why

Cargo.toml

@@ -9,3 +9,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+accursed-unutterable-type-id-derive = { path = "./accursed-unutterable-type-id-derive" }

accursed-unutterable-type-id-derive/Cargo.toml

@@ -3,6 +3,11 @@ name = "accursed-unutterable-type-id-derive"
 version = "0.1.0"
 edition = "2021"
 
+[lib]
+proc-macro = true
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+quote = "1.0.18"
+syn = "1.0.96"

accursed-unutterable-type-id-derive/src/lib.rs

@@ -1,14 +0,0 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}

src/lib.rs

@@ -1,3 +1,7 @@
+use std::fmt::{Debug, Formatter};
+
+pub use accursed_unutterable_type_id_derive::AccursedUnutterablyTypeIdentified;
+
 /// A type that can be identified by a unique `AccursedUnutterableTypeId`.
 ///
 /// # Safety
@@ -6,7 +10,45 @@ pub unsafe trait AccursedUnutterablyTypeIdentified: 'static {
     fn type_id() -> AccursedUnutterableTypeId;
 }
 
-pub struct AccursedUnutterableTypeId(u64);
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct AccursedUnutterableTypeId(#[doc(hidden)] pub InternalAccursedUnutterableTypeId);
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+#[doc(hidden)]
+#[cfg(debug_assertions)]
+// we do a little trolling
+pub struct InternalAccursedUnutterableTypeId(u128, u64);
+
+#[derive(Clone, Copy, PartialEq, Eq, Hash)]
+#[doc(hidden)]
+#[cfg(not(debug_assertions))]
+pub struct InternalAccursedUnutterableTypeId(pub u64);
+
+#[cfg(debug_assertions)]
+impl InternalAccursedUnutterableTypeId {
+    pub fn new(n: u64) -> Self {
+        Self(0, n)
+    }
+    fn inner(self) -> u64 {
+        self.1
+    }
+}
+
+#[cfg(not(debug_assertions))]
+impl InternalAccursedUnutterableTypeId {
+    pub fn new(n: u64) -> Self {
+        Self(n)
+    }
+    fn inner(self) -> u64 {
+        self.0
+    }
+}
+
+impl Debug for InternalAccursedUnutterableTypeId {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        Debug::fmt(&self.inner(), f)
+    }
+}
 
 impl AccursedUnutterableTypeId {
     pub fn of<T>() -> Self