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safe transmute: gracefully bubble-up layout errors 

Changes `.unwrap()`s to `?` to avoid ICEs. Adds ui tests.

Fixes #129327
This commit is contained in:
Jack Wrenn 2024-08-21 17:01:32 +00:00
parent 982c6f8721
commit e2328ebd7f
9 changed files with 121 additions and 49 deletions
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18
compiler/rustc_transmute/src/layout/tree.rs
View File

@ -179,7 +179,7 @@ pub(crate) mod rustc {
};
use super::Tree;
use crate::layout::rustc::{Def, Ref};
use crate::layout::rustc::{layout_of, Def, Ref};
#[derive(Debug, Copy, Clone)]
pub(crate) enum Err {
@ -206,7 +206,7 @@ pub(crate) mod rustc {
impl<'tcx> Tree<Def<'tcx>, Ref<'tcx>> {
pub fn from_ty(ty: Ty<'tcx>, cx: LayoutCx<'tcx, TyCtxt<'tcx>>) -> Result<Self, Err> {
use rustc_target::abi::HasDataLayout;
let layout = ty_layout(cx, ty);
let layout = layout_of(cx, ty)?;
if let Err(e) = ty.error_reported() {
return Err(Err::TypeError(e));
@ -239,7 +239,7 @@ pub(crate) mod rustc {
let FieldsShape::Array { stride, count } = &layout.fields else {
return Err(Err::NotYetSupported);
};
let inner_layout = ty_layout(cx, *inner_ty);
let inner_layout = layout_of(cx, *inner_ty)?;
assert_eq!(*stride, inner_layout.size);
let elt = Tree::from_ty(*inner_ty, cx)?;
Ok(std::iter::repeat(elt)
@ -254,7 +254,7 @@ pub(crate) mod rustc {
},
ty::Ref(lifetime, ty, mutability) => {
let layout = ty_layout(cx, *ty);
let layout = layout_of(cx, *ty)?;
let align = layout.align.abi.bytes_usize();
let size = layout.size.bytes_usize();
Ok(Tree::Ref(Ref {
@ -280,7 +280,7 @@ pub(crate) mod rustc {
FieldsShape::Primitive => {
assert_eq!(members.len(), 1);
let inner_ty = members[0];
let inner_layout = ty_layout(cx, inner_ty);
let inner_layout = layout_of(cx, inner_ty)?;
Self::from_ty(inner_ty, cx)
}
FieldsShape::Arbitrary { offsets, .. } => {
@ -413,7 +413,7 @@ pub(crate) mod rustc {
let padding = Self::padding(padding_needed.bytes_usize());
let field_ty = ty_field(cx, (ty, layout), field_idx);
let field_layout = ty_layout(cx, field_ty);
let field_layout = layout_of(cx, field_ty)?;
let field_tree = Self::from_ty(field_ty, cx)?;
struct_tree = struct_tree.then(padding).then(field_tree);
@ -471,7 +471,7 @@ pub(crate) mod rustc {
|fields, (idx, field_def)| {
let field_def = Def::Field(field_def);
let field_ty = ty_field(cx, (ty, layout), idx);
let field_layout = ty_layout(cx, field_ty);
let field_layout = layout_of(cx, field_ty)?;
let field = Self::from_ty(field_ty, cx)?;
let trailing_padding_needed = layout.size - field_layout.size;
let trailing_padding = Self::padding(trailing_padding_needed.bytes_usize());
@ -484,10 +484,6 @@ pub(crate) mod rustc {
}
}
pub(crate) fn ty_layout<'tcx>(cx: LayoutCx<'tcx, TyCtxt<'tcx>>, ty: Ty<'tcx>) -> Layout<'tcx> {
crate::layout::rustc::layout_of(cx, ty).unwrap()
}
fn ty_field<'tcx>(
cx: LayoutCx<'tcx, TyCtxt<'tcx>>,
(ty, layout): (Ty<'tcx>, Layout<'tcx>),

13
compiler/rustc_transmute/src/maybe_transmutable/mod.rs
View File

@ -44,18 +44,11 @@ mod rustc {
let Self { src, dst, assume, context } = self;
let layout_cx = LayoutCx { tcx: context, param_env: ParamEnv::reveal_all() };
let layout_of = |ty| {
crate::layout::rustc::layout_of(layout_cx, ty)
.map_err(|_| Err::NotYetSupported)
.and_then(|_| Tree::from_ty(ty, layout_cx))
};
// Convert `src` and `dst` from their rustc representations, to `Tree`-based
// representations. If these conversions fail, conclude that the transmutation is
// unacceptable; the layouts of both the source and destination types must be
// well-defined.
let src = layout_of(src);
let dst = layout_of(dst);
// representations.
let src = Tree::from_ty(src, layout_cx);
let dst = Tree::from_ty(dst, layout_cx);
match (src, dst) {
(Err(Err::TypeError(_)), _) | (_, Err(Err::TypeError(_))) => {

