalid reservation \ | |
968 | place: {:?} borrow_index: {:?}", | |
969 | place_span.0, borrow_index | |
970 | ); | |
b7449926 | 971 | return; |
ff7c6d11 XL |
972 | } |
973 | } | |
974 | ||
b7449926 XL |
975 | // Check is_empty() first because it's the common case, and doing that |
976 | // way we avoid the clone() call. | |
dfeec247 | 977 | if !self.access_place_error_reported.is_empty() |
ba9703b0 | 978 | && self.access_place_error_reported.contains(&(place_span.0, place_span.1)) |
0531ce1d XL |
979 | { |
980 | debug!( | |
981 | "access_place: suppressing error place_span=`{:?}` kind=`{:?}`", | |
982 | place_span, kind | |
983 | ); | |
b7449926 | 984 | return; |
2c00a5a8 XL |
985 | } |
986 | ||
dfeec247 XL |
987 | let mutability_error = self.check_access_permissions( |
988 | place_span, | |
989 | rw, | |
990 | is_local_mutation_allowed, | |
991 | flow_state, | |
992 | location, | |
993 | ); | |
ff7c6d11 | 994 | let conflict_error = |
48663c56 | 995 | self.check_access_for_conflict(location, place_span, sd, rw, flow_state); |
ff7c6d11 | 996 | |
532ac7d7 | 997 | if let (Activation(_, borrow_idx), true) = (kind.1, conflict_error) { |
60c5eb7d | 998 | // Suppress this warning when there's an error being emitted for the |
532ac7d7 XL |
999 | // same borrow: fixing the error is likely to fix the warning. |
1000 | self.reservation_warnings.remove(&borrow_idx); | |
1001 | } | |
1002 | ||
2c00a5a8 | 1003 | if conflict_error || mutability_error { |
dfeec247 | 1004 | debug!("access_place: logging error place_span=`{:?}` kind=`{:?}`", place_span, kind); |
ba9703b0 | 1005 | self.access_place_error_reported.insert((place_span.0, place_span.1)); |
2c00a5a8 | 1006 | } |
ff7c6d11 XL |
1007 | } |
1008 | ||
1009 | fn check_access_for_conflict( | |
1010 | &mut self, | |
48663c56 | 1011 | location: Location, |
ba9703b0 | 1012 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 1013 | sd: AccessDepth, |
ff7c6d11 | 1014 | rw: ReadOrWrite, |
dc9dc135 | 1015 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1016 | ) -> bool { |
83c7162d | 1017 | debug!( |
48663c56 XL |
1018 | "check_access_for_conflict(location={:?}, place_span={:?}, sd={:?}, rw={:?})", |
1019 | location, place_span, sd, rw, | |
83c7162d XL |
1020 | ); |
1021 | ||
ff7c6d11 | 1022 | let mut error_reported = false; |
0bf4aa26 | 1023 | let tcx = self.infcx.tcx; |
dc9dc135 | 1024 | let body = self.body; |
94b46f34 | 1025 | let borrow_set = self.borrow_set.clone(); |
74b04a01 XL |
1026 | |
1027 | // Use polonius output if it has been enabled. | |
1028 | let polonius_output = self.polonius_output.clone(); | |
1029 | let borrows_in_scope = if let Some(polonius) = &polonius_output { | |
1030 | let location = self.location_table.start_index(location); | |
1031 | Either::Left(polonius.errors_at(location).iter().copied()) | |
1032 | } else { | |
1033 | Either::Right(flow_state.borrows.iter()) | |
1034 | }; | |
1035 | ||
94b46f34 XL |
1036 | each_borrow_involving_path( |
1037 | self, | |
1038 | tcx, | |
dc9dc135 | 1039 | body, |
48663c56 | 1040 | location, |
ff7c6d11 | 1041 | (sd, place_span.0), |
94b46f34 | 1042 | &borrow_set, |
74b04a01 | 1043 | borrows_in_scope, |
8faf50e0 | 1044 | |this, borrow_index, borrow| match (rw, borrow.kind) { |
ff7c6d11 XL |
1045 | // Obviously an activation is compatible with its own |
1046 | // reservation (or even prior activating uses of same | |
1047 | // borrow); so don't check if they interfere. | |
1048 | // | |
1049 | // NOTE: *reservations* do conflict with themselves; | |
1050 | // thus aren't injecting unsoundenss w/ this check.) | |
83c7162d | 1051 | (Activation(_, activating), _) if activating == borrow_index => { |
ff7c6d11 XL |
1052 | debug!( |
1053 | "check_access_for_conflict place_span: {:?} sd: {:?} rw: {:?} \ | |
83c7162d | 1054 | skipping {:?} b/c activation of same borrow_index", |
ff7c6d11 XL |
1055 | place_span, |
1056 | sd, | |
1057 | rw, | |
83c7162d | 1058 | (borrow_index, borrow), |
ff7c6d11 XL |
1059 | ); |
1060 | Control::Continue | |
1061 | } | |
1062 | ||
ba9703b0 XL |
1063 | (Read(_), BorrowKind::Shared | BorrowKind::Shallow) |
1064 | | ( | |
1065 | Read(ReadKind::Borrow(BorrowKind::Shallow)), | |
1066 | BorrowKind::Unique | BorrowKind::Mut { .. }, | |
1067 | ) => Control::Continue, | |
0bf4aa26 XL |
1068 | |
1069 | (Write(WriteKind::Move), BorrowKind::Shallow) => { | |
1070 | // Handled by initialization checks. | |
ff7c6d11 XL |
1071 | Control::Continue |
1072 | } | |
1073 | ||
ba9703b0 | 1074 | (Read(kind), BorrowKind::Unique | BorrowKind::Mut { .. }) => { |
ff7c6d11 | 1075 | // Reading from mere reservations of mutable-borrows is OK. |
48663c56 XL |
1076 | if !is_active(&this.dominators, borrow, location) { |
1077 | assert!(allow_two_phase_borrow(borrow.kind)); | |
ff7c6d11 XL |
1078 | return Control::Continue; |
1079 | } | |
1080 | ||
0bf4aa26 | 1081 | error_reported = true; |
ff7c6d11 | 1082 | match kind { |
dfeec247 | 1083 | ReadKind::Copy => { |
5099ac24 FG |
1084 | let err = this |
1085 | .report_use_while_mutably_borrowed(location, place_span, borrow); | |
1086 | this.buffer_error(err); | |
ff7c6d11 XL |
1087 | } |
1088 | ReadKind::Borrow(bk) => { | |
5099ac24 FG |
1089 | let err = |
1090 | this.report_conflicting_borrow(location, place_span, bk, borrow); | |
1091 | this.buffer_error(err); | |
ff7c6d11 XL |
1092 | } |
1093 | } | |
1094 | Control::Break | |
1095 | } | |
1096 | ||
ba9703b0 XL |
1097 | ( |
1098 | Reservation(WriteKind::MutableBorrow(bk)), | |
1099 | BorrowKind::Shallow | BorrowKind::Shared, | |
3dfed10e XL |
1100 | ) if { tcx.migrate_borrowck() && this.borrow_set.contains(&location) } => { |
1101 | let bi = this.borrow_set.get_index_of(&location).unwrap(); | |
532ac7d7 XL |
1102 | debug!( |
1103 | "recording invalid reservation of place: {:?} with \ | |
1104 | borrow index {:?} as warning", | |
dfeec247 | 1105 | place_span.0, bi, |
532ac7d7 XL |
1106 | ); |
1107 | // rust-lang/rust#56254 - This was previously permitted on | |
1108 | // the 2018 edition so we emit it as a warning. We buffer | |
1109 | // these sepately so that we only emit a warning if borrow | |
1110 | // checking was otherwise successful. | |
dfeec247 | 1111 | this.reservation_warnings |
ba9703b0 | 1112 | .insert(bi, (place_span.0, place_span.1, location, bk, borrow.clone())); |
532ac7d7 XL |
1113 | |
1114 | // Don't suppress actual errors. | |
1115 | Control::Continue | |
1116 | } | |
1117 | ||
ba9703b0 | 1118 | (Reservation(kind) | Activation(kind, _) | Write(kind), _) => { |
ff7c6d11 | 1119 | match rw { |
532ac7d7 | 1120 | Reservation(..) => { |
ff7c6d11 XL |
1121 | debug!( |
1122 | "recording invalid reservation of \ | |
1123 | place: {:?}", | |
1124 | place_span.0 | |
1125 | ); | |
ba9703b0 | 1126 | this.reservation_error_reported.insert(place_span.0); |
0531ce1d | 1127 | } |
ff7c6d11 XL |
1128 | Activation(_, activating) => { |
1129 | debug!( | |
1130 | "observing check_place for activation of \ | |
1131 | borrow_index: {:?}", | |
1132 | activating | |
1133 | ); | |
0531ce1d XL |
1134 | } |
1135 | Read(..) | Write(..) => {} | |
ff7c6d11 XL |
1136 | } |
1137 | ||
0bf4aa26 | 1138 | error_reported = true; |
ff7c6d11 XL |
1139 | match kind { |
1140 | WriteKind::MutableBorrow(bk) => { | |
5099ac24 FG |
1141 | let err = |
1142 | this.report_conflicting_borrow(location, place_span, bk, borrow); | |
1143 | this.buffer_error(err); | |
ff7c6d11 | 1144 | } |
dfeec247 XL |
1145 | WriteKind::StorageDeadOrDrop => this |
1146 | .report_borrowed_value_does_not_live_long_enough( | |
48663c56 | 1147 | location, |
ff7c6d11 | 1148 | borrow, |
94b46f34 | 1149 | place_span, |
dfeec247 XL |
1150 | Some(kind), |
1151 | ), | |
ff7c6d11 | 1152 | WriteKind::Mutate => { |
