Check vtable projections for validity in miri

This commit is contained in:
Michael Goulet 2024-09-22 20:00:01 -04:00
parent 648d024a78
commit 702a644b74
22 changed files with 143 additions and 87 deletions

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@ -161,13 +161,13 @@ pub(crate) fn codegen_const_value<'tcx>(
fx.module.declare_func_in_func(func_id, &mut fx.bcx.func);
fx.bcx.ins().func_addr(fx.pointer_type, local_func_id)
}
GlobalAlloc::VTable(ty, trait_ref) => {
GlobalAlloc::VTable(ty, dyn_ty) => {
let data_id = data_id_for_vtable(
fx.tcx,
&mut fx.constants_cx,
fx.module,
ty,
trait_ref,
dyn_ty.principal(),
);
let local_data_id =
fx.module.declare_data_in_func(data_id, &mut fx.bcx.func);
@ -456,8 +456,8 @@ fn define_all_allocs(tcx: TyCtxt<'_>, module: &mut dyn Module, cx: &mut Constant
GlobalAlloc::Memory(target_alloc) => {
data_id_for_alloc_id(cx, module, alloc_id, target_alloc.inner().mutability)
}
GlobalAlloc::VTable(ty, trait_ref) => {
data_id_for_vtable(tcx, cx, module, ty, trait_ref)
GlobalAlloc::VTable(ty, dyn_ty) => {
data_id_for_vtable(tcx, cx, module, ty, dyn_ty.principal())
}
GlobalAlloc::Static(def_id) => {
if tcx.codegen_fn_attrs(def_id).flags.contains(CodegenFnAttrFlags::THREAD_LOCAL)

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@ -224,10 +224,10 @@ impl<'gcc, 'tcx> ConstCodegenMethods<'tcx> for CodegenCx<'gcc, 'tcx> {
value
}
GlobalAlloc::Function { instance, .. } => self.get_fn_addr(instance),
GlobalAlloc::VTable(ty, trait_ref) => {
GlobalAlloc::VTable(ty, dyn_ty) => {
let alloc = self
.tcx
.global_alloc(self.tcx.vtable_allocation((ty, trait_ref)))
.global_alloc(self.tcx.vtable_allocation((ty, dyn_ty.principal())))
.unwrap_memory();
let init = const_alloc_to_gcc(self, alloc);
self.static_addr_of(init, alloc.inner().align, None)

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@ -290,10 +290,10 @@ impl<'ll, 'tcx> ConstCodegenMethods<'tcx> for CodegenCx<'ll, 'tcx> {
self.get_fn_addr(instance.polymorphize(self.tcx)),
self.data_layout().instruction_address_space,
),
GlobalAlloc::VTable(ty, trait_ref) => {
GlobalAlloc::VTable(ty, dyn_ty) => {
let alloc = self
.tcx
.global_alloc(self.tcx.vtable_allocation((ty, trait_ref)))
.global_alloc(self.tcx.vtable_allocation((ty, dyn_ty.principal())))
.unwrap_memory();
let init = const_alloc_to_llvm(self, alloc, /*static*/ false);
let value = self.static_addr_of(init, alloc.inner().align, None);

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@ -198,7 +198,7 @@ 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 `{$expected_trait}` was expected
using vtable for `{$vtable_dyn_type}` but `{$expected_dyn_type}` was expected
const_eval_lazy_lock =
consider wrapping this expression in `std::sync::LazyLock::new(|| ...)`
@ -459,7 +459,7 @@ const_eval_validation_invalid_fn_ptr = {$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_invalid_vtable_trait = {$front_matter}: wrong trait in wide pointer vtable: expected `{$expected_dyn_type}`, but encountered `{$vtable_dyn_type}`
const_eval_validation_mutable_ref_to_immutable = {$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