4
tests/ui/transmutability/arrays/huge-len.stderr
View File

@ -2,7 +2,7 @@ error[E0277]: `()` cannot be safely transmuted into `ExplicitlyPadded`
--> $DIR/huge-len.rs:21:41
|
LL | assert::is_maybe_transmutable::<(), ExplicitlyPadded>();
| ^^^^^^^^^^^^^^^^ analyzing the transmutability of `ExplicitlyPadded` is not yet supported
| ^^^^^^^^^^^^^^^^ values of the type `ExplicitlyPadded` are too big for the current architecture
|
note: required by a bound in `is_maybe_transmutable`
--> $DIR/huge-len.rs:8:14
@ -17,7 +17,7 @@ error[E0277]: `ExplicitlyPadded` cannot be safely transmuted into `()`
--> $DIR/huge-len.rs:24:55
|
LL | assert::is_maybe_transmutable::<ExplicitlyPadded, ()>();
| ^^ analyzing the transmutability of `ExplicitlyPadded` is not yet supported
| ^^ values of the type `ExplicitlyPadded` are too big for the current architecture
|
note: required by a bound in `is_maybe_transmutable`
--> $DIR/huge-len.rs:8:14

26
tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.rs Normal file
View File

@ -0,0 +1,26 @@
// An unknown destination type should be gracefully handled.
#![crate_type = "lib"]
#![feature(transmutability)]
#![allow(incomplete_features)]
mod assert {
use std::mem::BikeshedIntrinsicFrom;
pub fn is_transmutable<Src, Dst>()
where
Dst: BikeshedIntrinsicFrom<Src>
{}
}
fn should_gracefully_handle_unknown_dst_field() {
#[repr(C)] struct Src;
#[repr(C)] struct Dst(Missing); //~ cannot find type
assert::is_transmutable::<Src, Dst>(); //~ ERROR cannot be safely transmuted
}
fn should_gracefully_handle_unknown_dst_ref_field() {
#[repr(C)] struct Src(&'static Src);
#[repr(C)] struct Dst(&'static Missing); //~ cannot find type
assert::is_transmutable::<Src, Dst>(); //~ ERROR cannot be safely transmuted
}

46
tests/ui/transmutability/malformed-program-gracefulness/unknown_dst_field.stderr Normal file
View File

@ -0,0 +1,46 @@
error[E0412]: cannot find type `Missing` in this scope
--> $DIR/unknown_dst_field.rs:18:27
|
LL | #[repr(C)] struct Dst(Missing);
| ^^^^^^^ not found in this scope
error[E0412]: cannot find type `Missing` in this scope
--> $DIR/unknown_dst_field.rs:24:36
|
LL | #[repr(C)] struct Dst(&'static Missing);
| ^^^^^^^ not found in this scope
error[E0277]: `should_gracefully_handle_unknown_dst_field::Src` cannot be safely transmuted into `should_gracefully_handle_unknown_dst_field::Dst`
--> $DIR/unknown_dst_field.rs:19:36
|
LL | assert::is_transmutable::<Src, Dst>();
| ^^^ `should_gracefully_handle_unknown_dst_field::Dst` has an unknown layout
|
note: required by a bound in `is_transmutable`
--> $DIR/unknown_dst_field.rs:12:14
|
LL | pub fn is_transmutable<Src, Dst>()
| --------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src>
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
error[E0277]: `should_gracefully_handle_unknown_dst_ref_field::Src` cannot be safely transmuted into `should_gracefully_handle_unknown_dst_ref_field::Dst`
--> $DIR/unknown_dst_field.rs:25:36
|
LL | assert::is_transmutable::<Src, Dst>();
| ^^^ `should_gracefully_handle_unknown_dst_ref_field::Dst` has an unknown layout
|
note: required by a bound in `is_transmutable`
--> $DIR/unknown_dst_field.rs:12:14
|
LL | pub fn is_transmutable<Src, Dst>()
| --------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src>
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0277, E0412.
For more information about an error, try `rustc --explain E0277`.

