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place evaluation: require the original pointer to be aligned if an access happens

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This commit is contained in:
Ralf Jung 2023-09-05 15:12:18 +02:00
parent ea9a24e32e
commit f3f9b795bd
22 changed files with 266 additions and 219 deletions
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1
compiler/rustc_abi/src/lib.rs
View File

@ -681,6 +681,7 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
impl Align {
pub const ONE: Align = Align { pow2: 0 };
// LLVM has a maximal supported alignment of 2^29, we inherit that.
pub const MAX: Align = Align { pow2: 29 };
#[inline]

6
compiler/rustc_const_eval/src/const_eval/eval_queries.rs
View File

@ -1,3 +1,5 @@
use std::mem;
use either::{Left, Right};
use rustc_hir::def::DefKind;
@ -73,9 +75,9 @@ fn eval_body_using_ecx<'mir, 'tcx>(
None => InternKind::Constant,
}
};
ecx.machine.check_alignment = CheckAlignment::No; // interning doesn't need to respect alignment
let check_alignment = mem::replace(&mut ecx.machine.check_alignment, CheckAlignment::No); // interning doesn't need to respect alignment
intern_const_alloc_recursive(ecx, intern_kind, &ret)?;
// we leave alignment checks off, since this `ecx` will not be used for further evaluation anyway
ecx.machine.check_alignment = check_alignment;
debug!("eval_body_using_ecx done: {:?}", ret);
Ok(ret)

7
compiler/rustc_const_eval/src/errors.rs
View File

@ -5,8 +5,9 @@
use rustc_hir::ConstContext;
use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
use rustc_middle::mir::interpret::{
CheckInAllocMsg, ExpectedKind, InterpError, InvalidMetaKind, InvalidProgramInfo, PointerKind,
ResourceExhaustionInfo, UndefinedBehaviorInfo, UnsupportedOpInfo, ValidationErrorInfo,
CheckInAllocMsg, ExpectedKind, InterpError, InvalidMetaKind, InvalidProgramInfo, Misalignment,
PointerKind, ResourceExhaustionInfo, UndefinedBehaviorInfo, UnsupportedOpInfo,
ValidationErrorInfo,
};
use rustc_middle::ty::{self, Ty};
use rustc_span::Span;
@ -567,7 +568,7 @@ fn add_args<G: EmissionGuarantee>(
builder.set_arg("bad_pointer_message", bad_pointer_message(msg, handler));
}
AlignmentCheckFailed { required, has } => {
AlignmentCheckFailed(Misalignment { required, has }) => {
builder.set_arg("required", required.bytes());
builder.set_arg("has", has.bytes());
}

92
compiler/rustc_const_eval/src/interpret/memory.rs
View File

@ -22,8 +22,8 @@
use super::{
alloc_range, AllocBytes, AllocId, AllocMap, AllocRange, Allocation, CheckInAllocMsg,
GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak, Pointer, PointerArithmetic, Provenance,
Scalar,
GlobalAlloc, InterpCx, InterpResult, Machine, MayLeak, Misalignment, Pointer,
PointerArithmetic, Provenance, Scalar,
};
#[derive(Debug, PartialEq, Copy, Clone)]
@ -372,7 +372,7 @@ fn get_ptr_access(
self.check_and_deref_ptr(
ptr,
size,
M::enforce_alignment(self).then_some(align),
align,
CheckInAllocMsg::MemoryAccessTest,
|alloc_id, offset, prov| {
let (size, align) = self
@ -382,9 +382,8 @@ fn get_ptr_access(
)
}
/// Check if the given pointer points to live memory of given `size` and `align`
/// (ignoring `M::enforce_alignment`). The caller can control the error message for the
/// out-of-bounds case.
/// Check if the given pointer points to live memory of given `size` and `align`.
/// The caller can control the error message for the out-of-bounds case.
#[inline(always)]
pub fn check_ptr_access_align(
&self,
@ -393,7 +392,7 @@ pub fn check_ptr_access_align(
align: Align,
msg: CheckInAllocMsg,
) -> InterpResult<'tcx> {
self.check_and_deref_ptr(ptr, size, Some(align), msg, |alloc_id, _, _| {
self.check_and_deref_ptr(ptr, size, align, msg, |alloc_id, _, _| {
let (size, align) = self.get_live_alloc_size_and_align(alloc_id, msg)?;
Ok((size, align, ()))
})?;
@ -402,15 +401,14 @@ pub fn check_ptr_access_align(
/// Low-level helper function to check if a ptr is in-bounds and potentially return a reference
/// to the allocation it points to. Supports both shared and mutable references, as the actual
/// checking is offloaded to a helper closure. `align` defines whether and which alignment check
/// is done.
/// checking is offloaded to a helper closure.
///
/// If this returns `None`, the size is 0; it can however return `Some` even for size 0.
fn check_and_deref_ptr<T>(
&self,
ptr: Pointer<Option<M::Provenance>>,
size: Size,
align: Option<Align>,
align: Align,
msg: CheckInAllocMsg,
alloc_size: impl FnOnce(
AllocId,
@ -426,9 +424,7 @@ fn check_and_deref_ptr<T>(
throw_ub!(DanglingIntPointer(addr, msg));
}
// Must be aligned.
if let Some(align) = align {
self.check_offset_align(addr, align)?;
}
self.check_misalign(Self::offset_misalignment(addr, align))?;
None
}
Ok((alloc_id, offset, prov)) => {
@ -450,18 +446,7 @@ fn check_and_deref_ptr<T>(
}
// Test align. Check this last; if both bounds and alignment are violated
// we want the error to be about the bounds.
if let Some(align) = align {
if M::use_addr_for_alignment_check(self) {
// `use_addr_for_alignment_check` can only be true if `OFFSET_IS_ADDR` is true.
self.check_offset_align(ptr.addr().bytes(), align)?;
} else {
// Check allocation alignment and offset alignment.
if alloc_align.bytes() < align.bytes() {
throw_ub!(AlignmentCheckFailed { has: alloc_align, required: align });
}
self.check_offset_align(offset.bytes(), align)?;
}
}
self.check_misalign(self.alloc_misalignment(ptr, offset, align, alloc_align))?;
// We can still be zero-sized in this branch, in which case we have to
// return `None`.
@ -470,16 +455,59 @@ fn check_and_deref_ptr<T>(
})
}
fn check_offset_align(&self, offset: u64, align: Align) -> InterpResult<'tcx> {
#[inline(always)]
pub(super) fn check_misalign(&self, misaligned: Option<Misalignment>) -> InterpResult<'tcx> {
if M::enforce_alignment(self) {
if let Some(misaligned) = misaligned {
throw_ub!(AlignmentCheckFailed(misaligned))
}
}
Ok(())
}
#[must_use]
fn offset_misalignment(offset: u64, align: Align) -> Option<Misalignment> {
if offset % align.bytes() == 0 {
Ok(())
None
} else {
// The biggest power of two through which `offset` is divisible.
let offset_pow2 = 1 << offset.trailing_zeros();
throw_ub!(AlignmentCheckFailed {
has: Align::from_bytes(offset_pow2).unwrap(),
required: align
});
Some(Misalignment { has: Align::from_bytes(offset_pow2).unwrap(), required: align })
}
}
#[must_use]
fn alloc_misalignment(
&self,
ptr: Pointer<Option<M::Provenance>>,
offset: Size,
align: Align,
alloc_align: Align,
) -> Option<Misalignment> {
if M::use_addr_for_alignment_check(self) {
// `use_addr_for_alignment_check` can only be true if `OFFSET_IS_ADDR` is true.
Self::offset_misalignment(ptr.addr().bytes(), align)
} else {
// Check allocation alignment and offset alignment.
if alloc_align.bytes() < align.bytes() {
Some(Misalignment { has: alloc_align, required: align })
} else {
Self::offset_misalignment(offset.bytes(), align)
}
}
}
pub(super) fn is_ptr_misaligned(
&self,
ptr: Pointer<Option<M::Provenance>>,
align: Align,
) -> Option<Misalignment> {
match self.ptr_try_get_alloc_id(ptr) {
Err(addr) => Self::offset_misalignment(addr, align),
Ok((alloc_id, offset, _prov)) => {
let (_size, alloc_align, _kind) = self.get_alloc_info(alloc_id);
self.alloc_misalignment(ptr, offset, align, alloc_align)
}
}
}
}
@ -597,7 +625,7 @@ pub fn get_ptr_alloc<'a>(
let ptr_and_alloc = self.check_and_deref_ptr(
ptr,
size,
M::enforce_alignment(self).then_some(align),
align,
CheckInAllocMsg::MemoryAccessTest,
|alloc_id, offset, prov| {
let alloc = self.get_alloc_raw(alloc_id)?;

