a2318651d4
Fix the size of niche enums with ZST alignment 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. Fixes #99836 r? `@eddyb`
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