1
Fork 0

Safe Transmute: Enable handling references, including recursive types

This patch enables support for references in Safe Transmute, by generating
nested obligations during trait selection. Specifically, when we call
`confirm_transmutability_candidate(...)`, we now recursively traverse the
`rustc_transmute::Answer` tree and create obligations for all the `Answer`
variants, some of which include multiple nested `Answer`s.

Also, to handle recursive types, enable support for coinduction for the Safe
Transmute trait (`BikeshedIntrinsicFrom`) by adding the `#[rustc_coinduction]`
annotation.

Also fix some small logic issues when reducing the `or` and `and` combinations
in `rustc_transmute`, so that we don't end up with additional redundant
`Answer`s in the tree.

Co-authored-by: Jack Wrenn <jack@wrenn.fyi>
This commit is contained in:
Bryan Garza 2023-04-21 16:49:36 -07:00
parent 97d328012b
commit 8f1cec8d84
26 changed files with 460 additions and 103 deletions

View file

@ -2783,6 +2783,14 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
rustc_transmute::Reason::DstIsTooBig => { rustc_transmute::Reason::DstIsTooBig => {
format!("The size of `{src}` is smaller than the size of `{dst}`") format!("The size of `{src}` is smaller than the size of `{dst}`")
} }
rustc_transmute::Reason::DstHasStricterAlignment => {
format!(
"The alignment of `{src}` should be stricter than that of `{dst}`, but it is not"
)
}
rustc_transmute::Reason::DstIsMoreUnique => {
format!("`{src}` is a shared reference, but `{dst}` is a unique reference")
}
}; };
(custom_err_msg, Some(reason_msg)) (custom_err_msg, Some(reason_msg))
} }
@ -2791,7 +2799,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
span, span,
"Inconsistent rustc_transmute::is_transmutable(...) result, got Yes", "Inconsistent rustc_transmute::is_transmutable(...) result, got Yes",
), ),
_ => span_bug!(span, "Unsupported rustc_transmute::Reason variant"), other => span_bug!(span, "Unsupported rustc_transmute::Answer variant: `{other:?}`"),
} }
} }

View file

@ -13,7 +13,7 @@ use rustc_infer::infer::{DefineOpaqueTypes, InferOk};
use rustc_middle::traits::SelectionOutputTypeParameterMismatch; use rustc_middle::traits::SelectionOutputTypeParameterMismatch;
use rustc_middle::ty::{ use rustc_middle::ty::{
self, Binder, GenericParamDefKind, InternalSubsts, SubstsRef, ToPolyTraitRef, ToPredicate, self, Binder, GenericParamDefKind, InternalSubsts, SubstsRef, ToPolyTraitRef, ToPredicate,
TraitRef, Ty, TyCtxt, TypeVisitableExt, TraitPredicate, TraitRef, Ty, TyCtxt, TypeVisitableExt,
}; };
use rustc_session::config::TraitSolver; use rustc_session::config::TraitSolver;
use rustc_span::def_id::DefId; use rustc_span::def_id::DefId;
@ -279,10 +279,61 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
ImplSourceBuiltinData { nested: obligations } ImplSourceBuiltinData { nested: obligations }
} }
#[instrument(skip(self))]
fn confirm_transmutability_candidate( fn confirm_transmutability_candidate(
&mut self, &mut self,
obligation: &TraitObligation<'tcx>, obligation: &TraitObligation<'tcx>,
) -> Result<ImplSourceBuiltinData<PredicateObligation<'tcx>>, SelectionError<'tcx>> { ) -> Result<ImplSourceBuiltinData<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
fn flatten_answer_tree<'tcx>(
tcx: TyCtxt<'tcx>,
obligation: &TraitObligation<'tcx>,
predicate: TraitPredicate<'tcx>,
answer: rustc_transmute::Answer<rustc_transmute::layout::rustc::Ref<'tcx>>,
) -> Result<Vec<PredicateObligation<'tcx>>, SelectionError<'tcx>> {
match answer {
rustc_transmute::Answer::Yes => Ok(vec![]),
rustc_transmute::Answer::No(_) => Err(Unimplemented),
// FIXME(bryangarza): Add separate `IfAny` case, instead of treating as `IfAll`
rustc_transmute::Answer::IfAll(answers)
| rustc_transmute::Answer::IfAny(answers) => {
let mut nested = vec![];
for flattened in answers
.into_iter()
.map(|answer| flatten_answer_tree(tcx, obligation, predicate, answer))
{
nested.extend(flattened?);
}
Ok(nested)
}
rustc_transmute::Answer::IfTransmutable { src, dst } => {
let trait_def_id = obligation.predicate.def_id();
let scope = predicate.trait_ref.substs.type_at(2);
let assume_const = predicate.trait_ref.substs.const_at(3);
let make_obl = |from_ty, to_ty| {
let trait_ref1 = tcx.mk_trait_ref(
trait_def_id,
[
ty::GenericArg::from(to_ty),
ty::GenericArg::from(from_ty),
ty::GenericArg::from(scope),
ty::GenericArg::from(assume_const),
],
);
Obligation::with_depth(
tcx,
obligation.cause.clone(),
obligation.recursion_depth + 1,
obligation.param_env,
trait_ref1,
)
};
// // FIXME(bryangarza): Check src.mutability or dst.mutability to know whether dst -> src obligation is needed
Ok(vec![make_obl(src.ty, dst.ty), make_obl(dst.ty, src.ty)])
}
}
}
debug!(?obligation, "confirm_transmutability_candidate"); debug!(?obligation, "confirm_transmutability_candidate");
// We erase regions here because transmutability calls layout queries, // We erase regions here because transmutability calls layout queries,
@ -312,10 +363,10 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
assume, assume,
); );
match maybe_transmutable { info!(?maybe_transmutable);
rustc_transmute::Answer::Yes => Ok(ImplSourceBuiltinData { nested: vec![] }), let nested = flatten_answer_tree(self.tcx(), obligation, predicate, maybe_transmutable)?;
_ => Err(Unimplemented), info!(?nested);
} Ok(ImplSourceBuiltinData { nested })
} }
/// This handles the case where an `auto trait Foo` impl is being used. /// This handles the case where an `auto trait Foo` impl is being used.

