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Forbid casts of raw pointers to trait objects with the same trait, but different args

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This commit is contained in:
Maybe Waffle 2024-01-22 17:22:09 +00:00 committed by Maybe Lapkin
parent 36b1f4411d
commit d06cf5b399
4 changed files with 31 additions and 19 deletions
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6
compiler/rustc_hir_typeck/src/cast.rs
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@ -44,7 +44,7 @@
use rustc_middle::ty::TyCtxt;
use rustc_middle::ty::{self, Ty, TypeAndMut, TypeVisitableExt, VariantDef};
use rustc_session::lint;
use rustc_span::def_id::{DefId, LOCAL_CRATE};
use rustc_span::def_id::LOCAL_CRATE;
use rustc_span::symbol::sym;
use rustc_span::Span;
use rustc_span::DUMMY_SP;
@ -73,7 +73,7 @@ enum PointerKind<'tcx> {
/// No metadata attached, ie pointer to sized type or foreign type
Thin,
/// A trait object
VTable(Option<DefId>),
VTable(Option<ty::Binder<'tcx, ty::ExistentialTraitRef<'tcx>>>),
/// Slice
Length,
/// The unsize info of this projection or opaque type
@ -101,7 +101,7 @@ fn pointer_kind(
Ok(match *t.kind() {
ty::Slice(_) | ty::Str => Some(PointerKind::Length),
ty::Dynamic(tty, _, ty::Dyn) => Some(PointerKind::VTable(tty.principal_def_id())),
ty::Dynamic(tty, _, ty::Dyn) => Some(PointerKind::VTable(tty.principal())),
ty::Adt(def, args) if def.is_struct() => match def.non_enum_variant().tail_opt() {
None => Some(PointerKind::Thin),
Some(f) => {

12
tests/ui/cast/cast-rfc0401-vtable-kinds.rs
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@ -16,13 +16,6 @@ impl<T> Foo<T> for () {}
impl Foo<u32> for u32 { fn foo(&self, _: u32) -> u32 { self+43 } }
impl Bar for () {}
unsafe fn round_trip_and_call<'a>(t: *const (dyn Foo<u32>+'a)) -> u32 {
let foo_e : *const dyn Foo<u32> = t as *const _;
let r_1 = foo_e as *mut dyn Foo<u32>;
(&*r_1).foo(0)
}
#[repr(C)]
struct FooS<T:?Sized>(T);
#[repr(C)]
@ -38,11 +31,6 @@ fn tuple_i32_to_u32<T:?Sized>(u: *const (i32, T)) -> *const (u32, T) {
fn main() {
let x = 4u32;
let y : &dyn Foo<u32> = &x;
let fl = unsafe { round_trip_and_call(y as *const dyn Foo<u32>) };
assert_eq!(fl, (43+4));
let s = FooS([0,1,2]);
let u: &FooS<[u32]> = &s;
let u: *const FooS<[u32]> = u;

6
tests/ui/cast/ptr-to-trait-obj-different-args.rs
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@ -19,12 +19,12 @@ fn main() {
let b: *const dyn B = a as _; //~ error: casting `*const dyn A` as `*const dyn B` is invalid
let x: *const dyn Trait<X> = &();
let y: *const dyn Trait<Y> = x as _;
let y: *const dyn Trait<Y> = x as _; //~ error: casting `*const dyn Trait<X>` as `*const dyn Trait<Y>` is invalid
_ = (b, y);
}
fn generic<T>(x: *const dyn Trait<X>, t: *const dyn Trait<T>) {
let _: *const dyn Trait<T> = x as _;
let _: *const dyn Trait<X> = t as _;
let _: *const dyn Trait<T> = x as _; //~ error: casting `*const (dyn Trait<X> + 'static)` as `*const dyn Trait<T>` is invalid
let _: *const dyn Trait<X> = t as _; //~ error: casting `*const (dyn Trait<T> + 'static)` as `*const dyn Trait<X>` is invalid
}

26
tests/ui/cast/ptr-to-trait-obj-different-args.stderr
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@ -6,6 +6,30 @@ LL | let b: *const dyn B = a as _;
|
= note: vtable kinds may not match
error: aborting due to 1 previous error
error[E0606]: casting `*const dyn Trait<X>` as `*const dyn Trait<Y>` is invalid
--> $DIR/ptr-to-trait-obj-different-args.rs:22:34
|
LL | let y: *const dyn Trait<Y> = x as _;
| ^^^^^^
|
= note: vtable kinds may not match
error[E0606]: casting `*const (dyn Trait<X> + 'static)` as `*const dyn Trait<T>` is invalid
--> $DIR/ptr-to-trait-obj-different-args.rs:28:34
|
LL | let _: *const dyn Trait<T> = x as _;
| ^^^^^^
|
= note: vtable kinds may not match
error[E0606]: casting `*const (dyn Trait<T> + 'static)` as `*const dyn Trait<X>` is invalid
--> $DIR/ptr-to-trait-obj-different-args.rs:29:34
|
LL | let _: *const dyn Trait<X> = t as _;
| ^^^^^^
|
= note: vtable kinds may not match
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0606`.