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::print::with_no_trimmed_paths;
16use rustc_middle::ty::{
17    self, CoroutineArgsExt, InstanceKind, ScalarInt, Ty, TyCtxt, TypeVisitableExt, Upcast, Variance,
18};
19use rustc_middle::{bug, span_bug};
20use rustc_trait_selection::traits::ObligationCtxt;
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 (mut bb, parent) in parent.iter_enumerated_mut() {
225            stack.clear();
226            stack.insert(bb);
227            loop {
228                let Some(parent) = parent.take() else { break };
229                let no_cycle = stack.insert(parent);
230                if !no_cycle {
231                    self.fail(
232                        Location { block: bb, statement_index: 0 },
233                        format!(
234                            "Cleanup control flow violation: Cycle involving edge {bb:?} -> {parent:?}",
235                        ),
236                    );
237                    break;
238                }
239                bb = parent;
240            }
241        }
242    }
243
244    fn check_unwind_edge(&mut self, location: Location, unwind: UnwindAction) {
245        let is_cleanup = self.body.basic_blocks[location.block].is_cleanup;
246        match unwind {
247            UnwindAction::Cleanup(unwind) => {
248                if is_cleanup {
249                    self.fail(location, "`UnwindAction::Cleanup` in cleanup block");
250                }
251                self.check_edge(location, unwind, EdgeKind::Unwind);
252            }
253            UnwindAction::Continue => {
254                if is_cleanup {
255                    self.fail(location, "`UnwindAction::Continue` in cleanup block");
256                }
257
258                if !self.can_unwind {
259                    self.fail(location, "`UnwindAction::Continue` in no-unwind function");
260                }
261            }
262            UnwindAction::Terminate(UnwindTerminateReason::InCleanup) => {
263                if !is_cleanup {
264                    self.fail(
265                        location,
266                        "`UnwindAction::Terminate(InCleanup)` in a non-cleanup block",
267                    );
268                }
269            }
270            // These are allowed everywhere.
271            UnwindAction::Unreachable | UnwindAction::Terminate(UnwindTerminateReason::Abi) => (),
272        }
273    }
274
275    fn is_critical_call_edge(&self, target: Option<BasicBlock>, unwind: UnwindAction) -> bool {
276        let Some(target) = target else { return false };
277        matches!(unwind, UnwindAction::Cleanup(_) | UnwindAction::Terminate(_))
278            && self.body.basic_blocks.predecessors()[target].len() > 1
279    }
280}
281
282impl<'a, 'tcx> Visitor<'tcx> for CfgChecker<'a, 'tcx> {
283    fn visit_local(&mut self, local: Local, _context: PlaceContext, location: Location) {
284        if self.body.local_decls.get(local).is_none() {
285            self.fail(
286                location,
287                format!("local {local:?} has no corresponding declaration in `body.local_decls`"),
288            );
289        }
290    }
291
292    fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
293        match &statement.kind {
294            StatementKind::AscribeUserType(..) => {
295                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
296                    self.fail(
297                        location,
298                        "`AscribeUserType` should have been removed after drop lowering phase",
299                    );
300                }
301            }
302            StatementKind::FakeRead(..) => {
303                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
304                    self.fail(
305                        location,
306                        "`FakeRead` should have been removed after drop lowering phase",
307                    );
308                }
309            }
310            StatementKind::SetDiscriminant { .. } => {
311                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
312                    self.fail(location, "`SetDiscriminant`is not allowed until deaggregation");
313                }
314            }
315            StatementKind::Deinit(..) => {
316                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
317                    self.fail(location, "`Deinit`is not allowed until deaggregation");
318                }
319            }
320            StatementKind::Retag(kind, _) => {
321                // FIXME(JakobDegen) The validator should check that `self.body.phase <
322                // DropsLowered`. However, this causes ICEs with generation of drop shims, which
323                // seem to fail to set their `MirPhase` correctly.
324                if matches!(kind, RetagKind::TwoPhase) {
325                    self.fail(location, format!("explicit `{kind:?}` is forbidden"));
326                }
327            }
328            StatementKind::Coverage(kind) => {
329                if self.body.phase >= MirPhase::Analysis(AnalysisPhase::PostCleanup)
330                    && let CoverageKind::BlockMarker { .. } | CoverageKind::SpanMarker { .. } = kind
331                {
332                    self.fail(
333                        location,
334                        format!("{kind:?} should have been removed after analysis"),
335                    );
336                }
337            }
338            StatementKind::Assign(..)
339            | StatementKind::StorageLive(_)
340            | StatementKind::StorageDead(_)
341            | StatementKind::Intrinsic(_)
342            | StatementKind::ConstEvalCounter
343            | StatementKind::PlaceMention(..)
