This application malfunctions when compiled for AVR and run on an Arduino Uno.

It logs the following to the serial port:

Hello, world!
wat 248 57351 7936
debug buf [0, 57568, 7967] mapped
debug buf [63488, 2016, 31] copied
debug buf [0, 57568, 7967] in-loop
debug buf [248, 57351, 7936] enumerate
debug as_byte_slice() [248, 0, 7, 224, 0, 31]

If compiled with less aggressive optimization (opt-level = "s") it emits the correct

Hello, world!
wat 248 57351 7936
debug buf [248, 57351, 7936] mapped
debug buf [63488, 2016, 31] copied
debug buf [248, 57351, 7936] in-loop
debug buf [248, 57351, 7936] enumerate
debug as_byte_slice() [248, 0, 7, 224, 0, 31]

This malfunction interferes with the SPI transfers performed by the st7789 display driver (results in incorrect colors).

The app that led to the discovery of this bug malfunctions even with opt-level="s".

In addition to nightly-2022-05-10 (from rust-toolchain.toml), whichever nightly-x86_64-unknown-linux-gnu I happen to have installed also malfunctions.