GDC2 compilation warnings

[Don]

bearophile wrote:
> - Signed unsigned comparison warning: unless D invents some other very good solution, this warning is a ugly but necessary patch over one hole of the C language that D too has.

This is bug 259, one of the first issues ever reported in bugzilla.
Can you please stop reporting obvious issues as if you were the first 
person who ever noticed them?

Note that the spec has always said that the compiler generates a 
warning. It's just a bug that it doesn't at present.
Note also that range propagation for integer types should fix this in 
the most common cases, so warnings will be much less frequent than in C. 
At present, the implementation of range propagation is very incomplete.