344            | StatementKind::BackwardIncompatibleDropHint { .. }
345            | StatementKind::Nop => {}
346        }
347
348        self.super_statement(statement, location);
349    }
350
351    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
352        match &terminator.kind {
353            TerminatorKind::Goto { target } => {
354                self.check_edge(location, *target, EdgeKind::Normal);
355            }
356            TerminatorKind::SwitchInt { targets, discr: _ } => {
357                for (_, target) in targets.iter() {
358                    self.check_edge(location, target, EdgeKind::Normal);
359                }
360                self.check_edge(location, targets.otherwise(), EdgeKind::Normal);
361
362                self.value_cache.clear();
363                self.value_cache.extend(targets.iter().map(|(value, _)| value));
364                let has_duplicates = targets.iter().len() != self.value_cache.len();
365                if has_duplicates {
366                    self.fail(
367                        location,
368                        format!(
369                            "duplicated values in `SwitchInt` terminator: {:?}",
370                            terminator.kind,
371                        ),
372                    );
373                }
374            }
375            TerminatorKind::Drop { target, unwind, .. } => {
376                self.check_edge(location, *target, EdgeKind::Normal);
377                self.check_unwind_edge(location, *unwind);
378            }
379            TerminatorKind::Call { func, args, .. }
380            | TerminatorKind::TailCall { func, args, .. } => {
381                // FIXME(explicit_tail_calls): refactor this & add tail-call specific checks
382                if let TerminatorKind::Call { target, unwind, destination, .. } = terminator.kind {
383                    if let Some(target) = target {
384                        self.check_edge(location, target, EdgeKind::Normal);
385                    }
386                    self.check_unwind_edge(location, unwind);
387
388                    // The code generation assumes that there are no critical call edges. The
389                    // assumption is used to simplify inserting code that should be executed along
390                    // the return edge from the call. FIXME(tmiasko): Since this is a strictly code
391                    // generation concern, the code generation should be responsible for handling
392                    // it.
393                    if self.body.phase >= MirPhase::Runtime(RuntimePhase::Optimized)
394                        && self.is_critical_call_edge(target, unwind)
395                    {
396                        self.fail(
397                            location,
398                            format!(
399                                "encountered critical edge in `Call` terminator {:?}",
400                                terminator.kind,
401                            ),
402                        );
403                    }
404
405                    // The call destination place and Operand::Move place used as an argument might
406                    // be passed by a reference to the callee. Consequently they cannot be packed.
407                    if is_within_packed(self.tcx, &self.body.local_decls, destination).is_some() {
408                        // This is bad! The callee will expect the memory to be aligned.
409                        self.fail(
410                            location,
411                            format!(
412                                "encountered packed place in `Call` terminator destination: {:?}",
413                                terminator.kind,
414                            ),
415                        );
416                    }
417                }
418
419                for arg in args {
420                    if let Operand::Move(place) = &arg.node {
421                        if is_within_packed(self.tcx, &self.body.local_decls, *place).is_some() {
422                            // This is bad! The callee will expect the memory to be aligned.
423                            self.fail(
424                                location,
425                                format!(
426                                    "encountered `Move` of a packed place in `Call` terminator: {:?}",
427                                    terminator.kind,
428                                ),
429                            );
430                        }
431                    }
432                }
433
434                if let ty::FnDef(did, ..) = func.ty(&self.body.local_decls, self.tcx).kind()
435                    && self.body.phase >= MirPhase::Runtime(RuntimePhase::Optimized)
436                    && matches!(self.tcx.codegen_fn_attrs(did).inline, InlineAttr::Force { .. })
437                {
438                    self.fail(location, "`#[rustc_force_inline]`-annotated function not inlined");
439                }
440            }
441            TerminatorKind::Assert { target, unwind, .. } => {
442                self.check_edge(location, *target, EdgeKind::Normal);
443                self.check_unwind_edge(location, *unwind);
444            }
445            TerminatorKind::Yield { resume, drop, .. } => {
446                if self.body.coroutine.is_none() {
447                    self.fail(location, "`Yield` cannot appear outside coroutine bodies");
448                }
449                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
450                    self.fail(location, "`Yield` should have been replaced by coroutine lowering");
451                }
452                self.check_edge(location, *resume, EdgeKind::Normal);
453                if let Some(drop) = drop {
454                    self.check_edge(location, *drop, EdgeKind::Normal);
455                }
