Only mark unaligned types in buffers #505
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cc @aldanor |
aldanor
reviewed
Nov 21, 2016
| @@ -727,7 +728,9 @@ inline PYBIND11_NOINLINE void register_structured_dtype( | |||
| if (field.offset > offset) | |||
| oss << (field.offset - offset) << 'x'; | |||
| // note that '=' is required to cover the case of unaligned fields | |||
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Minor, but maybe this comment line should be updated to reflect what's happening below
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This looks ok, I guess, and doesn't seem to break anything (I don't see much value since comparing format strings directly is a bad idea, but it doesn't harm to have aligned fields mark as aligned). |
dean0x7d
reviewed
Nov 21, 2016
| @@ -787,6 +790,7 @@ struct npy_format_descriptor<T, enable_if_t<is_pod_struct<T>::value>> { | |||
| #define PYBIND11_FIELD_DESCRIPTOR_EX(T, Field, Name) \ | |||
| ::pybind11::detail::field_descriptor { \ | |||
| Name, offsetof(T, Field), sizeof(decltype(std::declval<T>().Field)), \ | |||
| std::alignment_of<decltype(std::declval<T>().Field)>::value, \ | |||
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Any reason not to use the alignof keyword? (AFAIK the template version only exists for historical reasons.)
Minor formatting note: see the position of the continuation \ in comparison to the lines above and below.
Previously all types are marked unaligned in buffer format strings, now we test for alignment before adding the '=' marker.
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Previously all types are marked unaligned in buffer format strings, now we test for alignment before adding the '=' marker.
It's not a problem to mark all types as unaligned per-se, it's equivalent because of the explicit padding, but this goes partway to allowing comparison to format strings from other sources, e.g. numpy. It's much easier to test for alignment here rather than parsing the string and trying to work it out. In combination with my other PR #488 , it will be possible to construct a
vector<struct>from a structured array without casting in some cases (namely where the member names are identical and there's no multibyte padding).