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Rollup of 7 pull requests #124277

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Apr 23, 2024
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12 changes: 3 additions & 9 deletions compiler/rustc_const_eval/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -82,12 +82,6 @@ const_eval_double_storage_live =
const_eval_dyn_call_not_a_method =
`dyn` call trying to call something that is not a method

const_eval_dyn_call_vtable_mismatch =
`dyn` call on a pointer whose vtable does not match its type

const_eval_dyn_star_call_vtable_mismatch =
`dyn*` call on a pointer whose vtable does not match its type

const_eval_error = {$error_kind ->
[static] could not evaluate static initializer
[const] evaluation of constant value failed
Expand Down Expand Up @@ -192,6 +186,8 @@ const_eval_invalid_uninit_bytes_unknown =
const_eval_invalid_vtable_pointer =
using {$pointer} as vtable pointer but it does not point to a vtable

const_eval_invalid_vtable_trait =
using vtable for trait `{$vtable_trait}` but trait `{$expected_trait}` was expected

const_eval_live_drop =
destructor of `{$dropped_ty}` cannot be evaluated at compile-time
Expand Down Expand Up @@ -401,9 +397,6 @@ const_eval_unterminated_c_string =
const_eval_unwind_past_top =
unwinding past the topmost frame of the stack

const_eval_upcast_mismatch =
upcast on a pointer whose vtable does not match its type

## The `front_matter`s here refer to either `const_eval_front_matter_invalid_value` or `const_eval_front_matter_invalid_value_with_path`.
## (We'd love to sort this differently to make that more clear but tidy won't let us...)
const_eval_validation_box_to_static = {$front_matter}: encountered a box pointing to a static variable in a constant
Expand Down Expand Up @@ -450,6 +443,7 @@ const_eval_validation_invalid_fn_ptr = {$front_matter}: encountered {$value}, bu
const_eval_validation_invalid_ref_meta = {$front_matter}: encountered invalid reference metadata: total size is bigger than largest supported object
const_eval_validation_invalid_ref_slice_meta = {$front_matter}: encountered invalid reference metadata: slice is bigger than largest supported object
const_eval_validation_invalid_vtable_ptr = {$front_matter}: encountered {$value}, but expected a vtable pointer
const_eval_validation_invalid_vtable_trait = {$front_matter}: wrong trait in wide pointer vtable: expected `{$ref_trait}`, but encountered `{$vtable_trait}`
const_eval_validation_mutable_ref_to_immutable = {$front_matter}: encountered mutable reference or box pointing to read-only memory
const_eval_validation_never_val = {$front_matter}: encountered a value of the never type `!`
const_eval_validation_null_box = {$front_matter}: encountered a null box
Expand Down
17 changes: 17 additions & 0 deletions compiler/rustc_const_eval/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -498,6 +498,7 @@ impl<'a> ReportErrorExt for UndefinedBehaviorInfo<'a> {
InvalidTag(_) => const_eval_invalid_tag,
InvalidFunctionPointer(_) => const_eval_invalid_function_pointer,
InvalidVTablePointer(_) => const_eval_invalid_vtable_pointer,
InvalidVTableTrait { .. } => const_eval_invalid_vtable_trait,
InvalidStr(_) => const_eval_invalid_str,
InvalidUninitBytes(None) => const_eval_invalid_uninit_bytes_unknown,
InvalidUninitBytes(Some(_)) => const_eval_invalid_uninit_bytes,
Expand Down Expand Up @@ -537,13 +538,21 @@ impl<'a> ReportErrorExt for UndefinedBehaviorInfo<'a> {
| DeadLocal
| UninhabitedEnumVariantWritten(_)
| UninhabitedEnumVariantRead(_) => {}

