src/librustc/mir/interpret/error.rs

   1 use std::{fmt, env};
   2
   3 use crate::hir;
   4 use crate::hir::map::definitions::DefPathData;
   5 use crate::mir;
   6 use crate::ty::{self, Ty, layout};
   7 use crate::ty::layout::{Size, Align, LayoutError};
   8 use rustc_target::spec::abi::Abi;
   9 use rustc_macros::HashStable;
  10
  11 use super::{RawConst, Pointer, CheckInAllocMsg, ScalarMaybeUndef};
  12
  13 use backtrace::Backtrace;
  14
  15 use crate::ty::query::TyCtxtAt;
  16 use errors::DiagnosticBuilder;
  17
  18 use syntax_pos::{Pos, Span};
  19 use syntax::symbol::Symbol;
  20
  21 #[derive(Debug, Copy, Clone, PartialEq, Eq, HashStable, RustcEncodable, RustcDecodable)]
  22 pub enum ErrorHandled {
  23     /// Already reported a lint or an error for this evaluation.
  24     Reported,
  25     /// Don't emit an error, the evaluation failed because the MIR was generic
  26     /// and the substs didn't fully monomorphize it.
  27     TooGeneric,
  28 }
  29
  30 impl ErrorHandled {
  31     pub fn assert_reported(self) {
  32         match self {
  33             ErrorHandled::Reported => {},
  34             ErrorHandled::TooGeneric => bug!("MIR interpretation failed without reporting an error \
  35                                               even though it was fully monomorphized"),
  36         }
  37     }
  38 }
  39
  40 CloneTypeFoldableImpls! {
  41     ErrorHandled,
  42 }
  43
  44 pub type ConstEvalRawResult<'tcx> = Result<RawConst<'tcx>, ErrorHandled>;
  45 pub type ConstEvalResult<'tcx> = Result<&'tcx ty::Const<'tcx>, ErrorHandled>;
  46
  47 #[derive(Clone, Debug, RustcEncodable, RustcDecodable)]
  48 pub struct ConstEvalErr<'tcx> {
  49     pub span: Span,
  50     pub error: crate::mir::interpret::InterpError<'tcx>,
  51     pub stacktrace: Vec<FrameInfo<'tcx>>,
  52 }
  53
  54 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
  55 pub struct FrameInfo<'tcx> {
  56     /// This span is in the caller.
  57     pub call_site: Span,
  58     pub instance: ty::Instance<'tcx>,
  59     pub lint_root: Option<hir::HirId>,
  60 }
  61
  62 impl<'tcx> fmt::Display for FrameInfo<'tcx> {
  63     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
  64         ty::tls::with(|tcx| {
  65             if tcx.def_key(self.instance.def_id()).disambiguated_data.data
  66                 == DefPathData::ClosureExpr
  67             {
  68                 write!(f, "inside call to closure")?;
  69             } else {
  70                 write!(f, "inside call to `{}`", self.instance)?;
  71             }
  72             if !self.call_site.is_dummy() {
  73                 let lo = tcx.sess.source_map().lookup_char_pos(self.call_site.lo());
  74                 write!(f, " at {}:{}:{}", lo.file.name, lo.line, lo.col.to_usize() + 1)?;
  75             }
  76             Ok(())
  77         })
  78     }
  79 }
  80
  81 impl<'tcx> ConstEvalErr<'tcx> {
  82     pub fn struct_error(
  83         &self,
  84         tcx: TyCtxtAt<'tcx>,
  85         message: &str,
  86     ) -> Result<DiagnosticBuilder<'tcx>, ErrorHandled> {
  87         self.struct_generic(tcx, message, None)
  88     }
  89
  90     pub fn report_as_error(&self, tcx: TyCtxtAt<'tcx>, message: &str) -> ErrorHandled {
  91         let err = self.struct_error(tcx, message);
  92         match err {
  93             Ok(mut err) => {
  94                 err.emit();
  95                 ErrorHandled::Reported
  96             },
  97             Err(err) => err,
  98         }
  99     }
 100
 101     pub fn report_as_lint(
 102         &self,
