Fix Box allocator drop elaboration #143672
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rustbot
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Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt |
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r? compiler since wesleywiser is off rotation |
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r? compiler |
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r? compiler |
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lmao I should have just taken this PR when I saw it right when it was opened |
oli-obk
reviewed
Jul 16, 2025
| // types with destructors still need an empty drop ladder to clear it | ||
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| // currently no rust types can trigger this path in a context where drop flags exist | ||
| // however, a future box-like "DerefMove" trait would allow it |
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so... should we span_bug! here until such a time?
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New version of #131146.
Clearing Box's drop flag after running its destructor can cause it to skip dropping its allocator, so just don't. Its cleared by the drop ladder code afterwards already.
Unlike the last PR this also handles other types with destructors properly, in the event that we can have open drops on them in the future (by partial initialization or DerefMove or something).
Finally, I also added tests for the interaction with async drop here but I discovered #143658, so one of the tests has a
knownbugannotation. Not sure if it should be in this PR at all though.Fixes #131082
r? wesleywiser - prev. reviewer