rustc_middle/mir/interpret/
error.rs

1use std::any::Any;
2use std::backtrace::Backtrace;
3use std::borrow::Cow;
4use std::{convert, fmt, mem, ops};
5
6use either::Either;
7use rustc_abi::{Align, Size, VariantIdx, WrappingRange};
8use rustc_data_structures::sync::Lock;
9use rustc_errors::{DiagArgName, DiagArgValue, DiagMessage, ErrorGuaranteed, IntoDiagArg};
10use rustc_macros::{HashStable, TyDecodable, TyEncodable};
11use rustc_session::CtfeBacktrace;
12use rustc_span::def_id::DefId;
13use rustc_span::{DUMMY_SP, Span, Symbol};
14
15use super::{AllocId, AllocRange, ConstAllocation, Pointer, Scalar};
16use crate::error;
17use crate::mir::{ConstAlloc, ConstValue};
18use crate::ty::{self, Mutability, Ty, TyCtxt, ValTree, layout, tls};
19
20#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
21pub enum ErrorHandled {
22    /// Already reported an error for this evaluation, and the compilation is
23    /// *guaranteed* to fail. Warnings/lints *must not* produce `Reported`.
24    Reported(ReportedErrorInfo, Span),
25    /// Don't emit an error, the evaluation failed because the MIR was generic
26    /// and the args didn't fully monomorphize it.
27    TooGeneric(Span),
28}
29
30impl From<ReportedErrorInfo> for ErrorHandled {
31    #[inline]
32    fn from(error: ReportedErrorInfo) -> ErrorHandled {
33        ErrorHandled::Reported(error, DUMMY_SP)
34    }
35}
36
37impl ErrorHandled {
38    pub(crate) fn with_span(self, span: Span) -> Self {
39        match self {
40            ErrorHandled::Reported(err, _span) => ErrorHandled::Reported(err, span),
41            ErrorHandled::TooGeneric(_span) => ErrorHandled::TooGeneric(span),
42        }
43    }
44
45    pub fn emit_note(&self, tcx: TyCtxt<'_>) {
46        match self {
47            &ErrorHandled::Reported(err, span) => {
48                if !err.allowed_in_infallible && !span.is_dummy() {
49                    tcx.dcx().emit_note(error::ErroneousConstant { span });
50                }
51            }
52            &ErrorHandled::TooGeneric(_) => {}
53        }
54    }
55}
56
57#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
58pub struct ReportedErrorInfo {
59    error: ErrorGuaranteed,
60    /// Whether this error is allowed to show up even in otherwise "infallible" promoteds.
61    /// This is for things like overflows during size computation or resource exhaustion.
62    allowed_in_infallible: bool,
63}
64
65impl ReportedErrorInfo {
66    #[inline]
67    pub fn const_eval_error(error: ErrorGuaranteed) -> ReportedErrorInfo {
68        ReportedErrorInfo { allowed_in_infallible: false, error }
69    }
70
71    /// Use this when the error that led to this is *not* a const-eval error
72    /// (e.g., a layout or type checking error).
73    #[inline]
74    pub fn non_const_eval_error(error: ErrorGuaranteed) -> ReportedErrorInfo {
75        ReportedErrorInfo { allowed_in_infallible: true, error }
76    }
77
78    /// Use this when the error that led to this *is* a const-eval error, but
79    /// we do allow it to occur in infallible constants (e.g., resource exhaustion).
80    #[inline]
81    pub fn allowed_in_infallible(error: ErrorGuaranteed) -> ReportedErrorInfo {
82        ReportedErrorInfo { allowed_in_infallible: true, error }
83    }
84
85    pub fn is_allowed_in_infallible(&self) -> bool {
86        self.allowed_in_infallible
87    }
88}
89
90impl From<ReportedErrorInfo> for ErrorGuaranteed {
91    #[inline]
92    fn from(val: ReportedErrorInfo) -> Self {
93        val.error
94    }
95}
96
97/// An error type for the `const_to_valtree` query. Some error should be reported with a "use-site span",
98/// which means the query cannot emit the error, so those errors are represented as dedicated variants here.
99#[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
100pub enum ValTreeCreationError<'tcx> {
101    /// The constant is too big to be valtree'd.
102    NodesOverflow,
103    /// The constant references mutable or external memory, so it cannot be valtree'd.
104    InvalidConst,
105    /// Values of this type, or this particular value, are not supported as valtrees.
106    NonSupportedType(Ty<'tcx>),
107    /// The error has already been handled by const evaluation.
