Test interaction of unions with non-zero/niche-filling optimization #60590
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Notably this nails down part of the behavior that MaybeUninit assumes, e.g. that a Option<MaybeUninit<&u8>> does not take advantage of non-zero optimization, and thus is a safe construct.
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Added explanation, as well as a test of a non-non-zero/niche-filled enum in a union. |
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@bors r+ rollup |
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@bors r=nikomatsakis,Centril rollup |
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…r=nikomatsakis,Centril Test interaction of unions with non-zero/niche-filling optimization Notably this nails down part of the behavior that MaybeUninit assumes, e.g. that a Option<MaybeUninit<&u8>> does not take advantage of non-zero optimization, and thus is a safe construct. It also verifies the status quo: that even unions that could theoretically take advantage of niches don't. (relevant: rust-lang#36394)
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Rollup of 6 pull requests Successful merges: - #60590 (Test interaction of unions with non-zero/niche-filling optimization) - #60745 (Perform constant propagation into terminators) - #60895 (Enable thumbv7a-pc-windows-msvc target build end to end in rust/master) - #60908 (Fix lints handling in rustdoc) - #60960 (Stop using gensyms in HIR lowering) - #60962 (Fix data types indication) Failed merges: r? @ghost
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Notably this nails down part of the behavior that MaybeUninit assumes, e.g. that a Option<MaybeUninit<&u8>> does not take advantage of non-zero optimization, and thus is a safe construct.
It also verifies the status quo: that even unions that could theoretically take advantage of niches don't. (relevant: #36394)