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@ -522,12 +522,9 @@ impl<'a> ReportErrorExt for UndefinedBehaviorInfo<'a> {
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>")),
);
InvalidVTableTrait { expected_dyn_type, vtable_dyn_type } => {
diag.arg("expected_dyn_type", expected_dyn_type.to_string());
diag.arg("vtable_dyn_type", vtable_dyn_type.to_string());
}
PointerUseAfterFree(alloc_id, msg) => {
diag.arg("alloc_id", alloc_id)
@ -777,12 +774,9 @@ 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>")),
);
InvalidMetaWrongTrait { vtable_dyn_type, expected_dyn_type } => {
err.arg("vtable_dyn_type", vtable_dyn_type.to_string());
err.arg("expected_dyn_type", expected_dyn_type.to_string());
}
NullPtr { .. }
| ConstRefToMutable

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@ -128,7 +128,7 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
CastKind::DynStar => {
if let ty::Dynamic(data, _, ty::DynStar) = cast_ty.kind() {
// Initial cast from sized to dyn trait
let vtable = self.get_vtable_ptr(src.layout.ty, data.principal())?;
let vtable = self.get_vtable_ptr(src.layout.ty, data)?;
let vtable = Scalar::from_maybe_pointer(vtable, self);
let data = self.read_immediate(src)?.to_scalar();
let _assert_pointer_like = data.to_pointer(self)?;
@ -446,12 +446,12 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
}
// Get the destination trait vtable and return that.
let new_vptr = self.get_vtable_ptr(ty, data_b.principal())?;
let new_vptr = self.get_vtable_ptr(ty, data_b)?;
self.write_immediate(Immediate::new_dyn_trait(old_data, new_vptr, self), dest)
}
(_, &ty::Dynamic(data, _, ty::Dyn)) => {
// Initial cast from sized to dyn trait
let vtable = self.get_vtable_ptr(src_pointee_ty, data.principal())?;
let vtable = self.get_vtable_ptr(src_pointee_ty, data)?;
let ptr = self.read_pointer(src)?;
let val = Immediate::new_dyn_trait(ptr, vtable, &*self.tcx);
self.write_immediate(val, dest)

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@ -943,12 +943,13 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
if offset.bytes() != 0 {
throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
}
let Some(GlobalAlloc::VTable(ty, vtable_trait)) = self.tcx.try_get_global_alloc(alloc_id)
let Some(GlobalAlloc::VTable(ty, vtable_dyn_type)) =
self.tcx.try_get_global_alloc(alloc_id)
else {
throw_ub!(InvalidVTablePointer(Pointer::new(alloc_id, offset)))
};
if let Some(expected_trait) = expected_trait {
self.check_vtable_for_type(vtable_trait, expected_trait)?;
if let Some(expected_dyn_type) = expected_trait {
self.check_vtable_for_type(vtable_dyn_type, expected_dyn_type)?;
}
Ok(ty)
}
@ -1113,11 +1114,8 @@ impl<'a, 'tcx, M: Machine<'tcx>> std::fmt::Debug for DumpAllocs<'a, 'tcx, M> {
Some(GlobalAlloc::Function { instance, .. }) => {
write!(fmt, " (fn: {instance})")?;
}
Some(GlobalAlloc::VTable(ty, Some(trait_ref))) => {
write!(fmt, " (vtable: impl {trait_ref} for {ty})")?;
}
Some(GlobalAlloc::VTable(ty, None)) => {
write!(fmt, " (vtable: impl <auto trait> for {ty})")?;
Some(GlobalAlloc::VTable(ty, dyn_ty)) => {
write!(fmt, " (vtable: impl {dyn_ty} for {ty})")?;
}
Some(GlobalAlloc::Static(did)) => {
write!(fmt, " (static: {})", self.ecx.tcx.def_path_str(did))?;

