[issue39689] struct and memoryview tests rely on undefined behavior (as revealed by clang 9)

[Stefan Krah]

Stefan Krah <stefan at bytereef.org> added the comment:

Concerning memoryview, I've looked at this very briefly: memoryview
does not pack values directly, it casts first, which is legal:


#define PACK_SINGLE(ptr, src, type) \
    do {                                     \
        type x;                              \
        x = (type)src;                       \
        memcpy(ptr, (char *)&x, sizeof x);   \
    } while (0)


This macro has exposed compiler bugs before.

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nosy: +skrah

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<https://bugs.python.org/issue39689>
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