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Rollup merge of #95516 - RalfJung:ptrs-not-ints, r=dtolnay

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ptr_metadata test: avoid ptr-to-int transmutes

Pointers can have provenance, integers don't, so transmuting pointers to integers creates "non-standard" values and it is unclear how well those can be supported (https://github.com/rust-lang/unsafe-code-guidelines/issues/286).

So for this test let's take the safer option and use a pointer type instead. That also makes Miri happy. :)
This commit is contained in:
Matthias Krüger 2022-04-01 12:07:02 +02:00 • committed by GitHub
commit 3245e61298
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1 changed files with 5 additions and 5 deletions
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10
library/core/tests/ptr.rs
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@ -490,11 +490,11 @@ fn ptr_metadata() {
let vtable_5: DynMetadata<dyn Display> =
metadata(&Pair(true, 7_u32) as &Pair<bool, dyn Display>);
unsafe {
let address_1: usize = std::mem::transmute(vtable_1);
let address_2: usize = std::mem::transmute(vtable_2);
let address_3: usize = std::mem::transmute(vtable_3);
let address_4: usize = std::mem::transmute(vtable_4);
let address_5: usize = std::mem::transmute(vtable_5);
let address_1: *const () = std::mem::transmute(vtable_1);
let address_2: *const () = std::mem::transmute(vtable_2);
let address_3: *const () = std::mem::transmute(vtable_3);
let address_4: *const () = std::mem::transmute(vtable_4);
let address_5: *const () = std::mem::transmute(vtable_5);
// Different trait => different vtable pointer
assert_ne!(address_1, address_2);
// Different erased type => different vtable pointer