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@ -1,6 +1,6 @@
use rustc_middle::mir::interpret::{InterpResult, Pointer};
use rustc_middle::ty::layout::LayoutOf;
use rustc_middle::ty::{self, Ty, TyCtxt, VtblEntry};
use rustc_middle::ty::{self, ExistentialPredicateStableCmpExt, Ty, TyCtxt, VtblEntry};
use rustc_target::abi::{Align, Size};
use tracing::trace;
@ -11,26 +11,25 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
/// Creates a dynamic vtable for the given type and vtable origin. This is used only for
/// objects.
///
/// The `trait_ref` encodes the erased self type. Hence, if we are making an object `Foo<Trait>`
/// from a value of type `Foo<T>`, then `trait_ref` would map `T: Trait`. `None` here means that
/// this is an auto trait without any methods, so we only need the basic vtable (drop, size,
/// align).
/// The `dyn_ty` encodes the erased self type. Hence, if we are making an object
/// `Foo<dyn Trait<Assoc = A> + Send>` from a value of type `Foo<T>`, then `dyn_ty`
/// would be `Trait<Assoc = A> + Send`. If this list doesn't have a principal trait ref,
/// we only need the basic vtable prefix (drop, size, align).
pub fn get_vtable_ptr(
&self,
ty: Ty<'tcx>,
poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
dyn_ty: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> InterpResult<'tcx, Pointer<Option<M::Provenance>>> {
trace!("get_vtable(trait_ref={:?})", poly_trait_ref);
trace!("get_vtable(ty={ty:?}, dyn_ty={dyn_ty:?})");
let (ty, poly_trait_ref) = self.tcx.erase_regions((ty, poly_trait_ref));
let (ty, dyn_ty) = self.tcx.erase_regions((ty, dyn_ty));
// All vtables must be monomorphic, bail out otherwise.
ensure_monomorphic_enough(*self.tcx, ty)?;
ensure_monomorphic_enough(*self.tcx, poly_trait_ref)?;
ensure_monomorphic_enough(*self.tcx, dyn_ty)?;
let salt = M::get_global_alloc_salt(self, None);
let vtable_symbolic_allocation =
self.tcx.reserve_and_set_vtable_alloc(ty, poly_trait_ref, salt);
let vtable_symbolic_allocation = self.tcx.reserve_and_set_vtable_alloc(ty, dyn_ty, salt);
let vtable_ptr = self.global_root_pointer(Pointer::from(vtable_symbolic_allocation))?;
Ok(vtable_ptr.into())
}
@ -64,17 +63,45 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
/// expected trait type.
pub(super) fn check_vtable_for_type(
&self,
vtable_trait: Option<ty::PolyExistentialTraitRef<'tcx>>,
expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
vtable_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
expected_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
) -> InterpResult<'tcx> {
let eq = match (expected_trait.principal(), vtable_trait) {
(Some(a), Some(b)) => self.eq_in_param_env(a, b),
(None, None) => true,
_ => false,
};
if !eq {
throw_ub!(InvalidVTableTrait { expected_trait, vtable_trait });
// We check validity by comparing the lists of predicates for equality. We *could* instead
// check that the dynamic type to which the vtable belongs satisfies all the expected
// predicates, but that would likely be a lot slower and seems unnecessarily permissive.
// FIXME: we are skipping auto traits for now, but might revisit this in the future.
let mut sorted_vtable: Vec<_> = vtable_dyn_type.without_auto_traits().collect();
let mut sorted_expected: Vec<_> = expected_dyn_type.without_auto_traits().collect();
// `skip_binder` here is okay because `stable_cmp` doesn't look at binders
sorted_vtable.sort_by(|a, b| a.skip_binder().stable_cmp(*self.tcx, &b.skip_binder()));
sorted_vtable.dedup();
sorted_expected.sort_by(|a, b| a.skip_binder().stable_cmp(*self.tcx, &b.skip_binder()));
sorted_expected.dedup();
if sorted_vtable.len() != sorted_expected.len() {
throw_ub!(InvalidVTableTrait { vtable_dyn_type, expected_dyn_type });
}
for (a_pred, b_pred) in std::iter::zip(sorted_vtable, sorted_expected) {
let is_eq = match (a_pred.skip_binder(), b_pred.skip_binder()) {
(
ty::ExistentialPredicate::Trait(a_data),
ty::ExistentialPredicate::Trait(b_data),
) => self.eq_in_param_env(a_pred.rebind(a_data), b_pred.rebind(b_data)),
(
ty::ExistentialPredicate::Projection(a_data),
ty::ExistentialPredicate::Projection(b_data),
) => self.eq_in_param_env(a_pred.rebind(a_data), b_pred.rebind(b_data)),
_ => false,
};
if !is_eq {
throw_ub!(InvalidVTableTrait { vtable_dyn_type, expected_dyn_type });
}
}
Ok(())
}

