What's the deal with "Warning: explicit element-wise assignment..."

[John Colvin via Digitalmars-d]

On Tuesday, 29 April 2014 at 18:09:00 UTC, bearophile wrote:
> In Phobos there are awkward names like walkLength

walkLength is a really good name. Clear, concise, to the point. 
It's not often that you can make such a short name that explains 
the behaviour so well.