View file

@ -30,33 +30,46 @@ impl fmt::Debug for Byte {
} }
pub(crate) trait Def: Debug + Hash + Eq + PartialEq + Copy + Clone {} pub(crate) trait Def: Debug + Hash + Eq + PartialEq + Copy + Clone {}
pub trait Ref: Debug + Hash + Eq + PartialEq + Copy + Clone {} pub trait Ref: Debug + Hash + Eq + PartialEq + Copy + Clone {
fn min_align(&self) -> usize {
1
}
fn is_mutable(&self) -> bool {
false
}
}
impl Def for ! {} impl Def for ! {}
impl Ref for ! {} impl Ref for ! {}
#[cfg(feature = "rustc")] #[cfg(feature = "rustc")]
pub(crate) mod rustc { pub mod rustc {
use rustc_middle::mir::Mutability; use rustc_middle::mir::Mutability;
use rustc_middle::ty; use rustc_middle::ty::{self, Ty};
use rustc_middle::ty::Region;
use rustc_middle::ty::Ty;
/// A reference in the layout. /// A reference in the layout.
#[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone, Copy)] #[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone, Copy)]
pub struct Ref<'tcx> { pub struct Ref<'tcx> {
lifetime: Region<'tcx>, pub lifetime: ty::Region<'tcx>,
ty: Ty<'tcx>, pub ty: Ty<'tcx>,
mutability: Mutability, pub mutability: Mutability,
pub align: usize,
} }
impl<'tcx> super::Ref for Ref<'tcx> {} impl<'tcx> super::Ref for Ref<'tcx> {
fn min_align(&self) -> usize {
self.align
}
impl<'tcx> Ref<'tcx> { fn is_mutable(&self) -> bool {
pub fn min_align(&self) -> usize { match self.mutability {
todo!() Mutability::Mut => true,
Mutability::Not => false,
}
} }
} }
impl<'tcx> Ref<'tcx> {}
/// A visibility node in the layout. /// A visibility node in the layout.
#[derive(Debug, Hash, Eq, PartialEq, Clone, Copy)] #[derive(Debug, Hash, Eq, PartialEq, Clone, Copy)]

View file

@ -365,6 +365,17 @@ pub(crate) mod rustc {
} }
})) }))
} }
ty::Ref(lifetime, ty, mutability) => {
let align = layout_of(tcx, *ty)?.align();
Ok(Tree::Ref(Ref {
lifetime: *lifetime,
ty: *ty,
mutability: *mutability,
align,
}))
}
_ => Err(Err::Unspecified), _ => Err(Err::Unspecified),
} }
} }

View file

@ -8,7 +8,7 @@ extern crate tracing;
pub(crate) use rustc_data_structures::fx::{FxIndexMap as Map, FxIndexSet as Set}; pub(crate) use rustc_data_structures::fx::{FxIndexMap as Map, FxIndexSet as Set};
pub(crate) mod layout; pub mod layout;
pub(crate) mod maybe_transmutable; pub(crate) mod maybe_transmutable;
#[derive(Default)] #[derive(Default)]
@ -21,10 +21,7 @@ pub struct Assume {
/// The type encodes answers to the question: "Are these types transmutable?" /// The type encodes answers to the question: "Are these types transmutable?"
#[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone)] #[derive(Debug, Hash, Eq, PartialEq, PartialOrd, Ord, Clone)]
pub enum Answer<R> pub enum Answer<R> {
where
R: layout::Ref,
{
/// `Src` is transmutable into `Dst`. /// `Src` is transmutable into `Dst`.
Yes, Yes,
@ -54,6 +51,10 @@ pub enum Reason {
DstIsPrivate, DstIsPrivate,
/// `Dst` is larger than `Src`, and the excess bytes were not exclusively uninitialized. /// `Dst` is larger than `Src`, and the excess bytes were not exclusively uninitialized.
DstIsTooBig, DstIsTooBig,
/// Src should have a stricter alignment than Dst, but it does not.
DstHasStricterAlignment,
/// Can't go from shared pointer to unique pointer
DstIsMoreUnique,
} }
#[cfg(feature = "rustc")] #[cfg(feature = "rustc")]

