remove redundant check for short-lived footers

Now it is all handled at the resolving stage.

crates/typst-layout/src/grid/layouter.rs

@@ -1486,12 +1486,18 @@ impl<'a> GridLayouter<'a> {
                 } else {
                     false
                 }
-            } else if let Some(Repeatable::Repeated(footer)) = &self.grid.footer {
+            } else if let Some(Repeatable::Repeated(_)) = &self.grid.footer {
                 // If no rows other than the footer have been laid out so far,
                 // and there are rows beside the footer, then don't lay it out
                 // at all. (Similar check from above, but for the case without
                 // headers.)
-                // TODO: widow prevention for non-repeated footers with a
+                //
+                // It is worth noting that the footer is made non-repeatable at
+                // the grid resolving stage if it is short-lived, that is, if
+                // it is at the start of the table (or right after headers at
+                // the start of the table).
+                // TODO(subfooters): explicitly check for short-lived footers.
+                // TODO(subfooters): widow prevention for non-repeated footers with a
                 // similar mechanism / when implementing multiple footers.
                 self.lrows.is_empty()
                     && may_progress_with_offset(
@@ -1502,7 +1508,6 @@ impl<'a> GridLayouter<'a> {
                         // zero anyway.
                         self.current.header_height + self.current.footer_height,
                     )
-                    && footer.start != 0
             } else {
                 false
             };

crates/typst-library/src/layout/grid/resolve.rs

@@ -1063,6 +1063,10 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
         let mut footer: Option<(usize, Span, Footer)> = None;
         let mut repeat_footer = false;
 
+        // If true, there has been at least one cell besides headers and
+        // footers. When false, footers at the end are forced to not repeat.
+        let mut at_least_one_cell = false;
+
         // We can't just use the cell's index in the 'cells' vector to
         // determine its automatic position, since cells could have arbitrary
         // positions, so the position of a cell in 'cells' can differ from its
@@ -1104,6 +1108,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
                 &mut repeat_footer,
                 &mut auto_index,
                 &mut resolved_cells,
+                &mut at_least_one_cell,
                 child,
             )?;
         }
@@ -1125,6 +1130,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
             footer,
             repeat_footer,
             row_amount,
+            at_least_one_cell,
         )?;
 
         Ok(CellGrid::new_internal(
@@ -1157,6 +1163,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
         repeat_footer: &mut bool,
         auto_index: &mut usize,
         resolved_cells: &mut Vec<Option<Entry<'x>>>,
+        at_least_one_cell: &mut bool,
         child: ResolvableGridChild<T, I>,
     ) -> SourceResult<()>
     where
@@ -1240,7 +1247,13 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
 
                 (Some(items), None)
             }
-            ResolvableGridChild::Item(item) => (None, Some(item)),
+            ResolvableGridChild::Item(item) => {
+                if matches!(item, ResolvableGridItem::Cell(_)) {
+                    *at_least_one_cell = true;
+                }
+
+                (None, Some(item))
+            }
         };
 
         let items = header_footer_items.into_iter().flatten().chain(simple_item);
@@ -1784,6 +1797,7 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
         footer: Option<(usize, Span, Footer)>,
         repeat_footer: bool,
         row_amount: usize,
+        at_least_one_cell: bool,
     ) -> SourceResult<Option<Repeatable<Footer>>> {
         // Repeat the gutter below a header (hence why we don't
         // subtract 1 from the gutter case).
@@ -1856,7 +1870,11 @@ impl<'x> CellGridResolver<'_, '_, 'x> {
             })
             .transpose()?
             .map(|footer| {
-                if repeat_footer {
+                // Don't repeat footers when the table only has headers and
+                // footers.
+                // TODO(subfooters): Switch this to marking the last N
+                // consecutive footers as short lived.
+                if repeat_footer && at_least_one_cell {
                     Repeatable::Repeated(footer)
                 } else {
                     Repeatable::NotRepeated(footer)

tests/suite/layout/grid/subheaders.typ

@@ -788,3 +788,19 @@
     [a],
   )
 )
+
+--- grid-subheaders-alone-with-gutter-and-footer-no-orphan-prevention ---
+#set page(height: 5.5em)
+#table(
+  gutter: 4pt,
+  table.header(
+    [L1]
+  ),
+  table.header(
+    level: 2,
+    [L2]
+  ),
+  table.footer(
+    [a],
+  )
+)