Add extern_spec for Option::unwrap and Result::unwrap

Author: coord-e

std.rs

@@ -13,3 +13,17 @@ fn _extern_spec_box_new<T>(x: T) -> Box<T> {
 fn _extern_spec_std_mem_swap<T>(x: &mut T, y: &mut T) {
     std::mem::swap(x, y);
 }
+
+#[thrust::extern_spec_fn]
+#[thrust::requires(opt != std::option::Option::<T0>::None())]
+#[thrust::ensures(std::option::Option::<T0>::Some(result) == opt)]
+fn _extern_spec_option_unwrap<T>(opt: Option<T>) -> T {
+    Option::unwrap(opt)
+}
+
+#[thrust::extern_spec_fn]
+#[thrust::requires(exists x:T0. res == std::result::Result::<T0, T1>::Ok(x))]
+#[thrust::ensures(std::result::Result::<T0, T1>::Ok(result) == res)]
+fn _extern_spec_result_unwrap<T, E: std::fmt::Debug>(res: Result<T, E>) -> T {
+    Result::unwrap(res)
+}