View file

@ -1,13 +1,13 @@
use crate::Map; pub(crate) mod query_context;
use crate::{Answer, Reason};
#[cfg(test)] #[cfg(test)]
mod tests; mod tests;
mod query_context; use crate::{
use query_context::QueryContext; layout::{self, dfa, Byte, Dfa, Nfa, Ref, Tree, Uninhabited},
maybe_transmutable::query_context::QueryContext,
Answer, Map, Reason,
};
use crate::layout::{self, dfa, Byte, Dfa, Nfa, Tree, Uninhabited};
pub(crate) struct MaybeTransmutableQuery<L, C> pub(crate) struct MaybeTransmutableQuery<L, C>
where where
C: QueryContext, C: QueryContext,
@ -53,6 +53,7 @@ where
} }
} }
// FIXME: Nix this cfg, so we can write unit tests independently of rustc
#[cfg(feature = "rustc")] #[cfg(feature = "rustc")]
mod rustc { mod rustc {
use super::*; use super::*;
@ -77,12 +78,11 @@ mod rustc {
match (src, dst) { match (src, dst) {
// Answer `Yes` here, because 'unknown layout' and type errors will already // Answer `Yes` here, because 'unknown layout' and type errors will already
// be reported by rustc. No need to spam the user with more errors. // be reported by rustc. No need to spam the user with more errors.
(Err(Err::TypeError(_)), _) => Err(Answer::Yes), (Err(Err::TypeError(_)), _) | (_, Err(Err::TypeError(_))) => Err(Answer::Yes),
(_, Err(Err::TypeError(_))) => Err(Answer::Yes), (Err(Err::Unknown), _) | (_, Err(Err::Unknown)) => Err(Answer::Yes),
(Err(Err::Unknown), _) => Err(Answer::Yes), (Err(Err::Unspecified), _) | (_, Err(Err::Unspecified)) => {
(_, Err(Err::Unknown)) => Err(Answer::Yes), Err(Answer::No(Reason::SrcIsUnspecified))
(Err(Err::Unspecified), _) => Err(Answer::No(Reason::SrcIsUnspecified)), }
(_, Err(Err::Unspecified)) => Err(Answer::No(Reason::DstIsUnspecified)),
(Ok(src), Ok(dst)) => Ok((src, dst)), (Ok(src), Ok(dst)) => Ok((src, dst)),
} }
}); });
@ -214,34 +214,99 @@ where
Answer::No(Reason::DstIsTooBig) Answer::No(Reason::DstIsTooBig)
} }
} else { } else {
let src_quantification = if self.assume.validity { let src_quantifier = if self.assume.validity {
// if the compiler may assume that the programmer is doing additional validity checks, // if the compiler may assume that the programmer is doing additional validity checks,
// (e.g.: that `src != 3u8` when the destination type is `bool`) // (e.g.: that `src != 3u8` when the destination type is `bool`)
// then there must exist at least one transition out of `src_state` such that the transmute is viable... // then there must exist at least one transition out of `src_state` such that the transmute is viable...
there_exists Quantifier::ThereExists
} else { } else {
// if the compiler cannot assume that the programmer is doing additional validity checks, // if the compiler cannot assume that the programmer is doing additional validity checks,
// then for all transitions out of `src_state`, such that the transmute is viable... // then for all transitions out of `src_state`, such that the transmute is viable...
// then there must exist at least one transition out of `src_state` such that the transmute is viable... // then there must exist at least one transition out of `dst_state` such that the transmute is viable...
for_all Quantifier::ForAll
}; };
src_quantification( let bytes_answer = src_quantifier.apply(
self.src.bytes_from(src_state).unwrap_or(&Map::default()), // for each of the byte transitions out of the `src_state`...
|(&src_validity, &src_state_prime)| { self.src.bytes_from(src_state).unwrap_or(&Map::default()).into_iter().map(
if let Some(dst_state_prime) = self.dst.byte_from(dst_state, src_validity) { |(&src_validity, &src_state_prime)| {
self.answer_memo(cache, src_state_prime, dst_state_prime) // ...try to find a matching transition out of `dst_state`.
} else if let Some(dst_state_prime) = if let Some(dst_state_prime) =
self.dst.byte_from(dst_state, Byte::Uninit) self.dst.byte_from(dst_state, src_validity)
{ {
self.answer_memo(cache, src_state_prime, dst_state_prime) self.answer_memo(cache, src_state_prime, dst_state_prime)
} else { } else if let Some(dst_state_prime) =
Answer::No(Reason::DstIsBitIncompatible) // otherwise, see if `dst_state` has any outgoing `Uninit` transitions
} // (any init byte is a valid uninit byte)