60
compiler/rustc_const_eval/src/interpret/operand.rs
View File

@ -10,7 +10,7 @@
use rustc_middle::ty::print::{FmtPrinter, PrettyPrinter};
use rustc_middle::ty::{ConstInt, Ty, TyCtxt};
use rustc_middle::{mir, ty};
use rustc_target::abi::{self, Abi, Align, HasDataLayout, Size};
use rustc_target::abi::{self, Abi, HasDataLayout, Size};
use super::{
alloc_range, from_known_layout, mir_assign_valid_types, AllocId, Frame, InterpCx, InterpResult,
@ -44,12 +44,16 @@ fn from(val: Scalar<Prov>) -> Self {
}
impl<Prov: Provenance> Immediate<Prov> {
pub fn from_pointer(ptr: Pointer<Prov>, cx: &impl HasDataLayout) -> Self {
Immediate::Scalar(Scalar::from_pointer(ptr, cx))
}
pub fn from_maybe_pointer(ptr: Pointer<Option<Prov>>, cx: &impl HasDataLayout) -> Self {
Immediate::Scalar(Scalar::from_maybe_pointer(ptr, cx))
pub fn new_pointer_with_meta(
ptr: Pointer<Option<Prov>>,
meta: MemPlaceMeta<Prov>,
cx: &impl HasDataLayout,
) -> Self {
let ptr = Scalar::from_maybe_pointer(ptr, cx);
match meta {
MemPlaceMeta::None => Immediate::from(ptr),
MemPlaceMeta::Meta(meta) => Immediate::ScalarPair(ptr, meta),
}
}
pub fn new_slice(ptr: Pointer<Option<Prov>>, len: u64, cx: &impl HasDataLayout) -> Self {
@ -328,14 +332,6 @@ pub(super) enum Operand<Prov: Provenance = AllocId> {
pub struct OpTy<'tcx, Prov: Provenance = AllocId> {
op: Operand<Prov>, // Keep this private; it helps enforce invariants.
pub layout: TyAndLayout<'tcx>,
/// rustc does not have a proper way to represent the type of a field of a `repr(packed)` struct:
/// it needs to have a different alignment than the field type would usually have.
/// So we represent this here with a separate field that "overwrites" `layout.align`.
/// This means `layout.align` should never be used for an `OpTy`!
/// `None` means "alignment does not matter since this is a by-value operand"
/// (`Operand::Immediate`); this field is only relevant for `Operand::Indirect`.
/// Also CTFE ignores alignment anyway, so this is for Miri only.
pub align: Option<Align>,
}
impl<Prov: Provenance> std::fmt::Debug for OpTy<'_, Prov> {
@ -351,18 +347,14 @@ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
impl<'tcx, Prov: Provenance> From<ImmTy<'tcx, Prov>> for OpTy<'tcx, Prov> {
#[inline(always)]
fn from(val: ImmTy<'tcx, Prov>) -> Self {
OpTy { op: Operand::Immediate(val.imm), layout: val.layout, align: None }
OpTy { op: Operand::Immediate(val.imm), layout: val.layout }
}
}
impl<'tcx, Prov: Provenance> From<MPlaceTy<'tcx, Prov>> for OpTy<'tcx, Prov> {
#[inline(always)]
fn from(mplace: MPlaceTy<'tcx, Prov>) -> Self {
OpTy {
op: Operand::Indirect(*mplace.mplace()),
layout: mplace.layout,
align: Some(mplace.align),
}
OpTy { op: Operand::Indirect(*mplace.mplace()), layout: mplace.layout }
}
}
@ -635,7 +627,7 @@ pub fn local_to_op(
throw_inval!(ConstPropNonsense);
}
}
Ok(OpTy { op, layout, align: Some(layout.align.abi) })
Ok(OpTy { op, layout })
}
/// Every place can be read from, so we can turn them into an operand.
@ -650,16 +642,14 @@ pub fn place_to_op(
Right((frame, local, offset)) => {
debug_assert!(place.layout.is_sized()); // only sized locals can ever be `Place::Local`.
let base = self.local_to_op(&self.stack()[frame], local, None)?;
let mut field = match offset {
Ok(match offset {
Some(offset) => base.offset(offset, place.layout, self)?,
None => {
// In the common case this hasn't been projected.
debug_assert_eq!(place.layout, base.layout);
base
}
};
field.align = Some(place.align);
Ok(field)
})
}
}
}
@ -747,27 +737,23 @@ pub(crate) fn const_val_to_op(
})
};
let layout = from_known_layout(self.tcx, self.param_env, layout, || self.layout_of(ty))?;
let op = match val_val {
let imm = match val_val {
mir::ConstValue::Indirect { alloc_id, offset } => {
// We rely on mutability being set correctly in that allocation to prevent writes
// where none should happen.
let ptr = self.global_base_pointer(Pointer::new(alloc_id, offset))?;
Operand::Indirect(MemPlace::from_ptr(ptr.into()))
return Ok(self.ptr_to_mplace(ptr.into(), layout).into());
}
mir::ConstValue::Scalar(x) => Operand::Immediate(adjust_scalar(x)?.into()),
mir::ConstValue::ZeroSized => Operand::Immediate(Immediate::Uninit),
mir::ConstValue::Scalar(x) => adjust_scalar(x)?.into(),
mir::ConstValue::ZeroSized => Immediate::Uninit,
mir::ConstValue::Slice { data, meta } => {
// We rely on mutability being set correctly in `data` to prevent writes
// where none should happen.
let ptr = Pointer::new(self.tcx.reserve_and_set_memory_alloc(data), Size::ZERO);
Operand::Immediate(Immediate::new_slice(
self.global_base_pointer(ptr)?.into(),
meta,
self,
))
Immediate::new_slice(self.global_base_pointer(ptr)?.into(), meta, self)
}
};
Ok(OpTy { op, layout, align: Some(layout.align.abi) })
Ok(OpTy { op: Operand::Immediate(imm), layout })
}
}
@ -780,6 +766,6 @@ mod size_asserts {
static_assert_size!(Immediate, 48);
static_assert_size!(ImmTy<'_>, 64);
static_assert_size!(Operand, 56);
static_assert_size!(OpTy<'_>, 80);
static_assert_size!(OpTy<'_>, 72);
// tidy-alphabetical-end
}

