Add -wnan switch to flag default NaN initializations

[claptrap]

On Friday, 21 August 2026 at 06:26:36 UTC, Walter Bright wrote:
> https://github.com/dlang/dmd/pull/23663

I know i've been arguing that zero init is not as much of an 
issue as people think, but Im also aware that it'll never change, 
too much hassle for little (very subjective) benefit for only 
some people.

So this is a pretty good solution.