error[E0570]: "rust-invalid" is not a supported ABI for the current target
  --> $DIR/unsupported-abi-transmute.rs:10:53
   |
LL |     let a = unsafe { mem::transmute::<usize, extern "rust-invalid" fn(i32)>(4) }(2);
   |                                                     ^^^^^^^^^^^^^^

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0570`.