}, self.dst.byte_from(dst_state, Byte::Uninit)
) {
self.answer_memo(cache, src_state_prime, dst_state_prime)
} else {
// otherwise, we've exhausted our options.
// the DFAs, from this point onwards, are bit-incompatible.
Answer::No(Reason::DstIsBitIncompatible)
}
},
),
);
// The below early returns reflect how this code would behave:
// if self.assume.validity {
// bytes_answer.or(refs_answer)
// } else {
// bytes_answer.and(refs_answer)
// }
// ...if `refs_answer` was computed lazily. The below early
// returns can be deleted without impacting the correctness of
// the algoritm; only its performance.
match bytes_answer {
Answer::No(..) if !self.assume.validity => return bytes_answer,
Answer::Yes if self.assume.validity => return bytes_answer,
_ => {}
};
let refs_answer = src_quantifier.apply(
// for each reference transition out of `src_state`...
self.src.refs_from(src_state).unwrap_or(&Map::default()).into_iter().map(
|(&src_ref, &src_state_prime)| {
// ...there exists a reference transition out of `dst_state`...
Quantifier::ThereExists.apply(
self.dst
.refs_from(dst_state)
.unwrap_or(&Map::default())
.into_iter()
.map(|(&dst_ref, &dst_state_prime)| {
if !src_ref.is_mutable() && dst_ref.is_mutable() {
Answer::No(Reason::DstIsMoreUnique)
} else if !self.assume.alignment
&& src_ref.min_align() < dst_ref.min_align()
{
Answer::No(Reason::DstHasStricterAlignment)
} else {
// ...such that `src` is transmutable into `dst`, if
// `src_ref` is transmutability into `dst_ref`.
Answer::IfTransmutable { src: src_ref, dst: dst_ref }
.and(self.answer_memo(
cache,
src_state_prime,
dst_state_prime,
))
}
}),
)
},
),
);
if self.assume.validity {
bytes_answer.or(refs_answer)
} else {
bytes_answer.and(refs_answer)
}
}; };
cache.insert((src_state, dst_state), answer.clone()); if let Some(..) = cache.insert((src_state, dst_state), answer.clone()) {
panic!("failed to correctly cache transmutability")
}
answer answer
} }
} }
@ -253,17 +318,21 @@ where
{ {
pub(crate) fn and(self, rhs: Self) -> Self { pub(crate) fn and(self, rhs: Self) -> Self {
match (self, rhs) { match (self, rhs) {
(Self::No(reason), _) | (_, Self::No(reason)) => Self::No(reason), (_, Self::No(reason)) | (Self::No(reason), _) => Self::No(reason),
(Self::Yes, Self::Yes) => Self::Yes,
(Self::Yes, other) | (other, Self::Yes) => other,
(Self::IfAll(mut lhs), Self::IfAll(ref mut rhs)) => { (Self::IfAll(mut lhs), Self::IfAll(ref mut rhs)) => {
lhs.append(rhs); lhs.append(rhs);
Self::IfAll(lhs) Self::IfAll(lhs)
} }
(constraint, Self::IfAll(mut constraints)) (constraint, Self::IfAll(mut constraints))
| (Self::IfAll(mut constraints), constraint) => { | (Self::IfAll(mut constraints), constraint) => {
constraints.push(constraint); constraints.push(constraint);
Self::IfAll(constraints) Self::IfAll(constraints)
} }
(lhs, rhs) => Self::IfAll(vec![lhs, rhs]), (lhs, rhs) => Self::IfAll(vec![lhs, rhs]),
} }
} }
@ -271,7 +340,7 @@ where
pub(crate) fn or(self, rhs: Self) -> Self { pub(crate) fn or(self, rhs: Self) -> Self {
match (self, rhs) { match (self, rhs) {
(Self::Yes, _) | (_, Self::Yes) => Self::Yes, (Self::Yes, _) | (_, Self::Yes) => Self::Yes,
(Self::No(lhr), Self::No(rhr)) => Self::No(lhr), (other, Self::No(reason)) | (Self::No(reason), other) => other,
(Self::IfAny(mut lhs), Self::IfAny(ref mut rhs)) => { (Self::IfAny(mut lhs), Self::IfAny(ref mut rhs)) => {
lhs.append(rhs); lhs.append(rhs);
Self::IfAny(lhs) Self::IfAny(lhs)
@ -319,3 +388,36 @@ where
); );
result result
} }
pub enum Quantifier {
ThereExists,
ForAll,
}
impl Quantifier {
pub fn apply<R, I>(&self, iter: I) -> Answer<R>
where
R: layout::Ref,
I: IntoIterator<Item = Answer<R>>,
{
use std::ops::ControlFlow::{Break, Continue};
let (init, try_fold_f): (_, fn(_, _) -> _) = match self {
Self::ThereExists => {
(Answer::No(Reason::DstIsBitIncompatible), |accum: Answer<R>, next| {
match accum.or(next) {
Answer::Yes => Break(Answer::Yes),
maybe => Continue(maybe),
}
})
}
Self::ForAll => (Answer::Yes, |accum: Answer<R>, next| match accum.and(next) {
Answer::No(reason) => Break(Answer::No(reason)),
maybe => Continue(maybe),
}),
};
let (Continue(result) | Break(result)) = iter.into_iter().try_fold(init, try_fold_f);
result
}
}

