rustc_mir_transform/
validate.rs

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1//! Validates the MIR to ensure that invariants are upheld.
2
3use rustc_abi::{ExternAbi, FIRST_VARIANT, Size};
4use rustc_attr_parsing::InlineAttr;
5use rustc_data_structures::fx::{FxHashMap, FxHashSet};
6use rustc_hir::LangItem;
7use rustc_index::IndexVec;
8use rustc_index::bit_set::DenseBitSet;
9use rustc_infer::infer::TyCtxtInferExt;
10use rustc_infer::traits::{Obligation, ObligationCause};
11use rustc_middle::mir::coverage::CoverageKind;
12use rustc_middle::mir::visit::{NonUseContext, PlaceContext, Visitor};
13use rustc_middle::mir::*;
14use rustc_middle::ty::adjustment::PointerCoercion;
15use rustc_middle::ty::{
16    self, CoroutineArgsExt, InstanceKind, ScalarInt, Ty, TyCtxt, TypeVisitableExt, Variance,
17};
18use rustc_middle::{bug, span_bug};
19use rustc_trait_selection::traits::ObligationCtxt;
20use rustc_type_ir::Upcast;
21
22use crate::util::{self, is_within_packed};
23
24#[derive(Copy, Clone, Debug, PartialEq, Eq)]
25enum EdgeKind {
26    Unwind,
27    Normal,
28}
29
30pub(super) struct Validator {
31    /// Describes at which point in the pipeline this validation is happening.
32    pub when: String,
33}
34
35impl<'tcx> crate::MirPass<'tcx> for Validator {
36    fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
37        // FIXME(JakobDegen): These bodies never instantiated in codegend anyway, so it's not
38        // terribly important that they pass the validator. However, I think other passes might
39        // still see them, in which case they might be surprised. It would probably be better if we
40        // didn't put this through the MIR pipeline at all.
41        if matches!(body.source.instance, InstanceKind::Intrinsic(..) | InstanceKind::Virtual(..)) {
42            return;
43        }
44        let def_id = body.source.def_id();
45        let typing_env = body.typing_env(tcx);
46        let can_unwind = if body.phase <= MirPhase::Runtime(RuntimePhase::Initial) {
47            // In this case `AbortUnwindingCalls` haven't yet been executed.
48            true
49        } else if !tcx.def_kind(def_id).is_fn_like() {
50            true
51        } else {
52            let body_ty = tcx.type_of(def_id).skip_binder();
53            let body_abi = match body_ty.kind() {
54                ty::FnDef(..) => body_ty.fn_sig(tcx).abi(),
55                ty::Closure(..) => ExternAbi::RustCall,
56                ty::CoroutineClosure(..) => ExternAbi::RustCall,
57                ty::Coroutine(..) => ExternAbi::Rust,
58                // No need to do MIR validation on error bodies
59                ty::Error(_) => return,
60                _ => span_bug!(body.span, "unexpected body ty: {body_ty:?}"),
61            };
62
63            ty::layout::fn_can_unwind(tcx, Some(def_id), body_abi)
64        };
65
66        let mut cfg_checker = CfgChecker {
67            when: &self.when,
68            body,
69            tcx,
70            unwind_edge_count: 0,
71            reachable_blocks: traversal::reachable_as_bitset(body),
72            value_cache: FxHashSet::default(),
73            can_unwind,
74        };
75        cfg_checker.visit_body(body);
76        cfg_checker.check_cleanup_control_flow();
77
78        // Also run the TypeChecker.
79        for (location, msg) in validate_types(tcx, typing_env, body, body) {
80            cfg_checker.fail(location, msg);
81        }
82
83        if let MirPhase::Runtime(_) = body.phase {
84            if let ty::InstanceKind::Item(_) = body.source.instance {
85                if body.has_free_regions() {
86                    cfg_checker.fail(
87                        Location::START,
88                        format!("Free regions in optimized {} MIR", body.phase.name()),
89                    );
90                }
91            }
92        }
93    }
94
95    fn is_required(&self) -> bool {
96        true
97    }
98}
99
100/// This checker covers basic properties of the control-flow graph, (dis)allowed statements and terminators.
101/// Everything checked here must be stable under substitution of generic parameters. In other words,
102/// this is about the *structure* of the MIR, not the *contents*.
103///
104/// Everything that depends on types, or otherwise can be affected by generic parameters,
105/// must be checked in `TypeChecker`.
106struct CfgChecker<'a, 'tcx> {
107    when: &'a str,
108    body: &'a Body<'tcx>,
109    tcx: TyCtxt<'tcx>,
110    unwind_edge_count: usize,
111    reachable_blocks: DenseBitSet<BasicBlock>,
112    value_cache: FxHashSet<u128>,
113    // If `false`, then the MIR must not contain `UnwindAction::Continue` or
114    // `TerminatorKind::Resume`.
115    can_unwind: bool,
116}
117
118impl<'a, 'tcx> CfgChecker<'a, 'tcx> {
119    #[track_caller]
120    fn fail(&self, location: Location, msg: impl AsRef<str>) {
121        // We might see broken MIR when other errors have already occurred.
122        assert!(
123            self.tcx.dcx().has_errors().is_some(),
124            "broken MIR in {:?} ({}) at {:?}:\n{}",
125            self.body.source.instance,
126            self.when,
127            location,
128            msg.as_ref(),
129        );
130    }
131
132    fn check_edge(&mut self, location: Location, bb: BasicBlock, edge_kind: EdgeKind) {
133        if bb == START_BLOCK {
134            self.fail(location, "start block must not have predecessors")
135        }
136        if let Some(bb) = self.body.basic_blocks.get(bb) {
137            let src = self.body.basic_blocks.get(location.block).unwrap();
138            match (src.is_cleanup, bb.is_cleanup, edge_kind) {
139                // Non-cleanup blocks can jump to non-cleanup blocks along non-unwind edges
140                (false, false, EdgeKind::Normal)
141                // Cleanup blocks can jump to cleanup blocks along non-unwind edges
142                | (true, true, EdgeKind::Normal) => {}
143                // Non-cleanup blocks can jump to cleanup blocks along unwind edges
144                (false, true, EdgeKind::Unwind) => {
145                    self.unwind_edge_count += 1;
146                }
147                // All other jumps are invalid
148                _ => {
149                    self.fail(
150                        location,
151                        format!(
152                            "{:?} edge to {:?} violates unwind invariants (cleanup {:?} -> {:?})",
153                            edge_kind,
154                            bb,
155                            src.is_cleanup,
156                            bb.is_cleanup,
157                        )
158                    )
159                }
160            }
161        } else {
162            self.fail(location, format!("encountered jump to invalid basic block {bb:?}"))
163        }
164    }
165
166    fn check_cleanup_control_flow(&self) {
167        if self.unwind_edge_count <= 1 {
168            return;
169        }
170        let doms = self.body.basic_blocks.dominators();
171        let mut post_contract_node = FxHashMap::default();
172        // Reusing the allocation across invocations of the closure
173        let mut dom_path = vec![];
174        let mut get_post_contract_node = |mut bb| {
175            let root = loop {
176                if let Some(root) = post_contract_node.get(&bb) {
177                    break *root;
178                }
179                let parent = doms.immediate_dominator(bb).unwrap();
180                dom_path.push(bb);
181                if !self.body.basic_blocks[parent].is_cleanup {
182                    break bb;
183                }
184                bb = parent;
185            };
186            for bb in dom_path.drain(..) {
187                post_contract_node.insert(bb, root);
188            }
189            root
190        };
191
192        let mut parent = IndexVec::from_elem(None, &self.body.basic_blocks);
193        for (bb, bb_data) in self.body.basic_blocks.iter_enumerated() {
194            if !bb_data.is_cleanup || !self.reachable_blocks.contains(bb) {
195                continue;
196            }
197            let bb = get_post_contract_node(bb);
198            for s in bb_data.terminator().successors() {
199                let s = get_post_contract_node(s);
200                if s == bb {
201                    continue;
202                }
203                let parent = &mut parent[bb];
204                match parent {
205                    None => {
206                        *parent = Some(s);
207                    }
208                    Some(e) if *e == s => (),
209                    Some(e) => self.fail(
210                        Location { block: bb, statement_index: 0 },
211                        format!(
212                            "Cleanup control flow violation: The blocks dominated by {:?} have edges to both {:?} and {:?}",
213                            bb,
214                            s,
215                            *e
216                        )
217                    ),
