C:UsersJason.rustuptoolchainsnightly-x86_64-pc-windows-msvclibrustlibsrcrust> rustup run nightly rustc --target
 arm-unknown-linux-gnueabihf -O -Z no-landing-pads src/libcore/lib.rs --out-dir C:/Users/Jason/rustlib/arm-unknown-linux
-gnueabihf/lib
error[E0601]: `main` function not found in crate `lib`
  |
  = note: consider adding a `main` function to `src/libcore/lib.rs`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0601`.

[dependencies]
"rust-libcore"="*"

C:UsersJasonReposrust-rasp [master +6 ~0 -0 !]> rustup run nightly cargo build --target=arm-unknown-linux-gnueabihf
   Compiling rust-libcore v0.0.3
error: couldn't read "C:\Users\Jason\.cargo\registry\src\github.com-1ecc6299db9ec823\rust-libcore-0.0.3\rust/src/libcore\..\stdsimd\coresimd\mod.rs": The system cannot find the path specified. (os error 3)
   --> C:UsersJason.cargoregistrysrcgithub.com-1ecc6299db9ec823rust-libcore-0.0.3rust/src/libcore/lib.rs:247:5
    |
247 | mod coresimd;
    |     ^^^^^^^^

error: aborting due to previous error

error: Could not compile `rust-libcore`.