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@ -452,8 +452,8 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValidityVisitor<'rt, 'tcx, M> {
self.path,
Ub(DanglingIntPointer{ .. } | InvalidVTablePointer(..)) =>
InvalidVTablePtr { value: format!("{vtable}") },
Ub(InvalidVTableTrait { expected_trait, vtable_trait }) => {
InvalidMetaWrongTrait { expected_trait, vtable_trait: *vtable_trait }
Ub(InvalidVTableTrait { vtable_dyn_type, expected_dyn_type }) => {
InvalidMetaWrongTrait { vtable_dyn_type, expected_dyn_type }
},
);
}
@ -1281,8 +1281,8 @@ impl<'rt, 'tcx, M: Machine<'tcx>> ValueVisitor<'tcx, M> for ValidityVisitor<'rt,
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 }
Ub(InvalidVTableTrait { vtable_dyn_type, expected_dyn_type }) => {
InvalidMetaWrongTrait { vtable_dyn_type, expected_dyn_type: *expected_dyn_type }
},
);
}

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@ -365,8 +365,10 @@ pub enum UndefinedBehaviorInfo<'tcx> {
InvalidVTablePointer(Pointer<AllocId>),
/// Using a vtable for the wrong trait.
InvalidVTableTrait {
expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
vtable_trait: Option<ty::PolyExistentialTraitRef<'tcx>>,
/// The vtable that was actually referenced by the wide pointer metadata.
vtable_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
/// The vtable that was expected at the point in MIR that it was accessed.
expected_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
},
/// Using a string that is not valid UTF-8,
InvalidStr(std::str::Utf8Error),
@ -479,8 +481,10 @@ pub enum ValidationErrorKind<'tcx> {
value: String,
},
InvalidMetaWrongTrait {
expected_trait: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
vtable_trait: Option<ty::PolyExistentialTraitRef<'tcx>>,
/// The vtable that was actually referenced by the wide pointer metadata.
vtable_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
/// The vtable that was expected at the point in MIR that it was accessed.
expected_dyn_type: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
},
InvalidMetaSliceTooLarge {
ptr_kind: PointerKind,

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@ -232,9 +232,8 @@ impl<'s> AllocDecodingSession<'s> {
}
AllocDiscriminant::VTable => {
trace!("creating vtable alloc ID");
let ty = <Ty<'_> as Decodable<D>>::decode(decoder);
let poly_trait_ref =
<Option<ty::PolyExistentialTraitRef<'_>> as Decodable<D>>::decode(decoder);
let ty = Decodable::decode(decoder);
let poly_trait_ref = Decodable::decode(decoder);
trace!("decoded vtable alloc instance: {ty:?}, {poly_trait_ref:?}");
decoder.interner().reserve_and_set_vtable_alloc(ty, poly_trait_ref, CTFE_ALLOC_SALT)
}
@ -259,7 +258,10 @@ pub enum GlobalAlloc<'tcx> {
/// The alloc ID is used as a function pointer.
Function { instance: Instance<'tcx> },
/// This alloc ID points to a symbolic (not-reified) vtable.
VTable(Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>),
/// We remember the full dyn type, not just the principal trait, so that
/// const-eval and Miri can detect UB due to invalid transmutes of
/// `dyn Trait` types.
VTable(Ty<'tcx>, &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>),
/// The alloc ID points to a "lazy" static variable that did not get computed (yet).
/// This is also used to break the cycle in recursive statics.
Static(DefId),
@ -293,7 +295,7 @@ impl<'tcx> GlobalAlloc<'tcx> {
#[inline]
pub fn unwrap_vtable(&self) -> (Ty<'tcx>, Option<ty::PolyExistentialTraitRef<'tcx>>) {
match *self {
GlobalAlloc::VTable(ty, poly_trait_ref) => (ty, poly_trait_ref),
GlobalAlloc::VTable(ty, dyn_ty) => (ty, dyn_ty.principal()),
_ => bug!("expected vtable, got {:?}", self),
}
}
@ -398,10 +400,10 @@ impl<'tcx> TyCtxt<'tcx> {
pub fn reserve_and_set_vtable_alloc(
self,
ty: Ty<'tcx>,
poly_trait_ref: Option<ty::PolyExistentialTraitRef<'tcx>>,
dyn_ty: &'tcx ty::List<ty::PolyExistentialPredicate<'tcx>>,
salt: usize,
) -> AllocId {
self.reserve_and_set_dedup(GlobalAlloc::VTable(ty, poly_trait_ref), salt)
self.reserve_and_set_dedup(GlobalAlloc::VTable(ty, dyn_ty), salt)
}
/// Interns the `Allocation` and return a new `AllocId`, even if there's already an identical