48663c56 | 1153 | this.report_illegal_mutation_of_borrowed(location, place_span, borrow) |
ff7c6d11 XL |
1154 | } |
1155 | WriteKind::Move => { | |
48663c56 | 1156 | this.report_move_out_while_borrowed(location, place_span, borrow) |
ff7c6d11 XL |
1157 | } |
1158 | } | |
1159 | Control::Break | |
1160 | } | |
1161 | }, | |
1162 | ); | |
1163 | ||
1164 | error_reported | |
1165 | } | |
1166 | ||
1167 | fn mutate_place( | |
1168 | &mut self, | |
48663c56 | 1169 | location: Location, |
ba9703b0 | 1170 | place_span: (Place<'tcx>, Span), |
0bf4aa26 | 1171 | kind: AccessDepth, |
dc9dc135 | 1172 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1173 | ) { |
5099ac24 FG |
1174 | // Write of P[i] or *P requires P init'd. |
1175 | self.check_if_assigned_path_is_moved(location, place_span, flow_state); | |
ff7c6d11 | 1176 | |
94222f64 | 1177 | // Special case: you can assign an immutable local variable |
b7449926 XL |
1178 | // (e.g., `x = ...`) so long as it has never been initialized |
1179 | // before (at this point in the flow). | |
e74abb32 XL |
1180 | if let Some(local) = place_span.0.as_local() { |
1181 | if let Mutability::Not = self.body.local_decls[local].mutability { | |
b7449926 XL |
1182 | // check for reassignments to immutable local variables |
1183 | self.check_if_reassignment_to_immutable_state( | |
dfeec247 | 1184 | location, local, place_span, flow_state, |
b7449926 XL |
1185 | ); |
1186 | return; | |
1187 | } | |
1188 | } | |
1189 | ||
1190 | // Otherwise, use the normal access permission rules. | |
1191 | self.access_place( | |
48663c56 | 1192 | location, |
ff7c6d11 XL |
1193 | place_span, |
1194 | (kind, Write(WriteKind::Mutate)), | |
b7449926 | 1195 | LocalMutationIsAllowed::No, |
ff7c6d11 XL |
1196 | flow_state, |
1197 | ); | |
ff7c6d11 XL |
1198 | } |
1199 | ||
1200 | fn consume_rvalue( | |
1201 | &mut self, | |
48663c56 | 1202 | location: Location, |
416331ca | 1203 | (rvalue, span): (&'cx Rvalue<'tcx>, Span), |
dc9dc135 | 1204 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 XL |
1205 | ) { |
1206 | match *rvalue { | |
ba9703b0 | 1207 | Rvalue::Ref(_ /*rgn*/, bk, place) => { |
ff7c6d11 | 1208 | let access_kind = match bk { |
0bf4aa26 XL |
1209 | BorrowKind::Shallow => { |
1210 | (Shallow(Some(ArtificialField::ShallowBorrow)), Read(ReadKind::Borrow(bk))) | |
dfeec247 | 1211 | } |
ff7c6d11 | 1212 | BorrowKind::Shared => (Deep, Read(ReadKind::Borrow(bk))), |
2c00a5a8 | 1213 | BorrowKind::Unique | BorrowKind::Mut { .. } => { |
ff7c6d11 | 1214 | let wk = WriteKind::MutableBorrow(bk); |
48663c56 | 1215 | if allow_two_phase_borrow(bk) { |
ff7c6d11 XL |
1216 | (Deep, Reservation(wk)) |
1217 | } else { | |
1218 | (Deep, Write(wk)) | |
1219 | } | |
1220 | } | |
1221 | }; | |
1222 | ||
1223 | self.access_place( | |
48663c56 | 1224 | location, |
ff7c6d11 XL |
1225 | (place, span), |
1226 | access_kind, | |
1227 | LocalMutationIsAllowed::No, | |
1228 | flow_state, | |
1229 | ); | |
1230 | ||
0bf4aa26 XL |
1231 | let action = if bk == BorrowKind::Shallow { |
1232 | InitializationRequiringAction::MatchOn | |
1233 | } else { | |
1234 | InitializationRequiringAction::Borrow | |
1235 | }; | |
1236 | ||
83c7162d | 1237 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1238 | location, |
0bf4aa26 | 1239 | action, |
416331ca | 1240 | (place.as_ref(), span), |
ff7c6d11 XL |
1241 | flow_state, |
1242 | ); | |
1243 | } | |
1244 | ||
ba9703b0 | 1245 | Rvalue::AddressOf(mutability, place) => { |
dfeec247 XL |
1246 | let access_kind = match mutability { |
1247 | Mutability::Mut => ( | |
1248 | Deep, | |
1249 | Write(WriteKind::MutableBorrow(BorrowKind::Mut { | |
1250 | allow_two_phase_borrow: false, | |
1251 | })), | |
1252 | ), | |
1253 | Mutability::Not => (Deep, Read(ReadKind::Borrow(BorrowKind::Shared))), | |
1254 | }; | |
1255 | ||
1256 | self.access_place( | |
1257 | location, | |
1258 | (place, span), | |
1259 | access_kind, | |
1260 | LocalMutationIsAllowed::No, | |
1261 | flow_state, | |
1262 | ); | |
1263 | ||
1264 | self.check_if_path_or_subpath_is_moved( | |
1265 | location, | |
1266 | InitializationRequiringAction::Borrow, | |
1267 | (place.as_ref(), span), | |
1268 | flow_state, | |
1269 | ); | |
1270 | } | |
1271 | ||
f9f354fc XL |
1272 | Rvalue::ThreadLocalRef(_) => {} |
1273 | ||
ff7c6d11 XL |
1274 | Rvalue::Use(ref operand) |
1275 | | Rvalue::Repeat(ref operand, _) | |
1276 | | Rvalue::UnaryOp(_ /*un_op*/, ref operand) | |
c295e0f8 XL |
1277 | | Rvalue::Cast(_ /*cast_kind*/, ref operand, _ /*ty*/) |
1278 | | Rvalue::ShallowInitBox(ref operand, _ /*ty*/) => { | |
48663c56 | 1279 | self.consume_operand(location, (operand, span), flow_state) |
ff7c6d11 XL |
1280 | } |
1281 | ||
ba9703b0 | 1282 | Rvalue::Len(place) | Rvalue::Discriminant(place) => { |
ff7c6d11 | 1283 | let af = match *rvalue { |
0731742a XL |
1284 | Rvalue::Len(..) => Some(ArtificialField::ArrayLength), |
1285 | Rvalue::Discriminant(..) => None, | |
ff7c6d11 XL |
1286 | _ => unreachable!(), |
1287 | }; | |
1288 | self.access_place( | |
48663c56 | 1289 | location, |
ff7c6d11 | 1290 | (place, span), |
0731742a | 1291 | (Shallow(af), Read(ReadKind::Copy)), |
ff7c6d11 XL |
1292 | LocalMutationIsAllowed::No, |
1293 | flow_state, | |
1294 | ); | |
83c7162d | 1295 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1296 | location, |
ff7c6d11 | 1297 | InitializationRequiringAction::Use, |
416331ca | 1298 | (place.as_ref(), span), |
ff7c6d11 XL |
1299 | flow_state, |
1300 | ); | |
1301 | } | |
1302 | ||
6a06907d XL |
1303 | Rvalue::BinaryOp(_bin_op, box (ref operand1, ref operand2)) |
1304 | | Rvalue::CheckedBinaryOp(_bin_op, box (ref operand1, ref operand2)) => { | |
48663c56 XL |
1305 | self.consume_operand(location, (operand1, span), flow_state); |
1306 | self.consume_operand(location, (operand2, span), flow_state); | |
ff7c6d11 XL |
1307 | } |
1308 | ||
1309 | Rvalue::NullaryOp(_op, _ty) => { | |
1310 | // nullary ops take no dynamic input; no borrowck effect. | |
ff7c6d11 XL |
1311 | } |
1312 | ||
83c7162d XL |
1313 | Rvalue::Aggregate(ref aggregate_kind, ref operands) => { |
1314 | // We need to report back the list of mutable upvars that were | |
1315 | // moved into the closure and subsequently used by the closure, | |
1316 | // in order to populate our used_mut set. | |
8faf50e0 | 1317 | match **aggregate_kind { |
dfeec247 XL |
1318 | AggregateKind::Closure(def_id, _) | AggregateKind::Generator(def_id, _, _) => { |
1319 | let BorrowCheckResult { used_mut_upvars, .. } = | |
f9f354fc | 1320 | self.infcx.tcx.mir_borrowck(def_id.expect_local()); |
8faf50e0 XL |
1321 | debug!("{:?} used_mut_upvars={:?}", def_id, used_mut_upvars); |
1322 | for field in used_mut_upvars { | |
48663c56 | 1323 | self.propagate_closure_used_mut_upvar(&operands[field.index()]); |
83c7162d XL |
1324 | } |
1325 | } | |
8faf50e0 XL |
1326 | AggregateKind::Adt(..) |
1327 | | AggregateKind::Array(..) | |
1328 | | AggregateKind::Tuple { .. } => (), | |
83c7162d XL |
1329 | } |
1330 | ||
1331 | for operand in operands { | |
48663c56 XL |
1332 | self.consume_operand(location, (operand, span), flow_state); |
1333 | } | |
1334 | } | |
1335 | } | |
1336 | } | |
1337 | ||
1338 | fn propagate_closure_used_mut_upvar(&mut self, operand: &Operand<'tcx>) { | |
ba9703b0 | 1339 | let propagate_closure_used_mut_place = |this: &mut Self, place: Place<'tcx>| { |
5869c6ff XL |
1340 | // We have three possibilities here: |
1341 | // a. We are modifying something through a mut-ref | |
1342 | // b. We are modifying something that is local to our parent | |
1343 | // c. Current body is a nested closure, and we are modifying path starting from | |
1344 | // a Place captured by our parent closure. | |
1345 | ||
