Fix query cycle in needs drop code. #92804
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In a previous PR, an optimization was introduced in the needs drop code to ensure that we recurse through the query system, thereby improving caching and not duplicting work. However, this optimization did not correctly check for possible cycles in doing this. This change introduces that check.
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Thanks for the PR, @JakobDegen! Looks good to me from a query system POV -- but I don't know too much about needs_drop. Since @cjgillot assigned themselves to this PR too, I'll let them take another look. |
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I was interested in the query system POV too. I'm not familiar enough with this code to understand how this patch avoids the query cycle, and how it articulates with the check in r? @Mark-Simulacrum since you reviewed #90845 |
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This fix does not cover all the cases, I've started a zulip thread |
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Closing in favor of #93449 . |
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Closes #92725 .
In #90845, an optimization was introduced in the needs drop code to ensure that we recurse through the query system, thereby improving caching and not duplicating work. However, this optimization did not correctly check for possible cycles in doing this. This change introduces that check.
(the diff looks much bigger than it actually is thanks to indentation)