I was hoping to use const GIGABYTE: u64 = 1073741824; to make matching on a file size a little more readable.

I was surprised to see that I can match with a constant, but I can't match on e.g. GIGABYTE+1 or 2*GIGABYTE, which gives syntax errors (with or without parentheses -- thought it may be an order of operations issue).

I was even more surprised to see that I can't work around by calculating a value and using that for the range (let two_gigs = 2*GIGABYTE).

Is the best way to go about this just defining additional consts?

Is there a better strategy for naming interesting constants that you want to use in match patterns?

You could also just have the second one be 0..=TWO_GIGS, since they run in order, if you prefer. (But I generally support the "make them distinct" instinct.)