BoundsCheckFailed { len, index } => {
diag.arg("len", len);
diag.arg("index", index);
}
UnterminatedCString(ptr) | InvalidFunctionPointer(ptr) | InvalidVTablePointer(ptr) => {
diag.arg("pointer", ptr);
}
InvalidVTableTrait { expected_trait, vtable_trait } => {
diag.arg("expected_trait", expected_trait.to_string());
diag.arg(
"vtable_trait",
vtable_trait.map(|t| t.to_string()).unwrap_or_else(|| format!("<trivial>")),
);
}
PointerUseAfterFree(alloc_id, msg) => {
diag.arg("alloc_id", alloc_id)
.arg("bad_pointer_message", bad_pointer_message(msg, dcx));
Expand Down Expand Up @@ -634,6 +643,7 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
UninhabitedEnumVariant => const_eval_validation_uninhabited_enum_variant,
Uninit { .. } => const_eval_validation_uninit,
InvalidVTablePtr { .. } => const_eval_validation_invalid_vtable_ptr,
InvalidMetaWrongTrait { .. } => const_eval_validation_invalid_vtable_trait,
InvalidMetaSliceTooLarge { ptr_kind: PointerKind::Box } => {
const_eval_validation_invalid_box_slice_meta
}
Expand Down Expand Up @@ -773,6 +783,13 @@ impl<'tcx> ReportErrorExt for ValidationErrorInfo<'tcx> {
DanglingPtrNoProvenance { pointer, .. } => {
err.arg("pointer", pointer);
}
InvalidMetaWrongTrait { expected_trait: ref_trait, vtable_trait } => {
err.arg("ref_trait", ref_trait.to_string());
err.arg(
"vtable_trait",
vtable_trait.map(|t| t.to_string()).unwrap_or_else(|| format!("<trivial>")),
);
}
NullPtr { .. }
| PtrToStatic { .. }
| ConstRefToMutable
Expand Down
6 changes: 5 additions & 1 deletion compiler/rustc_const_eval/src/interpret/cast.rs
Original file line number Diff line number Diff line change
Expand Up @@ -393,14 +393,18 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let val = self.read_immediate(src)?;
if data_a.principal() == data_b.principal() {
// A NOP cast that doesn't actually change anything, should be allowed even with mismatching vtables.
// (But currently mismatching vtables violate the validity invariant so UB is triggered anyway.)
return self.write_immediate(*val, dest);
}
let (old_data, old_vptr) = val.to_scalar_pair();
let old_data = old_data.to_pointer(self)?;
let old_vptr = old_vptr.to_pointer(self)?;
let (ty, old_trait) = self.get_ptr_vtable(old_vptr)?;
if old_trait != data_a.principal() {
throw_ub_custom!(fluent::const_eval_upcast_mismatch);
throw_ub!(InvalidVTableTrait {
expected_trait: data_a,
vtable_trait: old_trait,
});
}
let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
Expand Down
17 changes: 12 additions & 5 deletions compiler/rustc_const_eval/src/interpret/place.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1020,16 +1020,20 @@ where
pub(super) fn unpack_dyn_trait(
&self,
mplace: &MPlaceTy<'tcx, M::Provenance>,
expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> InterpResult<'tcx, (MPlaceTy<'tcx, M::Provenance>, Pointer<Option<M::Provenance>>)> {
assert!(
matches!(mplace.layout.ty.kind(), ty::Dynamic(_, _, ty::Dyn)),
"`unpack_dyn_trait` only makes sense on `dyn*` types"
);
let vtable = mplace.meta().unwrap_meta().to_pointer(self)?;
let (ty, _) = self.get_ptr_vtable(vtable)?;
let layout = self.layout_of(ty)?;
let (ty, vtable_trait) = self.get_ptr_vtable(vtable)?;
if expected_trait.principal() != vtable_trait {
throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
}
// This is a kind of transmute, from a place with unsized type and metadata to
// a place with sized type and no metadata.
let layout = self.layout_of(ty)?;
let mplace =
MPlaceTy { mplace: MemPlace { meta: MemPlaceMeta::None, ..mplace.mplace }, layout };
Ok((mplace, vtable))
Expand All @@ -1040,6 +1044,7 @@ where
pub(super) fn unpack_dyn_star<P: Projectable<'tcx, M::Provenance>>(
&self,
val: &P,
expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> InterpResult<'tcx, (P, Pointer<Option<M::Provenance>>)> {
assert!(
matches!(val.layout().ty.kind(), ty::Dynamic(_, _, ty::DynStar)),
Expand All @@ -1048,10 +1053,12 @@ where
let data = self.project_field(val, 0)?;
let vtable = self.project_field(val, 1)?;
let vtable = self.read_pointer(&vtable.to_op(self)?)?;
let (ty, _) = self.get_ptr_vtable(vtable)?;
let (ty, vtable_trait) = self.get_ptr_vtable(vtable)?;
if expected_trait.principal() != vtable_trait {
throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
}
// `data` is already the right thing but has the wrong type. So we transmute it.
let layout = self.layout_of(ty)?;
// `data` is already the right thing but has the wrong type. So we transmute it, by
// projecting with offset 0.
let data = data.transmute(layout, self)?;
Ok((data, vtable))
}
Expand Down
20 changes: 10 additions & 10 deletions compiler/rustc_const_eval/src/interpret/terminator.rs
Original file line number Diff line number Diff line change
Expand Up @@ -803,11 +803,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let (vptr, dyn_ty, adjusted_receiver) = if let ty::Dynamic(data, _, ty::DynStar) =
receiver_place.layout.ty.kind()
{
let (recv, vptr) = self.unpack_dyn_star(&receiver_place)?;
let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
if dyn_trait != data.principal() {
throw_ub_custom!(fluent::const_eval_dyn_star_call_vtable_mismatch);
}
let (recv, vptr) = self.unpack_dyn_star(&receiver_place, data)?;
let (dyn_ty, _dyn_trait) = self.get_ptr_vtable(vptr)?;