191
compiler/rustc_const_eval/src/interpret/place.rs
View File

@ -16,7 +16,7 @@
use super::{
alloc_range, mir_assign_valid_types, AllocId, AllocRef, AllocRefMut, ImmTy, Immediate,
InterpCx, InterpResult, Machine, MemoryKind, OffsetMode, OpTy, Operand, Pointer,
InterpCx, InterpResult, Machine, MemoryKind, Misalignment, OffsetMode, OpTy, Operand, Pointer,
PointerArithmetic, Projectable, Provenance, Readable, Scalar,
};
@ -57,19 +57,11 @@ pub(super) struct MemPlace<Prov: Provenance = AllocId> {
/// Must not be present for sized types, but can be missing for unsized types
/// (e.g., `extern type`).
pub meta: MemPlaceMeta<Prov>,
/// Stores whether this place was created based on a sufficiently aligned pointer.
misaligned: Option<Misalignment>,
}
impl<Prov: Provenance> MemPlace<Prov> {
#[inline(always)]
pub fn from_ptr(ptr: Pointer<Option<Prov>>) -> Self {
MemPlace { ptr, meta: MemPlaceMeta::None }
}
#[inline(always)]
pub fn from_ptr_with_meta(ptr: Pointer<Option<Prov>>, meta: MemPlaceMeta<Prov>) -> Self {
MemPlace { ptr, meta }
}
/// Adjust the provenance of the main pointer (metadata is unaffected).
pub fn map_provenance(self, f: impl FnOnce(Option<Prov>) -> Option<Prov>) -> Self {
MemPlace { ptr: self.ptr.map_provenance(f), ..self }
@ -78,12 +70,7 @@ pub fn map_provenance(self, f: impl FnOnce(Option<Prov>) -> Option<Prov>) -> Sel
/// Turn a mplace into a (thin or wide) pointer, as a reference, pointing to the same space.
#[inline]
pub fn to_ref(self, cx: &impl HasDataLayout) -> Immediate<Prov> {
match self.meta {
MemPlaceMeta::None => Immediate::from(Scalar::from_maybe_pointer(self.ptr, cx)),
MemPlaceMeta::Meta(meta) => {
Immediate::ScalarPair(Scalar::from_maybe_pointer(self.ptr, cx), meta)
}
}
Immediate::new_pointer_with_meta(self.ptr, self.meta, cx)
}
#[inline]
@ -108,7 +95,7 @@ fn offset_with_meta_<'mir, 'tcx, M: Machine<'mir, 'tcx, Provenance = Prov>>(
}
OffsetMode::Wrapping => self.ptr.wrapping_offset(offset, ecx),
};
Ok(MemPlace { ptr, meta })
Ok(MemPlace { ptr, meta, misaligned: self.misaligned })
}
}
@ -117,11 +104,6 @@ fn offset_with_meta_<'mir, 'tcx, M: Machine<'mir, 'tcx, Provenance = Prov>>(
pub struct MPlaceTy<'tcx, Prov: Provenance = AllocId> {
mplace: MemPlace<Prov>,
pub layout: TyAndLayout<'tcx>,
/// rustc does not have a proper way to represent the type of a field of a `repr(packed)` struct:
/// it needs to have a different alignment than the field type would usually have.
/// So we represent this here with a separate field that "overwrites" `layout.align`.
/// This means `layout.align` should never be used for a `MPlaceTy`!
pub align: Align,
}
impl<Prov: Provenance> std::fmt::Debug for MPlaceTy<'_, Prov> {
@ -143,25 +125,7 @@ pub fn fake_alloc_zst(layout: TyAndLayout<'tcx>) -> Self {
assert!(layout.is_zst());
let align = layout.align.abi;
let ptr = Pointer::from_addr_invalid(align.bytes()); // no provenance, absolute address
MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None }, layout, align }
}
#[inline]
pub fn from_aligned_ptr(ptr: Pointer<Option<Prov>>, layout: TyAndLayout<'tcx>) -> Self {
MPlaceTy { mplace: MemPlace::from_ptr(ptr), layout, align: layout.align.abi }
}
#[inline]
pub fn from_aligned_ptr_with_meta(
ptr: Pointer<Option<Prov>>,
layout: TyAndLayout<'tcx>,
meta: MemPlaceMeta<Prov>,
) -> Self {
MPlaceTy {
mplace: MemPlace::from_ptr_with_meta(ptr, meta),
layout,
align: layout.align.abi,
}
MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None, misaligned: None }, layout }
}
/// Adjust the provenance of the main pointer (metadata is unaffected).
@ -204,11 +168,7 @@ fn offset_with_meta<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>(
layout: TyAndLayout<'tcx>,
ecx: &InterpCx<'mir, 'tcx, M>,
) -> InterpResult<'tcx, Self> {
Ok(MPlaceTy {
mplace: self.mplace.offset_with_meta_(offset, mode, meta, ecx)?,
align: self.align.restrict_for_offset(offset),
layout,
})
Ok(MPlaceTy { mplace: self.mplace.offset_with_meta_(offset, mode, meta, ecx)?, layout })
}
fn to_op<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>(
@ -239,11 +199,6 @@ pub(super) enum Place<Prov: Provenance = AllocId> {
pub struct PlaceTy<'tcx, Prov: Provenance = AllocId> {
place: Place<Prov>, // Keep this private; it helps enforce invariants.
pub layout: TyAndLayout<'tcx>,
/// rustc does not have a proper way to represent the type of a field of a `repr(packed)` struct:
