Remove default PartialOrd and Ord derives for salsa-structs (#868)

components/salsa-macro-rules/src/setup_input_struct.rs

@@ -60,7 +60,7 @@ macro_rules! setup_input_struct {
         ]
     ) => {
         $(#[$attr])*
-        #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+        #[derive(Copy, Clone, PartialEq, Eq, Hash)]
         $vis struct $Struct(salsa::Id);
 
         #[allow(clippy::all)]

components/salsa-macro-rules/src/setup_interned_struct.rs

@@ -72,7 +72,7 @@ macro_rules! setup_interned_struct {
         ]
     ) => {
         $(#[$attr])*
-        #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+        #[derive(Copy, Clone, PartialEq, Eq, Hash)]
         $vis struct $Struct< $($db_lt_arg)? >(
             $Id,
             std::marker::PhantomData < & $interior_lt salsa::plumbing::interned::Value <$StructWithStatic> >

components/salsa-macro-rules/src/setup_tracked_struct.rs

@@ -91,7 +91,7 @@ macro_rules! setup_tracked_struct {
         ]
     ) => {
         $(#[$attr])*
-        #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
+        #[derive(Copy, Clone, PartialEq, Eq, Hash)]
         $vis struct $Struct<$db_lt>(
             salsa::Id,
             std::marker::PhantomData < & $db_lt salsa::plumbing::tracked_struct::Value < $Struct<'static> > >

tests/tracked_with_struct_ord.rs

@@ -0,0 +1,37 @@
+//! Test that `PartialOrd` and `Ord` can be derived for tracked structs
+
+use salsa::{Database, DatabaseImpl};
+use test_log::test;
+
+#[salsa::input]
+#[derive(PartialOrd, Ord)]
+struct Input {
+    value: usize,
+}
+
+#[salsa::tracked(debug)]
+#[derive(Ord, PartialOrd)]
+struct MyTracked<'db> {
+    value: usize,
+}
+
+#[salsa::tracked]
+fn create_tracked(db: &dyn Database, input: Input) -> MyTracked<'_> {
+    MyTracked::new(db, input.value(db))
+}
+
+#[test]
+fn execute() {
+    DatabaseImpl::new().attach(|db| {
+        let input1 = Input::new(db, 20);
+        let input2 = Input::new(db, 10);
+
+        // Compares by ID and not by value.
+        assert!(input1 <= input2);
+
+        let t0: MyTracked = create_tracked(db, input1);
+        let t1: MyTracked = create_tracked(db, input2);
+
+        assert!(t0 <= t1);
+    })
+}