Fix the size of niche enums with ZST alignment #99959
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For enums with an aligned ZST variant, like `[T; 0]`, the niche layout was not computing a sufficient size to be consistent with alignment. Now we pad that size up to the alignment, and also make sure to only use the niche variant's ABI when the size and alignment still match.
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FWIW, #94075 (cc @mikebenfield) also adds the right |
eddyb
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Jul 30, 2022
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@bors r+ rollup=never Thanks! |
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☀️ Test successful - checks-actions |
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Finished benchmarking commit (a231865): comparison url. Instruction countThis benchmark run did not return any relevant results for this metric. Max RSS (memory usage)This benchmark run did not return any relevant results for this metric. CyclesResults
If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf. @rustbot label: -perf-regression Footnotes |
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For enums with an aligned ZST variant, like
[T; 0], the niche layoutwas not computing a sufficient size to be consistent with alignment. Now
we pad that size up to the alignment, and also make sure to only use the
niche variant's ABI when the size and alignment still match.
Fixes #99836
r? @eddyb