Fix/typechecker orderby

src/typing/checker.rs

@@ -144,11 +144,13 @@ impl Typechecker {
 
         for spec in specs {
             let t = match &spec.key {
-                SortKey::Expr(e) => self.check_expr(e, env),
+                SortKey::Expr(e) => self.order_key_type(e, env),
                 SortKey::Column(idx) => match returns.and_then(|rs| rs.get(*idx)) {
-                    Some(ReturnItem::Expr { expr, .. }) => self.check_expr(expr, env),
-                    // Aggregate output typing is a separate gap; pass-through.
-                    Some(ReturnItem::Aggregate { .. }) => SimpleType::Star,
+                    Some(ReturnItem::Expr { expr, .. }) => self.order_key_type(expr, env),
+                    // Type the aggregate by its result type so a non-orderable
+                    // result (e.g. COLLECT_LIST -> List) is rejected below instead
+                    // of being laundered through Star (reserved for base types).
+                    Some(ReturnItem::Aggregate { agg, .. }) => self.check_aggregator(agg, env),
                     None => {
                         self.errors.push(format!(
                             "ORDER BY column reference #{idx} is out of bounds for the \
@@ -172,8 +174,8 @@ impl Typechecker {
                 SortKey::ColumnField { col, path } => {
                     // Type the projected column, then walk the record path.
                     let mut t = match returns.and_then(|rs| rs.get(*col)) {
-                        Some(ReturnItem::Expr { expr, .. }) => self.check_expr(expr, env),
-                        Some(ReturnItem::Aggregate { .. }) => SimpleType::Star,
+                        Some(ReturnItem::Expr { expr, .. }) => self.order_key_type(expr, env),
+                        Some(ReturnItem::Aggregate { agg, .. }) => self.check_aggregator(agg, env),
                         None => {
                             self.errors.push(format!(
                                 "ORDER BY column reference #{col} is out of bounds for the \
@@ -212,6 +214,25 @@ impl Typechecker {
         }
     }
 
+    /// Type of an ORDER BY sort-key expression. `Star` is reserved for
+    /// base types in the gradual design, but two non-base values reach
+    /// sort keys laundered to `Star`: a constant record (via the
+    /// `simple_type_of_value` punt) and a repetition-group variable (via
+    /// `variable_type_to_simple_type`). Neither is orderable without
+    /// Feature GA04, so type them precisely here — locally to ORDER BY —
+    /// and let the §22.14 comparability check reject them. The global
+    /// typing keeps the punt (RETURN/WHERE still see them as `Star`).
+    fn order_key_type(&mut self, e: &Expr, env: &TypeEnvironment) -> SimpleType {
+        match e {
+            Expr::Const(v) => const_order_type(v),
+            Expr::Var(name) => match env.get(name) {
+                Some(VariableType::Group(_)) => SimpleType::Group(Box::new(SimpleType::Star)),
+                _ => self.check_expr(e, env),
+            },
+            _ => self.check_expr(e, env),
+        }
+    }
+
     /// Reject unbounded repetition unless its nearest prefix makes it finite.
     fn check_unbounded_repetition(&mut self, q: &Query) {
         for m in &q.matches {
@@ -1126,6 +1147,22 @@ fn create_context(desc: &Option<Descriptor>, t: VariableType) -> TypeEnvironment
     }
 }
 
+/// Like `simple_type_of_value`, but a constant record (possibly nested)
+/// types as `Record` instead of the `Star` punt, so the ORDER BY
+/// comparability check (§22.14) can reject it. Sort keys only, via
+/// `order_key_type`.
+fn const_order_type(v: &Value) -> SimpleType {
+    match v {
+        Value::Record(fields) => SimpleType::Record(
+            fields
+                .iter()
+                .map(|(k, vv)| (k.clone(), const_order_type(vv)))
+                .collect(),
+        ),
+        other => simple_type_of_value(other),
+    }
+}
+
 /// Map a literal `Value` to its `SimpleType`.
 ///
 /// List and Record values get a deliberately loose type — the precise

tests/typecheck_gaps_order_by_test.rs

@@ -290,3 +290,74 @@ fn runtime_treats_list_sort_key_as_equal_so_input_order_preserved() {
         _ => panic!("expected projected"),
     }
 }
+
+// ISO §22.14: an aggregate whose result type is non-orderable (a List from
+// COLLECT_LIST) must be rejected as a sort key, not laundered through Star and
+// silently treated as Equal at runtime. Regression for the ORDER BY-over-Star
+// soundness gap (Star is reserved for base types).
+#[test]
+fn typecheck_rejects_list_aggregate_in_sort_key() {
+    let r = compile_query(
+        "MATCH (x: User) RETURN x.city, COLLECT_LIST(x.name) GROUP BY x.city \
+         ORDER BY COLLECT_LIST(x.name)",
+    );
+    let err = r.expect_err("ORDER BY over a list-valued aggregate must be rejected");
+    assert!(
+        err.contains("comparable") || err.contains("22.14") || err.contains("GA04"),
+        "got: {err}"
+    );
+}
+
+// ISO §22.14: a record is not orderable (no Feature GA04). A constant
+// record used to launder to `Star` and slip past the comparability
+// check; regression for the `order_key_type` hardening.
+#[test]
+fn typecheck_rejects_const_record_in_sort_key() {
+    let r = compile_query("MATCH (x) RETURN RECORD { name: 'Alice' } AS r ORDER BY r");
+    let err = r.expect_err("ORDER BY over a record must be rejected");
+    assert!(
+        err.contains("comparable") || err.contains("22.14") || err.contains("GA04"),
+        "got: {err}"
+    );
+}
+
+// The fix is local to ORDER BY: projecting a constant record in RETURN
+// must keep working (it was typed as Star globally and still is).
+#[test]
+fn typecheck_accepts_const_record_in_return() {
+    let r = compile_query("MATCH (x) RETURN RECORD { name: 'Alice' } AS r");
+    assert!(r.is_ok(), "got: {:?}", r.err());
+}
+
+// Drilling into a *scalar* field of a record is fine: `r.name` is a
+// string, which is orderable.
+#[test]
+fn typecheck_accepts_record_scalar_field_in_sort_key() {
+    let r = compile_query("MATCH (x) RETURN RECORD { name: 'Alice' } AS r ORDER BY r.name");
+    assert!(r.is_ok(), "got: {:?}", r.err());
+}
+
+// A repetition-group variable (bound by `{n,m}`) is not a base type
+// and is not orderable; regression for the `order_key_type` hardening.
+#[test]
+fn typecheck_rejects_group_variable_in_sort_key() {
+    let r = compile_query("MATCH (a)-[e]->{1,2}(b) RETURN a, b ORDER BY e");
+    let err = r.expect_err("ORDER BY over a repetition group must be rejected");
+    assert!(
+        err.contains("comparable") || err.contains("22.14") || err.contains("GA04"),
+        "got: {err}"
+    );
+}
+
+// Drilling into a field that is itself a record stays non-orderable.
+#[test]
+fn typecheck_rejects_record_nested_record_field_in_sort_key() {
+    let r = compile_query(
+        "MATCH (x) RETURN RECORD { inner: RECORD { name: 'Alice' } } AS r ORDER BY r.inner",
+    );
+    let err = r.expect_err("ORDER BY over a nested record field must be rejected");
+    assert!(
+        err.contains("comparable") || err.contains("22.14") || err.contains("GA04"),
+        "got: {err}"
+    );
+}