12
tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.rs
View File

@ -13,8 +13,14 @@ mod assert {
{}
}
fn should_gracefully_handle_unknown_dst_field() {
#[repr(C)] struct Src;
#[repr(C)] struct Dst(Missing); //~ cannot find type
fn should_gracefully_handle_unknown_src_field() {
#[repr(C)] struct Src(Missing); //~ cannot find type
#[repr(C)] struct Dst();
assert::is_transmutable::<Src, Dst>(); //~ ERROR cannot be safely transmuted
}
fn should_gracefully_handle_unknown_src_ref_field() {
#[repr(C)] struct Src(&'static Missing); //~ cannot find type
#[repr(C)] struct Dst(&'static Dst);
assert::is_transmutable::<Src, Dst>(); //~ ERROR cannot be safely transmuted
}

31
tests/ui/transmutability/malformed-program-gracefulness/unknown_src_field.stderr
View File

@ -1,14 +1,20 @@
error[E0412]: cannot find type `Missing` in this scope
--> $DIR/unknown_src_field.rs:18:27
--> $DIR/unknown_src_field.rs:17:27
|
LL | #[repr(C)] struct Dst(Missing);
LL | #[repr(C)] struct Src(Missing);
| ^^^^^^^ not found in this scope
error[E0277]: `Src` cannot be safely transmuted into `Dst`
error[E0412]: cannot find type `Missing` in this scope
--> $DIR/unknown_src_field.rs:23:36
|
LL | #[repr(C)] struct Src(&'static Missing);
| ^^^^^^^ not found in this scope
error[E0277]: `should_gracefully_handle_unknown_src_field::Src` cannot be safely transmuted into `should_gracefully_handle_unknown_src_field::Dst`
--> $DIR/unknown_src_field.rs:19:36
|
LL | assert::is_transmutable::<Src, Dst>();
| ^^^ analyzing the transmutability of `Dst` is not yet supported
| ^^^ `should_gracefully_handle_unknown_src_field::Src` has an unknown layout
|
note: required by a bound in `is_transmutable`
--> $DIR/unknown_src_field.rs:12:14
@ -19,7 +25,22 @@ LL | where
LL | Dst: BikeshedIntrinsicFrom<Src>
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
error: aborting due to 2 previous errors
error[E0277]: `should_gracefully_handle_unknown_src_ref_field::Src` cannot be safely transmuted into `should_gracefully_handle_unknown_src_ref_field::Dst`
--> $DIR/unknown_src_field.rs:25:36
|
LL | assert::is_transmutable::<Src, Dst>();
| ^^^ `should_gracefully_handle_unknown_src_ref_field::Src` has an unknown layout
|
note: required by a bound in `is_transmutable`
--> $DIR/unknown_src_field.rs:12:14
|
LL | pub fn is_transmutable<Src, Dst>()
| --------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src>
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`
error: aborting due to 4 previous errors
Some errors have detailed explanations: E0277, E0412.
For more information about an error, try `rustc --explain E0277`.

1
tests/ui/transmutability/structs/repr/transmute_infinitely_recursive_type.rs
View File

@ -22,5 +22,4 @@ fn should_pad_explicitly_packed_field() {
//~^ ERROR: recursive type
assert::is_maybe_transmutable::<ExplicitlyPadded, ()>();
//~^ ERROR: cannot be safely transmuted
}

19
tests/ui/transmutability/structs/repr/transmute_infinitely_recursive_type.stderr
View File

@ -15,22 +15,7 @@ error[E0391]: cycle detected when computing layout of `should_pad_explicitly_pac
= note: cycle used when evaluating trait selection obligation `(): core::mem::transmutability::BikeshedIntrinsicFrom<should_pad_explicitly_packed_field::ExplicitlyPadded, core::mem::transmutability::Assume { alignment: false, lifetimes: false, safety: false, validity: false }>`
= note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
error[E0277]: `ExplicitlyPadded` cannot be safely transmuted into `()`
--> $DIR/transmute_infinitely_recursive_type.rs:24:55
|
LL | assert::is_maybe_transmutable::<ExplicitlyPadded, ()>();
| ^^ analyzing the transmutability of `ExplicitlyPadded` is not yet supported
|
note: required by a bound in `is_maybe_transmutable`
--> $DIR/transmute_infinitely_recursive_type.rs:14:14
|
LL | pub fn is_maybe_transmutable<Src, Dst>()
| --------------------- required by a bound in this function
LL | where
LL | Dst: BikeshedIntrinsicFrom<Src>,
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_maybe_transmutable`
error: aborting due to 2 previous errors
error: aborting due to 3 previous errors
Some errors have detailed explanations: E0072, E0277, E0391.
Some errors have detailed explanations: E0072, E0391.
For more information about an error, try `rustc --explain E0072`.