add UnwrapInfallible to Result

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

src/core/result.rs

@@ -3,10 +3,11 @@ mod log_debug_err;
 mod log_err;
 mod map_expect;
 mod not_found;
+mod unwrap_infallible;
 
 pub use self::{
 	debug_inspect::DebugInspect, log_debug_err::LogDebugErr, log_err::LogErr, map_expect::MapExpect,
-	not_found::NotFound,
+	not_found::NotFound, unwrap_infallible::UnwrapInfallible,
 };
 
 pub type Result<T = (), E = crate::Error> = std::result::Result<T, E>;

src/core/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() }
+	}
+}