When I compile a simple hello world program, "ahash" never compiles:

   error[E0658]: use of unstable library feature 'build_hasher_simple_hash_one'
   --> src/random_state.rs:463:5
463 | /     fn hash_one<T: Hash>(&self, x: T) -> u64 {
464 | |         RandomState::hash_one(self, x)
465 | |     }
    | |_____^
    = note: see issue #86161 <https://github.com/rust-lang/rust/issues/86161> for more information
    = help: add `#![feature(build_hasher_simple_hash_one)]` to the crate attributes to enable
For more information about this error, try `rustc --explain E0658`

In short: helloworld isn't compiling because of an unstable dependency, yet changing versions of solana-cli and/or solana-program doesn't help

Solana --version:

solana-cli 1.16.25 (src:8dd7d060; feat:2294205250, client:SolanaLabs)

Rustup --version:

rustup 1.26.0 (5af9b9484 2023-04-05)
info: This is the version for the rustup toolchain manager, not the rustc compiler.
info: The currently active `rustc` version is `rustc 1.75.0 (82e1608df 2023-12-21)`

rustup toolchain list

stable-x86_64-unknown-linux-gnu (default)
  • If this is your first solana program I would start with the Anchor framework
    – joebuild
    Commented Dec 31, 2023 at 14:43
  • The same thing happened to me. But, my rust is 1.75.0
    – harlenoo
    Commented Dec 31, 2023 at 15:50

1 Answer 1


The easiest way to fix this problem is to add:

ahash = "=0.8.6"

to your dependency list in Cargo.toml

or run:

cargo update -p [email protected] --precise 0.8.6

Error reason

The latest release of ahash uses build_hasher_simple_hash_one which was stabilized in 1.71 but the latest rustc version from the Solana tools is 1.68.0.

Solana has its own fork of rustc which is on a different version than your default rustc installation. You can get the Solana's rustc version by running:

$ cargo build-sbf --version
solana-cargo-build-sbf 1.17.0
platform-tools v1.37
rustc 1.68.0

This problem will get fixed once https://github.com/solana-labs/solana/issues/33504 is resolved.

  • 2
    It worked, thank you! And thanks again for the explanation, I really appreciate that! Commented Dec 31, 2023 at 18:27
  • I came across this issue when using the new seahorse-dev implementation. I recently updated Solana and Rust and as a result, got [email protected]. I downgraded to 0.8.6 using the cargo command.
    – gritty
    Commented Jan 16 at 3:16
  • cargo update solved it, thanks!
    – mirind4
    Commented Feb 7 at 6:53

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