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Rollup merge of #116056 - ouz-a:wide_ice, r=compiler-errors

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Make unsized casts illegal

Weirdly enough this https://github.com/rust-lang/rust/issues/115998 issue seems to exist since Rust 1.0 (couldn't check before that) but it's only recently been noticed. This change makes those casts illegal.

Fixes https://github.com/rust-lang/rust/issues/115998
This commit is contained in:
Matthias Krüger 2023-09-22 23:12:36 +02:00 • committed by GitHub
commit a38f2309fc
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3 changed files with 18 additions and 2 deletions
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5
compiler/rustc_hir_typeck/src/cast.rs
View file

@ -725,6 +725,9 @@ impl<'a, 'tcx> CastCheck<'tcx> {
}, },
// array-ptr-cast // array-ptr-cast
Ptr(mt) => { Ptr(mt) => {
if !fcx.type_is_sized_modulo_regions(fcx.param_env, mt.ty) {
return Err(CastError::IllegalCast);
}
self.check_ref_cast(fcx, TypeAndMut { mutbl, ty: inner_ty }, mt) self.check_ref_cast(fcx, TypeAndMut { mutbl, ty: inner_ty }, mt)
} }
_ => Err(CastError::NonScalar), _ => Err(CastError::NonScalar),
@ -735,7 +738,6 @@ impl<'a, 'tcx> CastCheck<'tcx> {
} }
_ => return Err(CastError::NonScalar), _ => return Err(CastError::NonScalar),
}; };
if let ty::Adt(adt_def, _) = *self.expr_ty.kind() { if let ty::Adt(adt_def, _) = *self.expr_ty.kind() {
if adt_def.did().krate != LOCAL_CRATE { if adt_def.did().krate != LOCAL_CRATE {
if adt_def.variants().iter().any(VariantDef::is_field_list_non_exhaustive) { if adt_def.variants().iter().any(VariantDef::is_field_list_non_exhaustive) {
@ -743,7 +745,6 @@ impl<'a, 'tcx> CastCheck<'tcx> {
} }
} }
} }
match (t_from, t_cast) { match (t_from, t_cast) {
// These types have invariants! can't cast into them. // These types have invariants! can't cast into them.
(_, Int(CEnum) | FnPtr) => Err(CastError::NonScalar), (_, Int(CEnum) | FnPtr) => Err(CastError::NonScalar),

6
tests/ui/cast/unsized-struct-cast.rs Normal file
View file

@ -0,0 +1,6 @@
pub struct Data([u8]);
fn main(){
const _: *const Data = &[] as *const Data;
//~^ ERROR: casting `&[_; 0]` as `*const Data` is invalid
}

9
tests/ui/cast/unsized-struct-cast.stderr Normal file
View file

@ -0,0 +1,9 @@
error[E0606]: casting `&[_; 0]` as `*const Data` is invalid
--> $DIR/unsized-struct-cast.rs:4:28
|
LL | const _: *const Data = &[] as *const Data;
| ^^^^^^^^^^^^^^^^^^
error: aborting due to previous error
For more information about this error, try `rustc --explain E0606`.