Move unhandled macro from database utils to core utils.

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

src/core/utils/mod.rs

@@ -20,6 +20,7 @@ pub mod sys;
 mod tests;
 pub mod time;
 pub mod two_phase_counter;
+pub mod unhandled;
 
 pub use ::ctor::{ctor, dtor};
 pub use ::tuwunel_macros::implement;

src/core/utils/unhandled.rs

@@ -0,0 +1,33 @@
+//! Indicate a branch which will never be taken. This induces optimal codegen in
+//! release-mode by emitting unsafe unreachable_unchecked(). In debug-mode it
+//! emits unimplemented() to panic on misplacement.
+
+#[cfg(disable)] // activate when more stable and callsites are vetted.
+// #[cfg(not(debug_assertions))]
+#[macro_export]
+macro_rules! unhandled {
+	($msg:literal) => {
+		// SAFETY: Eliminates branches never encountered in the codebase. This can
+		// promote optimization and reduce codegen. The developer must verify for every
+		// invoking callsite that the unhandled type is in no way involved and could not
+		// possibly be encountered.
+		unsafe {
+			std::hint::unreachable_unchecked();
+		}
+	};
+}
+
+//#[cfg(debug_assertions)]
+#[macro_export]
+macro_rules! unhandled {
+	($msg:literal) => {
+		$crate::maybe_unhandled!($msg);
+	};
+}
+
+#[macro_export]
+macro_rules! maybe_unhandled {
+	($msg:literal) => {
+		unimplemented!($msg)
+	};
+}