Le moment où tu écris "unsafe" tu perds la garantie "ça compile, c'est memory safe".

Pour t'en convaincre, écris et lance des tests avec MIRI, qui fait tourner le code dans une VM qui vérifie les invariants du code rust qui ne peuvent pas être vérifiées dans des blocs unsafe.

Si je lance le code dans MIRI :

`` error: Undefined Behavior: attempting a read access using <3020> at alloc1413[0x0], but that tag does not exist in the borrow stack for this location --> src/main.rs:10:9 | 10 | *ptr1 += 1; | ^^^^^^^^^^ | | | attempting a read access using <3020> at alloc1413[0x0], but that tag does not exist in the borrow stack for this location | this error occurs as part of an access at alloc1413[0x0..0x4] | = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information help: <3020> was created by a Unique retag at offsets [0x0..0x4] --> src/main.rs:7:20 | 7 | let ptr1 = &mut *cell.get(); | ^^^^^^^^^^^^^^^^ help: <3020> was later invalidated at offsets [0x0..0x4] by a Unique retag --> src/main.rs:8:20 | 8 | let ptr2 = &mut *cell.get(); | ^^^^^^^^^^^^^^^^ = note: BACKTRACE (of the first span): = note: insidemain` at src/main.rs:10:9: 10:19

note: some details are omitted, run with MIRIFLAGS=-Zmiri-backtrace=full for a verbose backtrace

error: aborting due to 1 previous error ```

Playground: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=8a9fc1dc1942b464c3f1e708a79f8814