456            }
457            TerminatorKind::FalseEdge { real_target, imaginary_target } => {
458                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
459                    self.fail(
460                        location,
461                        "`FalseEdge` should have been removed after drop elaboration",
462                    );
463                }
464                self.check_edge(location, *real_target, EdgeKind::Normal);
465                self.check_edge(location, *imaginary_target, EdgeKind::Normal);
466            }
467            TerminatorKind::FalseUnwind { real_target, unwind } => {
468                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
469                    self.fail(
470                        location,
471                        "`FalseUnwind` should have been removed after drop elaboration",
472                    );
473                }
474                self.check_edge(location, *real_target, EdgeKind::Normal);
475                self.check_unwind_edge(location, *unwind);
476            }
477            TerminatorKind::InlineAsm { targets, unwind, .. } => {
478                for &target in targets {
479                    self.check_edge(location, target, EdgeKind::Normal);
480                }
481                self.check_unwind_edge(location, *unwind);
482            }
483            TerminatorKind::CoroutineDrop => {
484                if self.body.coroutine.is_none() {
485                    self.fail(location, "`CoroutineDrop` cannot appear outside coroutine bodies");
486                }
487                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
488                    self.fail(
489                        location,
490                        "`CoroutineDrop` should have been replaced by coroutine lowering",
491                    );
492                }
493            }
494            TerminatorKind::UnwindResume => {
495                let bb = location.block;
496                if !self.body.basic_blocks[bb].is_cleanup {
497                    self.fail(location, "Cannot `UnwindResume` from non-cleanup basic block")
498                }
499                if !self.can_unwind {
500                    self.fail(location, "Cannot `UnwindResume` in a function that cannot unwind")
501                }
502            }
503            TerminatorKind::UnwindTerminate(_) => {
504                let bb = location.block;
505                if !self.body.basic_blocks[bb].is_cleanup {
506                    self.fail(location, "Cannot `UnwindTerminate` from non-cleanup basic block")
507                }
508            }
509            TerminatorKind::Return => {
510                let bb = location.block;
511                if self.body.basic_blocks[bb].is_cleanup {
512                    self.fail(location, "Cannot `Return` from cleanup basic block")
513                }
514            }
515            TerminatorKind::Unreachable => {}
516        }
517
518        self.super_terminator(terminator, location);
519    }
520
521    fn visit_source_scope(&mut self, scope: SourceScope) {
522        if self.body.source_scopes.get(scope).is_none() {
523            self.tcx.dcx().span_bug(
524                self.body.span,
525                format!(
526                    "broken MIR in {:?} ({}):\ninvalid source scope {:?}",
527                    self.body.source.instance, self.when, scope,
528                ),
529            );
530        }
531    }
532}
533
534/// A faster version of the validation pass that only checks those things which may break when
535/// instantiating any generic parameters.
536///
537/// `caller_body` is used to detect cycles in MIR inlining and MIR validation before
538/// `optimized_mir` is available.
539pub(super) fn validate_types<'tcx>(
540    tcx: TyCtxt<'tcx>,
541    typing_env: ty::TypingEnv<'tcx>,
542    body: &Body<'tcx>,
543    caller_body: &Body<'tcx>,
544) -> Vec<(Location, String)> {
545    let mut type_checker = TypeChecker { body, caller_body, tcx, typing_env, failures: Vec::new() };
546    // The type checker formats a bunch of strings with type names in it, but these strings
547    // are not always going to be encountered on the error path since the inliner also uses
548    // the validator, and there are certain kinds of inlining (even for valid code) that
549    // can cause validation errors (mostly around where clauses and rigid projections).
550    with_no_trimmed_paths!({
551        type_checker.visit_body(body);
552    });
553    type_checker.failures
554}
555
556struct TypeChecker<'a, 'tcx> {
557    body: &'a Body<'tcx>,
558    caller_body: &'a Body<'tcx>,
559    tcx: TyCtxt<'tcx>,
560    typing_env: ty::TypingEnv<'tcx>,
561    failures: Vec<(Location, String)>,
562}
563
564impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
565    fn fail(&mut self, location: Location, msg: impl Into<String>) {
566        self.failures.push((location, msg.into()));
567    }
568
569    /// Check if src can be assigned into dest.
570    /// This is not precise, it will accept some incorrect assignments.
571    fn mir_assign_valid_types(&self, src: Ty<'tcx>, dest: Ty<'tcx>) -> bool {
572        // Fast path before we normalize.
573        if src == dest {
574            // Equal types, all is good.
575            return true;
576        }
577
578        // We sometimes have to use `defining_opaque_types` for subtyping
579        // to succeed here and figuring out how exactly that should work
580        // is annoying. It is harmless enough to just not validate anything
581        // in that case. We still check this after analysis as all opaque
582        // types have been revealed at this point.
583        if (src, dest).has_opaque_types() {
584            return true;
585        }
586
587        // After borrowck subtyping should be fully explicit via
588        // `Subtype` projections.