1346 | // Handle (c), the path being modified is exactly the path captured by our parent | |
1347 | if let Some(field) = this.is_upvar_field_projection(place.as_ref()) { | |
1348 | this.used_mut_upvars.push(field); | |
1349 | return; | |
1350 | } | |
1351 | ||
1352 | for (place_ref, proj) in place.iter_projections().rev() { | |
1353 | // Handle (a) | |
1354 | if proj == ProjectionElem::Deref { | |
1355 | match place_ref.ty(this.body(), this.infcx.tcx).ty.kind() { | |
1356 | // We aren't modifying a variable directly | |
1357 | ty::Ref(_, _, hir::Mutability::Mut) => return, | |
1358 | ||
1359 | _ => {} | |
1360 | } | |
1361 | } | |
1362 | ||
1363 | // Handle (c) | |
1364 | if let Some(field) = this.is_upvar_field_projection(place_ref) { | |
416331ca | 1365 | this.used_mut_upvars.push(field); |
5869c6ff | 1366 | return; |
48663c56 | 1367 | } |
48663c56 | 1368 | } |
5869c6ff XL |
1369 | |
1370 | // Handle(b) | |
1371 | this.used_mut.insert(place.local); | |
48663c56 XL |
1372 | }; |
1373 | ||
1374 | // This relies on the current way that by-value | |
1375 | // captures of a closure are copied/moved directly | |
1376 | // when generating MIR. | |
1377 | match *operand { | |
ba9703b0 | 1378 | Operand::Move(place) | Operand::Copy(place) => { |
e74abb32 | 1379 | match place.as_local() { |
60c5eb7d | 1380 | Some(local) if !self.body.local_decls[local].is_user_variable() => { |
e74abb32 XL |
1381 | if self.body.local_decls[local].ty.is_mutable_ptr() { |
1382 | // The variable will be marked as mutable by the borrow. | |
1383 | return; | |
1384 | } | |
1385 | // This is an edge case where we have a `move` closure | |
1386 | // inside a non-move closure, and the inner closure | |
1387 | // contains a mutation: | |
1388 | // | |
1389 | // let mut i = 0; | |
1390 | // || { move || { i += 1; }; }; | |
1391 | // | |
1392 | // In this case our usual strategy of assuming that the | |
1393 | // variable will be captured by mutable reference is | |
1394 | // wrong, since `i` can be copied into the inner | |
1395 | // closure from a shared reference. | |
1396 | // | |
1397 | // As such we have to search for the local that this | |
1398 | // capture comes from and mark it as being used as mut. | |
1399 | ||
1400 | let temp_mpi = self.move_data.rev_lookup.find_local(local); | |
1401 | let init = if let [init_index] = *self.move_data.init_path_map[temp_mpi] { | |
1402 | &self.move_data.inits[init_index] | |
1403 | } else { | |
1404 | bug!("temporary should be initialized exactly once") | |
1405 | }; | |
48663c56 | 1406 | |
5099ac24 FG |
1407 | let InitLocation::Statement(loc) = init.location else { |
1408 | bug!("temporary initialized in arguments") | |
e74abb32 | 1409 | }; |
48663c56 | 1410 | |
60c5eb7d XL |
1411 | let body = self.body; |
1412 | let bbd = &body[loc.block]; | |
e74abb32 XL |
1413 | let stmt = &bbd.statements[loc.statement_index]; |
1414 | debug!("temporary assigned in: stmt={:?}", stmt); | |
48663c56 | 1415 | |
ba9703b0 | 1416 | if let StatementKind::Assign(box (_, Rvalue::Ref(_, _, source))) = stmt.kind |
e74abb32 XL |
1417 | { |
1418 | propagate_closure_used_mut_place(self, source); | |
1419 | } else { | |
1420 | bug!( | |
1421 | "closures should only capture user variables \ | |
1422 | or references to user variables" | |
1423 | ); | |
1424 | } | |
1425 | } | |
1426 | _ => propagate_closure_used_mut_place(self, place), | |
83c7162d XL |
1427 | } |
1428 | } | |
48663c56 | 1429 | Operand::Constant(..) => {} |
ff7c6d11 XL |
1430 | } |
1431 | } | |
1432 | ||
1433 | fn consume_operand( | |
1434 | &mut self, | |
48663c56 | 1435 | location: Location, |
416331ca | 1436 | (operand, span): (&'cx Operand<'tcx>, Span), |
dc9dc135 | 1437 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 XL |
1438 | ) { |
1439 | match *operand { | |
ba9703b0 | 1440 | Operand::Copy(place) => { |
ff7c6d11 XL |
1441 | // copy of place: check if this is "copy of frozen path" |
1442 | // (FIXME: see check_loans.rs) | |
1443 | self.access_place( | |
48663c56 | 1444 | location, |
ff7c6d11 XL |
1445 | (place, span), |
1446 | (Deep, Read(ReadKind::Copy)), | |
1447 | LocalMutationIsAllowed::No, | |
1448 | flow_state, | |
1449 | ); | |
1450 | ||
1451 | // Finally, check if path was already moved. | |
83c7162d | 1452 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1453 | location, |
ff7c6d11 | 1454 | InitializationRequiringAction::Use, |
416331ca | 1455 | (place.as_ref(), span), |
ff7c6d11 XL |
1456 | flow_state, |
1457 | ); | |
1458 | } | |
ba9703b0 | 1459 | Operand::Move(place) => { |
ff7c6d11 XL |
1460 | // move of place: check if this is move of already borrowed path |
1461 | self.access_place( | |
48663c56 | 1462 | location, |
ff7c6d11 XL |
1463 | (place, span), |
1464 | (Deep, Write(WriteKind::Move)), | |
1465 | LocalMutationIsAllowed::Yes, | |
1466 | flow_state, | |
1467 | ); | |
1468 | ||
1469 | // Finally, check if path was already moved. | |
83c7162d | 1470 | self.check_if_path_or_subpath_is_moved( |
48663c56 | 1471 | location, |
ff7c6d11 | 1472 | InitializationRequiringAction::Use, |
416331ca | 1473 | (place.as_ref(), span), |
ff7c6d11 XL |
1474 | flow_state, |
1475 | ); | |
1476 | } | |
1477 | Operand::Constant(_) => {} | |
1478 | } | |
1479 | } | |
1480 | ||
0bf4aa26 | 1481 | /// Checks whether a borrow of this place is invalidated when the function |
ff7c6d11 XL |
1482 | /// exits |
1483 | fn check_for_invalidation_at_exit( | |
1484 | &mut self, | |
48663c56 | 1485 | location: Location, |
ff7c6d11 XL |
1486 | borrow: &BorrowData<'tcx>, |
1487 | span: Span, | |
ff7c6d11 XL |
1488 | ) { |
1489 | debug!("check_for_invalidation_at_exit({:?})", borrow); | |
ba9703b0 | 1490 | let place = borrow.borrowed_place; |
74b04a01 | 1491 | let mut root_place = PlaceRef { local: place.local, projection: &[] }; |
ff7c6d11 XL |
1492 | |
1493 | // FIXME(nll-rfc#40): do more precise destructor tracking here. For now | |
1494 | // we just know that all locals are dropped at function exit (otherwise | |
1495 | // we'll have a memory leak) and assume that all statics have a destructor. | |
1496 | // | |
1497 | // FIXME: allow thread-locals to borrow other thread locals? | |
416331ca | 1498 | |
dfeec247 | 1499 | let (might_be_alive, will_be_dropped) = |
74b04a01 | 1500 | if self.body.local_decls[root_place.local].is_ref_to_thread_local() { |
dfeec247 XL |
1501 | // Thread-locals might be dropped after the function exits |
1502 | // We have to dereference the outer reference because | |
1503 | // borrows don't conflict behind shared references. | |
74b04a01 | 1504 | root_place.projection = DEREF_PROJECTION; |
dfeec247 XL |
1505 | (true, true) |
1506 | } else { | |
1507 | (false, self.locals_are_invalidated_at_exit) | |
1508 | }; | |
ff7c6d11 XL |
1509 | |
1510 | if !will_be_dropped { | |
dfeec247 | 1511 | debug!("place_is_invalidated_at_exit({:?}) - won't be dropped", place); |
ff7c6d11 XL |
1512 | return; |
1513 | } | |
1514 | ||
ff7c6d11 XL |
1515 | let sd = if might_be_alive { Deep } else { Shallow(None) }; |
1516 | ||
0bf4aa26 XL |
1517 | if places_conflict::borrow_conflicts_with_place( |
1518 | self.infcx.tcx, | |
60c5eb7d | 1519 | &self.body, |
0bf4aa26 XL |
1520 | place, |
1521 | borrow.kind, | |
1522 | root_place, | |
0731742a XL |
1523 | sd, |
1524 | places_conflict::PlaceConflictBias::Overlap, | |
0bf4aa26 | 1525 | ) { |
ff7c6d11 XL |
1526 | debug!("check_for_invalidation_at_exit({:?}): INVALID", place); |
1527 | // FIXME: should be talking about the region lifetime instead | |
1528 | // of just a span here. | |
0bf4aa26 | 1529 | let span = self.infcx.tcx.sess.source_map().end_point(span); |
ff7c6d11 | 1530 | self.report_borrowed_value_does_not_live_long_enough( |
48663c56 | 1531 | location, |
ff7c6d11 | 1532 | borrow, |
94b46f34 XL |
