Read relative list validation sources from the cell being checked

A list source such as =$B1:$B2 is written for the rule's top-left cell.
list_items evaluated it there for every cell, so the dropdown and the
check showed and accepted the top-left cell's items everywhere. It now
takes the cell and shifts the source to it, as Excel does.

crates/engine/src/cmd/data/tests.rs

@@ -480,6 +480,25 @@ fn a_list_typed_without_quotes_is_saved_as_a_quoted_list() {
     assert_eq!(sheet_xml(&reopened), xml, "a second save writes the same rules");
 }
 
+#[test]
+fn a_relative_list_source_is_read_from_the_cell_being_checked() {
+    // As in Excel, `=$B1:$B2` on A3:A4,A1:A2 is written for A1 (the top-left cell of all the
+    // areas) and lists B4:B5 at A4. It used to list B1:B2 in every cell.
+    let mut s = Session::new();
+    s.new_workbook();
+    s.execute("range.setValues", json!({"range": "B1:B5", "values": [["a"], ["b"], ["c"], ["d"], ["e"]]})).unwrap();
+    s.execute("data.validation", json!({"range": "A3:A4,A1:A2", "type": "list", "formula1": "=$B1:$B2"})).unwrap();
+    let wb = s.doc().unwrap().wb.clone();
+    let dv = wb.active().unwrap().validations[0].clone();
+    for (cell, items) in [("A1", ["a", "b"]), ("A2", ["b", "c"]), ("A3", ["c", "d"]), ("A4", ["d", "e"])] {
+        let at = CellRef::parse(cell).unwrap();
+        assert_eq!(list_items(&wb, 0, at, &dv), items, "{cell}");
+        for v in ["a", "b", "c", "d", "e"] {
+            assert_eq!(check_validation(&wb, 0, at, v).is_none(), items.contains(&v), "{cell} with {v}");
+        }
+    }
+}
+
 #[test]
 fn a_rule_with_an_unknown_type_operator_or_error_style_is_refused() {
     // A typo used to give a rule that validates nothing (`type="none"`) or the wrong check,

crates/engine/src/cmd/data/validation.rs

@@ -152,8 +152,10 @@ fn list_source(f: &str) -> String {
     format!("\"{}\"", t.replace('"', "\"\""))
 }
 
-/// List entries of a list validation (literal or from a range).
-pub fn list_items(wb: &Workbook, sheet: usize, dv: &Validation) -> Vec<String> {
+/// List entries of a list validation (literal or from a range) for the cell `at`. A relative
+/// source is written for the rule's top-left cell and read from `at`, as in Excel (`=$B1:$B3` on
+/// A1:A9 lists B5:B7 at A5).
+pub fn list_items(wb: &Workbook, sheet: usize, at: CellRef, dv: &Validation) -> Vec<String> {
     let f = dv.f1.trim();
     if is_literal_list(f) {
         // A quoted list is a string literal: `""` inside stands for one `"`.
@@ -163,8 +165,8 @@ pub fn list_items(wb: &Workbook, sheet: usize, dv: &Validation) -> Vec<String> {
         };
         return items.split(',').map(|x| x.trim().to_string()).filter(|x| !x.is_empty()).collect();
     }
-    let at = RangeRef::top_left(&dv.ranges).unwrap_or_default();
-    match gridcraft_calc::evaluate(wb, sheet, at, f) {
+    let first = RangeRef::top_left(&dv.ranges).unwrap_or(at);
+    match gridcraft_calc::evaluate(wb, sheet, at, &formula_at(f, first, at)) {
         Value::Array(a) => a.data.iter().filter(|v| !v.is_empty()).map(Value::display).collect(),
         v if !v.is_empty() && !v.is_error() => vec![v.display()],
         _ => vec![],
@@ -200,7 +202,7 @@ pub fn check_validation(wb: &Workbook, sheet: usize, at: CellRef, input: &str) -
     let eval = |f: &str| gridcraft_calc::evaluate(wb, sheet, at, &formula_at(f, first, at));
     let num = |f: &str| eval(f).to_number().ok();
     let ok = match dv.kind {
-        ValidationKind::List => list_items(wb, sheet, dv).iter().any(|x| x.eq_ignore_ascii_case(input)),
+        ValidationKind::List => list_items(wb, sheet, at, dv).iter().any(|x| x.eq_ignore_ascii_case(input)),
         ValidationKind::Custom => eval(&dv.f1).to_bool().unwrap_or(false),
         ValidationKind::TextLength => {
             let n = input.chars().count() as f64;

crates/ui-egui/src/grid/editor.rs

@@ -125,7 +125,7 @@ pub(super) fn list_picker(app: &mut SheetApp, ui: &mut egui::Ui, geo: &Geo, was_
         app.grid.list_picker = None;
         return;
     };
-    let items = gridcraft_engine::cmd::data::list_items(&wb, si, &dv);
+    let items = gridcraft_engine::cmd::data::list_items(&wb, si, c, &dv);
     let r = geo.cell_rect(sh, c);
     // Fit the popup to its rows (up to LIST_PICKER_MAX_ROWS); without a minimum the scroll area collapses to its 64 px default.
     let height = list_picker_height(items.len(), LIST_PICKER_ROW_H, ui.spacing().item_spacing.y);