/// it needs to have a different alignment than the field type would usually have.
/// So we represent this here with a separate field that "overwrites" `layout.align`.
/// This means `layout.align` should never be used for a `PlaceTy`!
pub align: Align,
}
impl<Prov: Provenance> std::fmt::Debug for PlaceTy<'_, Prov> {
@ -259,7 +214,7 @@ fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
impl<'tcx, Prov: Provenance> From<MPlaceTy<'tcx, Prov>> for PlaceTy<'tcx, Prov> {
#[inline(always)]
fn from(mplace: MPlaceTy<'tcx, Prov>) -> Self {
PlaceTy { place: Place::Ptr(mplace.mplace), layout: mplace.layout, align: mplace.align }
PlaceTy { place: Place::Ptr(mplace.mplace), layout: mplace.layout }
}
}
@ -275,7 +230,7 @@ pub fn as_mplace_or_local(
&self,
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>)> {
match self.place {
Place::Ptr(mplace) => Left(MPlaceTy { mplace, layout: self.layout, align: self.align }),
Place::Ptr(mplace) => Left(MPlaceTy { mplace, layout: self.layout }),
Place::Local { frame, local, offset } => Right((frame, local, offset)),
}
}
@ -332,11 +287,7 @@ fn offset_with_meta<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>(
.offset(old_offset.unwrap_or(Size::ZERO).bytes(), offset.bytes())?,
);
PlaceTy {
place: Place::Local { frame, local, offset: Some(new_offset) },
align: self.align.restrict_for_offset(offset),
layout,
}
PlaceTy { place: Place::Local { frame, local, offset: Some(new_offset) }, layout }
}
})
}
@ -354,9 +305,7 @@ impl<'tcx, Prov: Provenance> OpTy<'tcx, Prov> {
#[inline(always)]
pub fn as_mplace_or_imm(&self) -> Either<MPlaceTy<'tcx, Prov>, ImmTy<'tcx, Prov>> {
match self.op() {
Operand::Indirect(mplace) => {
Left(MPlaceTy { mplace: *mplace, layout: self.layout, align: self.align.unwrap() })
}
Operand::Indirect(mplace) => Left(MPlaceTy { mplace: *mplace, layout: self.layout }),
Operand::Immediate(imm) => Right(ImmTy::from_immediate(*imm, self.layout)),
}
}
@ -377,7 +326,7 @@ pub fn assert_mem_place(&self) -> MPlaceTy<'tcx, Prov> {
pub trait Writeable<'tcx, Prov: Provenance>: Projectable<'tcx, Prov> {
fn as_mplace_or_local(
&self,
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, Align, TyAndLayout<'tcx>)>;
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)>;
fn force_mplace<'mir, M: Machine<'mir, 'tcx, Provenance = Prov>>(
&self,
@ -389,10 +338,9 @@ impl<'tcx, Prov: Provenance> Writeable<'tcx, Prov> for PlaceTy<'tcx, Prov> {
#[inline(always)]
fn as_mplace_or_local(
&self,
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, Align, TyAndLayout<'tcx>)>
{
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)> {
self.as_mplace_or_local()
.map_right(|(frame, local, offset)| (frame, local, offset, self.align, self.layout))
.map_right(|(frame, local, offset)| (frame, local, offset, self.layout))
}
#[inline(always)]
@ -408,8 +356,7 @@ impl<'tcx, Prov: Provenance> Writeable<'tcx, Prov> for MPlaceTy<'tcx, Prov> {
#[inline(always)]
fn as_mplace_or_local(
&self,
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, Align, TyAndLayout<'tcx>)>
{
) -> Either<MPlaceTy<'tcx, Prov>, (usize, mir::Local, Option<Size>, TyAndLayout<'tcx>)> {
Left(self.clone())
}
@ -428,6 +375,25 @@ impl<'mir, 'tcx: 'mir, Prov, M> InterpCx<'mir, 'tcx, M>
Prov: Provenance,
M: Machine<'mir, 'tcx, Provenance = Prov>,
{
pub fn ptr_with_meta_to_mplace(
&self,
ptr: Pointer<Option<M::Provenance>>,
meta: MemPlaceMeta<M::Provenance>,
layout: TyAndLayout<'tcx>,
) -> MPlaceTy<'tcx, M::Provenance> {
let misaligned = self.is_ptr_misaligned(ptr, layout.align.abi);
MPlaceTy { mplace: MemPlace { ptr, meta, misaligned }, layout }
}
pub fn ptr_to_mplace(
&self,
ptr: Pointer<Option<M::Provenance>>,
layout: TyAndLayout<'tcx>,
) -> MPlaceTy<'tcx, M::Provenance> {
assert!(layout.is_sized());
self.ptr_with_meta_to_mplace(ptr, MemPlaceMeta::None, layout)
}
/// Take a value, which represents a (thin or wide) reference, and make it a place.
/// Alignment is just based on the type. This is the inverse of `mplace_to_ref()`.
///
@ -449,7 +415,8 @@ pub fn ref_to_mplace(
// `ref_to_mplace` is called on raw pointers even if they don't actually get dereferenced;
// we hence can't call `size_and_align_of` since that asserts more validity than we want.
Ok(MPlaceTy::from_aligned_ptr_with_meta(ptr.to_pointer(self)?, layout, meta))
let ptr = ptr.to_pointer(self)?;
Ok(self.ptr_with_meta_to_mplace(ptr, meta, layout))
}
