Macro const_assert_mem_size 

macro_rules! const_assert_mem_size {
    ($type:ty, $size:expr $(,)?) => { ... };
}

Assert at compile time that a type has a specific in-memory size in bytes.

The assertion is only effective on 64-bit archs since we don’t care about 32-bit Android ARM (the only 32-bit arch we compile to, and making the assertion more complicated just for that is not worth it).

Usage: const_assert_mem_size!(u64, 8);