Add compile-fail test for getter and setter visibility

salsa-2022-tests/tests/compile-fail/get-set-on-private-field.rs

@@ -0,0 +1,31 @@
+#[salsa::jar(db = Db)]
+pub struct Jar(a::MyInput);
+
+mod a {
+    use crate::Jar;
+
+    #[salsa::input(jar = Jar)]
+    pub struct MyInput {
+        field: u32,
+    }
+}
+
+pub trait Db: salsa::DbWithJar<Jar> {}
+
+#[salsa::db(Jar)]
+#[derive(Default)]
+struct Database {
+    storage: salsa::Storage<Self>,
+}
+
+impl salsa::Database for Database {}
+
+impl Db for Database {}
+
+fn main() {
+    let mut db = Database::default();
+    let input = a::MyInput::new(&mut db, 22);
+
+    input.field(&db);
+    input.set_field(&mut db).to(23);
+}

salsa-2022-tests/tests/compile-fail/get-set-on-private-field.stderr

@@ -0,0 +1,17 @@
+error[E0624]: associated function `field` is private
+  --> tests/compile-fail/get-set-on-private-field.rs:29:11
+   |
+7  |     #[salsa::input(jar = Jar)]
+   |     -------------------------- private associated function defined here
+...
+29 |     input.field(&db);
+   |           ^^^^^ private associated function
+
+error[E0624]: associated function `set_field` is private
+  --> tests/compile-fail/get-set-on-private-field.rs:30:11
+   |
+7  |     #[salsa::input(jar = Jar)]
+   |     -------------------------- private associated function defined here
+...
+30 |     input.set_field(&mut db).to(23);
+   |           ^^^^^^^^^ private associated function