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//! Test for a tracked struct where an untracked field has a
//! very poorly chosen hash impl (always returns 0).
//!
//! This demonstrates that tracked struct ids will always change if
//! untracked fields on a struct change values, because although struct
//! ids are based on the *hash* of the untracked fields, ids are generational
//! based on the field values.
use salsa::{Database as Db, Setter};
use test_log::test;
#[salsa::input]
struct MyInput {
field: u64,
}
#[derive(PartialEq, Eq, PartialOrd, Ord, Debug, Clone)]
struct BadHash {
field: u64,
}
impl From<u64> for BadHash {
fn from(value: u64) -> Self {
Self { field: value }
}
}
impl std::hash::Hash for BadHash {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
state.write_i16(0);
}
}
#[salsa::tracked]
struct MyTracked<'db> {
field: BadHash,
}
#[salsa::tracked]
fn the_fn(db: &dyn Db, input: MyInput) {
let tracked0 = MyTracked::new(db, BadHash::from(input.field(db)));
assert_eq!(tracked0.field(db).field, input.field(db));
}
#[test]
fn execute() {
let mut db = salsa::DatabaseImpl::new();
let input = MyInput::new(&db, 1);
the_fn(&db, input);
input.set_field(&mut db).to(0);
the_fn(&db, input);
}
#[salsa::tracked]
fn create_tracked<'db>(db: &'db dyn Db, input: MyInput) -> MyTracked<'db> {
MyTracked::new(db, BadHash::from(input.field(db)))
}
#[salsa::tracked]
fn with_tracked<'db>(db: &'db dyn Db, tracked: MyTracked<'db>) -> u64 {
tracked.field(db).field
}
#[test]
fn dependent_query() {
let mut db = salsa::DatabaseImpl::new();
let input = MyInput::new(&db, 1);
let tracked = create_tracked(&db, input);
assert_eq!(with_tracked(&db, tracked), 1);
input.set_field(&mut db).to(0);
// We now re-run the query that creates the tracked struct.
//
// Salsa will re-use the `MyTracked` struct from the previous revision,
// but practically it has been re-created due to generational ids.
let tracked = create_tracked(&db, input);
assert_eq!(with_tracked(&db, tracked), 0);
input.set_field(&mut db).to(2);
let tracked = create_tracked(&db, input);
assert_eq!(with_tracked(&db, tracked), 2);
}
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