Closed
Description
Allocating a type with alignment bigger than 4 bytes sometimes gets allocated on address which is not a multiple of that alignment, causing accesses to fail debug_assert! in slice::from_raw_parts_*
struct Something {
x: f64,
y: f32
}
fn main() -> anyhow::Result<()> {
esp_idf_sys::link_patches();
esp_idf_svc::log::EspLogger::initialize_default();
log::info!("align_of::<Something>(): {}", std::mem::align_of::<Something>());
log::info!("size_of::<Something>(): {}", std::mem::size_of::<Something>());
loop {
let r = rand::random::<usize>() % 100;
let mut v = Vec::with_capacity(r);
log::info!("pointer: 0x{:x}", v.as_ptr() as usize);
log::info!("v.as_ptr() % std::mem::align_of::<Something>() == {}", v.as_ptr() as usize % std::mem::align_of::<Something>());
unsafe { v.set_len(r); };
log::info!("fill");
for x in &mut v {
*x = Something {
x: 10f64,
y: 20f32
};
}
log::info!("filled");
std::thread::sleep(std::time::Duration::from_millis(100));
}
Ok(())
}Note that the alignment of Something is 8, and sometimes the pointer is not a multiple of 8, causing a panic in for x in &mut v { in debug builds.
Happens on ESP32 with Rust STD library, using https://github.com/ivmarkov/rust-esp32-std-demo