589        let variance = if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
590            Variance::Invariant
591        } else {
592            Variance::Covariant
593        };
594
595        crate::util::relate_types(self.tcx, self.typing_env, variance, src, dest)
596    }
597
598    /// Check that the given predicate definitely holds in the param-env of this MIR body.
599    fn predicate_must_hold_modulo_regions(
600        &self,
601        pred: impl Upcast<TyCtxt<'tcx>, ty::Predicate<'tcx>>,
602    ) -> bool {
603        let pred: ty::Predicate<'tcx> = pred.upcast(self.tcx);
604
605        // We sometimes have to use `defining_opaque_types` for predicates
606        // to succeed here and figuring out how exactly that should work
607        // is annoying. It is harmless enough to just not validate anything
608        // in that case. We still check this after analysis as all opaque
609        // types have been revealed at this point.
610        if pred.has_opaque_types() {
611            return true;
612        }
613
614        let (infcx, param_env) = self.tcx.infer_ctxt().build_with_typing_env(self.typing_env);
615        let ocx = ObligationCtxt::new(&infcx);
616        ocx.register_obligation(Obligation::new(
617            self.tcx,
618            ObligationCause::dummy(),
619            param_env,
620            pred,
621        ));
622        ocx.select_all_or_error().is_empty()
623    }
624}
625
626impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
627    fn visit_operand(&mut self, operand: &Operand<'tcx>, location: Location) {
628        // This check is somewhat expensive, so only run it when -Zvalidate-mir is passed.
629        if self.tcx.sess.opts.unstable_opts.validate_mir
630            && self.body.phase < MirPhase::Runtime(RuntimePhase::Initial)
631        {
632            // `Operand::Copy` is only supposed to be used with `Copy` types.
633            if let Operand::Copy(place) = operand {
634                let ty = place.ty(&self.body.local_decls, self.tcx).ty;
635
636                if !self.tcx.type_is_copy_modulo_regions(self.typing_env, ty) {
637                    self.fail(location, format!("`Operand::Copy` with non-`Copy` type {ty}"));
638                }
639            }
640        }
641
642        self.super_operand(operand, location);
643    }
644
645    fn visit_projection_elem(
646        &mut self,
647        place_ref: PlaceRef<'tcx>,
648        elem: PlaceElem<'tcx>,
649        context: PlaceContext,
650        location: Location,
651    ) {
652        match elem {
653            ProjectionElem::OpaqueCast(ty)
654                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) =>
655            {
656                self.fail(
657                    location,
658                    format!("explicit opaque type cast to `{ty}` after `PostAnalysisNormalize`"),
659                )
660            }
661            ProjectionElem::Index(index) => {
662                let index_ty = self.body.local_decls[index].ty;
663                if index_ty != self.tcx.types.usize {
664                    self.fail(location, format!("bad index ({index_ty} != usize)"))
665                }
666            }
667            ProjectionElem::Deref
668                if self.body.phase >= MirPhase::Runtime(RuntimePhase::PostCleanup) =>
669            {
670                let base_ty = place_ref.ty(&self.body.local_decls, self.tcx).ty;
671
672                if base_ty.is_box() {
673                    self.fail(location, format!("{base_ty} dereferenced after ElaborateBoxDerefs"))
674                }
675            }
676            ProjectionElem::Field(f, ty) => {
677                let parent_ty = place_ref.ty(&self.body.local_decls, self.tcx);
678                let fail_out_of_bounds = |this: &mut Self, location| {
679                    this.fail(location, format!("Out of bounds field {f:?} for {parent_ty:?}"));
680                };
681                let check_equal = |this: &mut Self, location, f_ty| {
682                    if !this.mir_assign_valid_types(ty, f_ty) {
683                        this.fail(
684                            location,
685                            format!(
686                                "Field projection `{place_ref:?}.{f:?}` specified type `{ty}`, but actual type is `{f_ty}`"
687                            )
688                        )
689                    }
690                };
691
692                let kind = match parent_ty.ty.kind() {
693                    &ty::Alias(ty::Opaque, ty::AliasTy { def_id, args, .. }) => {
694                        self.tcx.type_of(def_id).instantiate(self.tcx, args).kind()
695                    }
696                    kind => kind,
697                };
698
699                match kind {
700                    ty::Tuple(fields) => {
701                        let Some(f_ty) = fields.get(f.as_usize()) else {
702                            fail_out_of_bounds(self, location);
703                            return;
704                        };
705                        check_equal(self, location, *f_ty);
706                    }
707                    ty::Adt(adt_def, args) => {
708                        // see <https://github.com/rust-lang/rust/blob/7601adcc764d42c9f2984082b49948af652df986/compiler/rustc_middle/src/ty/layout.rs#L861-L864>
709                        if self.tcx.is_lang_item(adt_def.did(), LangItem::DynMetadata) {
710                            self.fail(
711                                location,
712                                format!(
713                                    "You can't project to field {f:?} of `DynMetadata` because \
714                                     layout is weird and thinks it doesn't have fields."