108    ErrorHandled(ErrorHandled),
109}
110
111impl<'tcx> From<ErrorHandled> for ValTreeCreationError<'tcx> {
112    fn from(err: ErrorHandled) -> Self {
113        ValTreeCreationError::ErrorHandled(err)
114    }
115}
116
117impl<'tcx> From<InterpErrorInfo<'tcx>> for ValTreeCreationError<'tcx> {
118    fn from(err: InterpErrorInfo<'tcx>) -> Self {
119        // An error occurred outside the const-eval query, as part of constructing the valtree. We
120        // don't currently preserve the details of this error, since `InterpErrorInfo` cannot be put
121        // into a query result and it can only be access of some mutable or external memory.
122        let (_kind, backtrace) = err.into_parts();
123        backtrace.print_backtrace();
124        ValTreeCreationError::InvalidConst
125    }
126}
127
128impl<'tcx> ValTreeCreationError<'tcx> {
129    pub(crate) fn with_span(self, span: Span) -> Self {
130        use ValTreeCreationError::*;
131        match self {
132            ErrorHandled(handled) => ErrorHandled(handled.with_span(span)),
133            other => other,
134        }
135    }
136}
137
138pub type EvalToAllocationRawResult<'tcx> = Result<ConstAlloc<'tcx>, ErrorHandled>;
139pub type EvalStaticInitializerRawResult<'tcx> = Result<ConstAllocation<'tcx>, ErrorHandled>;
140pub type EvalToConstValueResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;
141pub type EvalToValTreeResult<'tcx> = Result<ValTree<'tcx>, ValTreeCreationError<'tcx>>;
142
143#[cfg(target_pointer_width = "64")]
144rustc_data_structures::static_assert_size!(InterpErrorInfo<'_>, 8);
145
146/// Packages the kind of error we got from the const code interpreter
147/// up with a Rust-level backtrace of where the error occurred.
148/// These should always be constructed by calling `.into()` on
149/// an `InterpError`. In `rustc_mir::interpret`, we have `throw_err_*`
150/// macros for this.
151///
152/// Interpreter errors must *not* be silently discarded (that will lead to a panic). Instead,
153/// explicitly call `discard_err` if this is really the right thing to do. Note that if
154/// this happens during const-eval or in Miri, it could lead to a UB error being lost!
155#[derive(Debug)]
156pub struct InterpErrorInfo<'tcx>(Box<InterpErrorInfoInner<'tcx>>);
157
158#[derive(Debug)]
159struct InterpErrorInfoInner<'tcx> {
160    kind: InterpErrorKind<'tcx>,
161    backtrace: InterpErrorBacktrace,
162}
163
164#[derive(Debug)]
165pub struct InterpErrorBacktrace {
166    backtrace: Option<Box<Backtrace>>,
167}
168
169impl InterpErrorBacktrace {
170    pub fn new() -> InterpErrorBacktrace {
171        let capture_backtrace = tls::with_opt(|tcx| {
172            if let Some(tcx) = tcx {
173                *Lock::borrow(&tcx.sess.ctfe_backtrace)
174            } else {
175                CtfeBacktrace::Disabled
176            }
177        });
178
179        let backtrace = match capture_backtrace {
180            CtfeBacktrace::Disabled => None,
181            CtfeBacktrace::Capture => Some(Box::new(Backtrace::force_capture())),
182            CtfeBacktrace::Immediate => {
183                // Print it now.
184                let backtrace = Backtrace::force_capture();
185                print_backtrace(&backtrace);
186                None
187            }
188        };
189
190        InterpErrorBacktrace { backtrace }
191    }
192
193    pub fn print_backtrace(&self) {
194        if let Some(backtrace) = self.backtrace.as_ref() {
195            print_backtrace(backtrace);
196        }
197    }
198}
199
200impl<'tcx> InterpErrorInfo<'tcx> {
201    pub fn into_parts(self) -> (InterpErrorKind<'tcx>, InterpErrorBacktrace) {
202        let InterpErrorInfo(box InterpErrorInfoInner { kind, backtrace }) = self;
203        (kind, backtrace)
204    }
205
206    pub fn into_kind(self) -> InterpErrorKind<'tcx> {
207        self.0.kind
208    }
209
210    pub fn from_parts(kind: InterpErrorKind<'tcx>, backtrace: InterpErrorBacktrace) -> Self {
211        Self(Box::new(InterpErrorInfoInner { kind, backtrace }))
212    }
213
214    #[inline]
215    pub fn kind(&self) -> &InterpErrorKind<'tcx> {
216        &self.0.kind
217    }
218}
219
220fn print_backtrace(backtrace: &Backtrace) {
221    eprintln!("\n\nAn error occurred in the MIR interpreter:\n{backtrace}");
222}
223
224impl From<ErrorHandled> for InterpErrorInfo<'_> {
225    fn from(err: ErrorHandled) -> Self {
226        InterpErrorKind::InvalidProgram(match err {
227            ErrorHandled::Reported(r, _span) => InvalidProgramInfo::AlreadyReported(r),
228            ErrorHandled::TooGeneric(_span) => InvalidProgramInfo::TooGeneric,
229        })
230        .into()
231    }
232}
233
234impl<'tcx> From<InterpErrorKind<'tcx>> for InterpErrorInfo<'tcx> {
235    fn from(kind: InterpErrorKind<'tcx>) -> Self {
236        InterpErrorInfo(Box::new(InterpErrorInfoInner {
237            kind,
238            backtrace: InterpErrorBacktrace::new(),
239        }))
240    }
241}
242
243/// Error information for when the program we executed turned out not to actually be a valid
244/// program. This cannot happen in stand-alone Miri (except for layout errors that are only detect
245/// during monomorphization), but it can happen during CTFE/ConstProp where we work on generic code
246/// or execution does not have all information available.
