std::mem::size_of::<type> is non-const

[lu-zero]

It is sort of surprising and makes a little harder to generate code using macros like:

macro_rules! read_buf {
    ($ty: ty) => ({
        let mut buf = [0; std::mem::size_of::<$ty>()];

     ....

[huonw]

This is a dupe of rust-lang/rfcs#1144. Unfortunately, the feature has some (possibly) surprising subtleties that make it trickier than one might hope.

Thanks for filing!