scanf can call procs with side-effects multiple times

[zacharycarter]

Two examples

1. Will output "Someone called me!" twice

import strscans

proc test(): string = 
  echo "Someone called me!"
  result = ",123123"

var a: int
discard scanf(test(), ",$i", a)

and -

https://gist.github.com/anonymous/a8de94b5468e22788f5c966f09218726#file-playground-nim-L43-L48

and

https://gist.github.com/zacharycarter/54d176226f7be1c6cf96f41daf38803d

If you run this example using the configuration file linked, you'll notice that the call to scanf actually generates code which steps the config parser.

This should probably not happen.