/// Turn a mplace into a (thin or wide) mutable raw pointer, pointing to the same space.
@ -491,8 +458,11 @@ pub(super) fn get_place_alloc(
let (size, _align) = self
.size_and_align_of_mplace(&mplace)?
.unwrap_or((mplace.layout.size, mplace.layout.align.abi));
// Due to packed places, only `mplace.align` matters.
self.get_ptr_alloc(mplace.ptr(), size, mplace.align)
// We check alignment separately, and *after* checking everything else.
// If an access is both OOB and misaligned, we want to see the bounds error.
let a = self.get_ptr_alloc(mplace.ptr(), size, Align::ONE)?;
self.check_misalign(mplace.mplace.misaligned)?;
Ok(a)
}
#[inline]
@ -504,8 +474,13 @@ pub(super) fn get_place_alloc_mut(
let (size, _align) = self
.size_and_align_of_mplace(&mplace)?
.unwrap_or((mplace.layout.size, mplace.layout.align.abi));
// Due to packed places, only `mplace.align` matters.
self.get_ptr_alloc_mut(mplace.ptr(), size, mplace.align)
// We check alignment separately, and raise that error *after* checking everything else.
// If an access is both OOB and misaligned, we want to see the bounds error.
// However we have to call `check_misalign` first to make the borrow checker happy.
let misalign_err = self.check_misalign(mplace.mplace.misaligned);
let a = self.get_ptr_alloc_mut(mplace.ptr(), size, Align::ONE)?;
misalign_err?;
Ok(a)
}
/// Converts a repr(simd) place into a place where `place_index` accesses the SIMD elements.
@ -520,8 +495,8 @@ pub fn mplace_to_simd(
let (len, e_ty) = mplace.layout.ty.simd_size_and_type(*self.tcx);
let array = Ty::new_array(self.tcx.tcx, e_ty, len);
let layout = self.layout_of(array)?;
assert_eq!(layout.size, mplace.layout.size);
Ok((MPlaceTy { layout, ..*mplace }, len))
let mplace = mplace.transmute(layout, self)?;
Ok((mplace, len))
}
/// Converts a repr(simd) place into a place where `place_index` accesses the SIMD elements.
@ -557,7 +532,7 @@ pub fn local_to_place(
Operand::Indirect(mplace) => Place::Ptr(*mplace),
}
};
Ok(PlaceTy { place, layout, align: layout.align.abi })
Ok(PlaceTy { place, layout })
}
/// Computes a place. You should only use this if you intend to write into this
@ -647,7 +622,7 @@ fn write_immediate_no_validate(
// See if we can avoid an allocation. This is the counterpart to `read_immediate_raw`,
// but not factored as a separate function.
let mplace = match dest.as_mplace_or_local() {
Right((frame, local, offset, align, layout)) => {
Right((frame, local, offset, layout)) => {
if offset.is_some() {
// This has been projected to a part of this local. We could have complicated
// logic to still keep this local as an `Operand`... but it's much easier to
@ -688,7 +663,7 @@ fn write_immediate_no_validate(
}
Operand::Indirect(mplace) => {
// The local is in memory, go on below.
MPlaceTy { mplace: *mplace, align, layout }
MPlaceTy { mplace: *mplace, layout }
}
}
}
@ -697,7 +672,7 @@ fn write_immediate_no_validate(
};
// This is already in memory, write there.
self.write_immediate_to_mplace_no_validate(src, mplace.layout, mplace.align, mplace.mplace)
self.write_immediate_to_mplace_no_validate(src, mplace.layout, mplace.mplace)
}
/// Write an immediate to memory.
@ -707,7 +682,6 @@ fn write_immediate_to_mplace_no_validate(
&mut self,
value: Immediate<M::Provenance>,
layout: TyAndLayout<'tcx>,
align: Align,
dest: MemPlace<M::Provenance>,
) -> InterpResult<'tcx> {
// Note that it is really important that the type here is the right one, and matches the
@ -716,9 +690,7 @@ fn write_immediate_to_mplace_no_validate(
// wrong type.
let tcx = *self.tcx;
let Some(mut alloc) =
self.get_place_alloc_mut(&MPlaceTy { mplace: dest, layout, align })?
else {
let Some(mut alloc) = self.get_place_alloc_mut(&MPlaceTy { mplace: dest, layout })? else {
// zero-sized access
return Ok(());
};
@ -736,9 +708,6 @@ fn write_immediate_to_mplace_no_validate(
alloc.write_scalar(alloc_range(Size::ZERO, size), scalar)
}
Immediate::ScalarPair(a_val, b_val) => {
// We checked `ptr_align` above, so all fields will have the alignment they need.
// We would anyway check against `ptr_align.restrict_for_offset(b_offset)`,
// which `ptr.offset(b_offset)` cannot possibly fail to satisfy.
let Abi::ScalarPair(a, b) = layout.abi else {
span_bug!(
self.cur_span(),
@ -767,7 +736,7 @@ pub fn write_uninit(
) -> InterpResult<'tcx> {
let mplace = match dest.as_mplace_or_local() {
Left(mplace) => mplace,
Right((frame, local, offset, align, layout)) => {
