checkedint call removal

[Andrew Godfrey via Digitalmars-d]

Suppose I call some logging function which has a faulty assertion 
in it. What about Walter's position prevents that assertion's 
effects from escaping the logging function and infecting my code? 
I know cross-module optimization is hard hence this may be 
unlikely, but still it shows something missing.

I know Walter has said repeatedly that at this point the program 
is invalid, Implying that it deserves whatever happens to it. I 
suspect this is a subtopic we should be discussing more directly. 
What are the boundaries?