247#[derive(Debug)]
248pub enum InvalidProgramInfo<'tcx> {
249    /// Resolution can fail if we are in a too generic context.
250    TooGeneric,
251    /// Abort in case errors are already reported.
252    AlreadyReported(ReportedErrorInfo),
253    /// An error occurred during layout computation.
254    Layout(layout::LayoutError<'tcx>),
255}
256
257/// Details of why a pointer had to be in-bounds.
258#[derive(Debug, Copy, Clone)]
259pub enum CheckInAllocMsg {
260    /// We are access memory.
261    MemoryAccess,
262    /// We are doing pointer arithmetic.
263    InboundsPointerArithmetic,
264    /// None of the above -- generic/unspecific inbounds test.
265    Dereferenceable,
266}
267
268/// Details of which pointer is not aligned.
269#[derive(Debug, Copy, Clone)]
270pub enum CheckAlignMsg {
271    /// The accessed pointer did not have proper alignment.
272    AccessedPtr,
273    /// The access occurred with a place that was based on a misaligned pointer.
274    BasedOn,
275}
276
277#[derive(Debug, Copy, Clone)]
278pub enum InvalidMetaKind {
279    /// Size of a `[T]` is too big
280    SliceTooBig,
281    /// Size of a DST is too big
282    TooBig,
283}
284
285impl IntoDiagArg for InvalidMetaKind {
286    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
287        DiagArgValue::Str(Cow::Borrowed(match self {
288            InvalidMetaKind::SliceTooBig => "slice_too_big",
289            InvalidMetaKind::TooBig => "too_big",
290        }))
291    }
292}
293
294/// Details of an access to uninitialized bytes / bad pointer bytes where it is not allowed.
295#[derive(Debug, Clone, Copy)]
296pub struct BadBytesAccess {
297    /// Range of the original memory access.
298    pub access: AllocRange,
299    /// Range of the bad memory that was encountered. (Might not be maximal.)
300    pub bad: AllocRange,
301}
302
303/// Information about a size mismatch.
304#[derive(Debug)]
305pub struct ScalarSizeMismatch {
306    pub target_size: u64,
307    pub data_size: u64,
308}
309
310/// Information about a misaligned pointer.
311#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
312pub struct Misalignment {
313    pub has: Align,
314    pub required: Align,
315}
316
317macro_rules! impl_into_diag_arg_through_debug {
318    ($($ty:ty),*$(,)?) => {$(
319        impl IntoDiagArg for $ty {
320            fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
321                DiagArgValue::Str(Cow::Owned(format!("{self:?}")))
322            }
323        }
324    )*}
325}
326
327// These types have nice `Debug` output so we can just use them in diagnostics.
328impl_into_diag_arg_through_debug! {
329    AllocId,
330    Pointer<AllocId>,
331    AllocRange,
332}
333
334/// Error information for when the program caused Undefined Behavior.
335#[derive(Debug)]
336pub enum UndefinedBehaviorInfo<'tcx> {
337    /// Free-form case. Only for errors that are never caught! Used by miri
338    Ub(String),
339    // FIXME(fee1-dead) these should all be actual variants of the enum instead of dynamically
340    // dispatched
341    /// A custom (free-form) fluent-translated error, created by `err_ub_custom!`.
342    Custom(crate::error::CustomSubdiagnostic<'tcx>),
343    /// Validation error.
344    ValidationError(ValidationErrorInfo<'tcx>),
345
346    /// Unreachable code was executed.
347    Unreachable,
348    /// A slice/array index projection went out-of-bounds.
