error[E0277]: expected a `FnOnce<(&str,)>` closure, found `unsafe extern "rust-intrinsic" fn(_) -> _ {transmute::<_, _>}`
  --> $DIR/coerce-unsafe-to-closure.rs:2:44
   |
LL |     let x: Option<&[u8]> = Some("foo").map(std::mem::transmute);
   |                                        --- ^^^^^^^^^^^^^^^^^^^ call the function in a closure: `|| unsafe { /* code */ }`
   |                                        |
   |                                        required by a bound introduced by this call
   |
   = help: the trait `FnOnce<(&str,)>` is not implemented for fn item `unsafe extern "rust-intrinsic" fn(_) -> _ {transmute::<_, _>}`
   = note: unsafe function cannot be called generically without an unsafe block
note: required by a bound in `Option::<T>::map`
  --> $SRC_DIR/core/src/option.rs:LL:COL

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.