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@ -1536,11 +1536,8 @@ pub fn write_allocations<'tcx>(
// gracefully handle it and allow buggy rustc to be debugged via allocation printing.
None => write!(w, " (deallocated)")?,
Some(GlobalAlloc::Function { instance, .. }) => write!(w, " (fn: {instance})")?,
Some(GlobalAlloc::VTable(ty, Some(trait_ref))) => {
write!(w, " (vtable: impl {trait_ref} for {ty})")?
}
Some(GlobalAlloc::VTable(ty, None)) => {
write!(w, " (vtable: impl <auto trait> for {ty})")?
Some(GlobalAlloc::VTable(ty, dyn_ty)) => {
write!(w, " (vtable: impl {dyn_ty} for {ty})")?
}
Some(GlobalAlloc::Static(did)) if !tcx.is_foreign_item(did) => {
match tcx.eval_static_initializer(did) {

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@ -1175,8 +1175,8 @@ fn collect_alloc<'tcx>(tcx: TyCtxt<'tcx>, alloc_id: AllocId, output: &mut MonoIt
output.push(create_fn_mono_item(tcx, instance, DUMMY_SP));
}
}
GlobalAlloc::VTable(ty, trait_ref) => {
let alloc_id = tcx.vtable_allocation((ty, trait_ref));
GlobalAlloc::VTable(ty, dyn_ty) => {
let alloc_id = tcx.vtable_allocation((ty, dyn_ty.principal()));
collect_alloc(tcx, alloc_id, output)
}
}

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@ -318,10 +318,10 @@ impl<'tcx> ReachableContext<'tcx> {
));
self.visit(instance.args);
}
GlobalAlloc::VTable(ty, trait_ref) => {
GlobalAlloc::VTable(ty, dyn_ty) => {
self.visit(ty);
// Manually visit to actually see the trait's `DefId`. Type visitors won't see it
if let Some(trait_ref) = trait_ref {
if let Some(trait_ref) = dyn_ty.principal() {
let ExistentialTraitRef { def_id, args } = trait_ref.skip_binder();
self.visit_def_id(def_id, "", &"");
self.visit(args);

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@ -712,8 +712,9 @@ impl<'tcx> Stable<'tcx> for mir::interpret::GlobalAlloc<'tcx> {
mir::interpret::GlobalAlloc::Function { instance, .. } => {
GlobalAlloc::Function(instance.stable(tables))
}
mir::interpret::GlobalAlloc::VTable(ty, trait_ref) => {
GlobalAlloc::VTable(ty.stable(tables), trait_ref.stable(tables))
mir::interpret::GlobalAlloc::VTable(ty, dyn_ty) => {
// FIXME: Should we record the whole vtable?
GlobalAlloc::VTable(ty.stable(tables), dyn_ty.principal().stable(tables))
}
mir::interpret::GlobalAlloc::Static(def) => {
GlobalAlloc::Static(tables.static_def(*def))

