Go shift count too large

Question

In Go's constant specification, it is mentioned that:

Numeric constants represent exact values of arbitrary precision and do not overflow.

So I tried

const VeryVeryBigNumber = 1 << 200

and it works. However, the biggest shift count I could try is 511 and using 512 will throw:

shift count too large: 512.

What does 512 represents? I have no intention to use it, I just want to know why is it limited to 511 in my machine (I'm using ubuntu 64 bit and go 1.9.2)?

Thanks

Answer 1

512 is kind of an arbitrary limit. The only thing the spec says is:

Implementation restriction: Although numeric constants have arbitrary precision in the language, a compiler may implement them using an internal representation with limited precision. That said, every implementation must:

Represent integer constants with at least 256 bits.

Unfortunately, the comments around the limits don't give a reason.

At some point, a limit has to be used. I would recommend sticking to the required 256.