218                }
219            }
220        }
221
222        // Check for cycles
223        let mut stack = FxHashSet::default();
224        for i in 0..parent.len() {
225            let mut bb = BasicBlock::from_usize(i);
226            stack.clear();
227            stack.insert(bb);
228            loop {
229                let Some(parent) = parent[bb].take() else { break };
230                let no_cycle = stack.insert(parent);
231                if !no_cycle {
232                    self.fail(
233                        Location { block: bb, statement_index: 0 },
234                        format!(
235                            "Cleanup control flow violation: Cycle involving edge {bb:?} -> {parent:?}",
236                        ),
237                    );
238                    break;
239                }
240                bb = parent;
241            }
242        }
243    }
244
245    fn check_unwind_edge(&mut self, location: Location, unwind: UnwindAction) {
246        let is_cleanup = self.body.basic_blocks[location.block].is_cleanup;
247        match unwind {
248            UnwindAction::Cleanup(unwind) => {
249                if is_cleanup {
250                    self.fail(location, "`UnwindAction::Cleanup` in cleanup block");
251                }
252                self.check_edge(location, unwind, EdgeKind::Unwind);
253            }
254            UnwindAction::Continue => {
255                if is_cleanup {
256                    self.fail(location, "`UnwindAction::Continue` in cleanup block");
257                }
258
259                if !self.can_unwind {
260                    self.fail(location, "`UnwindAction::Continue` in no-unwind function");
261                }
262            }
263            UnwindAction::Terminate(UnwindTerminateReason::InCleanup) => {
264                if !is_cleanup {
265                    self.fail(
266                        location,
267                        "`UnwindAction::Terminate(InCleanup)` in a non-cleanup block",
268                    );
269                }
270            }
271            // These are allowed everywhere.
272            UnwindAction::Unreachable | UnwindAction::Terminate(UnwindTerminateReason::Abi) => (),
273        }
274    }
275
276    fn is_critical_call_edge(&self, target: Option<BasicBlock>, unwind: UnwindAction) -> bool {
277        let Some(target) = target else { return false };
278        matches!(unwind, UnwindAction::Cleanup(_) | UnwindAction::Terminate(_))
279            && self.body.basic_blocks.predecessors()[target].len() > 1
280    }
281}
282
283impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
284    fn visit_local(&mut self, local: Local, _context: PlaceContext, location: Location) {
285        if self.body.local_decls.get(local).is_none() {
286            self.fail(
287                location,
288                format!("local {local:?} has no corresponding declaration in `body.local_decls`"),
289            );
290        }
291    }
292
293    fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
294        match &statement.kind {
295            StatementKind::AscribeUserType(..) => {
296                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
297                    self.fail(
298                        location,
299                        "`AscribeUserType` should have been removed after drop lowering phase",
300                    );
301                }
302            }
303            StatementKind::FakeRead(..) => {
304                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
305                    self.fail(
306                        location,
307                        "`FakeRead` should have been removed after drop lowering phase",
308                    );
309                }
310            }
311            StatementKind::SetDiscriminant { .. } => {
312                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
313                    self.fail(location, "`SetDiscriminant`is not allowed until deaggregation");
314                }
315            }
316            StatementKind::Deinit(..) => {
317                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
318                    self.fail(location, "`Deinit`is not allowed until deaggregation");
319                }
320            }
321            StatementKind::Retag(kind, _) => {
322                // FIXME(JakobDegen) The validator should check that `self.body.phase <
323                // DropsLowered`. However, this causes ICEs with generation of drop shims, which
324                // seem to fail to set their `MirPhase` correctly.
325                if matches!(kind, RetagKind::TwoPhase) {
326                    self.fail(location, format!("explicit `{kind:?}` is forbidden"));
327                }
328            }
329            StatementKind::Coverage(kind) => {
330                if self.body.phase >= MirPhase::Analysis(AnalysisPhase::PostCleanup)
331                    && let CoverageKind::BlockMarker { .. } | CoverageKind::SpanMarker { .. } = kind
332                {
333                    self.fail(
334                        location,
335                        format!("{kind:?} should have been removed after analysis"),
336                    );
337                }
338            }
339            StatementKind::Assign(..)
340            | StatementKind::StorageLive(_)
341            | StatementKind::StorageDead(_)
342            | StatementKind::Intrinsic(_)
343            | StatementKind::ConstEvalCounter
344            | StatementKind::PlaceMention(..)
345            | StatementKind::BackwardIncompatibleDropHint { .. }
346            | StatementKind::Nop => {}
347        }
348
349        self.super_statement(statement, location);
350    }
351
352    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
353        match &terminator.kind {
354            TerminatorKind::Goto { target } => {
355                self.check_edge(location, *target, EdgeKind::Normal);
356            }
357            TerminatorKind::SwitchInt { targets, discr: _ } => {
358                for (_, target) in targets.iter() {
359                    self.check_edge(location, target, EdgeKind::Normal);
360                }
361                self.check_edge(location, targets.otherwise(), EdgeKind::Normal);
362
363                self.value_cache.clear();
364                self.value_cache.extend(targets.iter().map(|(value, _)| value));
365                let has_duplicates = targets.iter().len() != self.value_cache.len();
366                if has_duplicates {
367                    self.fail(
368                        location,
369                        format!(
370                            "duplicated values in `SwitchInt` terminator: {:?}",
371                            terminator.kind,
372                        ),
373                    );
374                }
375            }
376            TerminatorKind::Drop { target, unwind, .. } => {
377                self.check_edge(location, *target, EdgeKind::Normal);
378                self.check_unwind_edge(location, *unwind);
379            }
380            TerminatorKind::Call { func, args, .. }
381            | TerminatorKind::TailCall { func, args, .. } => {
382                // FIXME(explicit_tail_calls): refactor this & add tail-call specific checks
383                if let TerminatorKind::Call { target, unwind, destination, .. } = terminator.kind {
384                    if let Some(target) = target {
385                        self.check_edge(location, target, EdgeKind::Normal);
386                    }
387                    self.check_unwind_edge(location, unwind);
388
389                    // The code generation assumes that there are no critical call edges. The
390                    // assumption is used to simplify inserting code that should be executed along
391                    // the return edge from the call. FIXME(tmiasko): Since this is a strictly code
392                    // generation concern, the code generation should be responsible for handling
393                    // it.
394                    if self.body.phase >= MirPhase::Runtime(RuntimePhase::Optimized)
395                        && self.is_critical_call_edge(target, unwind)
396                    {
397                        self.fail(
398                            location,
399                            format!(
400                                "encountered critical edge in `Call` terminator {:?}",
401                                terminator.kind,
402                            ),
403                        );
404                    }
405
406                    // The call destination place and Operand::Move place used as an argument might
407                    // be passed by a reference to the callee. Consequently they cannot be packed.
408                    if is_within_packed(self.tcx, &self.body.local_decls, destination).is_some() {
409                        // This is bad! The callee will expect the memory to be aligned.