349    BoundsCheckFailed { len: u64, index: u64 },
350    /// Something was divided by 0 (x / 0).
351    DivisionByZero,
352    /// Something was "remainded" by 0 (x % 0).
353    RemainderByZero,
354    /// Signed division overflowed (INT_MIN / -1).
355    DivisionOverflow,
356    /// Signed remainder overflowed (INT_MIN % -1).
357    RemainderOverflow,
358    /// Overflowing inbounds pointer arithmetic.
359    PointerArithOverflow,
360    /// Overflow in arithmetic that may not overflow.
361    ArithOverflow { intrinsic: Symbol },
362    /// Shift by too much.
363    ShiftOverflow { intrinsic: Symbol, shift_amount: Either<u128, i128> },
364    /// Invalid metadata in a wide pointer
365    InvalidMeta(InvalidMetaKind),
366    /// Reading a C string that does not end within its allocation.
367    UnterminatedCString(Pointer<AllocId>),
368    /// Using a pointer after it got freed.
369    PointerUseAfterFree(AllocId, CheckInAllocMsg),
370    /// Used a pointer outside the bounds it is valid for.
371    PointerOutOfBounds {
372        alloc_id: AllocId,
373        alloc_size: Size,
374        ptr_offset: i64,
375        /// The size of the memory range that was expected to be in-bounds.
376        inbounds_size: i64,
377        msg: CheckInAllocMsg,
378    },
379    /// Using an integer as a pointer in the wrong way.
380    DanglingIntPointer {
381        addr: u64,
382        /// The size of the memory range that was expected to be in-bounds (or 0 if we need an
383        /// allocation but not any actual memory there, e.g. for function pointers).
384        inbounds_size: i64,
385        msg: CheckInAllocMsg,
386    },
387    /// Used a pointer with bad alignment.
388    AlignmentCheckFailed(Misalignment, CheckAlignMsg),
389    /// Writing to read-only memory.
390    WriteToReadOnly(AllocId),
391    /// Trying to access the data behind a function pointer.
392    DerefFunctionPointer(AllocId),
393    /// Trying to access the data behind a vtable pointer.
394    DerefVTablePointer(AllocId),
395    /// Using a non-boolean `u8` as bool.
396    InvalidBool(u8),
397    /// Using a non-character `u32` as character.
398    InvalidChar(u32),
399    /// The tag of an enum does not encode an actual discriminant.
400    InvalidTag(Scalar<AllocId>),
401    /// Using a pointer-not-to-a-function as function pointer.
402    InvalidFunctionPointer(Pointer<AllocId>),
403    /// Using a pointer-not-to-a-vtable as vtable pointer.
404    InvalidVTablePointer(Pointer<AllocId>),
405    /// Using a vtable for the wrong trait.
406    InvalidVTableTrait {
407        /// The vtable that was actually referenced by the wide pointer metadata.
408        vtable_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
409        /// The vtable that was expected at the point in MIR that it was accessed.
410        expected_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
411    },
412    /// Using a string that is not valid UTF-8,
413    InvalidStr(std::str::Utf8Error),
414    /// Using uninitialized data where it is not allowed.
415    InvalidUninitBytes(Option<(AllocId, BadBytesAccess)>),
416    /// Working with a local that is not currently live.
417    DeadLocal,
418    /// Data size is not equal to target size.
419    ScalarSizeMismatch(ScalarSizeMismatch),
420    /// A discriminant of an uninhabited enum variant is written.
421    UninhabitedEnumVariantWritten(VariantIdx),
422    /// An uninhabited enum variant is projected.
423    UninhabitedEnumVariantRead(Option<VariantIdx>),
424    /// Trying to set discriminant to the niched variant, but the value does not match.
425    InvalidNichedEnumVariantWritten { enum_ty: Ty<'tcx> },
426    /// ABI-incompatible argument types.
427    AbiMismatchArgument { caller_ty: Ty<'tcx>, callee_ty: Ty<'tcx> },
428    /// ABI-incompatible return types.