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@ -16,5 +16,5 @@ impl T1 for i32 {
fn main() {
let r = Box::new(0) as Box<dyn T1>;
let r2: Box<dyn T2> = unsafe { std::mem::transmute(r) };
r2.method2(); //~ERROR: using vtable for trait `T1` but trait `T2` was expected
r2.method2(); //~ERROR: using vtable for `T1` but `T2` was expected
}

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@ -1,8 +1,8 @@
error: Undefined Behavior: using vtable for trait `T1` but trait `T2` was expected
error: Undefined Behavior: using vtable for `T1` but `T2` was expected
--> tests/fail/dyn-call-trait-mismatch.rs:LL:CC
|
LL | r2.method2();
| ^^^^^^^^^^^^ using vtable for trait `T1` but trait `T2` was expected
| ^^^^^^^^^^^^ using vtable for `T1` but `T2` was expected
|
= 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

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@ -63,6 +63,6 @@ fn main() {
let baz: &dyn Baz = &1;
let baz_fake: *const dyn Bar = std::mem::transmute(baz);
let _err = baz_fake as *const dyn Foo;
//~^ERROR: using vtable for trait `Baz` but trait `Bar` was expected
//~^ERROR: using vtable for `Baz` but `Bar` was expected
}
}

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@ -1,8 +1,8 @@
error: Undefined Behavior: using vtable for trait `Baz` but trait `Bar` was expected
error: Undefined Behavior: using vtable for `Baz` but `Bar` was expected
--> tests/fail/dyn-upcast-trait-mismatch.rs:LL:CC
|
LL | let _err = baz_fake as *const dyn Foo;
| ^^^^^^^^ using vtable for trait `Baz` but trait `Bar` was expected
| ^^^^^^^^ using vtable for `Baz` but `Bar` was expected
|
= 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

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@ -0,0 +1,18 @@
trait Trait {
type Assoc;
fn foo(&self) -> Self::Assoc;
}
impl<T: Copy> Trait for T {
type Assoc = T;
fn foo(&self) -> T { *self }
}
fn main() {
let v: Box<dyn Trait<Assoc = u8>> = Box::new(2);
let v: Box<dyn Trait<Assoc = bool>> = unsafe { std::mem::transmute(v) }; //~ERROR: wrong trait
if v.foo() {
println!("huh");
}
}

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@ -0,0 +1,15 @@
error: Undefined Behavior: constructing invalid value: wrong trait in wide pointer vtable: expected `Trait<Assoc = bool>`, but encountered `Trait<Assoc = u8>`
--> tests/fail/validity/wrong-dyn-trait-assoc-type.rs:LL:CC
|
LL | let v: Box<dyn Trait<Assoc = bool>> = unsafe { std::mem::transmute(v) };
| ^^^^^^^^^^^^^^^^^^^^^^ constructing invalid value: wrong trait in wide pointer vtable: expected `Trait<Assoc = bool>`, but encountered `Trait<Assoc = u8>`
|
= 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 `main` at tests/fail/validity/wrong-dyn-trait-assoc-type.rs:LL:CC
note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
error: aborting due to 1 previous error

View File

@ -1,8 +1,8 @@
error: Undefined Behavior: constructing invalid value: wrong trait in wide pointer vtable: expected `std::fmt::Debug`, but encountered `<trivial>`
error: Undefined Behavior: constructing invalid value: wrong trait in wide pointer vtable: expected `std::fmt::Debug`, but encountered `std::marker::Send`
--> tests/fail/validity/wrong-dyn-trait.rs:LL:CC
|
LL | let _y: *const dyn fmt::Debug = unsafe { mem::transmute(x) };
| ^^^^^^^^^^^^^^^^^ constructing invalid value: wrong trait in wide pointer vtable: expected `std::fmt::Debug`, but encountered `<trivial>`
| ^^^^^^^^^^^^^^^^^ constructing invalid value: wrong trait in wide pointer vtable: expected `std::fmt::Debug`, but encountered `std::marker::Send`
|
= 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