410                        self.fail(
411                            location,
412                            format!(
413                                "encountered packed place in `Call` terminator destination: {:?}",
414                                terminator.kind,
415                            ),
416                        );
417                    }
418                }
419
420                for arg in args {
421                    if let Operand::Move(place) = &arg.node {
422                        if is_within_packed(self.tcx, &self.body.local_decls, *place).is_some() {
423                            // This is bad! The callee will expect the memory to be aligned.
424                            self.fail(
425                                location,
426                                format!(
427                                    "encountered `Move` of a packed place in `Call` terminator: {:?}",
428                                    terminator.kind,
429                                ),
430                            );
431                        }
432                    }
433                }
434
435                if let ty::FnDef(did, ..) = func.ty(&self.body.local_decls, self.tcx).kind()
436                    && self.body.phase >= MirPhase::Runtime(RuntimePhase::Optimized)
437                    && matches!(self.tcx.codegen_fn_attrs(did).inline, InlineAttr::Force { .. })
438                {
439                    self.fail(location, "`#[rustc_force_inline]`-annotated function not inlined");
440                }
441            }
442            TerminatorKind::Assert { target, unwind, .. } => {
443                self.check_edge(location, *target, EdgeKind::Normal);
444                self.check_unwind_edge(location, *unwind);
445            }
446            TerminatorKind::Yield { resume, drop, .. } => {
447                if self.body.coroutine.is_none() {
448                    self.fail(location, "`Yield` cannot appear outside coroutine bodies");
449                }
450                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
451                    self.fail(location, "`Yield` should have been replaced by coroutine lowering");
452                }
453                self.check_edge(location, *resume, EdgeKind::Normal);
454                if let Some(drop) = drop {
455                    self.check_edge(location, *drop, EdgeKind::Normal);
456                }
457            }
458            TerminatorKind::FalseEdge { real_target, imaginary_target } => {
459                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
460                    self.fail(
461                        location,
462                        "`FalseEdge` should have been removed after drop elaboration",
463                    );
464                }
465                self.check_edge(location, *real_target, EdgeKind::Normal);
466                self.check_edge(location, *imaginary_target, EdgeKind::Normal);
467            }
468            TerminatorKind::FalseUnwind { real_target, unwind } => {
469                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
470                    self.fail(
471                        location,
472                        "`FalseUnwind` should have been removed after drop elaboration",
473                    );
474                }
475                self.check_edge(location, *real_target, EdgeKind::Normal);
476                self.check_unwind_edge(location, *unwind);
477            }
478            TerminatorKind::InlineAsm { targets, unwind, .. } => {
479                for &target in targets {
480                    self.check_edge(location, target, EdgeKind::Normal);
481                }
482                self.check_unwind_edge(location, *unwind);
483            }
484            TerminatorKind::CoroutineDrop => {
485                if self.body.coroutine.is_none() {
486                    self.fail(location, "`CoroutineDrop` cannot appear outside coroutine bodies");
487                }
488                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
489                    self.fail(
490                        location,
491                        "`CoroutineDrop` should have been replaced by coroutine lowering",
492                    );
493                }
494            }
495            TerminatorKind::UnwindResume => {
496                let bb = location.block;
497                if !self.body.basic_blocks[bb].is_cleanup {
498                    self.fail(location, "Cannot `UnwindResume` from non-cleanup basic block")
499                }
500                if !self.can_unwind {
501                    self.fail(location, "Cannot `UnwindResume` in a function that cannot unwind")
502                }
503            }
504            TerminatorKind::UnwindTerminate(_) => {
505                let bb = location.block;
506                if !self.body.basic_blocks[bb].is_cleanup {
507                    self.fail(location, "Cannot `UnwindTerminate` from non-cleanup basic block")
508                }
509            }
510            TerminatorKind::Return => {
511                let bb = location.block;
512                if self.body.basic_blocks[bb].is_cleanup {
513                    self.fail(location, "Cannot `Return` from cleanup basic block")
514                }
515            }
516            TerminatorKind::Unreachable => {}
517        }
518
519        self.super_terminator(terminator, location);
520    }
521
522    fn visit_source_scope(&mut self, scope: SourceScope) {
523        if self.body.source_scopes.get(scope).is_none() {
524            self.tcx.dcx().span_bug(
525                self.body.span,
526                format!(
527                    "broken MIR in {:?} ({}):\ninvalid source scope {:?}",
528                    self.body.source.instance, self.when, scope,
529                ),
530            );
531        }
532    }
533}
534
535/// A faster version of the validation pass that only checks those things which may break when
536/// instantiating any generic parameters.
537///
538/// `caller_body` is used to detect cycles in MIR inlining and MIR validation before
539/// `optimized_mir` is available.
540pub(super) fn validate_types<'tcx>(
541    tcx: TyCtxt<'tcx>,
542    typing_env: ty::TypingEnv<'tcx>,
543    body: &Body<'tcx>,
544    caller_body: &Body<'tcx>,
545) -> Vec<(Location, String)> {
546    let mut type_checker = TypeChecker { body, caller_body, tcx, typing_env, failures: Vec::new() };
547    type_checker.visit_body(body);
548    type_checker.failures
549}
550
551struct TypeChecker<'a, 'tcx> {
552    body: &'a Body<'tcx>,
553    caller_body: &'a Body<'tcx>,
554    tcx: TyCtxt<'tcx>,
555    typing_env: ty::TypingEnv<'tcx>,
556    failures: Vec<(Location, String)>,
557}
558
559impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
560    fn fail(&mut self, location: Location, msg: impl Into<String>) {
561        self.failures.push((location, msg.into()));
562    }
563
564    /// Check if src can be assigned into dest.
565    /// This is not precise, it will accept some incorrect assignments.
566    fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
567        // Fast path before we normalize.
568        if src == dest {
569            // Equal types, all is good.
570            return true;
571        }
572
573        // We sometimes have to use `defining_opaque_types` for subtyping
574        // to succeed here and figuring out how exactly that should work
575        // is annoying. It is harmless enough to just not validate anything
576        // in that case. We still check this after analysis as all opaque
577        // types have been revealed at this point.
578        if (src, dest).has_opaque_types() {
579            return true;
580        }
581
582        // After borrowck subtyping should be fully explicit via
583        // `Subtype` projections.
584        let variance = if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
585            Variance::Invariant
586        } else {
587            Variance::Covariant
588        };
589
590        crate::util::relate_types(self.tcx, self.typing_env, variance, src, dest)
591    }
592
593    /// Check that the given predicate definitely holds in the param-env of this MIR body.
594    fn predicate_must_hold_modulo_regions(
595        &self,
596        pred: impl Upcast<TyCtxt<'tcx>, ty::Predicate<'tcx>>,
597    ) -> bool {
598        let pred: ty::Predicate<'tcx> = pred.upcast(self.tcx);
599
600        // We sometimes have to use `defining_opaque_types` for predicates
601        // to succeed here and figuring out how exactly that should work
602        // is annoying. It is harmless enough to just not validate anything
603        // in that case. We still check this after analysis as all opaque
604        // types have been revealed at this point.
605        if pred.has_opaque_types() {
606            return true;
607        }
608
609        let (infcx, param_env) = self.tcx.infer_ctxt().build_with_typing_env(self.typing_env);
610        let ocx = ObligationCtxt::new(&infcx);
611        ocx.register_obligation(Obligation::new(
612            self.tcx,
613            ObligationCause::dummy(),
614            param_env,
615            pred,
616        ));
617        ocx.select_all_or_error().is_empty()
618    }
619}
620
621impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
622    fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
623        // This check is somewhat expensive, so only run it when -Zvalidate-mir is passed.
624        if self.tcx.sess.opts.unstable_opts.validate_mir
625            && self.body.phase < MirPhase::Runtime(RuntimePhase::Initial)
626        {
627            // `Operand::Copy` is only supposed to be used with `Copy` types.