(vptr, dyn_ty, recv.ptr())
} else {
Expand All @@ -829,7 +826,10 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let vptr = receiver_place.meta().unwrap_meta().to_pointer(self)?;
let (dyn_ty, dyn_trait) = self.get_ptr_vtable(vptr)?;
if dyn_trait != data.principal() {
throw_ub_custom!(fluent::const_eval_dyn_call_vtable_mismatch);
throw_ub!(InvalidVTableTrait {
expected_trait: data,
vtable_trait: dyn_trait,
});
}

// It might be surprising that we use a pointer as the receiver even if this
Expand Down Expand Up @@ -939,13 +939,13 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let place = self.force_allocation(place)?;

let place = match place.layout.ty.kind() {
ty::Dynamic(_, _, ty::Dyn) => {
ty::Dynamic(data, _, ty::Dyn) => {
// Dropping a trait object. Need to find actual drop fn.
self.unpack_dyn_trait(&place)?.0
self.unpack_dyn_trait(&place, data)?.0
}
ty::Dynamic(_, _, ty::DynStar) => {
ty::Dynamic(data, _, ty::DynStar) => {
// Dropping a `dyn*`. Need to find actual drop fn.
self.unpack_dyn_star(&place)?.0
self.unpack_dyn_star(&place, data)?.0
}
_ => {
debug_assert_eq!(
Expand Down
23 changes: 19 additions & 4 deletions compiler/rustc_const_eval/src/interpret/validity.rs
Original file line number Diff line number Diff line change
Expand Up @@ -339,16 +339,22 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
) -> InterpResult<'tcx> {
let tail = self.ecx.tcx.struct_tail_erasing_lifetimes(pointee.ty, self.ecx.param_env);
match tail.kind() {
ty::Dynamic(_, _, ty::Dyn) => {
ty::Dynamic(data, _, ty::Dyn) => {
let vtable = meta.unwrap_meta().to_pointer(self.ecx)?;
// Make sure it is a genuine vtable pointer.
let (_ty, _trait) = try_validation!(
let (_dyn_ty, dyn_trait) = try_validation!(
self.ecx.get_ptr_vtable(vtable),
self.path,
Ub(DanglingIntPointer(..) | InvalidVTablePointer(..)) =>
InvalidVTablePtr { value: format!("{vtable}") }
);
// FIXME: check if the type/trait match what ty::Dynamic says?
// Make sure it is for the right trait.
if dyn_trait != data.principal() {
throw_validation_failure!(
self.path,
InvalidMetaWrongTrait { expected_trait: data, vtable_trait: dyn_trait }
);
}
}
ty::Slice(..) | ty::Str => {
let _len = meta.unwrap_meta().to_target_usize(self.ecx)?;
Expand Down Expand Up @@ -933,7 +939,16 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValueVisitor<'mir, 'tcx, M>
}
}
_ => {
self.walk_value(op)?; // default handler
// default handler
try_validation!(
self.walk_value(op),
self.path,
// It's not great to catch errors here, since we can't give a very good path,
// but it's better than ICEing.
Ub(InvalidVTableTrait { expected_trait, vtable_trait }) => {
InvalidMetaWrongTrait { expected_trait, vtable_trait: *vtable_trait }
},
);
}
}

Expand Down
8 changes: 4 additions & 4 deletions compiler/rustc_const_eval/src/interpret/visitor.rs
Original file line number Diff line number Diff line change
Expand Up @@ -88,22 +88,22 @@ pub trait ValueVisitor<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>>: Sized {
// Special treatment for special types, where the (static) layout is not sufficient.
match *ty.kind() {
// If it is a trait object, switch to the real type that was used to create it.
ty::Dynamic(_, _, ty::Dyn) => {
ty::Dynamic(data, _, ty::Dyn) => {
// Dyn types. This is unsized, and the actual dynamic type of the data is given by the
// vtable stored in the place metadata.
// unsized values are never immediate, so we can assert_mem_place
let op = v.to_op(self.ecx())?;
let dest = op.assert_mem_place();
let inner_mplace = self.ecx().unpack_dyn_trait(&dest)?.0;
let inner_mplace = self.ecx().unpack_dyn_trait(&dest, data)?.0;
trace!("walk_value: dyn object layout: {:#?}", inner_mplace.layout);
// recurse with the inner type
return self.visit_field(v, 0, &inner_mplace.into());
}
ty::Dynamic(_, _, ty::DynStar) => {
ty::Dynamic(data, _, ty::DynStar) => {
// DynStar types. Very different from a dyn type (but strangely part of the
// same variant in `TyKind`): These are pairs where the 2nd component is the
// vtable, and the first component is the data (which must be ptr-sized).
let data = self.ecx().unpack_dyn_star(v)?.0;
let data = self.ecx().unpack_dyn_star(v, data)?.0;
return self.visit_field(v, 0, &data);
}
// Slices do not need special handling here: they have `Array` field
Expand Down
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