Can't compile no_std code

[nazar-pc]

I included no_std dependency and got this confusing error:

  --> crates/subspace-proof-of-time/src/aes.rs:18:8
   |
   |     #[cfg(target_arch = "x86_64")]
18 |     if std::is_x86_feature_detected!("aes") {
   |        ^^^ use of undeclared crate or module `std`

Is it really compiling with no_std for x86-64? Why?
I thought it'll be building guest code for RISCV32IM with no_std instead.