 103         tcx: TyCtxtAt<'tcx>,
 104         message: &str,
 105         lint_root: hir::HirId,
 106         span: Option<Span>,
 107     ) -> ErrorHandled {
 108         let lint = self.struct_generic(
 109             tcx,
 110             message,
 111             Some(lint_root),
 112         );
 113         match lint {
 114             Ok(mut lint) => {
 115                 if let Some(span) = span {
 116                     let primary_spans = lint.span.primary_spans().to_vec();
 117                     // point at the actual error as the primary span
 118                     lint.replace_span_with(span);
 119                     // point to the `const` statement as a secondary span
 120                     // they don't have any label
 121                     for sp in primary_spans {
 122                         if sp != span {
 123                             lint.span_label(sp, "");
 124                         }
 125                     }
 126                 }
 127                 lint.emit();
 128                 ErrorHandled::Reported
 129             },
 130             Err(err) => err,
 131         }
 132     }
 133
 134     fn struct_generic(
 135         &self,
 136         tcx: TyCtxtAt<'tcx>,
 137         message: &str,
 138         lint_root: Option<hir::HirId>,
 139     ) -> Result<DiagnosticBuilder<'tcx>, ErrorHandled> {
 140         match self.error {
 141             InterpError::Layout(LayoutError::Unknown(_)) |
 142             InterpError::InvalidProgram(InvalidProgramMessage::TooGeneric) =>
 143                 return Err(ErrorHandled::TooGeneric),
 144             InterpError::Layout(LayoutError::SizeOverflow(_)) |
 145             InterpError::InvalidProgram(InvalidProgramMessage::TypeckError) =>
 146                 return Err(ErrorHandled::Reported),
 147             _ => {},
 148         }
 149         trace!("reporting const eval failure at {:?}", self.span);
 150         let mut err = if let Some(lint_root) = lint_root {
 151             let hir_id = self.stacktrace
 152                 .iter()
 153                 .rev()
 154                 .filter_map(|frame| frame.lint_root)
 155                 .next()
 156                 .unwrap_or(lint_root);
 157             tcx.struct_span_lint_hir(
 158                 crate::rustc::lint::builtin::CONST_ERR,
 159                 hir_id,
 160                 tcx.span,
 161                 message,
 162             )
 163         } else {
 164             struct_error(tcx, message)
 165         };
 166         err.span_label(self.span, self.error.to_string());
 167         // Skip the last, which is just the environment of the constant.  The stacktrace
 168         // is sometimes empty because we create "fake" eval contexts in CTFE to do work
 169         // on constant values.
 170         if self.stacktrace.len() > 0 {
 171             for frame_info in &self.stacktrace[..self.stacktrace.len()-1] {
 172                 err.span_label(frame_info.call_site, frame_info.to_string());
 173             }
 174         }
 175         Ok(err)
 176     }
 177 }
 178
 179 pub fn struct_error<'tcx>(tcx: TyCtxtAt<'tcx>, msg: &str) -> DiagnosticBuilder<'tcx> {
 180     struct_span_err!(tcx.sess, tcx.span, E0080, "{}", msg)
 181 }
 182
 183 /// Packages the kind of error we got from the const code interpreter
 184 /// up with a Rust-level backtrace of where the error occured.
 185 /// Thsese should always be constructed by calling `.into()` on
 186 /// a `InterpError`. In `librustc_mir::interpret`, we have the `err!`
 187 /// macro for this.
