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