[bsder]

Well, for starters, allocators. The standard library is now making adjustments around that, but it's not mainstream and most people don't use them and they don't get the same level of attention as the happy path.

However, Rust, the language has its issues on embedded.

Rust's ownership model is directly at odds with lots of embedded. These bits inside a register are owned by the ADC and these bits inside a register are owned by the DAC is not a happy thing in Rust.

Lack of arbitrary sized integers and how they slice.

Cargo. Quite annoying to deal with cargo and an embedded toolchain. The Rust embedded guys have done really good work if you're on ARM. If you're not, good luck.

That having been said, if you have to go implement something like Reference Counting in something not Rust, you will weep tears of blood debugging every single time your reference counts go wrong.

Embedded is engineering. It has tradeoffs. That's life.