 188 #[derive(Debug, Clone)]
 189 pub struct InterpErrorInfo<'tcx> {
 190     pub kind: InterpError<'tcx>,
 191     backtrace: Option<Box<Backtrace>>,
 192 }
 193
 194
 195 impl fmt::Display for InterpErrorInfo<'_> {
 196     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 197         write!(f, "{}", self.kind)
 198     }
 199 }
 200
 201 impl InterpErrorInfo<'_> {
 202     pub fn print_backtrace(&mut self) {
 203         if let Some(ref mut backtrace) = self.backtrace {
 204             print_backtrace(&mut *backtrace);
 205         }
 206     }
 207 }
 208
 209 fn print_backtrace(backtrace: &mut Backtrace) {
 210     backtrace.resolve();
 211     eprintln!("\n\nAn error occurred in miri:\n{:?}", backtrace);
 212 }
 213
 214 impl<'tcx> From<InterpError<'tcx>> for InterpErrorInfo<'tcx> {
 215     fn from(kind: InterpError<'tcx>) -> Self {
 216         let backtrace = match env::var("RUST_CTFE_BACKTRACE") {
 217             // Matching `RUST_BACKTRACE` -- we treat "0" the same as "not present".
 218             Ok(ref val) if val != "0" => {
 219                 let mut backtrace = Backtrace::new_unresolved();
 220
 221                 if val == "immediate" {
 222                     // Print it now.
 223                     print_backtrace(&mut backtrace);
 224                     None
 225                 } else {
 226                     Some(Box::new(backtrace))
 227                 }
 228             },
 229             _ => None,
 230         };
 231         InterpErrorInfo {
 232             kind,
 233             backtrace,
 234         }
 235     }
 236 }
 237
 238 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 239 pub enum PanicMessage<O> {
 240     Panic {
 241         msg: Symbol,
 242         line: u32,
 243         col: u32,
 244         file: Symbol,
 245     },
 246     BoundsCheck {
 247         len: O,
 248         index: O,
 249     },
 250     Overflow(mir::BinOp),
 251     OverflowNeg,
 252     DivisionByZero,
 253     RemainderByZero,
 254     GeneratorResumedAfterReturn,
 255     GeneratorResumedAfterPanic,
 256 }
 257
 258 /// Type for MIR `Assert` terminator error messages.
 259 pub type AssertMessage<'tcx> = PanicMessage<mir::Operand<'tcx>>;
 260
 261 impl<O> PanicMessage<O> {
 262     /// Getting a description does not require `O` to be printable, and does not
 263     /// require allocation.
 264     /// The caller is expected to handle `Panic` and `BoundsCheck` separately.
 265     pub fn description(&self) -> &'static str {
 266         use PanicMessage::*;
 267         match self {
 268             Overflow(mir::BinOp::Add) =>
 269                 "attempt to add with overflow",
 270             Overflow(mir::BinOp::Sub) =>
 271                 "attempt to subtract with overflow",
 272             Overflow(mir::BinOp::Mul) =>
 273                 "attempt to multiply with overflow",
 274             Overflow(mir::BinOp::Div) =>
 275                 "attempt to divide with overflow",
 276             Overflow(mir::BinOp::Rem) =>
 277                 "attempt to calculate the remainder with overflow",
 278             OverflowNeg =>
 279                 "attempt to negate with overflow",
 280             Overflow(mir::BinOp::Shr) =>
 281                 "attempt to shift right with overflow",
 282             Overflow(mir::BinOp::Shl) =>
 283                 "attempt to shift left with overflow",
 284             Overflow(op) =>
 285                 bug!("{:?} cannot overflow", op),
 286             DivisionByZero =>
 287                 "attempt to divide by zero",
 288             RemainderByZero =>
 289                 "attempt to calculate the remainder with a divisor of zero",
 290             GeneratorResumedAfterReturn =>
 291                 "generator resumed after completion",
 292             GeneratorResumedAfterPanic =>
 293                 "generator resumed after panicking",
 294             Panic { .. } | BoundsCheck { .. } =>
 295                 bug!("Unexpected PanicMessage"),
 296         }
 297     }
 298 }
 299
 300 impl<O: fmt::Debug> fmt::Debug for PanicMessage<O> {
 301     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 302         use PanicMessage::*;
 303         match self {
 304             Panic { ref msg, line, col, ref file } =>
 305                 write!(f, "the evaluated program panicked at '{}', {}:{}:{}", msg, file, line, col),
 306             BoundsCheck { ref len, ref index } =>
 307                 write!(f, "index out of bounds: the len is {:?} but the index is {:?}", len, index),
 308             _ =>
 309                 write!(f, "{}", self.description()),
 310         }
 311     }
 312 }
 313
 314 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 315 pub enum InvalidProgramMessage {
 316     /// Resolution can fail if we are in a too generic context
 317     TooGeneric,
 318     /// Cannot compute this constant because it depends on another one
 319     /// which already produced an error
 320     ReferencedConstant,
 321     /// Abort in case type errors are reached
 322     TypeckError,
 323 }
 324
 325 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 326 pub enum UndefinedBehaviourMessage {
 327 }
 328
 329 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 330 pub enum UnsupportedMessage {
 331 }
 332
 333 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 334 pub enum ResourceExhaustionMessage {
 335 }
 336
 337 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
 338 pub enum InterpError<'tcx> {
 339     /// The program panicked.