1533 | (place, span), |
1534 | None, | |
ff7c6d11 XL |
1535 | ) |
1536 | } | |
1537 | } | |
1538 | ||
2c00a5a8 | 1539 | /// Reports an error if this is a borrow of local data. |
dfeec247 | 1540 | /// This is called for all Yield expressions on movable generators |
0531ce1d | 1541 | fn check_for_local_borrow(&mut self, borrow: &BorrowData<'tcx>, yield_span: Span) { |
2c00a5a8 XL |
1542 | debug!("check_for_local_borrow({:?})", borrow); |
1543 | ||
ba9703b0 | 1544 | if borrow_of_local_data(borrow.borrowed_place) { |
416331ca | 1545 | let err = self.cannot_borrow_across_generator_yield( |
dfeec247 XL |
1546 | self.retrieve_borrow_spans(borrow).var_or_use(), |
1547 | yield_span, | |
1548 | ); | |
8faf50e0 | 1549 | |
5099ac24 | 1550 | self.buffer_error(err); |
2c00a5a8 XL |
1551 | } |
1552 | } | |
1553 | ||
dc9dc135 | 1554 | fn check_activations(&mut self, location: Location, span: Span, flow_state: &Flows<'cx, 'tcx>) { |
ff7c6d11 XL |
1555 | // Two-phase borrow support: For each activation that is newly |
1556 | // generated at this statement, check if it interferes with | |
1557 | // another borrow. | |
83c7162d XL |
1558 | let borrow_set = self.borrow_set.clone(); |
1559 | for &borrow_index in borrow_set.activations_at_location(location) { | |
1560 | let borrow = &borrow_set[borrow_index]; | |
1561 | ||
1562 | // only mutable borrows should be 2-phase | |
1563 | assert!(match borrow.kind { | |
0bf4aa26 | 1564 | BorrowKind::Shared | BorrowKind::Shallow => false, |
83c7162d XL |
1565 | BorrowKind::Unique | BorrowKind::Mut { .. } => true, |
1566 | }); | |
1567 | ||
1568 | self.access_place( | |
48663c56 | 1569 | location, |
ba9703b0 | 1570 | (borrow.borrowed_place, span), |
dfeec247 | 1571 | (Deep, Activation(WriteKind::MutableBorrow(borrow.kind), borrow_index)), |
83c7162d XL |
1572 | LocalMutationIsAllowed::No, |
1573 | flow_state, | |
1574 | ); | |
1575 | // We do not need to call `check_if_path_or_subpath_is_moved` | |
1576 | // again, as we already called it when we made the | |
1577 | // initial reservation. | |
1578 | } | |
ff7c6d11 | 1579 | } |
ff7c6d11 | 1580 | |
ff7c6d11 XL |
1581 | fn check_if_reassignment_to_immutable_state( |
1582 | &mut self, | |
48663c56 | 1583 | location: Location, |
b7449926 | 1584 | local: Local, |
ba9703b0 | 1585 | place_span: (Place<'tcx>, Span), |
dc9dc135 | 1586 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1587 | ) { |
b7449926 XL |
1588 | debug!("check_if_reassignment_to_immutable_state({:?})", local); |
1589 | ||
1590 | // Check if any of the initializiations of `local` have happened yet: | |
0bf4aa26 | 1591 | if let Some(init_index) = self.is_local_ever_initialized(local, flow_state) { |
b7449926 XL |
1592 | // And, if so, report an error. |
1593 | let init = &self.move_data.inits[init_index]; | |
dc9dc135 | 1594 | let span = init.span(&self.body); |
dfeec247 | 1595 | self.report_illegal_reassignment(location, place_span, span, place_span.0); |
ff7c6d11 XL |
1596 | } |
1597 | } | |
1598 | ||
83c7162d | 1599 | fn check_if_full_path_is_moved( |
ff7c6d11 | 1600 | &mut self, |
48663c56 | 1601 | location: Location, |
ff7c6d11 | 1602 | desired_action: InitializationRequiringAction, |
74b04a01 | 1603 | place_span: (PlaceRef<'tcx>, Span), |
dc9dc135 | 1604 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1605 | ) { |
ff7c6d11 | 1606 | let maybe_uninits = &flow_state.uninits; |
ff7c6d11 XL |
1607 | |
1608 | // Bad scenarios: | |
1609 | // | |
1610 | // 1. Move of `a.b.c`, use of `a.b.c` | |
1611 | // 2. Move of `a.b.c`, use of `a.b.c.d` (without first reinitializing `a.b.c.d`) | |
83c7162d | 1612 | // 3. Uninitialized `(a.b.c: &_)`, use of `*a.b.c`; note that with |
ff7c6d11 XL |
1613 | // partial initialization support, one might have `a.x` |
1614 | // initialized but not `a.b`. | |
1615 | // | |
1616 | // OK scenarios: | |
1617 | // | |
83c7162d XL |
1618 | // 4. Move of `a.b.c`, use of `a.b.d` |
1619 | // 5. Uninitialized `a.x`, initialized `a.b`, use of `a.b` | |
1620 | // 6. Copied `(a.b: &_)`, use of `*(a.b).c`; note that `a.b` | |
ff7c6d11 | 1621 | // must have been initialized for the use to be sound. |
83c7162d | 1622 | // 7. Move of `a.b.c` then reinit of `a.b.c.d`, use of `a.b.c.d` |
ff7c6d11 XL |
1623 | |
1624 | // The dataflow tracks shallow prefixes distinctly (that is, | |
1625 | // field-accesses on P distinctly from P itself), in order to | |
1626 | // track substructure initialization separately from the whole | |
1627 | // structure. | |
1628 | // | |
1629 | // E.g., when looking at (*a.b.c).d, if the closest prefix for | |
1630 | // which we have a MovePath is `a.b`, then that means that the | |
1631 | // initialization state of `a.b` is all we need to inspect to | |
1632 | // know if `a.b.c` is valid (and from that we infer that the | |
1633 | // dereference and `.d` access is also valid, since we assume | |
94222f64 | 1634 | // `a.b.c` is assigned a reference to an initialized and |
ff7c6d11 XL |
1635 | // well-formed record structure.) |
1636 | ||
1637 | // Therefore, if we seek out the *closest* prefix for which we | |
1638 | // have a MovePath, that should capture the initialization | |
1639 | // state for the place scenario. | |
1640 | // | |
83c7162d | 1641 | // This code covers scenarios 1, 2, and 3. |
ff7c6d11 | 1642 | |
b7449926 | 1643 | debug!("check_if_full_path_is_moved place: {:?}", place_span.0); |
dfeec247 XL |
1644 | let (prefix, mpi) = self.move_path_closest_to(place_span.0); |
1645 | if maybe_uninits.contains(mpi) { | |
1646 | self.report_use_of_moved_or_uninitialized( | |
1647 | location, | |
1648 | desired_action, | |
1649 | (prefix, place_span.0, place_span.1), | |
1650 | mpi, | |
1651 | ); | |
1652 | } // Only query longest prefix with a MovePath, not further | |
1653 | // ancestors; dataflow recurs on children when parents | |
1654 | // move (to support partial (re)inits). | |
1655 | // | |
1656 | // (I.e., querying parents breaks scenario 7; but may want | |
1657 | // to do such a query based on partial-init feature-gate.) | |
83c7162d XL |
1658 | } |
1659 | ||
60c5eb7d XL |
1660 | /// Subslices correspond to multiple move paths, so we iterate through the |
1661 | /// elements of the base array. For each element we check | |
1662 | /// | |
1663 | /// * Does this element overlap with our slice. | |
1664 | /// * Is any part of it uninitialized. | |
1665 | fn check_if_subslice_element_is_moved( | |
1666 | &mut self, | |
1667 | location: Location, | |
1668 | desired_action: InitializationRequiringAction, | |
74b04a01 XL |
1669 | place_span: (PlaceRef<'tcx>, Span), |
1670 | maybe_uninits: &BitSet<MovePathIndex>, | |
1b1a35ee XL |
1671 | from: u64, |
1672 | to: u64, | |
60c5eb7d XL |
1673 | ) { |
1674 | if let Some(mpi) = self.move_path_for_place(place_span.0) { | |
74b04a01 XL |
1675 | let move_paths = &self.move_data.move_paths; |
1676 | ||
1677 | let root_path = &move_paths[mpi]; | |
1678 | for (child_mpi, child_move_path) in root_path.children(move_paths) { | |
1679 | let last_proj = child_move_path.place.projection.last().unwrap(); | |
60c5eb7d XL |
1680 | if let ProjectionElem::ConstantIndex { offset, from_end, .. } = last_proj { |
1681 | debug_assert!(!from_end, "Array constant indexing shouldn't be `from_end`."); | |
1682 | ||
1683 | if (from..to).contains(offset) { | |
74b04a01 XL |
1684 | let uninit_child = |
1685 | self.move_data.find_in_move_path_or_its_descendants(child_mpi, |mpi| { | |
1686 | maybe_uninits.contains(mpi) | |
1687 | }); | |
1688 | ||
1689 | if let Some(uninit_child) = uninit_child { | |
60c5eb7d XL |
1690 | self.report_use_of_moved_or_uninitialized( |
1691 | location, | |
1692 | desired_action, | |
1693 | (place_span.0, place_span.0, place_span.1), | |