429    AbiMismatchReturn { caller_ty: Ty<'tcx>, callee_ty: Ty<'tcx> },
430}
431
432#[derive(Debug, Clone, Copy)]
433pub enum PointerKind {
434    Ref(Mutability),
435    Box,
436}
437
438impl IntoDiagArg for PointerKind {
439    fn into_diag_arg(self, _: &mut Option<std::path::PathBuf>) -> DiagArgValue {
440        DiagArgValue::Str(
441            match self {
442                Self::Ref(_) => "ref",
443                Self::Box => "box",
444            }
445            .into(),
446        )
447    }
448}
449
450#[derive(Debug)]
451pub struct ValidationErrorInfo<'tcx> {
452    pub path: Option<String>,
453    pub kind: ValidationErrorKind<'tcx>,
454}
455
456#[derive(Debug)]
457pub enum ExpectedKind {
458    Reference,
459    Box,
460    RawPtr,
461    InitScalar,
462    Bool,
463    Char,
464    Float,
465    Int,
466    FnPtr,
467    EnumTag,
468    Str,
469}
470
471impl From<PointerKind> for ExpectedKind {
472    fn from(x: PointerKind) -> ExpectedKind {
473        match x {
474            PointerKind::Box => ExpectedKind::Box,
475            PointerKind::Ref(_) => ExpectedKind::Reference,
476        }
477    }
478}
479
480#[derive(Debug)]
481pub enum ValidationErrorKind<'tcx> {
482    PointerAsInt {
483        expected: ExpectedKind,
484    },
485    PartialPointer,
486    PtrToUninhabited {
487        ptr_kind: PointerKind,
488        ty: Ty<'tcx>,
489    },
490    MutableRefToImmutable,
491    UnsafeCellInImmutable,
492    MutableRefInConst,
493    NullFnPtr,
494    NeverVal,
495    NullablePtrOutOfRange {
496        range: WrappingRange,
497        max_value: u128,
498    },
499    PtrOutOfRange {
500        range: WrappingRange,
501        max_value: u128,
502    },
503    OutOfRange {
504        value: String,
505        range: WrappingRange,
506        max_value: u128,
507    },
508    UninhabitedVal {
509        ty: Ty<'tcx>,
510    },
511    InvalidEnumTag {
512        value: String,
513    },
514    UninhabitedEnumVariant,
515    Uninit {
516        expected: ExpectedKind,
517    },
518    InvalidVTablePtr {
519        value: String,
520    },
521    InvalidMetaWrongTrait {
522        /// The vtable that was actually referenced by the wide pointer metadata.
523        vtable_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
524        /// The vtable that was expected at the point in MIR that it was accessed.
525        expected_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
526    },
527    InvalidMetaSliceTooLarge {
528        ptr_kind: PointerKind,
529    },
530    InvalidMetaTooLarge {
531        ptr_kind: PointerKind,
532    },
533    UnalignedPtr {
534        ptr_kind: PointerKind,
535        required_bytes: u64,
536        found_bytes: u64,
537    },
538    NullPtr {
539        ptr_kind: PointerKind,
540    },
541    DanglingPtrNoProvenance {
542        ptr_kind: PointerKind,
543        pointer: String,
544    },
545    DanglingPtrOutOfBounds {
546        ptr_kind: PointerKind,
547    },
548    DanglingPtrUseAfterFree {
549        ptr_kind: PointerKind,
550    },
551    InvalidBool {
552        value: String,
553    },
554    InvalidChar {
555        value: String,
556    },
557    InvalidFnPtr {
558        value: String,
559    },
560}
561
562/// Error information for when the program did something that might (or might not) be correct
563/// to do according to the Rust spec, but due to limitations in the interpreter, the
564/// operation could not be carried out. These limitations can differ between CTFE and the
565/// Miri engine, e.g., CTFE does not support dereferencing pointers at integral addresses.
566#[derive(Debug)]
567pub enum UnsupportedOpInfo {
568    /// Free-form case. Only for errors that are never caught! Used by Miri.
569    // FIXME still use translatable diagnostics
570    Unsupported(String),
571    /// Unsized local variables.
572    UnsizedLocal,
573    /// Extern type field with an indeterminate offset.
574    ExternTypeField,
575    //
576    // The variants below are only reachable from CTFE/const prop, miri will never emit them.
577    //
578    /// Overwriting parts of a pointer; without knowing absolute addresses, the resulting state
579    /// cannot be represented by the CTFE interpreter.
580    OverwritePartialPointer(Pointer<AllocId>),
581    /// Attempting to read or copy parts of a pointer to somewhere else; without knowing absolute
582    /// addresses, the resulting state cannot be represented by the CTFE interpreter.
583    ReadPartialPointer(Pointer<AllocId>),
584    /// Encountered a pointer where we needed an integer.
585    ReadPointerAsInt(Option<(AllocId, BadBytesAccess)>),
586    /// Accessing thread local statics
587    ThreadLocalStatic(DefId),
588    /// Accessing an unsupported extern static.
589    ExternStatic(DefId),
590}
591
592/// Error information for when the program exhausted the resources granted to it
593/// by the interpreter.
594#[derive(Debug)]
595pub enum ResourceExhaustionInfo {
596    /// The stack grew too big.