 340     Panic(PanicMessage<u64>),
 341     /// The program caused undefined behavior.
 342     UndefinedBehaviour(UndefinedBehaviourMessage),
 343     /// The program did something the interpreter does not support (some of these *might* be UB
 344     /// but the interpreter is not sure).
 345     Unsupported(UnsupportedMessage),
 346     /// The program was invalid (ill-typed, not sufficiently monomorphized, ...).
 347     InvalidProgram(InvalidProgramMessage),
 348     /// The program exhausted the interpreter's resources (stack/heap too big,
 349     /// execution takes too long, ..).
 350     ResourceExhaustion(ResourceExhaustionMessage),
 351
 352     /// THe above 5 variants are what we want to group all the remaining InterpError variants into
 353
 354     /// This variant is used by machines to signal their own errors that do not
 355     /// match an existing variant.
 356     MachineError(String),
 357
 358     /// Not actually an interpreter error -- used to signal that execution has exited
 359     /// with the given status code.  Used by Miri, but not by CTFE.
 360     Exit(i32),
 361
 362     FunctionAbiMismatch(Abi, Abi),
 363     FunctionArgMismatch(Ty<'tcx>, Ty<'tcx>),
 364     FunctionRetMismatch(Ty<'tcx>, Ty<'tcx>),
 365     FunctionArgCountMismatch,
 366     NoMirFor(String),
 367     UnterminatedCString(Pointer),
 368     DanglingPointerDeref,
 369     DoubleFree,
 370     InvalidMemoryAccess,
 371     InvalidFunctionPointer,
 372     InvalidBool,
 373     InvalidDiscriminant(ScalarMaybeUndef),
 374     PointerOutOfBounds {
 375         ptr: Pointer,
 376         msg: CheckInAllocMsg,
 377         allocation_size: Size,
 378     },
 379     InvalidNullPointerUsage,
 380     ReadPointerAsBytes,
 381     ReadBytesAsPointer,
 382     ReadForeignStatic,
 383     InvalidPointerMath,
 384     ReadUndefBytes(Size),
 385     DeadLocal,
 386     InvalidBoolOp(mir::BinOp),
 387     Unimplemented(String),
 388     DerefFunctionPointer,
 389     ExecuteMemory,
 390     Intrinsic(String),
 391     InvalidChar(u128),
 392     StackFrameLimitReached,
 393     OutOfTls,
 394     TlsOutOfBounds,
 395     AbiViolation(String),
 396     AlignmentCheckFailed {
 397         required: Align,
 398         has: Align,
 399     },
 400     ValidationFailure(String),
 401     CalledClosureAsFunction,
 402     VtableForArgumentlessMethod,
 403     ModifiedConstantMemory,
 404     ModifiedStatic,
 405     AssumptionNotHeld,
 406     InlineAsm,
 407     TypeNotPrimitive(Ty<'tcx>),
 408     ReallocatedWrongMemoryKind(String, String),
 409     DeallocatedWrongMemoryKind(String, String),
 410     ReallocateNonBasePtr,
 411     DeallocateNonBasePtr,
 412     IncorrectAllocationInformation(Size, Size, Align, Align),
 413     Layout(layout::LayoutError<'tcx>),
 414     HeapAllocZeroBytes,
 415     HeapAllocNonPowerOfTwoAlignment(u64),
 416     Unreachable,
 417     ReadFromReturnPointer,
 418     PathNotFound(Vec<String>),
 419     UnimplementedTraitSelection,
 420 }
 421
 422 pub type InterpResult<'tcx, T = ()> = Result<T, InterpErrorInfo<'tcx>>;
 423
 424 impl fmt::Display for InterpError<'_> {
 425     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 426         // Forward `Display` to `Debug`
 427         write!(f, "{:?}", self)
 428     }
 429 }
 430
 431 impl fmt::Debug for InterpError<'_> {
 432     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 433         use InterpError::*;
 434         match *self {
 435             PointerOutOfBounds { ptr, msg, allocation_size } => {
 436                 write!(f, "{} failed: pointer must be in-bounds at offset {}, \
 437                           but is outside bounds of allocation {} which has size {}",
 438                     msg, ptr.offset.bytes(), ptr.alloc_id, allocation_size.bytes())
 439             },