715                                ),
716                            );
717                        }
718
719                        let var = parent_ty.variant_index.unwrap_or(FIRST_VARIANT);
720                        let Some(field) = adt_def.variant(var).fields.get(f) else {
721                            fail_out_of_bounds(self, location);
722                            return;
723                        };
724                        check_equal(self, location, field.ty(self.tcx, args));
725                    }
726                    ty::Closure(_, args) => {
727                        let args = args.as_closure();
728                        let Some(&f_ty) = args.upvar_tys().get(f.as_usize()) else {
729                            fail_out_of_bounds(self, location);
730                            return;
731                        };
732                        check_equal(self, location, f_ty);
733                    }
734                    ty::CoroutineClosure(_, args) => {
735                        let args = args.as_coroutine_closure();
736                        let Some(&f_ty) = args.upvar_tys().get(f.as_usize()) else {
737                            fail_out_of_bounds(self, location);
738                            return;
739                        };
740                        check_equal(self, location, f_ty);
741                    }
742                    &ty::Coroutine(def_id, args) => {
743                        let f_ty = if let Some(var) = parent_ty.variant_index {
744                            // If we're currently validating an inlined copy of this body,
745                            // then it will no longer be parameterized over the original
746                            // args of the coroutine. Otherwise, we prefer to use this body
747                            // since we may be in the process of computing this MIR in the
748                            // first place.
749                            let layout = if def_id == self.caller_body.source.def_id() {
750                                self.caller_body.coroutine_layout_raw()
751                            } else if self.tcx.needs_coroutine_by_move_body_def_id(def_id)
752                                && let ty::ClosureKind::FnOnce =
753                                    args.as_coroutine().kind_ty().to_opt_closure_kind().unwrap()
754                                && self.caller_body.source.def_id()
755                                    == self.tcx.coroutine_by_move_body_def_id(def_id)
756                            {
757                                // Same if this is the by-move body of a coroutine-closure.
758                                self.caller_body.coroutine_layout_raw()
759                            } else {
760                                self.tcx.coroutine_layout(def_id, args.as_coroutine().kind_ty())
761                            };
762
763                            let Some(layout) = layout else {
764                                self.fail(
765                                    location,
766                                    format!("No coroutine layout for {parent_ty:?}"),
767                                );
768                                return;
769                            };
770
771                            let Some(&local) = layout.variant_fields[var].get(f) else {
772                                fail_out_of_bounds(self, location);
773                                return;
774                            };
775
776                            let Some(f_ty) = layout.field_tys.get(local) else {
777                                self.fail(
778                                    location,
779                                    format!("Out of bounds local {local:?} for {parent_ty:?}"),
780                                );
781                                return;
782                            };
783
784                            ty::EarlyBinder::bind(f_ty.ty).instantiate(self.tcx, args)
785                        } else {
786                            let Some(&f_ty) = args.as_coroutine().prefix_tys().get(f.index())
787                            else {
788                                fail_out_of_bounds(self, location);
789                                return;
790                            };
791
792                            f_ty
793                        };
794
795                        check_equal(self, location, f_ty);
796                    }
797                    _ => {
798                        self.fail(location, format!("{:?} does not have fields", parent_ty.ty));
799                    }
800                }
801            }
802            ProjectionElem::Subtype(ty) => {
803                if !util::sub_types(
804                    self.tcx,
805                    self.typing_env,
806                    ty,
807                    place_ref.ty(&self.body.local_decls, self.tcx).ty,
808                ) {
809                    self.fail(
810                        location,
811                        format!(
812                            "Failed subtyping {ty} and {}",
813                            place_ref.ty(&self.body.local_decls, self.tcx).ty
814                        ),
815                    )
816                }
817            }
818            ProjectionElem::UnwrapUnsafeBinder(unwrapped_ty) => {
819                let binder_ty = place_ref.ty(&self.body.local_decls, self.tcx);
820                let ty::UnsafeBinder(binder_ty) = *binder_ty.ty.kind() else {
821                    self.fail(
822                        location,
823                        format!("WrapUnsafeBinder does not produce a ty::UnsafeBinder"),
824                    );
825                    return;
826                };
827                let binder_inner_ty = self.tcx.instantiate_bound_regions_with_erased(*binder_ty);
828                if !self.mir_assign_valid_types(unwrapped_ty, binder_inner_ty) {
829                    self.fail(
830                        location,
831                        format!(
832                            "Cannot unwrap unsafe binder {binder_ty:?} into type {unwrapped_ty}"
833                        ),
834                    );
835                }
836            }
