[derive] Support IntoBytes on homogeneous generic structs#3488
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joshlf
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| let is_transparent = repr.is_transparent(); | ||
| let is_c = repr.is_c(); | ||
| let is_unmodified_c = is_c && repr.get_align().is_none() && repr.get_packed().is_none(); |
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Why are you checking for the absence of packed, which can only reduce the presence of padding?
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Just being conservative, but you've convinced me to just go all the way. Fixed.
Support deriving `IntoBytes` on unmodified `repr(C)` structs whose fields are all `T`, `[T; N]`, or a final `[T]` for the same generic type parameter `T`. All such fields have the same alignment, and each field's size is a multiple of that alignment. Thus, `repr(C)` introduces neither inter-field nor trailing padding. Use an `Identity<Type = T>` bound to have rustc verify that each field's element type actually resolves to `T`. This guards against macro-generated identifiers which compare equal in the derive but have different hygiene contexts. gherrit-pr-id: Gsxxjwwhqbpepd5p73rd6libcy7n44svt
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Support deriving
IntoByteson unmodifiedrepr(C)structs whosefields are all
T,[T; N], or a final[T]for the same generic typeparameter
T.All such fields have the same alignment, and each field's size is a
multiple of that alignment. Thus,
repr(C)introduces neitherinter-field nor trailing padding.
Use an
Identity<Type = T>bound to have rustc verify that each field'selement type actually resolves to
T. This guards againstmacro-generated identifiers which compare equal in the derive but have
different hygiene contexts.
IntoByteson homogeneous generic structs #3488Latest Update: v4 — Compare vs v3
📚 Full Patch History
Links show the diff between the row version and the column version.
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git fetch origin refs/heads/Gsxxjwwhqbpepd5p73rd6libcy7n44svt && git checkout -b pr-Gsxxjwwhqbpepd5p73rd6libcy7n44svt FETCH_HEADCheckout
git fetch origin refs/heads/Gsxxjwwhqbpepd5p73rd6libcy7n44svt && git checkout FETCH_HEADCherry Pick
git fetch origin refs/heads/Gsxxjwwhqbpepd5p73rd6libcy7n44svt && git cherry-pick FETCH_HEADPull
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