1694 | uninit_child, | |
1695 | ); | |
1696 | return; // don't bother finding other problems. | |
1697 | } | |
1698 | } | |
1699 | } | |
60c5eb7d XL |
1700 | } |
1701 | } | |
1702 | } | |
1703 | ||
83c7162d XL |
1704 | fn check_if_path_or_subpath_is_moved( |
1705 | &mut self, | |
48663c56 | 1706 | location: Location, |
83c7162d | 1707 | desired_action: InitializationRequiringAction, |
74b04a01 | 1708 | place_span: (PlaceRef<'tcx>, Span), |
dc9dc135 | 1709 | flow_state: &Flows<'cx, 'tcx>, |
83c7162d | 1710 | ) { |
83c7162d | 1711 | let maybe_uninits = &flow_state.uninits; |
83c7162d XL |
1712 | |
1713 | // Bad scenarios: | |
1714 | // | |
1715 | // 1. Move of `a.b.c`, use of `a` or `a.b` | |
1716 | // partial initialization support, one might have `a.x` | |
1717 | // initialized but not `a.b`. | |
1718 | // 2. All bad scenarios from `check_if_full_path_is_moved` | |
1719 | // | |
1720 | // OK scenarios: | |
1721 | // | |
1722 | // 3. Move of `a.b.c`, use of `a.b.d` | |
1723 | // 4. Uninitialized `a.x`, initialized `a.b`, use of `a.b` | |
1724 | // 5. Copied `(a.b: &_)`, use of `*(a.b).c`; note that `a.b` | |
1725 | // must have been initialized for the use to be sound. | |
1726 | // 6. Move of `a.b.c` then reinit of `a.b.c.d`, use of `a.b.c.d` | |
1727 | ||
48663c56 | 1728 | self.check_if_full_path_is_moved(location, desired_action, place_span, flow_state); |
ff7c6d11 | 1729 | |
5869c6ff XL |
1730 | if let Some((place_base, ProjectionElem::Subslice { from, to, from_end: false })) = |
1731 | place_span.0.last_projection() | |
dfeec247 | 1732 | { |
5869c6ff | 1733 | let place_ty = place_base.ty(self.body(), self.infcx.tcx); |
1b1a35ee | 1734 | if let ty::Array(..) = place_ty.ty.kind() { |
60c5eb7d XL |
1735 | self.check_if_subslice_element_is_moved( |
1736 | location, | |
1737 | desired_action, | |
5869c6ff | 1738 | (place_base, place_span.1), |
60c5eb7d | 1739 | maybe_uninits, |
5869c6ff XL |
1740 | from, |
1741 | to, | |
60c5eb7d XL |
1742 | ); |
1743 | return; | |
1744 | } | |
1745 | } | |
1746 | ||
ff7c6d11 XL |
1747 | // A move of any shallow suffix of `place` also interferes |
1748 | // with an attempt to use `place`. This is scenario 3 above. | |
1749 | // | |
1750 | // (Distinct from handling of scenarios 1+2+4 above because | |
1751 | // `place` does not interfere with suffixes of its prefixes, | |
0731742a | 1752 | // e.g., `a.b.c` does not interfere with `a.b.d`) |
83c7162d XL |
1753 | // |
1754 | // This code covers scenario 1. | |
ff7c6d11 | 1755 | |
b7449926 XL |
1756 | debug!("check_if_path_or_subpath_is_moved place: {:?}", place_span.0); |
1757 | if let Some(mpi) = self.move_path_for_place(place_span.0) { | |
74b04a01 XL |
1758 | let uninit_mpi = self |
1759 | .move_data | |
1760 | .find_in_move_path_or_its_descendants(mpi, |mpi| maybe_uninits.contains(mpi)); | |
1761 | ||
1762 | if let Some(uninit_mpi) = uninit_mpi { | |
ff7c6d11 | 1763 | self.report_use_of_moved_or_uninitialized( |
48663c56 | 1764 | location, |
ff7c6d11 | 1765 | desired_action, |
0bf4aa26 | 1766 | (place_span.0, place_span.0, place_span.1), |
74b04a01 | 1767 | uninit_mpi, |
ff7c6d11 XL |
1768 | ); |
1769 | return; // don't bother finding other problems. | |
1770 | } | |
1771 | } | |
1772 | } | |
1773 | ||
1774 | /// Currently MoveData does not store entries for all places in | |
1775 | /// the input MIR. For example it will currently filter out | |
1776 | /// places that are Copy; thus we do not track places of shared | |
1777 | /// reference type. This routine will walk up a place along its | |
1778 | /// prefixes, searching for a foundational place that *is* | |
1779 | /// tracked in the MoveData. | |
1780 | /// | |
1781 | /// An Err result includes a tag indicated why the search failed. | |
0531ce1d | 1782 | /// Currently this can only occur if the place is built off of a |
ff7c6d11 | 1783 | /// static variable, as we do not track those in the MoveData. |
74b04a01 | 1784 | fn move_path_closest_to(&mut self, place: PlaceRef<'tcx>) -> (PlaceRef<'tcx>, MovePathIndex) { |
60c5eb7d | 1785 | match self.move_data.rev_lookup.find(place) { |
dfeec247 XL |
1786 | LookupResult::Parent(Some(mpi)) | LookupResult::Exact(mpi) => { |
1787 | (self.move_data.move_paths[mpi].place.as_ref(), mpi) | |
1788 | } | |
1789 | LookupResult::Parent(None) => panic!("should have move path for every Local"), | |
ff7c6d11 XL |
1790 | } |
1791 | } | |
1792 | ||
74b04a01 | 1793 | fn move_path_for_place(&mut self, place: PlaceRef<'tcx>) -> Option<MovePathIndex> { |
ff7c6d11 XL |
1794 | // If returns None, then there is no move path corresponding |
1795 | // to a direct owner of `place` (which means there is nothing | |
1796 | // that borrowck tracks for its analysis). | |
1797 | ||
1798 | match self.move_data.rev_lookup.find(place) { | |
1799 | LookupResult::Parent(_) => None, | |
1800 | LookupResult::Exact(mpi) => Some(mpi), | |
1801 | } | |
1802 | } | |
1803 | ||
1804 | fn check_if_assigned_path_is_moved( | |
1805 | &mut self, | |
48663c56 | 1806 | location: Location, |
ba9703b0 | 1807 | (place, span): (Place<'tcx>, Span), |
dc9dc135 | 1808 | flow_state: &Flows<'cx, 'tcx>, |
ff7c6d11 | 1809 | ) { |
83c7162d | 1810 | debug!("check_if_assigned_path_is_moved place: {:?}", place); |
416331ca XL |
1811 | |
1812 | // None case => assigning to `x` does not require `x` be initialized. | |
5869c6ff | 1813 | for (place_base, elem) in place.iter_projections().rev() { |
e1599b0c | 1814 | match elem { |
416331ca XL |
1815 | ProjectionElem::Index(_/*operand*/) | |
1816 | ProjectionElem::ConstantIndex { .. } | | |
1817 | // assigning to P[i] requires P to be valid. | |
1818 | ProjectionElem::Downcast(_/*adt_def*/, _/*variant_idx*/) => | |
1819 | // assigning to (P->variant) is okay if assigning to `P` is okay | |
1820 | // | |
94222f64 | 1821 | // FIXME: is this true even if P is an adt with a dtor? |
416331ca XL |
1822 | { } |
1823 | ||
1824 | // assigning to (*P) requires P to be initialized | |
1825 | ProjectionElem::Deref => { | |
1826 | self.check_if_full_path_is_moved( | |
1827 | location, InitializationRequiringAction::Use, | |
5869c6ff | 1828 | (place_base, span), flow_state); |
416331ca XL |
1829 | // (base initialized; no need to |
1830 | // recur further) | |
ff7c6d11 XL |
1831 | break; |
1832 | } | |
416331ca XL |
1833 | |
1834 | ProjectionElem::Subslice { .. } => { | |
1835 | panic!("we don't allow assignments to subslices, location: {:?}", | |
1836 | location); | |
1837 | } | |
1838 | ||
1839 | ProjectionElem::Field(..) => { | |
1840 | // if type of `P` has a dtor, then | |
1841 | // assigning to `P.f` requires `P` itself | |
1842 | // be already initialized | |
1843 | let tcx = self.infcx.tcx; | |
5869c6ff | 1844 | let base_ty = place_base.ty(self.body(), tcx).ty; |
1b1a35ee | 1845 | match base_ty.kind() { |
416331ca XL |
1846 | ty::Adt(def, _) if def.has_dtor(tcx) => { |
1847 | self.check_if_path_or_subpath_is_moved( | |
1848 | location, InitializationRequiringAction::Assignment, | |
5869c6ff | 1849 | (place_base, span), flow_state); |
416331ca | 1850 | |
83c7162d XL |
1851 | // (base initialized; no need to |
1852 | // recur further) | |
1853 | break; | |
1854 | } | |
1855 | ||
416331ca XL |
1856 | // Once `let s; s.x = V; read(s.x);`, |
1857 | // is allowed, remove this match arm. | |
1858 | ty::Adt(..) | ty::Tuple(..) => { | |
5869c6ff | 1859 | check_parent_of_field(self, location, place_base, span, flow_state); |
416331ca | 1860 | |
dfeec247 XL |
1861 | // rust-lang/rust#21232, #54499, #54986: during period where we reject |
1862 | // partial initialization, do not complain about unnecessary `mut` on | |
1863 | // an attempt to do a partial initialization. | |
1864 | self.used_mut.insert(place.local); | |