837            _ => {}
838        }
839        self.super_projection_elem(place_ref, elem, context, location);
840    }
841
842    fn visit_var_debug_info(&mut self, debuginfo: &VarDebugInfo<'tcx>) {
843        if let Some(box VarDebugInfoFragment { ty, ref projection }) = debuginfo.composite {
844            if ty.is_union() || ty.is_enum() {
845                self.fail(
846                    START_BLOCK.start_location(),
847                    format!("invalid type {ty} in debuginfo for {:?}", debuginfo.name),
848                );
849            }
850            if projection.is_empty() {
851                self.fail(
852                    START_BLOCK.start_location(),
853                    format!("invalid empty projection in debuginfo for {:?}", debuginfo.name),
854                );
855            }
856            if projection.iter().any(|p| !matches!(p, PlaceElem::Field(..))) {
857                self.fail(
858                    START_BLOCK.start_location(),
859                    format!(
860                        "illegal projection {:?} in debuginfo for {:?}",
861                        projection, debuginfo.name
862                    ),
863                );
864            }
865        }
866        match debuginfo.value {
867            VarDebugInfoContents::Const(_) => {}
868            VarDebugInfoContents::Place(place) => {
869                if place.projection.iter().any(|p| !p.can_use_in_debuginfo()) {
870                    self.fail(
871                        START_BLOCK.start_location(),
872                        format!("illegal place {:?} in debuginfo for {:?}", place, debuginfo.name),
873                    );
874                }
875            }
876        }
877        self.super_var_debug_info(debuginfo);
878    }
879
880    fn visit_place(&mut self, place: &Place<'tcx>, cntxt: PlaceContext, location: Location) {
881        // Set off any `bug!`s in the type computation code
882        let _ = place.ty(&self.body.local_decls, self.tcx);
883
884        if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial)
885            && place.projection.len() > 1
886            && cntxt != PlaceContext::NonUse(NonUseContext::VarDebugInfo)
887            && place.projection[1..].contains(&ProjectionElem::Deref)
888        {
889            self.fail(
890                location,
891                format!("place {place:?} has deref as a later projection (it is only permitted as the first projection)"),
892            );
893        }
894
895        // Ensure all downcast projections are followed by field projections.
896        let mut projections_iter = place.projection.iter();
897        while let Some(proj) = projections_iter.next() {
898            if matches!(proj, ProjectionElem::Downcast(..)) {
899                if !matches!(projections_iter.next(), Some(ProjectionElem::Field(..))) {
900                    self.fail(
901                        location,
902                        format!(
903                            "place {place:?} has `Downcast` projection not followed by `Field`"
904                        ),
905                    );
906                }
907            }
908        }
909
910        self.super_place(place, cntxt, location);
911    }
912
913    fn visit_rvalue(&mut self, rvalue: &Rvalue<'tcx>, location: Location) {
914        macro_rules! check_kinds {
915            ($t:expr, $text:literal, $typat:pat) => {
916                if !matches!(($t).kind(), $typat) {
917                    self.fail(location, format!($text, $t));
918                }
919            };
920        }
921        match rvalue {
922            Rvalue::Use(_) | Rvalue::CopyForDeref(_) => {}
923            Rvalue::Aggregate(kind, fields) => match **kind {
924                AggregateKind::Tuple => {}
925                AggregateKind::Array(dest) => {
926                    for src in fields {
927                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
928                            self.fail(location, "array field has the wrong type");
929                        }
930                    }
931                }
932                AggregateKind::Adt(def_id, idx, args, _, Some(field)) => {
933                    let adt_def = self.tcx.adt_def(def_id);
934                    assert!(adt_def.is_union());
935                    assert_eq!(idx, FIRST_VARIANT);
936                    let dest_ty = self.tcx.normalize_erasing_regions(
937                        self.typing_env,
938                        adt_def.non_enum_variant().fields[field].ty(self.tcx, args),
939                    );
940                    if let [field] = fields.raw.as_slice() {
941                        let src_ty = field.ty(self.body, self.tcx);
942                        if !self.mir_assign_valid_types(src_ty, dest_ty) {
943                            self.fail(location, "union field has the wrong type");
944                        }
945                    } else {
946                        self.fail(location, "unions should have one initialized field");
947                    }
948                }
949                AggregateKind::Adt(def_id, idx, args, _, None) => {
950                    let adt_def = self.tcx.adt_def(def_id);
951                    assert!(!adt_def.is_union());
952                    let variant = &adt_def.variants()[idx];
953                    if variant.fields.len() != fields.len() {
954                        self.fail(location, "adt has the wrong number of initialized fields");
955                    }
956                    for (src, dest) in std::iter::zip(fields, &variant.fields) {
957                        let dest_ty = self
958                            .tcx
959                            .normalize_erasing_regions(self.typing_env, dest.ty(self.tcx, args));
960                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest_ty) {
961                            self.fail(location, "adt field has the wrong type");
962                        }
963                    }
964                }
965                AggregateKind::Closure(_, args) => {
966                    let upvars = args.as_closure().upvar_tys();
967                    if upvars.len() != fields.len() {
