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SetExpr: apply recursive-protection to Display - #2623
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LucaCappelletti94 merged 2 commits intoOct 16, 2026
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Printing a long left-deep chain of set operations recurses once per branch through SetExpr's Display and overflows the stack, e.g. a 25,000-branch UNION ALL chain on a 2 MB stack. Expr's Display already carries the recursive-protection attribute; SetExpr's did not.
LucaCappelletti94
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Oct 14, 2026
LucaCappelletti94
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LucaCappelletti94
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Other than the small nit of the comments verbosity, it looks good.
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| #[test] | ||
| fn long_set_operation_chain_display_does_not_stack_overflow() { | ||
| // `SetExpr`'s `Display` recurses once per branch of a set-operation chain. |
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Reduce a bit the comments verbosity please
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Done in 874616e — trimmed the comments down to the small-stack rationale and the iterative-teardown note. Thanks!
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #2623 +/- ##
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+ Coverage 81.16% 81.21% +0.05%
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Files 42 42
Lines 33769 33866 +97
Branches 33769 33866 +97
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+ Hits 27408 27505 +97
+ Misses 2797 2796 -1
- Partials 3564 3565 +1 ☔ View full report in Codecov by Harness. 🚀 New features to boost your workflow:
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LucaCappelletti94
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Reduce the comment verbosity: keep only the small-stack rationale and the iterative-teardown note.
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Printing a set-operation chain recurses once per branch through
SetExpr'sDisplay(left.fmt(f)), so a long chain overflows the stack: a 25,000-branchUNION ALLchain on a 2 MB release stack, as reported in the review on #2621.Expr'sDisplayalready carries#[cfg_attr(feature = "recursive-protection", recursive::recursive)];SetExpr's did not. This adds the same attribute.Follow-up to the review on #2621 (#2621 (review)):
Tests:
long_set_operation_chain_display_does_not_stack_overflowparses a 25,000-branchUNION ALLchain and prints it on a thread with a 256 KiB stack, so the check does not depend on the platform's default test-thread stack. With the attribute removed, the test binary aborts with a stack overflow (STATUS_STACK_OVERFLOWon Windows); with it, the test passes. The parsed chain is torn down iteratively, because its recursive drop glue would overflow that small stack too — drop is the separate, pre-existing concern noted in the review.Dialects: none