From what I know, modern GPUs are still programmed with C++ exclusively. See CUDA [0] for Nvidia and ROCm [1] for AMD.
Why is this? Why Rust is not loved there?
[0] https://docs.nvidia.com/cuda/
[1] https://github.com/ROCm-Developer-Tools/HIP
GPU programming =/= CPU programming. GPUs don't have complex execution paths with branching, and the programs that run are "memory safe" in the sense of what Rust aims to improve.
>> Why is this? Why Rust is not loved there?
History and demand.
CUDA is about 15 years old. MPI and similar parallel computing APIs are even older.
C, C++, and Fortran have been the "goto" programming languages for parallel and scientific computing for decades.
Rust is a relative newcomer that does not have enough demand yet to mandate CUDA APIs. It probably will some day.
Another concern is the number of decades-mature libraries that are used in parallel computing domains. It seems much more likely that any Rust support will initially be Rust wrappers around C or C++ APIs rather than native Rust implementations.
Some projects for Rust on CUDA are in progress:
https://github.com/Rust-GPU/Rust-CUDA
https://github.com/bheisler/RustaCUDA