View file

@ -5,6 +5,7 @@
/// notwithstanding whatever safety checks you have asked the compiler to [`Assume`] are satisfied. /// notwithstanding whatever safety checks you have asked the compiler to [`Assume`] are satisfied.
#[unstable(feature = "transmutability", issue = "99571")] #[unstable(feature = "transmutability", issue = "99571")]
#[lang = "transmute_trait"] #[lang = "transmute_trait"]
#[rustc_coinductive]
pub unsafe trait BikeshedIntrinsicFrom<Src, Context, const ASSUME: Assume = { Assume::NOTHING }> pub unsafe trait BikeshedIntrinsicFrom<Src, Context, const ASSUME: Assume = { Assume::NOTHING }>
where where
Src: ?Sized, Src: ?Sized,

View file

@ -23,7 +23,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 0]` in the defin
--> $DIR/should_require_well_defined_layout.rs:27:47 --> $DIR/should_require_well_defined_layout.rs:27:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `[String; 0]` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -65,7 +65,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 1]` in the defin
--> $DIR/should_require_well_defined_layout.rs:33:47 --> $DIR/should_require_well_defined_layout.rs:33:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `[String; 1]` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -107,7 +107,7 @@ error[E0277]: `u128` cannot be safely transmuted into `[String; 2]` in the defin
--> $DIR/should_require_well_defined_layout.rs:39:47 --> $DIR/should_require_well_defined_layout.rs:39:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `[String; 2]` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14

View file

@ -24,7 +24,7 @@ error[E0277]: `V0i8` cannot be safely transmuted into `u16` in the defining scop
--> $DIR/primitive_reprs_should_have_correct_length.rs:50:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:50:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0i8` is smaller than the size of `u16` | ^^^^^^ At least one value of `V0i8` isn't a bit-valid value of `u16`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -68,7 +68,7 @@ error[E0277]: `V0u8` cannot be safely transmuted into `u16` in the defining scop
--> $DIR/primitive_reprs_should_have_correct_length.rs:58:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:58:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0u8` is smaller than the size of `u16` | ^^^^^^ At least one value of `V0u8` isn't a bit-valid value of `u16`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -112,7 +112,7 @@ error[E0277]: `V0i16` cannot be safely transmuted into `u32` in the defining sco
--> $DIR/primitive_reprs_should_have_correct_length.rs:74:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:74:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0i16` is smaller than the size of `u32` | ^^^^^^ At least one value of `V0i16` isn't a bit-valid value of `u32`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -156,7 +156,7 @@ error[E0277]: `V0u16` cannot be safely transmuted into `u32` in the defining sco
--> $DIR/primitive_reprs_should_have_correct_length.rs:82:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:82:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0u16` is smaller than the size of `u32` | ^^^^^^ At least one value of `V0u16` isn't a bit-valid value of `u32`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -200,7 +200,7 @@ error[E0277]: `V0i32` cannot be safely transmuted into `u64` in the defining sco
--> $DIR/primitive_reprs_should_have_correct_length.rs:98:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:98:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0i32` is smaller than the size of `u64` | ^^^^^^ At least one value of `V0i32` isn't a bit-valid value of `u64`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -244,7 +244,7 @@ error[E0277]: `V0u32` cannot be safely transmuted into `u64` in the defining sco
--> $DIR/primitive_reprs_should_have_correct_length.rs:106:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:106:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0u32` is smaller than the size of `u64` | ^^^^^^ At least one value of `V0u32` isn't a bit-valid value of `u64`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -288,7 +288,7 @@ error[E0277]: `V0i64` cannot be safely transmuted into `u128` in the defining sc
--> $DIR/primitive_reprs_should_have_correct_length.rs:122:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:122:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0i64` is smaller than the size of `u128` | ^^^^^^ At least one value of `V0i64` isn't a bit-valid value of `u128`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -332,7 +332,7 @@ error[E0277]: `V0u64` cannot be safely transmuted into `u128` in the defining sc
--> $DIR/primitive_reprs_should_have_correct_length.rs:130:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:130:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0u64` is smaller than the size of `u128` | ^^^^^^ At least one value of `V0u64` isn't a bit-valid value of `u128`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -376,7 +376,7 @@ error[E0277]: `V0isize` cannot be safely transmuted into `[usize; 2]` in the def
--> $DIR/primitive_reprs_should_have_correct_length.rs:146:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:146:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0isize` is smaller than the size of `[usize; 2]` | ^^^^^^ At least one value of `V0isize` isn't a bit-valid value of `[usize; 2]`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14
@ -420,7 +420,7 @@ error[E0277]: `V0usize` cannot be safely transmuted into `[usize; 2]` in the def
--> $DIR/primitive_reprs_should_have_correct_length.rs:154:44 --> $DIR/primitive_reprs_should_have_correct_length.rs:154:44
| |
LL | assert::is_transmutable::<Current, Larger, Context>(); LL | assert::is_transmutable::<Current, Larger, Context>();
| ^^^^^^ The size of `V0usize` is smaller than the size of `[usize; 2]` | ^^^^^^ At least one value of `V0usize` isn't a bit-valid value of `[usize; 2]`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/primitive_reprs_should_have_correct_length.rs:12:14 --> $DIR/primitive_reprs_should_have_correct_length.rs:12:14

