cargo check error

[cassc]

cargo check produces the following error:

❯ cargo check
   Compiling proc-macro2 v1.0.37
   Compiling unicode-xid v0.2.2
   Compiling syn v1.0.91
   Compiling serde_derive v1.0.136
   Compiling version_check v0.9.4
   Compiling serde v1.0.136
    Checking cfg-if v1.0.0
   Compiling libc v0.2.123
error[E0463]: can't find crate for `std`

For more information about this error, try `rustc --explain E0463`.
error: could not compile `serde_derive` due to previous error
warning: build failed, waiting for other jobs to finish...
error[E0463]: can't find crate for `core`

error: build failed

Tried cargo check --workspace --all-features but still got the error. Any suggestions?

[cassc]

solved by removing rust-toolchain.toml, not sure why it's causing the problem.