ff7c6d11 | 1865 | } |
ff7c6d11 | 1866 | |
416331ca XL |
1867 | _ => {} |
1868 | } | |
ff7c6d11 XL |
1869 | } |
1870 | } | |
1871 | } | |
ff7c6d11 | 1872 | |
dc9dc135 XL |
1873 | fn check_parent_of_field<'cx, 'tcx>( |
1874 | this: &mut MirBorrowckCtxt<'cx, 'tcx>, | |
48663c56 | 1875 | location: Location, |
74b04a01 | 1876 | base: PlaceRef<'tcx>, |
a1dfa0c6 | 1877 | span: Span, |
dc9dc135 | 1878 | flow_state: &Flows<'cx, 'tcx>, |
a1dfa0c6 | 1879 | ) { |
0bf4aa26 XL |
1880 | // rust-lang/rust#21232: Until Rust allows reads from the |
1881 | // initialized parts of partially initialized structs, we | |
1882 | // will, starting with the 2018 edition, reject attempts | |
1883 | // to write to structs that are not fully initialized. | |
1884 | // | |
1885 | // In other words, *until* we allow this: | |
1886 | // | |
1887 | // 1. `let mut s; s.x = Val; read(s.x);` | |
1888 | // | |
1889 | // we will for now disallow this: | |
1890 | // | |
1891 | // 2. `let mut s; s.x = Val;` | |
1892 | // | |
1893 | // and also this: | |
1894 | // | |
1895 | // 3. `let mut s = ...; drop(s); s.x=Val;` | |
1896 | // | |
1897 | // This does not use check_if_path_or_subpath_is_moved, | |
1898 | // because we want to *allow* reinitializations of fields: | |
0731742a | 1899 | // e.g., want to allow |
0bf4aa26 XL |
1900 | // |
1901 | // `let mut s = ...; drop(s.x); s.x=Val;` | |
1902 | // | |
1903 | // This does not use check_if_full_path_is_moved on | |
1904 | // `base`, because that would report an error about the | |
1905 | // `base` as a whole, but in this scenario we *really* | |
1906 | // want to report an error about the actual thing that was | |
1907 | // moved, which may be some prefix of `base`. | |
1908 | ||
1909 | // Shallow so that we'll stop at any dereference; we'll | |
1910 | // report errors about issues with such bases elsewhere. | |
1911 | let maybe_uninits = &flow_state.uninits; | |
1912 | ||
1913 | // Find the shortest uninitialized prefix you can reach | |
1914 | // without going over a Deref. | |
1915 | let mut shortest_uninit_seen = None; | |
1916 | for prefix in this.prefixes(base, PrefixSet::Shallow) { | |
1917 | let mpi = match this.move_path_for_place(prefix) { | |
dfeec247 XL |
1918 | Some(mpi) => mpi, |
1919 | None => continue, | |
0bf4aa26 XL |
1920 | }; |
1921 | ||
1922 | if maybe_uninits.contains(mpi) { | |
dfeec247 XL |
1923 | debug!( |
1924 | "check_parent_of_field updating shortest_uninit_seen from {:?} to {:?}", | |
1925 | shortest_uninit_seen, | |
1926 | Some((prefix, mpi)) | |
1927 | ); | |
0bf4aa26 XL |
1928 | shortest_uninit_seen = Some((prefix, mpi)); |
1929 | } else { | |
1930 | debug!("check_parent_of_field {:?} is definitely initialized", (prefix, mpi)); | |
1931 | } | |
1932 | } | |
1933 | ||
1934 | if let Some((prefix, mpi)) = shortest_uninit_seen { | |
94222f64 XL |
1935 | // Check for a reassignment into an uninitialized field of a union (for example, |
1936 | // after a move out). In this case, do not report an error here. There is an | |
a1dfa0c6 XL |
1937 | // exception, if this is the first assignment into the union (that is, there is |
1938 | // no move out from an earlier location) then this is an attempt at initialization | |
1939 | // of the union - we should error in that case. | |
1940 | let tcx = this.infcx.tcx; | |
17df50a5 XL |
1941 | if base.ty(this.body(), tcx).ty.is_union() { |
1942 | if this.move_data.path_map[mpi].iter().any(|moi| { | |
1943 | this.move_data.moves[*moi].source.is_predecessor_of(location, this.body) | |
1944 | }) { | |
1945 | return; | |
a1dfa0c6 XL |
1946 | } |
1947 | } | |
1948 | ||
0bf4aa26 | 1949 | this.report_use_of_moved_or_uninitialized( |
48663c56 | 1950 | location, |
0bf4aa26 XL |
1951 | InitializationRequiringAction::PartialAssignment, |
1952 | (prefix, base, span), | |
1953 | mpi, | |
1954 | ); | |
1955 | } | |
1956 | } | |
1957 | } | |
8faf50e0 | 1958 | |
9fa01778 | 1959 | /// Checks the permissions for the given place and read or write kind |
ff7c6d11 | 1960 | /// |
9fa01778 | 1961 | /// Returns `true` if an error is reported. |
ff7c6d11 | 1962 | fn check_access_permissions( |
83c7162d | 1963 | &mut self, |
ba9703b0 | 1964 | (place, span): (Place<'tcx>, Span), |
ff7c6d11 XL |
1965 | kind: ReadOrWrite, |
1966 | is_local_mutation_allowed: LocalMutationIsAllowed, | |
dc9dc135 | 1967 | flow_state: &Flows<'cx, 'tcx>, |
8faf50e0 | 1968 | location: Location, |
ff7c6d11 XL |
1969 | ) -> bool { |
1970 | debug!( | |
0bf4aa26 | 1971 | "check_access_permissions({:?}, {:?}, is_local_mutation_allowed: {:?})", |
0531ce1d | 1972 | place, kind, is_local_mutation_allowed |
ff7c6d11 | 1973 | ); |
94b46f34 | 1974 | |
94b46f34 XL |
1975 | let error_access; |
1976 | let the_place_err; | |
1977 | ||
ff7c6d11 | 1978 | match kind { |
ba9703b0 XL |
1979 | Reservation(WriteKind::MutableBorrow( |
1980 | borrow_kind @ (BorrowKind::Unique | BorrowKind::Mut { .. }), | |
1981 | )) | |
1982 | | Write(WriteKind::MutableBorrow( | |
1983 | borrow_kind @ (BorrowKind::Unique | BorrowKind::Mut { .. }), | |
1984 | )) => { | |
94b46f34 XL |
1985 | let is_local_mutation_allowed = match borrow_kind { |
1986 | BorrowKind::Unique => LocalMutationIsAllowed::Yes, | |
1987 | BorrowKind::Mut { .. } => is_local_mutation_allowed, | |
0bf4aa26 | 1988 | BorrowKind::Shared | BorrowKind::Shallow => unreachable!(), |
94b46f34 | 1989 | }; |
416331ca | 1990 | match self.is_mutable(place.as_ref(), is_local_mutation_allowed) { |
94b46f34 XL |
1991 | Ok(root_place) => { |
1992 | self.add_used_mut(root_place, flow_state); | |
1993 | return false; | |
1994 | } | |
83c7162d | 1995 | Err(place_err) => { |
94b46f34 XL |
1996 | error_access = AccessKind::MutableBorrow; |
1997 | the_place_err = place_err; | |
ff7c6d11 XL |
1998 | } |
1999 | } | |
83c7162d | 2000 | } |
ff7c6d11 | 2001 | Reservation(WriteKind::Mutate) | Write(WriteKind::Mutate) => { |
416331ca | 2002 | match self.is_mutable(place.as_ref(), is_local_mutation_allowed) { |
94b46f34 XL |
2003 | Ok(root_place) => { |
2004 | self.add_used_mut(root_place, flow_state); | |
2005 | return false; | |
2006 | } | |
83c7162d | 2007 | Err(place_err) => { |
94b46f34 XL |
2008 | error_access = AccessKind::Mutate; |
2009 | the_place_err = place_err; | |
ff7c6d11 | 2010 | } |
ff7c6d11 XL |
2011 | } |
2012 | } | |
94b46f34 | 2013 | |
ba9703b0 XL |
2014 | Reservation( |
2015 | WriteKind::Move | |
2016 | | WriteKind::StorageDeadOrDrop | |
2017 | | WriteKind::MutableBorrow(BorrowKind::Shared) | |
2018 | | WriteKind::MutableBorrow(BorrowKind::Shallow), | |
2019 | ) | |
2020 | | Write( | |
2021 | WriteKind::Move | |
2022 | | WriteKind::StorageDeadOrDrop | |
2023 | | WriteKind::MutableBorrow(BorrowKind::Shared) | |
2024 | | WriteKind::MutableBorrow(BorrowKind::Shallow), | |
2025 | ) => { | |
5099ac24 FG |
2026 | if self.is_mutable(place.as_ref(), is_local_mutation_allowed).is_err() |
2027 | && !self.has_buffered_errors() | |
2028 | { | |
e74abb32 XL |
2029 | // rust-lang/rust#46908: In pure NLL mode this code path should be |
2030 | // unreachable, but we use `delay_span_bug` because we can hit this when | |
2031 | // dereferencing a non-Copy raw pointer *and* have `-Ztreat-err-as-bug` | |
2032 | // enabled. We don't want to ICE for that case, as other errors will have | |
2033 | // been emitted (#52262). | |
dfeec247 XL |
2034 | self.infcx.tcx.sess.delay_span_bug( |
2035 | span, | |
2036 | &format!( | |
2037 | "Accessing `{:?}` with the kind `{:?}` shouldn't be possible", | |
2038 | place, kind, | |
2039 | ), | |
2040 | ); | |
ff7c6d11 | 2041 | } |
94b46f34 XL |
2042 | return false; |
2043 | } | |
2044 | Activation(..) => { | |
2045 | // permission checks are done at Reservation point. | |
2046 | return false; | |