628            if let Operand::Copy(place) = operand {
629                let ty = place.ty(&self.body.local_decls, self.tcx).ty;
630
631                if !self.tcx.type_is_copy_modulo_regions(self.typing_env, ty) {
632                    self.fail(location, format!("`Operand::Copy` with non-`Copy` type {ty}"));
633                }
634            }
635        }
636
637        self.super_operand(operand, location);
638    }
639
640    fn visit_projection_elem(
641        &mut self,
642        place_ref: PlaceRef<'tcx>,
643        elem: PlaceElem<'tcx>,
644        context: PlaceContext,
645        location: Location,
646    ) {
647        match elem {
648            ProjectionElem::OpaqueCast(ty)
649                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) =>
650            {
651                self.fail(
652                    location,
653                    format!("explicit opaque type cast to `{ty}` after `PostAnalysisNormalize`"),
654                )
655            }
656            ProjectionElem::Index(index) => {
657                let index_ty = self.body.local_decls[index].ty;
658                if index_ty != self.tcx.types.usize {
659                    self.fail(location, format!("bad index ({index_ty:?} != usize)"))
660                }
661            }
662            ProjectionElem::Deref
663                if self.body.phase >= MirPhase::Runtime(RuntimePhase::PostCleanup) =>
664            {
665                let base_ty = place_ref.ty(&self.body.local_decls, self.tcx).ty;
666
667                if base_ty.is_box() {
668                    self.fail(
669                        location,
670                        format!("{base_ty:?} dereferenced after ElaborateBoxDerefs"),
671                    )
672                }
673            }
674            ProjectionElem::Field(f, ty) => {
675                let parent_ty = place_ref.ty(&self.body.local_decls, self.tcx);
676                let fail_out_of_bounds = |this: &mut Self, location| {
677                    this.fail(location, format!("Out of bounds field {f:?} for {parent_ty:?}"));
678                };
679                let check_equal = |this: &mut Self, location, f_ty| {
680                    if !this.mir_assign_valid_types(ty, f_ty) {
681                        this.fail(
682                            location,
683                            format!(
684                                "Field projection `{place_ref:?}.{f:?}` specified type `{ty:?}`, but actual type is `{f_ty:?}`"
685                            )
686                        )
687                    }
688                };
689
690                let kind = match parent_ty.ty.kind() {
691                    &ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
692                        self.tcx.type_of(def_id).instantiate(self.tcx, args).kind()
693                    }
694                    kind => kind,
695                };
696
697                match kind {
698                    ty::Tuple(fields) => {
699                        let Some(f_ty) = fields.get(f.as_usize()) else {
700                            fail_out_of_bounds(self, location);
701                            return;
702                        };
703                        check_equal(self, location, *f_ty);
704                    }
705                    ty::Adt(adt_def, args) => {
706                        // see <https://github.com/rust-lang/rust/blob/7601adcc764d42c9f2984082b49948af652df986/compiler/rustc_middle/src/ty/layout.rs#L861-L864>
707                        if self.tcx.is_lang_item(adt_def.did(), LangItem::DynMetadata) {
708                            self.fail(
709                                location,
710                                format!(
711                                    "You can't project to field {f:?} of `DynMetadata` because \
712                                     layout is weird and thinks it doesn't have fields."
713                                ),
714                            );
715                        }
716
717                        let var = parent_ty.variant_index.unwrap_or(FIRST_VARIANT);
718                        let Some(field) = adt_def.variant(var).fields.get(f) else {
719                            fail_out_of_bounds(self, location);
720                            return;
721                        };
722                        check_equal(self, location, field.ty(self.tcx, args));
723                    }
724                    ty::Closure(_, args) => {
725                        let args = args.as_closure();
726                        let Some(&f_ty) = args.upvar_tys().get(f.as_usize()) else {
727                            fail_out_of_bounds(self, location);
728                            return;
729                        };
730                        check_equal(self, location, f_ty);
731                    }
732                    ty::CoroutineClosure(_, args) => {
733                        let args = args.as_coroutine_closure();
734                        let Some(&f_ty) = args.upvar_tys().get(f.as_usize()) else {
735                            fail_out_of_bounds(self, location);
736                            return;
737                        };
738                        check_equal(self, location, f_ty);
739                    }
740                    &ty::Coroutine(def_id, args) => {
741                        let f_ty = if let Some(var) = parent_ty.variant_index {
742                            // If we're currently validating an inlined copy of this body,
743                            // then it will no longer be parameterized over the original
744                            // args of the coroutine. Otherwise, we prefer to use this body
745                            // since we may be in the process of computing this MIR in the
746                            // first place.
747                            let layout = if def_id == self.caller_body.source.def_id() {
748                                self.caller_body.coroutine_layout_raw()
749                            } else if self.tcx.needs_coroutine_by_move_body_def_id(def_id)
750                                && let ty::ClosureKind::FnOnce =
751                                    args.as_coroutine().kind_ty().to_opt_closure_kind().unwrap()
752                                && self.caller_body.source.def_id()
753                                    == self.tcx.coroutine_by_move_body_def_id(def_id)
754                            {
755                                // Same if this is the by-move body of a coroutine-closure.
756                                self.caller_body.coroutine_layout_raw()
757                            } else {
758                                self.tcx.coroutine_layout(def_id, args.as_coroutine().kind_ty())
759                            };
760
761                            let Some(layout) = layout else {
762                                self.fail(
763                                    location,
764                                    format!("No coroutine layout for {parent_ty:?}"),
765                                );
766                                return;
767                            };
768
769                            let Some(&local) = layout.variant_fields[var].get(f) else {
770                                fail_out_of_bounds(self, location);
771                                return;
772                            };
773
774                            let Some(f_ty) = layout.field_tys.get(local) else {
775                                self.fail(
776                                    location,
777                                    format!("Out of bounds local {local:?} for {parent_ty:?}"),
778                                );
779                                return;
780                            };
781
782                            ty::EarlyBinder::bind(f_ty.ty).instantiate(self.tcx, args)
783                        } else {
784                            let Some(&f_ty) = args.as_coroutine().prefix_tys().get(f.index())
785                            else {
786                                fail_out_of_bounds(self, location);
787                                return;
788                            };
789
790                            f_ty
791                        };
792
793                        check_equal(self, location, f_ty);
794                    }
795                    _ => {
796                        self.fail(location, format!("{:?} does not have fields", parent_ty.ty));
797                    }
798                }
799            }
800            ProjectionElem::Subtype(ty) => {
801                if !util::sub_types(
802                    self.tcx,
803                    self.typing_env,
804                    ty,
805                    place_ref.ty(&self.body.local_decls, self.tcx).ty,
806                ) {
807                    self.fail(
808                        location,
809                        format!(
810                            "Failed subtyping {ty:#?} and {:#?}",
811                            place_ref.ty(&self.body.local_decls, self.tcx).ty
812                        ),
813                    )
814                }
815            }
816            ProjectionElem::UnwrapUnsafeBinder(unwrapped_ty) => {
817                let binder_ty = place_ref.ty(&self.body.local_decls, self.tcx);
818                let ty::UnsafeBinder(binder_ty) = *binder_ty.ty.kind() else {
819                    self.fail(
820                        location,
821                        format!("WrapUnsafeBinder does not produce a ty::UnsafeBinder"),
822                    );
823                    return;
824                };
825                let binder_inner_ty = self.tcx.instantiate_bound_regions_with_erased(*binder_ty);
826                if !self.mir_assign_valid_types(unwrapped_ty, binder_inner_ty) {
827                    self.fail(
828                        location,
829                        format!(
830                            "Cannot unwrap unsafe binder {binder_ty:?} into type {unwrapped_ty:?}"
831                        ),
832                    );
833                }
834            }
835            _ => {}
836        }
837        self.super_projection_elem(place_ref, elem, context, location);
838    }
839
840    fn visit_var_debug_info(&mut self, debuginfo: &VarDebugInfo<'tcx>) {
841        if let Some(box VarDebugInfoFragment { ty, ref projection }) = debuginfo.composite {
842            if ty.is_union() || ty.is_enum() {
843                self.fail(
844                    START_BLOCK.start_location(),
845                    format!("invalid type {ty:?} in debuginfo for {:?}", debuginfo.name),
846                );
847            }
848            if projection.is_empty() {
849                self.fail(
850                    START_BLOCK.start_location(),
851                    format!("invalid empty projection in debuginfo for {:?}", debuginfo.name),
852                );
853            }
854            if projection.iter().any(|p| !matches!(p, PlaceElem::Field(..))) {
855                self.fail(
856                    START_BLOCK.start_location(),
857                    format!(
858                        "illegal projection {:?} in debuginfo for {:?}",
859                        projection, debuginfo.name
860                    ),
861                );
862            }
863        }
864        match debuginfo.value {
865            VarDebugInfoContents::Const(_) => {}
866            VarDebugInfoContents::Place(place) => {
867                if place.projection.iter().any(|p| !p.can_use_in_debuginfo()) {
868                    self.fail(
869                        START_BLOCK.start_location(),
870                        format!("illegal place {:?} in debuginfo for {:?}", place, debuginfo.name),
871                    );
872                }
873            }
874        }
875        self.super_var_debug_info(debuginfo);
876    }
877
878    fn visit_place(&mut self, place: &Place<'tcx>, cntxt: PlaceContext, location: Location) {
879        // Set off any `bug!`s in the type computation code
880        let _ = place.ty(&self.body.local_decls, self.tcx);
881
882        if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial)
883            && place.projection.len() > 1
884            && cntxt != PlaceContext::NonUse(NonUseContext::VarDebugInfo)
885            && place.projection[1..].contains(&ProjectionElem::Deref)
886        {
887            self.fail(
888                location,
889                format!("place {place:?} has deref as a later projection (it is only permitted as the first projection)"),
890            );
891        }
892
893        // Ensure all downcast projections are followed by field projections.