597    StackFrameLimitReached,
598    /// There is not enough memory (on the host) to perform an allocation.
599    MemoryExhausted,
600    /// The address space (of the target) is full.
601    AddressSpaceFull,
602    /// The compiler got an interrupt signal (a user ran out of patience).
603    Interrupted,
604}
605
606/// A trait for machine-specific errors (or other "machine stop" conditions).
607pub trait MachineStopType: Any + fmt::Debug + Send {
608    /// The diagnostic message for this error
609    fn diagnostic_message(&self) -> DiagMessage;
610    /// Add diagnostic arguments by passing name and value pairs to `adder`, which are passed to
611    /// fluent for formatting the translated diagnostic message.
612    fn add_args(self: Box<Self>, adder: &mut dyn FnMut(DiagArgName, DiagArgValue));
613}
614
615impl dyn MachineStopType {
616    #[inline(always)]
617    pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
618        let x: &dyn Any = self;
619        x.downcast_ref()
620    }
621}
622
623#[derive(Debug)]
624pub enum InterpErrorKind<'tcx> {
625    /// The program caused undefined behavior.
626    UndefinedBehavior(UndefinedBehaviorInfo<'tcx>),
627    /// The program did something the interpreter does not support (some of these *might* be UB
628    /// but the interpreter is not sure).
629    Unsupported(UnsupportedOpInfo),
630    /// The program was invalid (ill-typed, bad MIR, not sufficiently monomorphized, ...).
631    InvalidProgram(InvalidProgramInfo<'tcx>),
632    /// The program exhausted the interpreter's resources (stack/heap too big,
633    /// execution takes too long, ...).
634    ResourceExhaustion(ResourceExhaustionInfo),
635    /// Stop execution for a machine-controlled reason. This is never raised by
636    /// the core engine itself.
637    MachineStop(Box<dyn MachineStopType>),
638}
639
640impl InterpErrorKind<'_> {
641    /// Some errors do string formatting even if the error is never printed.
642    /// To avoid performance issues, there are places where we want to be sure to never raise these formatting errors,
643    /// so this method lets us detect them and `bug!` on unexpected errors.
644    pub fn formatted_string(&self) -> bool {
645        matches!(
646            self,
647            InterpErrorKind::Unsupported(UnsupportedOpInfo::Unsupported(_))
648                | InterpErrorKind::UndefinedBehavior(UndefinedBehaviorInfo::ValidationError { .. })
649                | InterpErrorKind::UndefinedBehavior(UndefinedBehaviorInfo::Ub(_))
650        )
651    }
652}
653
654// Macros for constructing / throwing `InterpErrorKind`
655#[macro_export]
656macro_rules! err_unsup {
657    ($($tt:tt)*) => {
658        $crate::mir::interpret::InterpErrorKind::Unsupported(
659            $crate::mir::interpret::UnsupportedOpInfo::$($tt)*
660        )
661    };
662}
663
664#[macro_export]
665macro_rules! err_unsup_format {
666    ($($tt:tt)*) => { $crate::err_unsup!(Unsupported(format!($($tt)*))) };
667}
668
669#[macro_export]
670macro_rules! err_inval {
671    ($($tt:tt)*) => {
672        $crate::mir::interpret::InterpErrorKind::InvalidProgram(
673            $crate::mir::interpret::InvalidProgramInfo::$($tt)*
674        )
675    };
676}
677
678#[macro_export]
679macro_rules! err_ub {
680    ($($tt:tt)*) => {
681        $crate::mir::interpret::InterpErrorKind::UndefinedBehavior(
682            $crate::mir::interpret::UndefinedBehaviorInfo::$($tt)*
683        )
684    };
685}
686
687#[macro_export]
688macro_rules! err_ub_format {
689    ($($tt:tt)*) => { $crate::err_ub!(Ub(format!($($tt)*))) };
690}
691
692#[macro_export]
693macro_rules! err_ub_custom {
694    ($msg:expr $(, $($name:ident = $value:expr),* $(,)?)?) => {{
695        $(
696            let ($($name,)*) = ($($value,)*);
697        )?
698        $crate::err_ub!(Custom(
699            $crate::error::CustomSubdiagnostic {
700                msg: || $msg,
701                add_args: Box::new(move |mut set_arg| {
702                    $($(
703                        set_arg(stringify!($name).into(), rustc_errors::IntoDiagArg::into_diag_arg($name, &mut None));
704                    )*)?