968                        self.fail(location, "closure has the wrong number of initialized fields");
969                    }
970                    for (src, dest) in std::iter::zip(fields, upvars) {
971                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
972                            self.fail(location, "closure field has the wrong type");
973                        }
974                    }
975                }
976                AggregateKind::Coroutine(_, args) => {
977                    let upvars = args.as_coroutine().upvar_tys();
978                    if upvars.len() != fields.len() {
979                        self.fail(location, "coroutine has the wrong number of initialized fields");
980                    }
981                    for (src, dest) in std::iter::zip(fields, upvars) {
982                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
983                            self.fail(location, "coroutine field has the wrong type");
984                        }
985                    }
986                }
987                AggregateKind::CoroutineClosure(_, args) => {
988                    let upvars = args.as_coroutine_closure().upvar_tys();
989                    if upvars.len() != fields.len() {
990                        self.fail(
991                            location,
992                            "coroutine-closure has the wrong number of initialized fields",
993                        );
994                    }
995                    for (src, dest) in std::iter::zip(fields, upvars) {
996                        if !self.mir_assign_valid_types(src.ty(self.body, self.tcx), dest) {
997                            self.fail(location, "coroutine-closure field has the wrong type");
998                        }
999                    }
1000                }
1001                AggregateKind::RawPtr(pointee_ty, mutability) => {
1002                    if !matches!(self.body.phase, MirPhase::Runtime(_)) {
1003                        // It would probably be fine to support this in earlier phases, but at the
1004                        // time of writing it's only ever introduced from intrinsic lowering, so
1005                        // earlier things just `bug!` on it.
1006                        self.fail(location, "RawPtr should be in runtime MIR only");
1007                    }
1008
1009                    if let [data_ptr, metadata] = fields.raw.as_slice() {
1010                        let data_ptr_ty = data_ptr.ty(self.body, self.tcx);
1011                        let metadata_ty = metadata.ty(self.body, self.tcx);
1012                        if let ty::RawPtr(in_pointee, in_mut) = data_ptr_ty.kind() {
1013                            if *in_mut != mutability {
1014                                self.fail(location, "input and output mutability must match");
1015                            }
1016
1017                            // FIXME: check `Thin` instead of `Sized`
1018                            if !in_pointee.is_sized(self.tcx, self.typing_env) {
1019                                self.fail(location, "input pointer must be thin");
1020                            }
1021                        } else {
1022                            self.fail(
1023                                location,
1024                                "first operand to raw pointer aggregate must be a raw pointer",
1025                            );
1026                        }
1027
1028                        // FIXME: Check metadata more generally
1029                        if pointee_ty.is_slice() {
1030                            if !self.mir_assign_valid_types(metadata_ty, self.tcx.types.usize) {
1031                                self.fail(location, "slice metadata must be usize");
1032                            }
1033                        } else if pointee_ty.is_sized(self.tcx, self.typing_env) {
1034                            if metadata_ty != self.tcx.types.unit {
1035                                self.fail(location, "metadata for pointer-to-thin must be unit");
1036                            }
1037                        }
1038                    } else {
1039                        self.fail(location, "raw pointer aggregate must have 2 fields");
1040                    }
1041                }
1042            },
1043            Rvalue::Ref(_, BorrowKind::Fake(_), _) => {
1044                if self.body.phase >= MirPhase::Runtime(RuntimePhase::Initial) {
1045                    self.fail(
1046                        location,
1047                        "`Assign` statement with a `Fake` borrow should have been removed in runtime MIR",
1048                    );
1049                }
1050            }
1051            Rvalue::Ref(..) => {}
1052            Rvalue::Len(p) => {
1053                let pty = p.ty(&self.body.local_decls, self.tcx).ty;
1054                check_kinds!(
1055                    pty,
1056                    "Cannot compute length of non-array type {:?}",
1057                    ty::Array(..) | ty::Slice(..)
1058                );
1059            }
1060            Rvalue::BinaryOp(op, vals) => {
1061                use BinOp::*;
1062                let a = vals.0.ty(&self.body.local_decls, self.tcx);
1063                let b = vals.1.ty(&self.body.local_decls, self.tcx);
1064                if crate::util::binop_right_homogeneous(*op) {
1065                    if let Eq | Lt | Le | Ne | Ge | Gt = op {
1066                        // The function pointer types can have lifetimes
1067                        if !self.mir_assign_valid_types(a, b) {
1068                            self.fail(
1069                                location,
1070                                format!("Cannot {op:?} compare incompatible types {a} and {b}"),
1071                            );
1072                        }
1073                    } else if a != b {
1074                        self.fail(
1075                            location,
1076                            format!("Cannot perform binary op {op:?} on unequal types {a} and {b}"),
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;
1506                if !matches!(
1507                    pty.kind(),
1508                    ty::Adt(..) | ty::Coroutine(..) | ty::Alias(ty::Opaque, ..)
