Fix pointer provenance in const serialize with zero sized type enum variants #3532
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ealmloff
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ealmloff
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jkelleyrtp
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Jan 10, 2025
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The new edition of rust includes extra checks for pointer providence that caught a bug in const serialize. When serializing an enum with zero sized type variants that still have an alignment of one, const serialize adds the alignment to the pointer before discarding the pointer. This PR fixes the issue by using
wrapping_byte_addinstead which allows the pointer to temporarily point to invalid memory as long as it is never read.Note while the new release of miri catches this bug, I haven't seen it anywhere in production and if it were to appear it would likely be caught at compile time because const serialize is used in const code