 440             ValidationFailure(ref err) => {
 441                 write!(f, "type validation failed: {}", err)
 442             }
 443             NoMirFor(ref func) => write!(f, "no mir for `{}`", func),
 444             FunctionAbiMismatch(caller_abi, callee_abi) =>
 445                 write!(f, "tried to call a function with ABI {:?} using caller ABI {:?}",
 446                     callee_abi, caller_abi),
 447             FunctionArgMismatch(caller_ty, callee_ty) =>
 448                 write!(f, "tried to call a function with argument of type {:?} \
 449                            passing data of type {:?}",
 450                     callee_ty, caller_ty),
 451             FunctionRetMismatch(caller_ty, callee_ty) =>
 452                 write!(f, "tried to call a function with return type {:?} \
 453                            passing return place of type {:?}",
 454                     callee_ty, caller_ty),
 455             FunctionArgCountMismatch =>
 456                 write!(f, "tried to call a function with incorrect number of arguments"),
 457             ReallocatedWrongMemoryKind(ref old, ref new) =>
 458                 write!(f, "tried to reallocate memory from {} to {}", old, new),
 459             DeallocatedWrongMemoryKind(ref old, ref new) =>
 460                 write!(f, "tried to deallocate {} memory but gave {} as the kind", old, new),
 461             InvalidChar(c) =>
 462                 write!(f, "tried to interpret an invalid 32-bit value as a char: {}", c),
 463             AlignmentCheckFailed { required, has } =>
 464                write!(f, "tried to access memory with alignment {}, but alignment {} is required",
 465                       has.bytes(), required.bytes()),
 466             TypeNotPrimitive(ty) =>
 467                 write!(f, "expected primitive type, got {}", ty),
 468             Layout(ref err) =>
 469                 write!(f, "rustc layout computation failed: {:?}", err),
 470             PathNotFound(ref path) =>
 471                 write!(f, "Cannot find path {:?}", path),
 472             IncorrectAllocationInformation(size, size2, align, align2) =>
 473                 write!(f, "incorrect alloc info: expected size {} and align {}, \
 474                            got size {} and align {}",
 475                     size.bytes(), align.bytes(), size2.bytes(), align2.bytes()),
 476             InvalidDiscriminant(val) =>
 477                 write!(f, "encountered invalid enum discriminant {}", val),
 478             Exit(code) =>
 479                 write!(f, "exited with status code {}", code),
 480             InvalidMemoryAccess =>
 481                 write!(f, "tried to access memory through an invalid pointer"),
 482             DanglingPointerDeref =>
 483                 write!(f, "dangling pointer was dereferenced"),
 484             DoubleFree =>
 485                 write!(f, "tried to deallocate dangling pointer"),
 486             InvalidFunctionPointer =>
 487                 write!(f, "tried to use a function pointer after offsetting it"),
 488             InvalidBool =>
 489                 write!(f, "invalid boolean value read"),
 490             InvalidNullPointerUsage =>
 491                 write!(f, "invalid use of NULL pointer"),
 492             ReadPointerAsBytes =>
 493                 write!(f, "a raw memory access tried to access part of a pointer value as raw \
 494                     bytes"),
 495             ReadBytesAsPointer =>
 496                 write!(f, "a memory access tried to interpret some bytes as a pointer"),
 497             ReadForeignStatic =>
 498                 write!(f, "tried to read from foreign (extern) static"),
 499             InvalidPointerMath =>
 500                 write!(f, "attempted to do invalid arithmetic on pointers that would leak base \