894        let mut projections_iter = place.projection.iter();
895        while let Some(proj) = projections_iter.next() {
896            if matches!(proj, ProjectionElem::Downcast(..)) {
897                if !matches!(projections_iter.next(), Some(ProjectionElem::Field(..))) {
898                    self.fail(
899                        location,
900                        format!(
901                            "place {place:?} has `Downcast` projection not followed by `Field`"
902                        ),
903                    );
904                }
905            }
906        }
907
908        self.super_place(place, cntxt, location);
909    }
910
911    fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
912        macro_rules! check_kinds {
913            ($t:expr, $text:literal, $typat:pat) => {
914                if !matches!(($t).kind(), $typat) {
915                    self.fail(location, format!($text, $t));
916                }
917            };
918        }
919        match rvalue {
920            Rvalue::Use(_) | Rvalue::CopyForDeref(_) => {}
921            Rvalue::Aggregate(kind, fields) => match **kind {
922                AggregateKind::Tuple => {}
923                AggregateKind::Array(dest) => {
924                    for src in fields {
925                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
926                            self.fail(location, "array field has the wrong type");
927                        }
928                    }
929                }
930                AggregateKind::Adt(def_id, idx, args, _, Some(field)) => {
931                    let adt_def = self.tcx.adt_def(def_id);
932                    assert!(adt_def.is_union());
933                    assert_eq!(idx, FIRST_VARIANT);
934                    let dest_ty = self.tcx.normalize_erasing_regions(
935                        self.typing_env,
936                        adt_def.non_enum_variant().fields[field].ty(self.tcx, args),
937                    );
938                    if let [field] = fields.raw.as_slice() {
939                        let src_ty = field.ty(self.body, self.tcx);
940                        if !self.mir_assign_valid_types(src_ty, dest_ty) {
941                            self.fail(location, "union field has the wrong type");
942                        }
943                    } else {
944                        self.fail(location, "unions should have one initialized field");
945                    }
946                }
947                AggregateKind::Adt(def_id, idx, args, _, None) => {
948                    let adt_def = self.tcx.adt_def(def_id);
949                    assert!(!adt_def.is_union());
950                    let variant = &adt_def.variants()[idx];
951                    if variant.fields.len() != fields.len() {
952                        self.fail(location, "adt has the wrong number of initialized fields");
953                    }
954                    for (src, dest) in std::iter::zip(fields, &variant.fields) {
955                        let dest_ty = self
956                            .tcx
957                            .normalize_erasing_regions(self.typing_env, dest.ty(self.tcx, args));
958                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest_ty) {
959                            self.fail(location, "adt field has the wrong type");
960                        }
961                    }
962                }
963                AggregateKind::Closure(_, args) => {
964                    let upvars = args.as_closure().upvar_tys();
965                    if upvars.len() != fields.len() {
966                        self.fail(location, "closure has the wrong number of initialized fields");
967                    }
968                    for (src, dest) in std::iter::zip(fields, upvars) {
969                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
970                            self.fail(location, "closure field has the wrong type");
971                        }
972                    }
973                }
974                AggregateKind::Coroutine(_, args) => {
975                    let upvars = args.as_coroutine().upvar_tys();
976                    if upvars.len() != fields.len() {
977                        self.fail(location, "coroutine has the wrong number of initialized fields");
978                    }
979                    for (src, dest) in std::iter::zip(fields, upvars) {
980                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
981                            self.fail(location, "coroutine field has the wrong type");
982                        }
983                    }
984                }
985                AggregateKind::CoroutineClosure(_, args) => {
986                    let upvars = args.as_coroutine_closure().upvar_tys();
987                    if upvars.len() != fields.len() {
988                        self.fail(
989                            location,
990                            "coroutine-closure has the wrong number of initialized fields",
991                        );
992                    }
993                    for (src, dest) in std::iter::zip(fields, upvars) {
994                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
995                            self.fail(location, "coroutine-closure field has the wrong type");
996                        }
997                    }
998                }
999                AggregateKind::RawPtr(pointee_ty, mutability) => {
1000                    if !matches!(self.body.phase, MirPhase::Runtime(_)) {
1001                        // It would probably be fine to support this in earlier phases, but at the
1002                        // time of writing it's only ever introduced from intrinsic lowering, so
1003                        // earlier things just `bug!` on it.
1004                        self.fail(location, "RawPtr should be in runtime MIR only");
1005                    }
1006
1007                    if let [data_ptr, metadata] = fields.raw.as_slice() {
1008                        let data_ptr_ty = data_ptr.ty(self.body, self.tcx);
1009                        let metadata_ty = metadata.ty(self.body, self.tcx);
1010                        if let ty::RawPtr(in_pointee, in_mut) = data_ptr_ty.kind() {
1011                            if *in_mut != mutability {
1012                                self.fail(location, "input and output mutability must match");
1013                            }
1014
1015                            // FIXME: check `Thin` instead of `Sized`
1016                            if !in_pointee.is_sized(self.tcx, self.typing_env) {
1017                                self.fail(location, "input pointer must be thin");
1018                            }
1019                        } else {
1020                            self.fail(
1021                                location,
1022                                "first operand to raw pointer aggregate must be a raw pointer",
1023                            );
1024                        }
1025
1026                        // FIXME: Check metadata more generally
1027                        if pointee_ty.is_slice() {
1028                            if !self.mir_assign_valid_types(metadata_ty, self.tcx.types.usize) {
1029                                self.fail(location, "slice metadata must be usize");
1030                            }
1031                        } else if pointee_ty.is_sized(self.tcx, self.typing_env) {
1032                            if metadata_ty != self.tcx.types.unit {
1033                                self.fail(location, "metadata for pointer-to-thin must be unit");
1034                            }
1035                        }
1036                    } else {
1037                        self.fail(location, "raw pointer aggregate must have 2 fields");
1038                    }
1039                }
1040            },
1041            Rvalue::Ref(_, BorrowKind::Fake(_), _) => {
1042                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
1043                    self.fail(
1044                        location,
1045                        "`Assign` statement with a `Fake` borrow should have been removed in runtime MIR",
1046                    );
1047                }
1048            }
1049            Rvalue::Ref(..) => {}
1050            Rvalue::Len(p) => {
1051                let pty = p.ty(&self.body.local_decls, self.tcx).ty;
1052                check_kinds!(
1053                    pty,
1054                    "Cannot compute length of non-array type {:?}",
1055                    ty::Array(..) | ty::Slice(..)