705                })
706            }
707        ))
708    }};
709}
710
711#[macro_export]
712macro_rules! err_exhaust {
713    ($($tt:tt)*) => {
714        $crate::mir::interpret::InterpErrorKind::ResourceExhaustion(
715            $crate::mir::interpret::ResourceExhaustionInfo::$($tt)*
716        )
717    };
718}
719
720#[macro_export]
721macro_rules! err_machine_stop {
722    ($($tt:tt)*) => {
723        $crate::mir::interpret::InterpErrorKind::MachineStop(Box::new($($tt)*))
724    };
725}
726
727// In the `throw_*` macros, avoid `return` to make them work with `try {}`.
728#[macro_export]
729macro_rules! throw_unsup {
730    ($($tt:tt)*) => { do yeet $crate::err_unsup!($($tt)*) };
731}
732
733#[macro_export]
734macro_rules! throw_unsup_format {
735    ($($tt:tt)*) => { do yeet $crate::err_unsup_format!($($tt)*) };
736}
737
738#[macro_export]
739macro_rules! throw_inval {
740    ($($tt:tt)*) => { do yeet $crate::err_inval!($($tt)*) };
741}
742
743#[macro_export]
744macro_rules! throw_ub {
745    ($($tt:tt)*) => { do yeet $crate::err_ub!($($tt)*) };
746}
747
748#[macro_export]
749macro_rules! throw_ub_format {
750    ($($tt:tt)*) => { do yeet $crate::err_ub_format!($($tt)*) };
751}
752
753#[macro_export]
754macro_rules! throw_ub_custom {
755    ($($tt:tt)*) => { do yeet $crate::err_ub_custom!($($tt)*) };
756}
757
758#[macro_export]
759macro_rules! throw_exhaust {
760    ($($tt:tt)*) => { do yeet $crate::err_exhaust!($($tt)*) };
761}
762
763#[macro_export]
764macro_rules! throw_machine_stop {
765    ($($tt:tt)*) => { do yeet $crate::err_machine_stop!($($tt)*) };
766}
767
768/// Guard type that panics on drop.
769#[derive(Debug)]
770struct Guard;
771
772impl Drop for Guard {
773    fn drop(&mut self) {
774        // We silence the guard if we are already panicking, to avoid double-panics.
775        if !std::thread::panicking() {
776            panic!(
777                "an interpreter error got improperly discarded; use `discard_err()` if this is intentional"
778            );
779        }
780    }
781}
782
783/// The result type used by the interpreter. This is a newtype around `Result`
784/// to block access to operations like `ok()` that discard UB errors.
785///
786/// We also make things panic if this type is ever implicitly dropped.
787#[derive(Debug)]
788#[must_use]
789pub struct InterpResult_<'tcx, T> {
790    res: Result<T, InterpErrorInfo<'tcx>>,
791    guard: Guard,
792}
793
794// Type alias to be able to set a default type argument.
795pub type InterpResult<'tcx, T = ()> = InterpResult_<'tcx, T>;
796
797impl<'tcx, T> ops::Try for InterpResult_<'tcx, T> {
798    type Output = T;
799    type Residual = InterpResult_<'tcx, convert::Infallible>;
800
801    #[inline]
802    fn from_output(output: Self::Output) -> Self {
803        InterpResult_::new(Ok(output))
804    }
805
806    #[inline]
807    fn branch(self) -> ops::ControlFlow<Self::Residual, Self::Output> {
808        match self.disarm() {
809            Ok(v) => ops::ControlFlow::Continue(v),
810            Err(e) => ops::ControlFlow::Break(InterpResult_::new(Err(e))),
811        }
812    }
813}
814
815impl<'tcx, T> ops::FromResidual for InterpResult_<'tcx, T> {
816    #[inline]
817    #[track_caller]
818    fn from_residual(residual: InterpResult_<'tcx, convert::Infallible>) -> Self {
819        match residual.disarm() {
820            Err(e) => Self::new(Err(e)),
821        }
822    }
823}
824
825// Allow `yeet`ing `InterpError` in functions returning `InterpResult_`.
826impl<'tcx, T> ops::FromResidual<ops::Yeet<InterpErrorKind<'tcx>>> for InterpResult_<'tcx, T> {
827    #[inline]
828    fn from_residual(ops::Yeet(e): ops::Yeet<InterpErrorKind<'tcx>>) -> Self {
829        Self::new(Err(e.into()))
830    }
831}
832
833// Allow `?` on `Result<_, InterpError>` in functions returning `InterpResult_`.
834// This is useful e.g. for `option.ok_or_else(|| err_ub!(...))`.
