How to type cast fixed size byte arrays in solc 0.5.x?

Question

In solc 0.4.28 I was able to do:

uint foo = 42;
bytes28 bar = bytes28(foo);

but in 0.5.9 I'm getting the error:

TypeError: Explicit type conversion not allowed from "uint256" to "bytes28".
        bytes28 bar = bytes28(foo);

Answer 1

I figured it out... You have to cast the uint to the same length so in this case it would be:

bytes28 bar = bytes28(uint224(foo));

If it were bytes16 it would be:

bytes16 bar = bytes28(uint128(foo));

bytes vs bits:
28 / 32 == 224 / 256
16 / 32 == 128 / 256