1509                ) {
1510                    self.fail(
1511                        location,
1512                        format!(
1513                            "`SetDiscriminant` is only allowed on ADTs and coroutines, not {pty}"
1514                        ),
1515                    );
1516                }
1517            }
1518            StatementKind::Deinit(..) => {
1519                if self.body.phase < MirPhase::Runtime(RuntimePhase::Initial) {
1520                    self.fail(location, "`Deinit`is not allowed until deaggregation");
1521                }
1522            }
1523            StatementKind::Retag(kind, _) => {
1524                // FIXME(JakobDegen) The validator should check that `self.body.phase <
1525                // DropsLowered`. However, this causes ICEs with generation of drop shims, which
1526                // seem to fail to set their `MirPhase` correctly.
1527                if matches!(kind, RetagKind::TwoPhase) {
1528                    self.fail(location, format!("explicit `{kind:?}` is forbidden"));
1529                }
1530            }
1531            StatementKind::StorageLive(_)
1532            | StatementKind::StorageDead(_)
1533            | StatementKind::Coverage(_)
1534            | StatementKind::ConstEvalCounter
1535            | StatementKind::PlaceMention(..)
1536            | StatementKind::BackwardIncompatibleDropHint { .. }
1537            | StatementKind::Nop => {}
1538        }
1539
1540        self.super_statement(statement, location);
1541    }
1542
1543    fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
1544        match &terminator.kind {
1545            TerminatorKind::SwitchInt { targets, discr } => {
1546                let switch_ty = discr.ty(&self.body.local_decls, self.tcx);
1547
1548                let target_width = self.tcx.sess.target.pointer_width;
1549
1550                let size = Size::from_bits(match switch_ty.kind() {
1551                    ty::Uint(uint) => uint.normalize(target_width).bit_width().unwrap(),
1552                    ty::Int(int) => int.normalize(target_width).bit_width().unwrap(),
1553                    ty::Char => 32,
1554                    ty::Bool => 1,
1555                    other => bug!("unhandled type: {:?}", other),
1556                });
1557
1558                for (value, _) in targets.iter() {
1559                    if ScalarInt::try_from_uint(value, size).is_none() {
1560                        self.fail(
1561                            location,
1562                            format!("the value {value:#x} is not a proper {switch_ty}"),
1563                        )
1564                    }
1565                }
1566            }
1567            TerminatorKind::Call { func, .. } | TerminatorKind::TailCall { func, .. } => {
1568                let func_ty = func.ty(&self.body.local_decls, self.tcx);
1569                match func_ty.kind() {
1570                    ty::FnPtr(..) | ty::FnDef(..) => {}
1571                    _ => self.fail(
1572                        location,
1573                        format!(
1574                            "encountered non-callable type {func_ty} in `{}` terminator",
1575                            terminator.kind.name()
1576                        ),
1577                    ),
1578                }
1579
1580                if let TerminatorKind::TailCall { .. } = terminator.kind {
1581                    // FIXME(explicit_tail_calls): implement tail-call specific checks here (such
1582                    // as signature matching, forbidding closures, etc)
1583                }
1584            }
1585            TerminatorKind::Assert { cond, .. } => {
1586                let cond_ty = cond.ty(&self.body.local_decls, self.tcx);
1587                if cond_ty != self.tcx.types.bool {
1588                    self.fail(
1589                        location,
1590                        format!(
1591                            "encountered non-boolean condition of type {cond_ty} in `Assert` terminator"
1592                        ),
1593                    );
1594                }
1595            }
1596            TerminatorKind::Goto { .. }
1597            | TerminatorKind::Drop { .. }
1598            | TerminatorKind::Yield { .. }
1599            | TerminatorKind::FalseEdge { .. }
1600            | TerminatorKind::FalseUnwind { .. }
1601            | TerminatorKind::InlineAsm { .. }
1602            | TerminatorKind::CoroutineDrop
1603            | TerminatorKind::UnwindResume
1604            | TerminatorKind::UnwindTerminate(_)
1605            | TerminatorKind::Return
1606            | TerminatorKind::Unreachable => {}
1607        }
1608
1609        self.super_terminator(terminator, location);
1610    }
1611}
rustc_mir_transform/validate.rs

rustc_mir_transform/
validate.rs