ff7c6d11 | 2047 | } |
ba9703b0 XL |
2048 | Read( |
2049 | ReadKind::Borrow( | |
2050 | BorrowKind::Unique | |
2051 | | BorrowKind::Mut { .. } | |
2052 | | BorrowKind::Shared | |
2053 | | BorrowKind::Shallow, | |
2054 | ) | |
2055 | | ReadKind::Copy, | |
2056 | ) => { | |
94b46f34 XL |
2057 | // Access authorized |
2058 | return false; | |
2059 | } | |
ff7c6d11 XL |
2060 | } |
2061 | ||
60c5eb7d XL |
2062 | // rust-lang/rust#21232, #54986: during period where we reject |
2063 | // partial initialization, do not complain about mutability | |
2064 | // errors except for actual mutation (as opposed to an attempt | |
2065 | // to do a partial initialization). | |
dfeec247 XL |
2066 | let previously_initialized = |
2067 | self.is_local_ever_initialized(place.local, flow_state).is_some(); | |
60c5eb7d | 2068 | |
94b46f34 | 2069 | // at this point, we have set up the error reporting state. |
60c5eb7d | 2070 | if previously_initialized { |
dfeec247 | 2071 | self.report_mutability_error(place, span, the_place_err, error_access, location); |
0bf4aa26 XL |
2072 | true |
2073 | } else { | |
2074 | false | |
60c5eb7d | 2075 | } |
0bf4aa26 XL |
2076 | } |
2077 | ||
dc9dc135 XL |
2078 | fn is_local_ever_initialized( |
2079 | &self, | |
2080 | local: Local, | |
2081 | flow_state: &Flows<'cx, 'tcx>, | |
2082 | ) -> Option<InitIndex> { | |
0bf4aa26 XL |
2083 | let mpi = self.move_data.rev_lookup.find_local(local); |
2084 | let ii = &self.move_data.init_path_map[mpi]; | |
2085 | for &index in ii { | |
2086 | if flow_state.ever_inits.contains(index) { | |
2087 | return Some(index); | |
2088 | } | |
2089 | } | |
2090 | None | |
ff7c6d11 XL |
2091 | } |
2092 | ||
83c7162d | 2093 | /// Adds the place into the used mutable variables set |
74b04a01 | 2094 | fn add_used_mut(&mut self, root_place: RootPlace<'tcx>, flow_state: &Flows<'cx, 'tcx>) { |
83c7162d | 2095 | match root_place { |
dfeec247 | 2096 | RootPlace { place_local: local, place_projection: [], is_local_mutation_allowed } => { |
0bf4aa26 XL |
2097 | // If the local may have been initialized, and it is now currently being |
2098 | // mutated, then it is justified to be annotated with the `mut` | |
2099 | // keyword, since the mutation may be a possible reassignment. | |
dfeec247 | 2100 | if is_local_mutation_allowed != LocalMutationIsAllowed::Yes |
74b04a01 | 2101 | && self.is_local_ever_initialized(local, flow_state).is_some() |
0bf4aa26 | 2102 | { |
74b04a01 | 2103 | self.used_mut.insert(local); |
83c7162d XL |
2104 | } |
2105 | } | |
8faf50e0 | 2106 | RootPlace { |
dfeec247 | 2107 | place_local: _, |
416331ca | 2108 | place_projection: _, |
8faf50e0 XL |
2109 | is_local_mutation_allowed: LocalMutationIsAllowed::Yes, |
2110 | } => {} | |
83c7162d | 2111 | RootPlace { |
dfeec247 | 2112 | place_local, |
e1599b0c | 2113 | place_projection: place_projection @ [.., _], |
83c7162d XL |
2114 | is_local_mutation_allowed: _, |
2115 | } => { | |
416331ca | 2116 | if let Some(field) = self.is_upvar_field_projection(PlaceRef { |
dfeec247 XL |
2117 | local: place_local, |
2118 | projection: place_projection, | |
416331ca | 2119 | }) { |
83c7162d XL |
2120 | self.used_mut_upvars.push(field); |
2121 | } | |
2122 | } | |
83c7162d XL |
2123 | } |
2124 | } | |
2125 | ||
0bf4aa26 | 2126 | /// Whether this value can be written or borrowed mutably. |
83c7162d | 2127 | /// Returns the root place if the place passed in is a projection. |
74b04a01 | 2128 | fn is_mutable( |
ff7c6d11 | 2129 | &self, |
74b04a01 | 2130 | place: PlaceRef<'tcx>, |
ff7c6d11 | 2131 | is_local_mutation_allowed: LocalMutationIsAllowed, |
74b04a01 | 2132 | ) -> Result<RootPlace<'tcx>, PlaceRef<'tcx>> { |
5869c6ff XL |
2133 | debug!("is_mutable: place={:?}, is_local...={:?}", place, is_local_mutation_allowed); |
2134 | match place.last_projection() { | |
2135 | None => { | |
2136 | let local = &self.body.local_decls[place.local]; | |
ff7c6d11 XL |
2137 | match local.mutability { |
2138 | Mutability::Not => match is_local_mutation_allowed { | |
8faf50e0 | 2139 | LocalMutationIsAllowed::Yes => Ok(RootPlace { |
dfeec247 | 2140 | place_local: place.local, |
416331ca | 2141 | place_projection: place.projection, |
8faf50e0 XL |
2142 | is_local_mutation_allowed: LocalMutationIsAllowed::Yes, |
2143 | }), | |
2144 | LocalMutationIsAllowed::ExceptUpvars => Ok(RootPlace { | |
dfeec247 | 2145 | place_local: place.local, |
416331ca | 2146 | place_projection: place.projection, |
8faf50e0 XL |
2147 | is_local_mutation_allowed: LocalMutationIsAllowed::ExceptUpvars, |
2148 | }), | |
ff7c6d11 XL |
2149 | LocalMutationIsAllowed::No => Err(place), |
2150 | }, | |
8faf50e0 | 2151 | Mutability::Mut => Ok(RootPlace { |
dfeec247 | 2152 | place_local: place.local, |
416331ca | 2153 | place_projection: place.projection, |
8faf50e0 XL |
2154 | is_local_mutation_allowed, |
2155 | }), | |
ff7c6d11 XL |
2156 | } |
2157 | } | |
5869c6ff | 2158 | Some((place_base, elem)) => { |
e1599b0c | 2159 | match elem { |
ff7c6d11 | 2160 | ProjectionElem::Deref => { |
5869c6ff | 2161 | let base_ty = place_base.ty(self.body(), self.infcx.tcx).ty; |
ff7c6d11 XL |
2162 | |
2163 | // Check the kind of deref to decide | |
1b1a35ee | 2164 | match base_ty.kind() { |
b7449926 | 2165 | ty::Ref(_, _, mutbl) => { |
94b46f34 | 2166 | match mutbl { |
ff7c6d11 | 2167 | // Shared borrowed data is never mutable |
dfeec247 | 2168 | hir::Mutability::Not => Err(place), |
ff7c6d11 XL |
2169 | // Mutably borrowed data is mutable, but only if we have a |
2170 | // unique path to the `&mut` | |
dfeec247 | 2171 | hir::Mutability::Mut => { |
48663c56 | 2172 | let mode = match self.is_upvar_field_projection(place) { |
dfeec247 | 2173 | Some(field) if self.upvars[field.index()].by_ref => { |
ff7c6d11 XL |
2174 | is_local_mutation_allowed |
2175 | } | |
2176 | _ => LocalMutationIsAllowed::Yes, | |
2177 | }; | |
2178 | ||
5869c6ff | 2179 | self.is_mutable(place_base, mode) |
ff7c6d11 XL |
2180 | } |
2181 | } | |
2182 | } | |
b7449926 | 2183 | ty::RawPtr(tnm) => { |
ff7c6d11 XL |
2184 | match tnm.mutbl { |
2185 | // `*const` raw pointers are not mutable | |
dfeec247 | 2186 | hir::Mutability::Not => Err(place), |
83c7162d XL |
2187 | // `*mut` raw pointers are always mutable, regardless of |
2188 | // context. The users have to check by themselves. | |
dfeec247 XL |
2189 | hir::Mutability::Mut => Ok(RootPlace { |
2190 | place_local: place.local, | |
2191 | place_projection: place.projection, | |
2192 | is_local_mutation_allowed, | |
2193 | }), | |
ff7c6d11 XL |
2194 | } |
2195 | } | |
2196 | // `Box<T>` owns its content, so mutable if its location is mutable | |
5869c6ff XL |
2197 | _ if base_ty.is_box() => { |
2198 | self.is_mutable(place_base, is_local_mutation_allowed) | |
2199 | } | |
ff7c6d11 XL |
2200 | // Deref should only be for reference, pointers or boxes |
2201 | _ => bug!("Deref of unexpected type: {:?}", base_ty), | |
2202 | } | |
2203 | } | |
2204 | // All other projections are owned by their base path, so mutable if | |
2205 | // base path is mutable | |
2206 | ProjectionElem::Field(..) | |
2207 | | ProjectionElem::Index(..) | |
2208 | | ProjectionElem::ConstantIndex { .. } | |
2209 | | ProjectionElem::Subslice { .. } | |
2210 | | ProjectionElem::Downcast(..) => { | |
48663c56 | 2211 | let upvar_field_projection = self.is_upvar_field_projection(place); |
8faf50e0 | 2212 | if let Some(field) = upvar_field_projection { |
48663c56 | 2213 | let upvar = &self.upvars[field.index()]; |
ff7c6d11 | 2214 | debug!( |
5869c6ff XL |
2215 | "is_mutable: upvar.mutability={:?} local_mutation_is_allowed={:?} \ |
2216 | place={:?}, place_base={:?}", | |
2217 | upvar, is_local_mutation_allowed, place, place_base | |
ff7c6d11 | 2218 | ); |