View file

@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `void::repr_rust` in the d
--> $DIR/should_require_well_defined_layout.rs:29:47 --> $DIR/should_require_well_defined_layout.rs:29:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `void::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:14:14 --> $DIR/should_require_well_defined_layout.rs:14:14
@ -68,7 +68,7 @@ error[E0277]: `u128` cannot be safely transmuted into `singleton::repr_rust` in
--> $DIR/should_require_well_defined_layout.rs:35:47 --> $DIR/should_require_well_defined_layout.rs:35:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `singleton::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:14:14 --> $DIR/should_require_well_defined_layout.rs:14:14
@ -112,7 +112,7 @@ error[E0277]: `u128` cannot be safely transmuted into `duplex::repr_rust` in the
--> $DIR/should_require_well_defined_layout.rs:41:47 --> $DIR/should_require_well_defined_layout.rs:41:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `duplex::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:14:14 --> $DIR/should_require_well_defined_layout.rs:14:14

View file

@ -2,7 +2,7 @@ error[E0277]: `Src` cannot be safely transmuted into `Dst` in the defining scope
--> $DIR/should_pad_variants.rs:44:36 --> $DIR/should_pad_variants.rs:44:36
| |
LL | assert::is_transmutable::<Src, Dst, Context>(); LL | assert::is_transmutable::<Src, Dst, Context>();
| ^^^ The size of `Src` is smaller than the size of `Dst` | ^^^ At least one value of `Src` isn't a bit-valid value of `Dst`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/should_pad_variants.rs:13:14 --> $DIR/should_pad_variants.rs:13:14

View file

@ -0,0 +1,27 @@
// check-fail
#![feature(transmutability)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume {
alignment: true,
lifetimes: false,
safety: true,
validity: false,
}
}>
{}
}
fn main() {
#[repr(C)] struct A(bool, &'static A);
#[repr(C)] struct B(u8, &'static B);
// FIXME(bryangarza): Make 2 variants of this test, depending on mutability.
// Right now, we are being strict by default and checking A->B and B->A both.
assert::is_maybe_transmutable::<&'static A, &'static B>(); //~ ERROR `B` cannot be safely transmuted into `A`
}

View file

@ -0,0 +1,25 @@
error[E0277]: `B` cannot be safely transmuted into `A` in the defining scope of `assert::Context`
--> $DIR/recursive-wrapper-types-bit-compatible.rs:26:49
|
LL | assert::is_maybe_transmutable::<&'static A, &'static B>();
| ^^^^^^^^^^ At least one value of `B` isn't a bit-valid value of `A`
|
note: required by a bound in `is_maybe_transmutable`
--> $DIR/recursive-wrapper-types-bit-compatible.rs:10:14
|
LL | pub fn is_maybe_transmutable<Src, Dst>()
| --------------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src, Context, {
| ______________^
LL | | Assume {
LL | | alignment: true,
LL | | lifetimes: false,
... |
LL | | }
LL | | }>
| |__________^ required by this bound in `is_maybe_transmutable`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.

