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fix: don't leak GC roots in Table::copy - #14627
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`Table::copy` copies each element by reading it with `Table::get` and writing it with `Table::set`. For GC reference tables, `Table::get` creates a LIFO `Rooted` in the caller's current root scope. Nothing in `Table::copy` released those roots, so when it was called on a plain `&mut Store` rather than inside a `RootScope`, every copied object stayed rooted until the store was dropped. Repeated copies grew the root set and kept the GC heap from shrinking across collections. Enter a GC LIFO scope around each element's get/set pair and exit it afterwards, so the temporary root is released before the next element is copied. Assisted-by: claude:claude-opus-5-5 Signed-off-by: Roman Volosatovs <rvolosatovs@riseup.net>
alexcrichton
approved these changes
Oct 9, 2026
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Table::copycopies each element by reading it withTable::getand writing it withTable::set. For GC reference tables,Table::getcreates a LIFORootedin the caller's current root scope. Nothing inTable::copyreleased those roots, so when it was called on a plain&mut Storerather than inside aRootScope, every copied object stayed rooted until the store was dropped. Repeated copies grew the root set and kept the GC heap from shrinking across collections.Enter a GC LIFO scope around each element's get/set pair and exit it afterwards, so the temporary root is released before the next element is copied.