 501                     addresses, e.g., comparing pointers into different allocations"),
 502             DeadLocal =>
 503                 write!(f, "tried to access a dead local variable"),
 504             DerefFunctionPointer =>
 505                 write!(f, "tried to dereference a function pointer"),
 506             ExecuteMemory =>
 507                 write!(f, "tried to treat a memory pointer as a function pointer"),
 508             StackFrameLimitReached =>
 509                 write!(f, "reached the configured maximum number of stack frames"),
 510             OutOfTls =>
 511                 write!(f, "reached the maximum number of representable TLS keys"),
 512             TlsOutOfBounds =>
 513                 write!(f, "accessed an invalid (unallocated) TLS key"),
 514             CalledClosureAsFunction =>
 515                 write!(f, "tried to call a closure through a function pointer"),
 516             VtableForArgumentlessMethod =>
 517                 write!(f, "tried to call a vtable function without arguments"),
 518             ModifiedConstantMemory =>
 519                 write!(f, "tried to modify constant memory"),
 520             ModifiedStatic =>
 521                 write!(f, "tried to modify a static's initial value from another static's \
 522                     initializer"),
 523             AssumptionNotHeld =>
 524                 write!(f, "`assume` argument was false"),
 525             InlineAsm =>
 526                 write!(f, "miri does not support inline assembly"),
 527             ReallocateNonBasePtr =>
 528                 write!(f, "tried to reallocate with a pointer not to the beginning of an \
 529                     existing object"),
 530             DeallocateNonBasePtr =>
 531                 write!(f, "tried to deallocate with a pointer not to the beginning of an \
 532                     existing object"),
 533             HeapAllocZeroBytes =>
 534                 write!(f, "tried to re-, de- or allocate zero bytes on the heap"),
 535             Unreachable =>
 536                 write!(f, "entered unreachable code"),
 537             ReadFromReturnPointer =>
 538                 write!(f, "tried to read from the return pointer"),
 539             UnimplementedTraitSelection =>
 540                 write!(f, "there were unresolved type arguments during trait selection"),
 541             TypeckError =>
 542                 write!(f, "encountered constants with type errors, stopping evaluation"),
 543             TooGeneric =>
 544                 write!(f, "encountered overly generic constant"),
 545             ReferencedConstant =>
 546                 write!(f, "referenced constant has errors"),
 547             InfiniteLoop =>
 548                 write!(f, "duplicate interpreter state observed here, const evaluation will never \
 549                     terminate"),
 550             InvalidBoolOp(_) =>
 551                 write!(f, "invalid boolean operation"),
 552             UnterminatedCString(_) =>
 553                 write!(f, "attempted to get length of a null terminated string, but no null \
 554                     found before end of allocation"),
 555             ReadUndefBytes(_) =>
 556                 write!(f, "attempted to read undefined bytes"),
 557             HeapAllocNonPowerOfTwoAlignment(_) =>
 558                 write!(f, "tried to re-, de-, or allocate heap memory with alignment that is \
 559                     not a power of two"),
 560             MachineError(ref msg) |
 561             Unimplemented(ref msg) |
 562             AbiViolation(ref msg) |
 563             Intrinsic(ref msg) =>
 564                 write!(f, "{}", msg),
 565             Panic(ref msg) =>
 566                 write!(f, "{:?}", msg),
 567         }
 568     }
 569 }