Cryptol doesn't emit `Unused name` warnings when it should

[RyanGlScott]

If you load the following example:

f : [8]
f = 0x00
  where
    fInit = 0x01

g : [8]
g = 0x00
  where
    gInit = 0x01
    xs = [gInit] # [x | x <- xs]

You will see the following warning:

$ cabal -v0 run exe:cryptol -- -c ":load Bug.cry"
Loading module Cryptol
Loading module Cryptol
Loading module Main
[warning] at /Users/rscott/Documents/Hacking/Haskell/cryptol/Bug.cry:4:5--4:10
    Unused name: fInit

You will see a warning that fInit is unused, which is correct---fInit is indeed not used anywhere in the body of f. On the other hand, Cryptol does not emit any warnings for gInit or xs, despite neither of them being used in the body of g. I find this behavior surprising.

[sauclovian-g]

I don't find it surprising (gInit is used by xs and xs is used by ginit; it takes a more sophisticated check than the obvious to detect that the cycle is itself unused) but I do agree it ought to be fixed...