[lwip-devel] [bug #26273] etharp.c : fix alignment issue in etharp_raw

[Simon Goldschmidt]

Follow-up Comment #7, bug #26273 (project lwip):

> The compiler assumes all pointers to structs are properly aligned.

If the struct is inside another *packed* struct, the compiler should not
assume proper alignment but cope with any alignment!

> I disagree that what you're seeing is a compiler bug.

Your example is the other way round: the code in question does not cast from
2-byte-aligned to 4-byte-aligned but from 4-byte-aligned to 2-byte-aligned. In
your example this would be:

u32_t buffer[10];
u8_t *ptr, i;

ptr = (u8_t *) &buffer[1];
i = *ptr;

Any compiler should doe that porperly! (Only our code in question is using
structs, not u8/u32_t, but I don't see why that should make a difference)

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