5869c6ff | 2219 | match (upvar.place.mutability, is_local_mutation_allowed) { |
ba9703b0 XL |
2220 | ( |
2221 | Mutability::Not, | |
2222 | LocalMutationIsAllowed::No | |
2223 | | LocalMutationIsAllowed::ExceptUpvars, | |
2224 | ) => Err(place), | |
ff7c6d11 XL |
2225 | (Mutability::Not, LocalMutationIsAllowed::Yes) |
2226 | | (Mutability::Mut, _) => { | |
83c7162d XL |
2227 | // Subtle: this is an upvar |
2228 | // reference, so it looks like | |
2229 | // `self.foo` -- we want to double | |
48663c56 | 2230 | // check that the location `*self` |
83c7162d XL |
2231 | // is mutable (i.e., this is not a |
2232 | // `Fn` closure). But if that | |
2233 | // check succeeds, we want to | |
2234 | // *blame* the mutability on | |
2235 | // `place` (that is, | |
2236 | // `self.foo`). This is used to | |
2237 | // propagate the info about | |
2238 | // whether mutability declarations | |
2239 | // are used outwards, so that we register | |
2240 | // the outer variable as mutable. Otherwise a | |
2241 | // test like this fails to record the `mut` | |
2242 | // as needed: | |
2243 | // | |
2244 | // ``` | |
2245 | // fn foo<F: FnOnce()>(_f: F) { } | |
2246 | // fn main() { | |
2247 | // let var = Vec::new(); | |
2248 | // foo(move || { | |
2249 | // var.push(1); | |
2250 | // }); | |
2251 | // } | |
2252 | // ``` | |
5869c6ff XL |
2253 | let _ = |
2254 | self.is_mutable(place_base, is_local_mutation_allowed)?; | |
8faf50e0 | 2255 | Ok(RootPlace { |
dfeec247 | 2256 | place_local: place.local, |
416331ca | 2257 | place_projection: place.projection, |
8faf50e0 XL |
2258 | is_local_mutation_allowed, |
2259 | }) | |
ff7c6d11 XL |
2260 | } |
2261 | } | |
2262 | } else { | |
5869c6ff | 2263 | self.is_mutable(place_base, is_local_mutation_allowed) |
ff7c6d11 XL |
2264 | } |
2265 | } | |
2266 | } | |
2267 | } | |
2268 | } | |
2269 | } | |
48663c56 XL |
2270 | |
2271 | /// If `place` is a field projection, and the field is being projected from a closure type, | |
2272 | /// then returns the index of the field being projected. Note that this closure will always | |
2273 | /// be `self` in the current MIR, because that is the only time we directly access the fields | |
2274 | /// of a closure type. | |
c295e0f8 | 2275 | fn is_upvar_field_projection(&self, place_ref: PlaceRef<'tcx>) -> Option<Field> { |
f035d41b | 2276 | path_utils::is_upvar_field_projection(self.infcx.tcx, &self.upvars, place_ref, self.body()) |
48663c56 | 2277 | } |
ff7c6d11 XL |
2278 | } |
2279 | ||
5099ac24 FG |
2280 | mod error { |
2281 | use super::*; | |
2282 | ||
2283 | pub struct BorrowckErrors<'tcx> { | |
2284 | /// This field keeps track of move errors that are to be reported for given move indices. | |
2285 | /// | |
2286 | /// There are situations where many errors can be reported for a single move out (see #53807) | |
2287 | /// and we want only the best of those errors. | |
2288 | /// | |
2289 | /// The `report_use_of_moved_or_uninitialized` function checks this map and replaces the | |
2290 | /// diagnostic (if there is one) if the `Place` of the error being reported is a prefix of the | |
2291 | /// `Place` of the previous most diagnostic. This happens instead of buffering the error. Once | |
2292 | /// all move errors have been reported, any diagnostics in this map are added to the buffer | |
2293 | /// to be emitted. | |
2294 | /// | |
2295 | /// `BTreeMap` is used to preserve the order of insertions when iterating. This is necessary | |
2296 | /// when errors in the map are being re-added to the error buffer so that errors with the | |
2297 | /// same primary span come out in a consistent order. | |
2298 | buffered_move_errors: | |
2299 | BTreeMap<Vec<MoveOutIndex>, (PlaceRef<'tcx>, DiagnosticBuilder<'tcx>)>, | |
2300 | /// Errors to be reported buffer | |
2301 | buffered: Vec<Diagnostic>, | |
2302 | /// Set to Some if we emit an error during borrowck | |
2303 | tainted_by_errors: Option<ErrorReported>, | |
2304 | } | |
2305 | ||
2306 | impl BorrowckErrors<'_> { | |
2307 | pub fn new() -> Self { | |
2308 | BorrowckErrors { | |
2309 | buffered_move_errors: BTreeMap::new(), | |
2310 | buffered: Default::default(), | |
2311 | tainted_by_errors: None, | |
2312 | } | |
2313 | } | |
2314 | ||
2315 | pub fn buffer_error(&mut self, t: DiagnosticBuilder<'_>) { | |
2316 | self.tainted_by_errors = Some(ErrorReported {}); | |
2317 | t.buffer(&mut self.buffered); | |
2318 | } | |
2319 | ||
2320 | // For diagnostics we must not set `tainted_by_errors`. | |
2321 | pub fn buffer_non_error_diag(&mut self, t: DiagnosticBuilder<'_>) { | |
2322 | t.buffer(&mut self.buffered); | |
2323 | } | |
2324 | ||
2325 | pub fn set_tainted_by_errors(&mut self) { | |
2326 | self.tainted_by_errors = Some(ErrorReported {}); | |
2327 | } | |
2328 | } | |
2329 | ||
2330 | impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { | |
2331 | pub fn buffer_error(&mut self, t: DiagnosticBuilder<'_>) { | |
2332 | self.errors.buffer_error(t); | |
2333 | } | |
2334 | ||
2335 | pub fn buffer_non_error_diag(&mut self, t: DiagnosticBuilder<'_>) { | |
2336 | self.errors.buffer_non_error_diag(t); | |
2337 | } | |
2338 | ||
2339 | pub fn buffer_move_error( | |
2340 | &mut self, | |
2341 | move_out_indices: Vec<MoveOutIndex>, | |
2342 | place_and_err: (PlaceRef<'tcx>, DiagnosticBuilder<'tcx>), | |
2343 | ) -> bool { | |
2344 | if let Some((_, mut diag)) = | |
2345 | self.errors.buffered_move_errors.insert(move_out_indices, place_and_err) | |
2346 | { | |
2347 | // Cancel the old diagnostic so we don't ICE | |
2348 | diag.cancel(); | |
2349 | false | |
2350 | } else { | |
2351 | true | |
2352 | } | |
2353 | } | |
2354 | ||
2355 | pub fn emit_errors(&mut self) -> Option<ErrorReported> { | |
2356 | // Buffer any move errors that we collected and de-duplicated. | |
2357 | for (_, (_, diag)) in std::mem::take(&mut self.errors.buffered_move_errors) { | |
2358 | // We have already set tainted for this error, so just buffer it. | |
2359 | diag.buffer(&mut self.errors.buffered); | |
2360 | } | |
2361 | ||
2362 | if !self.errors.buffered.is_empty() { | |
2363 | self.errors.buffered.sort_by_key(|diag| diag.sort_span); | |
2364 | ||
2365 | for diag in self.errors.buffered.drain(..) { | |
2366 | self.infcx.tcx.sess.diagnostic().emit_diagnostic(&diag); | |
2367 | } | |
2368 | } | |
2369 | ||
2370 | self.errors.tainted_by_errors | |
2371 | } | |
2372 | ||
2373 | pub fn has_buffered_errors(&self) -> bool { | |
2374 | self.errors.buffered.is_empty() | |
2375 | } | |
2376 | ||
2377 | pub fn has_move_error( | |
2378 | &self, | |
2379 | move_out_indices: &[MoveOutIndex], | |
2380 | ) -> Option<&(PlaceRef<'tcx>, DiagnosticBuilder<'cx>)> { | |
2381 | self.errors.buffered_move_errors.get(move_out_indices) | |
2382 | } | |
2383 | } | |
2384 | } | |
2385 | ||
ff7c6d11 XL |
2386 | /// The degree of overlap between 2 places for borrow-checking. |
2387 | enum Overlap { | |
2388 | /// The places might partially overlap - in this case, we give | |
2389 | /// up and say that they might conflict. This occurs when | |
2390 | /// different fields of a union are borrowed. For example, | |
2391 | /// if `u` is a union, we have no way of telling how disjoint | |
2392 | /// `u.a.x` and `a.b.y` are. | |
2393 | Arbitrary, | |
2394 | /// The places have the same type, and are either completely disjoint | |
0731742a | 2395 | /// or equal - i.e., they can't "partially" overlap as can occur with |
ff7c6d11 XL |
2396 | /// unions. This is the "base case" on which we recur for extensions |
2397 | /// of the place. | |
2398 | EqualOrDisjoint, | |
2399 | /// The places are disjoint, so we know all extensions of them | |
2400 | /// will also be disjoint. | |
2401 | Disjoint, | |
2402 | } |