Right((frame, local, offset, layout)) => {
if offset.is_some() {
// This has been projected to a part of this local. We could have complicated
// logic to still keep this local as an `Operand`... but it's much easier to
@ -783,7 +752,7 @@ pub fn write_uninit(
}
Operand::Indirect(mplace) => {
// The local is in memory, go on below.
MPlaceTy { mplace: *mplace, layout, align }
MPlaceTy { mplace: *mplace, layout }
}
}
}
@ -876,7 +845,6 @@ fn copy_op_no_validate(
self.write_immediate_to_mplace_no_validate(
*src_val,
src.layout(),
dest_mem.align,
dest_mem.mplace,
)
};
@ -903,14 +871,19 @@ fn copy_op_no_validate(
// type does not have Scalar/ScalarPair layout.
// (Or as the `Assign` docs put it, assignments "not producing primitives" must be
// non-overlapping.)
// We check alignment separately, and *after* checking everything else.
// If an access is both OOB and misaligned, we want to see the bounds error.
self.mem_copy(
src.ptr(),
src.align,
Align::ONE,
dest.ptr(),
dest.align,
Align::ONE,
dest_size,
/*nonoverlapping*/ true,
)
)?;
self.check_misalign(src.mplace.misaligned)?;
self.check_misalign(dest.mplace.misaligned)?;
Ok(())
}
/// Ensures that a place is in memory, and returns where it is.
@ -944,7 +917,6 @@ pub fn force_allocation(
self.write_immediate_to_mplace_no_validate(
local_val,
local_layout,
local_layout.align.abi,
mplace.mplace,
)?;
}
@ -974,7 +946,7 @@ pub fn force_allocation(
Place::Ptr(mplace) => mplace,
};
// Return with the original layout and align, so that the caller can go on
Ok(MPlaceTy { mplace, layout: place.layout, align: place.align })
Ok(MPlaceTy { mplace, layout: place.layout })
}
pub fn allocate_dyn(
@ -987,7 +959,7 @@ pub fn allocate_dyn(
span_bug!(self.cur_span(), "cannot allocate space for `extern` type, size is not known")
};
let ptr = self.allocate_ptr(size, align, kind)?;
Ok(MPlaceTy::from_aligned_ptr_with_meta(ptr.into(), layout, meta))
Ok(self.ptr_with_meta_to_mplace(ptr.into(), meta, layout))
}
pub fn allocate(
@ -999,7 +971,7 @@ pub fn allocate(
self.allocate_dyn(layout, kind, MemPlaceMeta::None)
}
/// Returns a wide MPlace of type `&'static [mut] str` to a new 1-aligned allocation.
/// Returns a wide MPlace of type `str` to a new 1-aligned allocation.
pub fn allocate_str(
&mut self,
str: &str,
@ -1008,15 +980,8 @@ pub fn allocate_str(
) -> InterpResult<'tcx, MPlaceTy<'tcx, M::Provenance>> {
let ptr = self.allocate_bytes_ptr(str.as_bytes(), Align::ONE, kind, mutbl)?;
let meta = Scalar::from_target_usize(u64::try_from(str.len()).unwrap(), self);
let mplace = MemPlace { ptr: ptr.into(), meta: MemPlaceMeta::Meta(meta) };
let ty = Ty::new_ref(
self.tcx.tcx,
self.tcx.lifetimes.re_static,
ty::TypeAndMut { ty: self.tcx.types.str_, mutbl },
);
let layout = self.layout_of(ty).unwrap();
Ok(MPlaceTy { mplace, layout, align: layout.align.abi })
let layout = self.layout_of(self.tcx.types.str_).unwrap();
Ok(self.ptr_with_meta_to_mplace(ptr.into(), MemPlaceMeta::Meta(meta), layout))
}
/// Writes the aggregate to the destination.
@ -1055,7 +1020,7 @@ pub fn raw_const_to_mplace(
let _ = self.tcx.global_alloc(raw.alloc_id);
let ptr = self.global_base_pointer(Pointer::from(raw.alloc_id))?;
let layout = self.layout_of(raw.ty)?;
Ok(MPlaceTy::from_aligned_ptr(ptr.into(), layout))
Ok(self.ptr_to_mplace(ptr.into(), layout))
}
/// Turn a place with a `dyn Trait` type into a place with the actual dynamic type.
@ -1071,12 +1036,10 @@ pub(super) fn unpack_dyn_trait(
let vtable = mplace.meta().unwrap_meta().to_pointer(self)?;
let (ty, _) = self.get_ptr_vtable(vtable)?;
let layout = self.layout_of(ty)?;
let mplace = MPlaceTy {
mplace: MemPlace { meta: MemPlaceMeta::None, ..mplace.mplace },
layout,
align: layout.align.abi,
};
// This is a kind of transmute, from a place with unsized type and metadata to
// a place with sized type and no metadata.
let mplace =
MPlaceTy { mplace: MemPlace { meta: MemPlaceMeta::None, ..mplace.mplace }, layout };
Ok((mplace, vtable))
}
@ -1108,10 +1071,10 @@ mod size_asserts {
use super::*;
use rustc_data_structures::static_assert_size;
// tidy-alphabetical-start
static_assert_size!(MemPlace, 40);
static_assert_size!(MemPlace, 48);
static_assert_size!(MemPlaceMeta, 24);
static_assert_size!(MPlaceTy<'_>, 64);
static_assert_size!(Place, 40);
static_assert_size!(Place, 48);
static_assert_size!(PlaceTy<'_>, 64);
// tidy-alphabetical-end
}

