Rust in Android: move fast and fix things

Re:Rust in Android: move fast and fix things by j-krieger on Thursday November 13, 2025 @04:13PM (#45920630)

This doesn't 'cast' anything. The compiler prevents this because it would allow references that outlive their owners. Freely 'casting' only works for data that is static in nature anyways, at which point a coercion is taking place. Any other way involves `std::mem::transmute` or `Box::leak` and the like.

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Re:Rust in Android: move fast and fix things by tick_tock_tick on Thursday November 13, 2025 @04:21PM (#45920711)

Here is a nice segfault in perfectly legal safe Rust https://play.rust-lang.org/?version=stable&mode=debug&editio...

I'd call it casting thought technically maybe it's not you might want to call it something else? You don't need transmute or leak. The issue is only 10 years old now https://github.com/rust-lang/rust/issues/25860

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Re:Rust in Android: move fast and fix things by dwattttt on Thursday November 13, 2025 @04:34PM (#45920891)

Yes, that's an existing soundness hole in the compiler. You won't accidentally code it up yourself though.

If the bar is "deliberately malicious code results in a segfault", get back to me when they fix

  memcpy(0x10000, 0x20000, 0x10);

EDIT: and even that's being charitable; the Rust issue is viewed as a compiler bug which should be fixed.

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