move core result into core utils

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/result/unwrap_infallible.rs

@@ -0,0 +1,17 @@
+use std::convert::Infallible;
+
+use super::{DebugInspect, Result};
+use crate::error;
+
+pub trait UnwrapInfallible<T> {
+	fn unwrap_infallible(self) -> T;
+}
+
+impl<T> UnwrapInfallible<T> for Result<T, Infallible> {
+	#[inline]
+	fn unwrap_infallible(self) -> T {
+		// SAFETY: Branchless unwrap for errors that can never happen. In debug
+		// mode this is asserted.
+		unsafe { self.debug_inspect_err(error::infallible).unwrap_unchecked() }
+	}
+}