View file

@ -0,0 +1,25 @@
// check-fail
#![feature(transmutability)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume {
alignment: true,
lifetimes: false,
safety: true,
validity: false,
}
}>
{}
}
fn main() {
#[repr(C)] struct A(bool, &'static A);
#[repr(C)] struct B(u8, &'static B);
assert::is_maybe_transmutable::<&'static B, &'static A>(); //~ ERROR `B` cannot be safely transmuted into `A`
}

View file

@ -0,0 +1,25 @@
error[E0277]: `B` cannot be safely transmuted into `A` in the defining scope of `assert::Context`
--> $DIR/recursive-wrapper-types-bit-incompatible.rs:24:49
|
LL | assert::is_maybe_transmutable::<&'static B, &'static A>();
| ^^^^^^^^^^ At least one value of `B` isn't a bit-valid value of `A`
|
note: required by a bound in `is_maybe_transmutable`
--> $DIR/recursive-wrapper-types-bit-incompatible.rs:10:14
|
LL | pub fn is_maybe_transmutable<Src, Dst>()
| --------------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src, Context, {
| ______________^
LL | | Assume {
LL | | alignment: true,
LL | | lifetimes: false,
... |
LL | | }
LL | | }>
| |__________^ required by this bound in `is_maybe_transmutable`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0277`.

View file

@ -0,0 +1,26 @@
// check-pass
#![feature(transmutability)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume {
alignment: true,
lifetimes: false,
safety: true,
validity: false,
}
}>
{}
}
fn main() {
#[repr(C)] struct A(&'static B);
#[repr(C)] struct B(&'static A);
assert::is_maybe_transmutable::<&'static A, &'static B>();
assert::is_maybe_transmutable::<&'static B, &'static A>();
}

View file

@ -1,11 +1,5 @@
// revisions: current next // check-fail
//[next] compile-flags: -Ztrait-solver=next
//! Transmutations involving references are not yet supported.
#![crate_type = "lib"]
#![feature(transmutability)] #![feature(transmutability)]
#![allow(dead_code, incomplete_features, non_camel_case_types)]
mod assert { mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom}; use std::mem::{Assume, BikeshedIntrinsicFrom};
@ -24,7 +18,7 @@ mod assert {
{} {}
} }
fn not_yet_implemented() { fn main() {
#[repr(C)] struct Unit; #[repr(C)] struct Unit;
assert::is_maybe_transmutable::<&'static Unit, &'static Unit>(); //~ ERROR cannot be safely transmuted assert::is_maybe_transmutable::<&'static u8, &'static Unit>(); //~ ERROR `Unit` cannot be safely transmuted into `u8`
} }

View file

@ -1,11 +1,11 @@
error[E0277]: `&Unit` cannot be safely transmuted into `&Unit` in the defining scope of `assert::Context` error[E0277]: `Unit` cannot be safely transmuted into `u8` in the defining scope of `assert::Context`
--> $DIR/references.rs:29:52 --> $DIR/u8-to-unit.rs:23:50
| |
LL | assert::is_maybe_transmutable::<&'static Unit, &'static Unit>(); LL | assert::is_maybe_transmutable::<&'static u8, &'static Unit>();
| ^^^^^^^^^^^^^ `&Unit` does not have a well-specified layout | ^^^^^^^^^^^^^ The size of `Unit` is smaller than the size of `u8`
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/references.rs:16:14 --> $DIR/u8-to-unit.rs:10:14
| |
LL | pub fn is_maybe_transmutable<Src, Dst>() LL | pub fn is_maybe_transmutable<Src, Dst>()
| --------------------- required by a bound in this function | --------------------- required by a bound in this function

View file

@ -0,0 +1,24 @@
// check-pass
#![feature(transmutability)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume {
alignment: true,
lifetimes: false,
safety: true,
validity: false,
}
}>
{}
}
fn main() {
#[repr(C)] struct Unit;
assert::is_maybe_transmutable::<&'static Unit, &'static Unit>();
}

View file

@ -0,0 +1,24 @@
// check-fail
#![feature(transmutability)]
mod assert {
use std::mem::{Assume, BikeshedIntrinsicFrom};
pub struct Context;
pub fn is_maybe_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src, Context, {
Assume {
alignment: true,
lifetimes: true,
safety: true,
validity: true,
}
}>
{}
}
fn main() {
#[repr(C)] struct Unit;
assert::is_maybe_transmutable::<&'static Unit, &'static u8>(); //~ ERROR `Unit` cannot be safely transmuted into `u8`
}