1056                );
1057            }
1058            Rvalue::BinaryOp(op, vals) => {
1059                use BinOp::*;
1060                let a = vals.0.ty(&self.body.local_decls, self.tcx);
1061                let b = vals.1.ty(&self.body.local_decls, self.tcx);
1062                if crate::util::binop_right_homogeneous(*op) {
1063                    if let Eq | Lt | Le | Ne | Ge | Gt = op {
1064                        // The function pointer types can have lifetimes
1065                        if !self.mir_assign_valid_types(a, b) {
1066                            self.fail(
1067                                location,
1068                                format!("Cannot {op:?} compare incompatible types {a:?} and {b:?}"),
1069                            );
1070                        }
1071                    } else if a != b {
1072                        self.fail(
1073                            location,
1074                            format!(
1075                                "Cannot perform binary op {op:?} on unequal types {a:?} and {b:?}"
1076                            ),
1077                        );
1078                    }
1079                }
1080
1081                match op {
1082                    Offset => {
1083                        check_kinds!(a, "Cannot offset non-pointer type {:?}", ty::RawPtr(..));
1084                        if b != self.tcx.types.isize && b != self.tcx.types.usize {
1085                            self.fail(location, format!("Cannot offset by non-isize type {b:?}"));
1086                        }
1087                    }
1088                    Eq | Lt | Le | Ne | Ge | Gt => {
1089                        for x in [a, b] {
1090                            check_kinds!(
1091                                x,
1092                                "Cannot {op:?} compare type {:?}",
1093                                ty::Bool
1094                                    | ty::Char
1095                                    | ty::Int(..)
1096                                    | ty::Uint(..)
1097                                    | ty::Float(..)
1098                                    | ty::RawPtr(..)
1099                                    | ty::FnPtr(..)
1100                            )
1101                        }
1102                    }
1103                    Cmp => {
1104                        for x in [a, b] {
1105                            check_kinds!(
1106                                x,
1107                                "Cannot three-way compare non-integer type {:?}",
1108                                ty::Char | ty::Uint(..) | ty::Int(..)
1109                            )
1110                        }
1111                    }
1112                    AddUnchecked | AddWithOverflow | SubUnchecked | SubWithOverflow
1113                    | MulUnchecked | MulWithOverflow | Shl | ShlUnchecked | Shr | ShrUnchecked => {
1114                        for x in [a, b] {
1115                            check_kinds!(
1116                                x,
1117                                "Cannot {op:?} non-integer type {:?}",
1118                                ty::Uint(..) | ty::Int(..)
1119                            )
1120                        }
1121                    }
1122                    BitAnd | BitOr | BitXor => {
1123                        for x in [a, b] {
1124                            check_kinds!(
1125                                x,
1126                                "Cannot perform bitwise op {op:?} on type {:?}",
1127                                ty::Uint(..) | ty::Int(..) | ty::Bool
1128                            )
1129                        }
1130                    }
1131                    Add | Sub | Mul | Div | Rem => {
1132                        for x in [a, b] {
1133                            check_kinds!(
1134                                x,
1135                                "Cannot perform arithmetic {op:?} on type {:?}",
1136                                ty::Uint(..) | ty::Int(..) | ty::Float(..)
1137                            )
1138                        }
1139                    }
1140                }
1141            }
1142            Rvalue::UnaryOp(op, operand) => {
1143                let a = operand.ty(&self.body.local_decls, self.tcx);
1144                match op {
1145                    UnOp::Neg => {
1146                        check_kinds!(a, "Cannot negate type {:?}", ty::Int(..) | ty::Float(..))
1147                    }
1148                    UnOp::Not => {
1149                        check_kinds!(
1150                            a,
1151                            "Cannot binary not type {:?}",
1152                            ty::Int(..) | ty::Uint(..) | ty::Bool
1153                        );
1154                    }
1155                    UnOp::PtrMetadata => {
1156                        check_kinds!(
1157                            a,
1158                            "Cannot PtrMetadata non-pointer non-reference type {:?}",
1159                            ty::RawPtr(..) | ty::Ref(..)
1160                        );
1161                    }
1162                }
1163            }
1164            Rvalue::ShallowInitBox(operand, _) => {
1165                let a = operand.ty(&self.body.local_decls, self.tcx);
1166                check_kinds!(a, "Cannot shallow init type {:?}", ty::RawPtr(..));
1167            }
1168            Rvalue::Cast(kind, operand, target_type) => {
1169                let op_ty = operand.ty(self.body, self.tcx);
1170                match kind {
1171                    // FIXME: Add Checks for these
1172                    CastKind::PointerWithExposedProvenance | CastKind::PointerExposeProvenance => {}
1173                    CastKind::PointerCoercion(PointerCoercion::ReifyFnPointer, _) => {
1174                        // FIXME: check signature compatibility.
1175                        check_kinds!(
1176                            op_ty,
1177                            "CastKind::{kind:?} input must be a fn item, not {:?}",
1178                            ty::FnDef(..)
1179                        );
1180                        check_kinds!(
1181                            target_type,
1182                            "CastKind::{kind:?} output must be a fn pointer, not {:?}",
1183                            ty::FnPtr(..)
1184                        );
1185                    }
1186                    CastKind::PointerCoercion(PointerCoercion::UnsafeFnPointer, _) => {
1187                        // FIXME: check safety and signature compatibility.
1188                        check_kinds!(
1189                            op_ty,
1190                            "CastKind::{kind:?} input must be a fn pointer, not {:?}",
1191                            ty::FnPtr(..)
1192                        );
1193                        check_kinds!(
1194                            target_type,
1195                            "CastKind::{kind:?} output must be a fn pointer, not {:?}",
1196                            ty::FnPtr(..)
1197                        );
1198                    }
1199                    CastKind::PointerCoercion(PointerCoercion::ClosureFnPointer(..), _) => {
1200                        // FIXME: check safety, captures, and signature compatibility.
1201                        check_kinds!(
1202                            op_ty,
1203                            "CastKind::{kind:?} input must be a closure, not {:?}",
1204                            ty::Closure(..)
1205                        );
1206                        check_kinds!(
1207                            target_type,
1208                            "CastKind::{kind:?} output must be a fn pointer, not {:?}",
1209                            ty::FnPtr(..)
1210                        );
1211                    }
1212                    CastKind::PointerCoercion(PointerCoercion::MutToConstPointer, _) => {
1213                        // FIXME: check same pointee?
1214                        check_kinds!(
1215                            op_ty,
1216                            "CastKind::{kind:?} input must be a raw mut pointer, not {:?}",
1217                            ty::RawPtr(_, Mutability::Mut)
1218                        );
1219                        check_kinds!(
1220                            target_type,
1221                            "CastKind::{kind:?} output must be a raw const pointer, not {:?}",
1222                            ty::RawPtr(_, Mutability::Not)
1223                        );
1224                        if self.body.phase >= MirPhase::Analysis(AnalysisPhase::PostCleanup) {
1225                            self.fail(location, format!("After borrowck, MIR disallows {kind:?}"));
1226                        }
1227                    }
1228                    CastKind::PointerCoercion(PointerCoercion::ArrayToPointer, _) => {
1229                        // FIXME: Check pointee types
1230                        check_kinds!(
1231                            op_ty,
1232                            "CastKind::{kind:?} input must be a raw pointer, not {:?}",
1233                            ty::RawPtr(..)
