int nan

[Walter Bright]

Michiel Helvensteijn wrote:
> * Add 'uninitialized' to the set of possible states of each type. Every time
> a variable is read, assert that it is initialized first. Use the static
> analysis techniques that *are* available (a set that will continue to grow)
> to eliminate these tests (and the extended state) where possible.

I believe this is what valgrind does by instrumenting each variable at 
runtime.