View file

@ -1,11 +1,11 @@
error[E0277]: `&Unit` cannot be safely transmuted into `&Unit` in the defining scope of `assert::Context` error[E0277]: `Unit` cannot be safely transmuted into `u8` in the defining scope of `assert::Context`
--> $DIR/references.rs:29:52 --> $DIR/unit-to-u8.rs:23:52
| |
LL | assert::is_maybe_transmutable::<&'static Unit, &'static Unit>(); LL | assert::is_maybe_transmutable::<&'static Unit, &'static u8>();
| ^^^^^^^^^^^^^ `&Unit` does not have a well-specified layout | ^^^^^^^^^^^ The size of `Unit` is smaller than the size of `u8`
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/references.rs:16:14 --> $DIR/unit-to-u8.rs:10:14
| |
LL | pub fn is_maybe_transmutable<Src, Dst>() LL | pub fn is_maybe_transmutable<Src, Dst>()
| --------------------- required by a bound in this function | --------------------- required by a bound in this function

View file

@ -2,7 +2,7 @@ error[E0277]: `()` cannot be safely transmuted into `W<'_>` in the defining scop
--> $DIR/region-infer.rs:20:5 --> $DIR/region-infer.rs:20:5
| |
LL | test(); LL | test();
| ^^^^ `W<'_>` does not have a well-specified layout | ^^^^ The size of `()` is smaller than the size of `W<'_>`
| |
note: required by a bound in `test` note: required by a bound in `test`
--> $DIR/region-infer.rs:11:12 --> $DIR/region-infer.rs:11:12

View file

@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
--> $DIR/should_require_well_defined_layout.rs:29:47 --> $DIR/should_require_well_defined_layout.rs:29:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `should_reject_repr_rust::unit::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -68,7 +68,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
--> $DIR/should_require_well_defined_layout.rs:35:47 --> $DIR/should_require_well_defined_layout.rs:35:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `should_reject_repr_rust::tuple::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -112,7 +112,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
--> $DIR/should_require_well_defined_layout.rs:41:47 --> $DIR/should_require_well_defined_layout.rs:41:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `should_reject_repr_rust::braces::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -156,7 +156,7 @@ error[E0277]: `u128` cannot be safely transmuted into `aligned::repr_rust` in th
--> $DIR/should_require_well_defined_layout.rs:47:47 --> $DIR/should_require_well_defined_layout.rs:47:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `aligned::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -200,7 +200,7 @@ error[E0277]: `u128` cannot be safely transmuted into `packed::repr_rust` in the
--> $DIR/should_require_well_defined_layout.rs:53:47 --> $DIR/should_require_well_defined_layout.rs:53:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `packed::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14
@ -244,7 +244,7 @@ error[E0277]: `u128` cannot be safely transmuted into `nested::repr_c` in the de
--> $DIR/should_require_well_defined_layout.rs:60:47 --> $DIR/should_require_well_defined_layout.rs:60:47
| |
LL | assert::is_maybe_transmutable::<u128, repr_c>(); LL | assert::is_maybe_transmutable::<u128, repr_c>();
| ^^^^^^ `nested::repr_c` does not have a well-specified layout | ^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14

View file

@ -24,7 +24,7 @@ error[E0277]: `u128` cannot be safely transmuted into `should_reject_repr_rust::
--> $DIR/should_require_well_defined_layout.rs:31:43 --> $DIR/should_require_well_defined_layout.rs:31:43
| |
LL | assert::is_maybe_transmutable::<u128, repr_rust>(); LL | assert::is_maybe_transmutable::<u128, repr_rust>();
| ^^^^^^^^^ `should_reject_repr_rust::repr_rust` does not have a well-specified layout | ^^^^^^^^^ `u128` does not have a well-specified layout
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/should_require_well_defined_layout.rs:13:14 --> $DIR/should_require_well_defined_layout.rs:13:14

View file

@ -2,7 +2,7 @@ error[E0277]: `Src` cannot be safely transmuted into `Dst` in the defining scope
--> $DIR/should_pad_variants.rs:44:36 --> $DIR/should_pad_variants.rs:44:36
| |
LL | assert::is_transmutable::<Src, Dst, Context>(); LL | assert::is_transmutable::<Src, Dst, Context>();
| ^^^ The size of `Src` is smaller than the size of `Dst` | ^^^ At least one value of `Src` isn't a bit-valid value of `Dst`
| |
note: required by a bound in `is_transmutable` note: required by a bound in `is_transmutable`
--> $DIR/should_pad_variants.rs:13:14 --> $DIR/should_pad_variants.rs:13:14

View file

@ -2,7 +2,7 @@ error[E0277]: `B` cannot be safely transmuted into `A` in the defining scope of
--> $DIR/transmute-padding-ice.rs:27:40 --> $DIR/transmute-padding-ice.rs:27:40
| |
LL | assert::is_maybe_transmutable::<B, A>(); LL | assert::is_maybe_transmutable::<B, A>();
| ^ The size of `B` is smaller than the size of `A` | ^ At least one value of `B` isn't a bit-valid value of `A`
| |
note: required by a bound in `is_maybe_transmutable` note: required by a bound in `is_maybe_transmutable`
--> $DIR/transmute-padding-ice.rs:11:14 --> $DIR/transmute-padding-ice.rs:11:14