835impl<'tcx, T, E: Into<InterpErrorInfo<'tcx>>> ops::FromResidual<Result<convert::Infallible, E>>
836    for InterpResult_<'tcx, T>
837{
838    #[inline]
839    fn from_residual(residual: Result<convert::Infallible, E>) -> Self {
840        match residual {
841            Err(e) => Self::new(Err(e.into())),
842        }
843    }
844}
845
846impl<'tcx, T, E: Into<InterpErrorInfo<'tcx>>> From<Result<T, E>> for InterpResult<'tcx, T> {
847    #[inline]
848    fn from(value: Result<T, E>) -> Self {
849        Self::new(value.map_err(|e| e.into()))
850    }
851}
852
853impl<'tcx, T, V: FromIterator<T>> FromIterator<InterpResult<'tcx, T>> for InterpResult<'tcx, V> {
854    fn from_iter<I: IntoIterator<Item = InterpResult<'tcx, T>>>(iter: I) -> Self {
855        Self::new(iter.into_iter().map(|x| x.disarm()).collect())
856    }
857}
858
859impl<'tcx, T> InterpResult_<'tcx, T> {
860    #[inline(always)]
861    fn new(res: Result<T, InterpErrorInfo<'tcx>>) -> Self {
862        Self { res, guard: Guard }
863    }
864
865    #[inline(always)]
866    fn disarm(self) -> Result<T, InterpErrorInfo<'tcx>> {
867        mem::forget(self.guard);
868        self.res
869    }
870
871    /// Discard the error information in this result. Only use this if ignoring Undefined Behavior is okay!
872    #[inline]
873    pub fn discard_err(self) -> Option<T> {
874        self.disarm().ok()
875    }
876
877    /// Look at the `Result` wrapped inside of this.
878    /// Must only be used to report the error!
879    #[inline]
880    pub fn report_err(self) -> Result<T, InterpErrorInfo<'tcx>> {
881        self.disarm()
882    }
883
884    #[inline]
885    pub fn map<U>(self, f: impl FnOnce(T) -> U) -> InterpResult<'tcx, U> {
886        InterpResult_::new(self.disarm().map(f))
887    }
888
889    #[inline]
890    pub fn map_err_info(
891        self,
892        f: impl FnOnce(InterpErrorInfo<'tcx>) -> InterpErrorInfo<'tcx>,
893    ) -> InterpResult<'tcx, T> {
894        InterpResult_::new(self.disarm().map_err(f))
895    }
896
897    #[inline]
898    pub fn map_err_kind(
899        self,
900        f: impl FnOnce(InterpErrorKind<'tcx>) -> InterpErrorKind<'tcx>,
901    ) -> InterpResult<'tcx, T> {
902        InterpResult_::new(self.disarm().map_err(|mut e| {
903            e.0.kind = f(e.0.kind);
904            e
905        }))
906    }
907
908    #[inline]
909    pub fn inspect_err_kind(self, f: impl FnOnce(&InterpErrorKind<'tcx>)) -> InterpResult<'tcx, T> {
910        InterpResult_::new(self.disarm().inspect_err(|e| f(&e.0.kind)))
911    }
912
913    #[inline]
914    #[track_caller]
915    pub fn unwrap(self) -> T {
916        self.disarm().unwrap()
917    }
918
919    #[inline]
920    #[track_caller]
921    pub fn unwrap_or_else(self, f: impl FnOnce(InterpErrorInfo<'tcx>) -> T) -> T {
922        self.disarm().unwrap_or_else(f)
923    }
924
925    #[inline]
926    #[track_caller]
927    pub fn expect(self, msg: &str) -> T {
928        self.disarm().expect(msg)
929    }
930
931    #[inline]
932    pub fn and_then<U>(self, f: impl FnOnce(T) -> InterpResult<'tcx, U>) -> InterpResult<'tcx, U> {
933        InterpResult_::new(self.disarm().and_then(|t| f(t).disarm()))
934    }
935
936    /// Returns success if both `self` and `other` succeed, while ensuring we don't
937    /// accidentally drop an error.
938    ///
939    /// If both are an error, `self` will be reported.
940    #[inline]
941    pub fn and<U>(self, other: InterpResult<'tcx, U>) -> InterpResult<'tcx, (T, U)> {
942        match self.disarm() {
943            Ok(t) => interp_ok((t, other?)),
944            Err(e) => {
945                // Discard the other error.
946                drop(other.disarm());
947                // Return `self`.
948                InterpResult_::new(Err(e))
949            }
950        }
951    }
952}
953
954#[inline(always)]
955pub fn interp_ok<'tcx, T>(x: T) -> InterpResult<'tcx, T> {
956    InterpResult_::new(Ok(x))
957}
rustc_middle/mir/interpret/error.rs

rustc_middle/mir/interpret/
error.rs