1234                        );
1235                        check_kinds!(
1236                            target_type,
1237                            "CastKind::{kind:?} output must be a raw pointer, not {:?}",
1238                            ty::RawPtr(..)
1239                        );
1240                        if self.body.phase >= MirPhase::Analysis(AnalysisPhase::PostCleanup) {
1241                            self.fail(location, format!("After borrowck, MIR disallows {kind:?}"));
1242                        }
1243                    }
1244                    CastKind::PointerCoercion(PointerCoercion::Unsize, _) => {
1245                        // Pointers being unsize coerced should at least implement
1246                        // `CoerceUnsized`.
1247                        if !self.predicate_must_hold_modulo_regions(ty::TraitRef::new(
1248                            self.tcx,
1249                            self.tcx.require_lang_item(
1250                                LangItem::CoerceUnsized,
1251                                Some(self.body.source_info(location).span),
1252                            ),
1253                            [op_ty, *target_type],
1254                        )) {
1255                            self.fail(location, format!("Unsize coercion, but `{op_ty}` isn't coercible to `{target_type}`"));
1256                        }
1257                    }
1258                    CastKind::PointerCoercion(PointerCoercion::DynStar, _) => {
1259                        // FIXME(dyn-star): make sure nothing needs to be done here.
1260                    }
1261                    CastKind::IntToInt | CastKind::IntToFloat => {
1262                        let input_valid = op_ty.is_integral() || op_ty.is_char() || op_ty.is_bool();
1263                        let target_valid = target_type.is_numeric() || target_type.is_char();
1264                        if !input_valid || !target_valid {
1265                            self.fail(
1266                                location,
1267                                format!("Wrong cast kind {kind:?} for the type {op_ty}"),
1268                            );
1269                        }
1270                    }
1271                    CastKind::FnPtrToPtr => {
1272                        check_kinds!(
1273                            op_ty,
1274                            "CastKind::{kind:?} input must be a fn pointer, not {:?}",
1275                            ty::FnPtr(..)
1276                        );
1277                        check_kinds!(
1278                            target_type,
1279                            "CastKind::{kind:?} output must be a raw pointer, not {:?}",
1280                            ty::RawPtr(..)
1281                        );
1282                    }
1283                    CastKind::PtrToPtr => {
1284                        check_kinds!(
1285                            op_ty,
1286                            "CastKind::{kind:?} input must be a raw pointer, not {:?}",
1287                            ty::RawPtr(..)
1288                        );
1289                        check_kinds!(
1290                            target_type,
1291                            "CastKind::{kind:?} output must be a raw pointer, not {:?}",
1292                            ty::RawPtr(..)
1293                        );
1294                    }
1295                    CastKind::FloatToFloat | CastKind::FloatToInt => {
1296                        if !op_ty.is_floating_point() || !target_type.is_numeric() {
1297                            self.fail(
1298                                location,
1299                                format!(
1300                                    "Trying to cast non 'Float' as {kind:?} into {target_type:?}"
1301                                ),
1302                            );
1303                        }
1304                    }
1305                    CastKind::Transmute => {
1306                        if let MirPhase::Runtime(..) = self.body.phase {
1307                            // Unlike `mem::transmute`, a MIR `Transmute` is well-formed
1308                            // for any two `Sized` types, just potentially UB to run.
1309
1310                            if !self
1311                                .tcx
1312                                .normalize_erasing_regions(self.typing_env, op_ty)
1313                                .is_sized(self.tcx, self.typing_env)
1314                            {
1315                                self.fail(
1316                                    location,
1317                                    format!("Cannot transmute from non-`Sized` type {op_ty:?}"),
1318                                );
1319                            }
1320                            if !self
1321                                .tcx
1322                                .normalize_erasing_regions(self.typing_env, *target_type)
1323                                .is_sized(self.tcx, self.typing_env)
1324                            {
1325                                self.fail(
1326                                    location,
1327                                    format!("Cannot transmute to non-`Sized` type {target_type:?}"),
1328                                );
1329                            }
1330                        } else {
1331                            self.fail(
1332                                location,
1333                                format!(
1334                                    "Transmute is not supported in non-runtime phase {:?}.",
1335                                    self.body.phase
1336                                ),
1337                            );
1338                        }
1339                    }
1340                }
1341            }
1342            Rvalue::NullaryOp(NullOp::OffsetOf(indices), container) => {
1343                let fail_out_of_bounds = |this: &mut Self, location, field, ty| {
1344                    this.fail(location, format!("Out of bounds field {field:?} for {ty:?}"));
1345                };
1346
1347                let mut current_ty = *container;
1348
1349                for (variant, field) in indices.iter() {
1350                    match current_ty.kind() {
1351                        ty::Tuple(fields) => {
1352                            if variant != FIRST_VARIANT {
1353                                self.fail(
1354                                    location,
1355                                    format!("tried to get variant {variant:?} of tuple"),
1356                                );
1357                                return;
1358                            }
1359                            let Some(&f_ty) = fields.get(field.as_usize()) else {
1360                                fail_out_of_bounds(self, location, field, current_ty);
1361                                return;
1362                            };
1363
1364                            current_ty = self.tcx.normalize_erasing_regions(self.typing_env, f_ty);
1365                        }
1366                        ty::Adt(adt_def, args) => {
1367                            let Some(field) = adt_def.variant(variant).fields.get(field) else {
1368                                fail_out_of_bounds(self, location, field, current_ty);
1369                                return;
1370                            };
1371
1372                            let f_ty = field.ty(self.tcx, args);
1373                            current_ty = self.tcx.normalize_erasing_regions(self.typing_env, f_ty);
1374                        }
1375                        _ => {
1376                            self.fail(
1377                                location,
1378                                format!("Cannot get offset ({variant:?}, {field:?}) from type {current_ty:?}"),
1379                            );
1380                            return;
1381                        }
1382                    }
1383                }
1384            }
1385            Rvalue::Repeat(_, _)
1386            | Rvalue::ThreadLocalRef(_)
1387            | Rvalue::RawPtr(_, _)
1388            | Rvalue::NullaryOp(
1389                NullOp::SizeOf | NullOp::AlignOf | NullOp::UbChecks | NullOp::ContractChecks,
1390                _,
1391            )
1392            | Rvalue::Discriminant(_) => {}
1393
1394            Rvalue::WrapUnsafeBinder(op, ty) => {
1395                let unwrapped_ty = op.ty(self.body, self.tcx);
1396                let ty::UnsafeBinder(binder_ty) = *ty.kind() else {
1397                    self.fail(
1398                        location,
1399                        format!("WrapUnsafeBinder does not produce a ty::UnsafeBinder"),
1400                    );
1401                    return;
1402                };
1403                let binder_inner_ty = self.tcx.instantiate_bound_regions_with_erased(*binder_ty);
1404                if !self.mir_assign_valid_types(unwrapped_ty, binder_inner_ty) {
1405                    self.fail(
1406                        location,
1407                        format!("Cannot wrap {unwrapped_ty:?} into unsafe binder {binder_ty:?}"),
1408                    );
1409                }
1410            }
1411        }
1412        self.super_rvalue(rvalue, location);
1413    }
1414
1415    fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
1416        match &statement.kind {
1417            StatementKind::Assign(box (dest, rvalue)) => {
1418                // LHS and RHS of the assignment must have the same type.
