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Article · Through the layers
Rust Enum Niches: How Option<T> Can Cost No Extra Byte
Measured Rust enum layouts showing how invalid payload values encode Option discriminants, which optimizations are guaranteed, and what repr changes.
Posts tagged "memory layout"
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Investigation · Part 6 of 10 · Types under the hood
Where a Type Becomes a Layout: Fields, Padding, and Reordering
The same three fields take 8 bytes in Rust and 12 in C, because rustc reorders them and C does not. I measured both, plus repr(C) and repr(packed), and this is the one place where a type leaves a physical trace the processor can touch.