1
compiler/rustc_const_eval/src/interpret/projection.rs
View File

@ -267,6 +267,7 @@ pub fn project_array_fields<'a, P: Projectable<'tcx, M::Provenance>>(
let len = base.len(self)?;
let field_layout = base.layout().field(self, 0);
// Ensure that all the offsets are in-bounds once, up-front.
debug!("project_array_fields: {base:?} {len}");
base.offset(len * stride, self.layout_of(self.tcx.types.unit).unwrap(), self)?;
// Create the iterator.
Ok(ArrayIterator { base, range: 0..len, stride, field_layout, _phantom: PhantomData })

10
compiler/rustc_const_eval/src/interpret/step.rs
View File

@ -7,6 +7,7 @@
use rustc_middle::mir;
use rustc_middle::mir::interpret::{InterpResult, Scalar};
use rustc_middle::ty::layout::LayoutOf;
use rustc_target::abi::Align;
use super::{ImmTy, InterpCx, Machine, Projectable};
use crate::util;
@ -206,15 +207,12 @@ pub fn eval_rvalue_into_place(
let elem_size = first.layout.size;
let first_ptr = first.ptr();
let rest_ptr = first_ptr.offset(elem_size, self)?;
// For the alignment of `rest_ptr`, we crucially do *not* use `first.align` as
// that place might be more aligned than its type mandates (a `u8` array could
// be 4-aligned if it sits at the right spot in a struct). We have to also factor
// in element size.
// No alignment requirement since `copy_op` above already checked it.
self.mem_copy_repeatedly(
first_ptr,
dest.align,
Align::ONE,
rest_ptr,
dest.align.restrict_for_offset(elem_size),
Align::ONE,
elem_size,
length - 1,
/*nonoverlapping:*/ true,

16
compiler/rustc_const_eval/src/interpret/validity.rs
View File

@ -13,14 +13,14 @@
use rustc_data_structures::fx::FxHashSet;
use rustc_hir as hir;
use rustc_middle::mir::interpret::{
ExpectedKind, InterpError, InvalidMetaKind, PointerKind, ValidationErrorInfo,
ExpectedKind, InterpError, InvalidMetaKind, Misalignment, PointerKind, ValidationErrorInfo,
ValidationErrorKind, ValidationErrorKind::*,
};
use rustc_middle::ty;
use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_span::symbol::{sym, Symbol};
use rustc_target::abi::{
Abi, FieldIdx, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange,
Abi, Align, FieldIdx, Scalar as ScalarAbi, Size, VariantIdx, Variants, WrappingRange,
};
use std::hash::Hash;
@ -385,7 +385,7 @@ fn check_safe_pointer(
CheckInAllocMsg::InboundsTest, // will anyway be replaced by validity message
),
self.path,
Ub(AlignmentCheckFailed { required, has }) => UnalignedPtr {
Ub(AlignmentCheckFailed(Misalignment { required, has })) => UnalignedPtr {
ptr_kind,
required_bytes: required.bytes(),
found_bytes: has.bytes()
@ -781,14 +781,8 @@ fn visit_value(&mut self, op: &OpTy<'tcx, M::Provenance>) -> InterpResult<'tcx>
// Optimization: we just check the entire range at once.
// NOTE: Keep this in sync with the handling of integer and float
// types above, in `visit_primitive`.
// In run-time mode, we accept pointers in here. This is actually more
// permissive than a per-element check would be, e.g., we accept
// a &[u8] that contains a pointer even though bytewise checking would
// reject it. However, that's good: We don't inherently want
// to reject those pointers, we just do not have the machinery to
// talk about parts of a pointer.
// We also accept uninit, for consistency with the slow path.
let alloc = self.ecx.get_ptr_alloc(mplace.ptr(), size, mplace.align)?.expect("we already excluded size 0");
// No need for an alignment check here, this is not an actual memory access.
let alloc = self.ecx.get_ptr_alloc(mplace.ptr(), size, Align::ONE)?.expect("we already excluded size 0");
match alloc.get_bytes_strip_provenance() {
// In the happy case, we needn't check anything else.

9
compiler/rustc_middle/src/mir/interpret/error.rs
View File

@ -261,6 +261,13 @@ pub struct ScalarSizeMismatch {
pub data_size: u64,
}
/// Information about a misaligned pointer.
#[derive(Copy, Clone, Hash, PartialEq, Eq, Debug)]
pub struct Misalignment {
pub has: Align,
pub required: Align,
}
macro_rules! impl_into_diagnostic_arg_through_debug {
($($ty:ty),*$(,)?) => {$(
impl IntoDiagnosticArg for $ty {
@ -322,7 +329,7 @@ pub enum UndefinedBehaviorInfo<'tcx> {
/// Using an integer as a pointer in the wrong way.
DanglingIntPointer(u64, CheckInAllocMsg),
/// Used a pointer with bad alignment.
AlignmentCheckFailed { required: Align, has: Align },
AlignmentCheckFailed(Misalignment),
/// Writing to read-only memory.
WriteToReadOnly(AllocId),
/// Trying to access the data behind a function pointer.

2
compiler/rustc_middle/src/mir/interpret/mod.rs
View File

@ -144,7 +144,7 @@ macro_rules! throw_ub_custom {
pub use self::error::{
struct_error, BadBytesAccess, CheckInAllocMsg, ErrorHandled, EvalToAllocationRawResult,
EvalToConstValueResult, EvalToValTreeResult, ExpectedKind, InterpError, InterpErrorInfo,
InterpResult, InvalidMetaKind, InvalidProgramInfo, MachineStopType, PointerKind,
InterpResult, InvalidMetaKind, InvalidProgramInfo, MachineStopType, Misalignment, PointerKind,
ReportedErrorInfo, ResourceExhaustionInfo, ScalarSizeMismatch, UndefinedBehaviorInfo,
UnsupportedOpInfo, ValidationErrorInfo, ValidationErrorKind,
};

5
src/tools/miri/src/helpers.rs
View File

@ -697,10 +697,7 @@ fn deref_pointer_as(
) -> InterpResult<'tcx, MPlaceTy<'tcx, Provenance>> {
let this = self.eval_context_ref();
let ptr = this.read_pointer(op)?;
let mplace = MPlaceTy::from_aligned_ptr(ptr, layout);
Ok(mplace)
Ok(this.ptr_to_mplace(ptr, layout))
}
/// Calculates the MPlaceTy given the offset and layout of an access on an operand

2
src/tools/miri/src/shims/unix/fs.rs
View File

@ -1370,7 +1370,7 @@ fn linux_readdir64(
("d_reclen", size.into()),
("d_type", file_type.into()),
],
&MPlaceTy::from_aligned_ptr(entry, dirent64_layout),
&this.ptr_to_mplace(entry, dirent64_layout),
)?;
let name_ptr = entry.offset(Size::from_bytes(d_name_offset), this)?;

2
src/tools/miri/src/shims/unix/linux/sync.rs
View File

@ -34,7 +34,7 @@ pub fn futex<'tcx>(
let thread = this.get_active_thread();
// This is a vararg function so we have to bring our own type for this pointer.
let addr = MPlaceTy::from_aligned_ptr(addr, this.machine.layouts.i32);
let addr = this.ptr_to_mplace(addr, this.machine.layouts.i32);
let addr_usize = addr.ptr().addr().bytes();
let futex_private = this.eval_libc_i32("FUTEX_PRIVATE_FLAG");