1419                let left_ty = dest.ty(&self.body.local_decls, self.tcx).ty;
1420                let right_ty = rvalue.ty(&self.body.local_decls, self.tcx);
1421
1422                if !self.mir_assign_valid_types(right_ty, left_ty) {
1423                    self.fail(
1424                        location,
1425                        format!(
1426                            "encountered `{:?}` with incompatible types:\n\
1427                            left-hand side has type: {}\n\
1428                            right-hand side has type: {}",
1429                            statement.kind, left_ty, right_ty,
1430                        ),
1431                    );
1432                }
1433                if let Rvalue::CopyForDeref(place) = rvalue {
1434                    if place.ty(&self.body.local_decls, self.tcx).ty.builtin_deref(true).is_none() {
1435                        self.fail(
1436                            location,
1437                            "`CopyForDeref` should only be used for dereferenceable types",
1438                        )
1439                    }
1440                }
1441            }
1442            StatementKind::AscribeUserType(..) => {
1443                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
1444                    self.fail(
1445                        location,
1446                        "`AscribeUserType` should have been removed after drop lowering phase",
1447                    );
1448                }
1449            }
1450            StatementKind::FakeRead(..) => {
1451                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
1452                    self.fail(
1453                        location,
1454                        "`FakeRead` should have been removed after drop lowering phase",
1455                    );
1456                }
1457            }
1458            StatementKind::Intrinsic(box NonDivergingIntrinsic::Assume(op)) => {
1459                let ty = op.ty(&self.body.local_decls, self.tcx);
1460                if !ty.is_bool() {
1461                    self.fail(
1462                        location,
1463                        format!("`assume` argument must be `bool`, but got: `{ty}`"),
1464                    );
1465                }
1466            }
1467            StatementKind::Intrinsic(box NonDivergingIntrinsic::CopyNonOverlapping(
1468                CopyNonOverlapping { src, dst, count },
1469            )) => {
1470                let src_ty = src.ty(&self.body.local_decls, self.tcx);
1471                let op_src_ty = if let Some(src_deref) = src_ty.builtin_deref(true) {
1472                    src_deref
1473                } else {
1474                    self.fail(
1475                        location,
1476                        format!("Expected src to be ptr in copy_nonoverlapping, got: {src_ty}"),
1477                    );
1478                    return;
1479                };
1480                let dst_ty = dst.ty(&self.body.local_decls, self.tcx);
1481                let op_dst_ty = if let Some(dst_deref) = dst_ty.builtin_deref(true) {
1482                    dst_deref
1483                } else {
1484                    self.fail(
1485                        location,
1486                        format!("Expected dst to be ptr in copy_nonoverlapping, got: {dst_ty}"),
1487                    );
1488                    return;
1489                };
1490                // since CopyNonOverlapping is parametrized by 1 type,
1491                // we only need to check that they are equal and not keep an extra parameter.
1492                if !self.mir_assign_valid_types(op_src_ty, op_dst_ty) {
1493                    self.fail(location, format!("bad arg ({op_src_ty:?} != {op_dst_ty:?})"));
1494                }
1495
1496                let op_cnt_ty = count.ty(&self.body.local_decls, self.tcx);
1497                if op_cnt_ty != self.tcx.types.usize {
1498                    self.fail(location, format!("bad arg ({op_cnt_ty:?} != usize)"))
1499                }
1500            }
1501            StatementKind::SetDiscriminant { place, .. } => {
1502                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
1503                    self.fail(location, "`SetDiscriminant`is not allowed until deaggregation");
1504                }
1505                let pty = place.ty(&self.body.local_decls, self.tcx).ty.kind();
1506                if !matches!(pty, ty::Adt(..) | ty::Coroutine(..) | ty::Alias(ty::Opaque, ..)) {
1507                    self.fail(
1508                        location,
1509                        format!(
1510                            "`SetDiscriminant` is only allowed on ADTs and coroutines, not {pty:?}"
1511                        ),
1512                    );
1513                }
1514            }
1515            StatementKind::Deinit(..) => {
1516                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
1517                    self.fail(location, "`Deinit`is not allowed until deaggregation");
1518                }
1519            }
1520            StatementKind::Retag(kind, _) => {
1521                // FIXME(JakobDegen) The validator should check that `self.body.phase <
1522                // DropsLowered`. However, this causes ICEs with generation of drop shims, which
1523                // seem to fail to set their `MirPhase` correctly.
1524                if matches!(kind, RetagKind::TwoPhase) {
1525                    self.fail(location, format!("explicit `{kind:?}` is forbidden"));
1526                }
1527            }
1528            StatementKind::StorageLive(_)
1529            | StatementKind::StorageDead(_)
1530            | StatementKind::Coverage(_)
1531            | StatementKind::ConstEvalCounter
1532            | StatementKind::PlaceMention(..)
1533            | StatementKind::BackwardIncompatibleDropHint { .. }
1534            | StatementKind::Nop => {}
1535        }
1536
1537        self.super_statement(statement, location);
1538    }
1539
1540    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
1541        match &terminator.kind {
1542            TerminatorKind::SwitchInt { targets, discr } => {
1543                let switch_ty = discr.ty(&self.body.local_decls, self.tcx);
1544
1545                let target_width = self.tcx.sess.target.pointer_width;
1546
1547                let size = Size::from_bits(match switch_ty.kind() {
1548                    ty::Uint(uint) => uint.normalize(target_width).bit_width().unwrap(),
1549                    ty::Int(int) => int.normalize(target_width).bit_width().unwrap(),
1550                    ty::Char => 32,
1551                    ty::Bool => 1,
1552                    other => bug!("unhandled type: {:?}", other),
1553                });
1554
1555                for (value, _) in targets.iter() {
1556                    if ScalarInt::try_from_uint(value, size).is_none() {
1557                        self.fail(
1558                            location,
1559                            format!("the value {value:#x} is not a proper {switch_ty:?}"),
1560                        )
1561                    }
1562                }
1563            }
1564            TerminatorKind::Call { func, .. } | TerminatorKind::TailCall { func, .. } => {
1565                let func_ty = func.ty(&self.body.local_decls, self.tcx);
1566                match func_ty.kind() {
1567                    ty::FnPtr(..) | ty::FnDef(..) => {}
1568                    _ => self.fail(
1569                        location,
1570                        format!(
1571                            "encountered non-callable type {func_ty} in `{}` terminator",
1572                            terminator.kind.name()
1573                        ),
1574                    ),
1575                }
1576
1577                if let TerminatorKind::TailCall { .. } = terminator.kind {
1578                    // FIXME(explicit_tail_calls): implement tail-call specific checks here (such
1579                    // as signature matching, forbidding closures, etc)
1580                }
1581            }
1582            TerminatorKind::Assert { cond, .. } => {
1583                let cond_ty = cond.ty(&self.body.local_decls, self.tcx);
1584                if cond_ty != self.tcx.types.bool {
1585                    self.fail(
1586                        location,
1587                        format!(
1588                            "encountered non-boolean condition of type {cond_ty} in `Assert` terminator"
1589                        ),
1590                    );
1591                }
1592            }
1593            TerminatorKind::Goto { .. }
1594            | TerminatorKind::Drop { .. }
1595            | TerminatorKind::Yield { .. }
1596            | TerminatorKind::FalseEdge { .. }
1597            | TerminatorKind::FalseUnwind { .. }
1598            | TerminatorKind::InlineAsm { .. }
1599            | TerminatorKind::CoroutineDrop
1600            | TerminatorKind::UnwindResume
1601            | TerminatorKind::UnwindTerminate(_)
1602            | TerminatorKind::Return
1603            | TerminatorKind::Unreachable => {}
1604        }
1605
1606        self.super_terminator(terminator, location);
1607    }
1608}
rustc_mir_transform/validate.rs

rustc_mir_transform/
validate.rs
