Against enforce()

[Kagamin]

Walter Bright Wrote:

> 1. Asserts and contracts are for detecting program BUGS. They are not for 
> validating user input, checking for disk full, file not found errors, etc.
> 
> 2. Enforce is for validating user input, checking for disk full, file not found 
> errors, etc. Enforce is NOT for use in contracts or checking for program bugs.
> 
> 
> Any use of enforce in Phobos that is checking for program bugs is itself a bug 
> and should be entered into bugzilla for fixing.

So this is a bug? This is a contract, not a validation of user input.

struct Iota(N, S) if ((isIntegral!N || isPointer!N) && isIntegral!S)
 {
    private N current, pastLast;
    private S step;
    this(N current, N pastLast, S step)
    {
        enforce((current <= pastLast && step > 0) ||
                (current >= pastLast && step < 0));
        this.current = current;
        this.step = step;