4
src/tools/miri/src/shims/windows/sync.rs
View File

@ -322,8 +322,8 @@ fn WaitOnAddress(
let layout = this.machine.layouts.uint(size).unwrap();
let futex_val = this
.read_scalar_atomic(&MPlaceTy::from_aligned_ptr(ptr, layout), AtomicReadOrd::Relaxed)?;
let compare_val = this.read_scalar(&MPlaceTy::from_aligned_ptr(compare, layout))?;
.read_scalar_atomic(&this.ptr_to_mplace(ptr, layout), AtomicReadOrd::Relaxed)?;
let compare_val = this.read_scalar(&this.ptr_to_mplace(compare, layout))?;
if futex_val == compare_val {
// If the values are the same, we have to block.

30
src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs Normal file
View File

@ -0,0 +1,30 @@
/// This tests that when a field sits at a well-aligned offset, accessing the field
/// requires high alignment even if the field type has lower alignment requirements.
#[repr(C, align(16))]
#[derive(Default, Copy, Clone)]
pub struct Aligned {
_pad: [u8; 11],
packed: Packed,
}
#[repr(packed)]
#[derive(Default, Copy, Clone)]
pub struct Packed {
_pad: [u8; 5],
x: u8,
}
unsafe fn foo(x: *const Aligned) -> u8 {
unsafe { (*x).packed.x } //~ERROR: accessing memory with alignment 1, but alignment 16 is required
}
fn main() {
unsafe {
let mem = [Aligned::default(); 16];
let odd_ptr = std::ptr::addr_of!(mem).cast::<u8>().add(1);
// `odd_ptr` is now not aligned enough for `Aligned`.
// If accessing the nested field `packed.x` can exploit that it is at offset 16
// in a 16-aligned struct, this has to be UB.
foo(odd_ptr.cast());
}
}

20
src/tools/miri/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.stderr Normal file
View File

@ -0,0 +1,20 @@
error: Undefined Behavior: accessing memory with alignment ALIGN, but alignment ALIGN is required
--> $DIR/field_requires_parent_struct_alignment2.rs:LL:CC
|
LL | unsafe { (*x).packed.x }
| ^^^^^^^^^^^^^ accessing memory with alignment ALIGN, but alignment ALIGN is required
|
= help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior
= help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information
= note: BACKTRACE:
= note: inside `foo` at $DIR/field_requires_parent_struct_alignment2.rs:LL:CC
note: inside `main`
--> $DIR/field_requires_parent_struct_alignment2.rs:LL:CC
|
LL | foo(odd_ptr.cast());
| ^^^^^^^^^^^^^^^^^^^
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
error: aborting due to previous error

1
tests/ui/const-generics/generic_const_exprs/issue-80742.rs
View File

@ -3,6 +3,7 @@
// failure-status: 101
// normalize-stderr-test "note: .*\n\n" -> ""
// normalize-stderr-test "thread 'rustc' panicked.*\n" -> ""
// normalize-stderr-test "(error: internal compiler error: [^:]+):\d+:\d+: " -> "$1:LL:CC: "
// rustc-env:RUST_BACKTRACE=0
// This test used to cause an ICE in rustc_mir::interpret::step::eval_rvalue_into_place

4
tests/ui/const-generics/generic_const_exprs/issue-80742.stderr
View File

@ -1,9 +1,9 @@
error: internal compiler error: compiler/rustc_const_eval/src/interpret/step.rs:274:21: SizeOf MIR operator called for unsized type dyn Debug
error: internal compiler error: compiler/rustc_const_eval/src/interpret/step.rs:LL:CC: SizeOf MIR operator called for unsized type dyn Debug
--> $SRC_DIR/core/src/mem/mod.rs:LL:COL
Box<dyn Any>
query stack during panic:
#0 [eval_to_allocation_raw] const-evaluating + checking `<impl at $DIR/issue-80742.rs:25:1: 27:32>::{constant#0}`
#0 [eval_to_allocation_raw] const-evaluating + checking `<impl at $DIR/issue-80742.rs:26:1: 28:32>::{constant#0}`
#1 [eval_to_valtree] evaluating type-level constant
end of query stack
error: aborting due to previous error

1
tests/ui/consts/const-deref-ptr.rs
View File

@ -3,5 +3,6 @@
fn main() {
static C: u64 = unsafe {*(0xdeadbeef as *const u64)};
//~^ ERROR could not evaluate static initializer
//~| dangling pointer
println!("{}", C);
}

11
tests/ui/consts/const-eval/raw-pointer-ub.rs
View File

@ -26,6 +26,17 @@
// The actual error points into the implementation of `copy_to_nonoverlapping`.
};
const MISALIGNED_FIELD: () = unsafe {
#[repr(align(16))]
struct Aligned(f32);
let mem = [0f32; 8];
let ptr = mem.as_ptr().cast::<Aligned>();
// Accessing an f32 field but we still require the alignment of the pointer type.
let _val = (*ptr).0; //~ERROR: evaluation of constant value failed
//~^NOTE: accessing memory with alignment 4, but alignment 16 is required
};
const OOB: () = unsafe {
let mem = [0u32; 1];
let ptr = mem.as_ptr().cast::<u64>();

10
tests/ui/consts/const-eval/raw-pointer-ub.stderr
View File

@ -26,11 +26,17 @@ LL | y.copy_to_nonoverlapping(&mut z, 1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0080]: evaluation of constant value failed
--> $DIR/raw-pointer-ub.rs:32:16
--> $DIR/raw-pointer-ub.rs:36:16
|
LL | let _val = (*ptr).0;
| ^^^^^^^^ accessing memory with alignment 4, but alignment 16 is required
error[E0080]: evaluation of constant value failed
--> $DIR/raw-pointer-ub.rs:43:16
|
LL | let _val = *ptr;
| ^^^^ memory access failed: allocN has size 4, so pointer to 8 bytes starting at offset 0 is out-of-bounds
error: aborting due to 4 previous errors
error: aborting due to 5 previous errors
For more information about this error, try `rustc --explain E0080`.