D needs to publicize its speed of compilation

[Walter Bright]

On 12/28/2017 5:22 AM, Atila Neves wrote:
> On Thursday, 28 December 2017 at 07:21:28 UTC, Walter Bright wrote:
>> On 12/27/2017 1:23 PM, Atila Neves wrote:
>>> However, my experience has been that D has fast builds from scratch, but is 
>>> really really slow for incremental builds.
>> You can do fast incremental builds with D by not putting all the files on the 
>> command line. Just put one.
> 
> I don't build the compiler command-line myself, nor do I want to. Even then, 
> recompiling one file isn't useful to me, what is is to recompile what's needed 
> and run the tests. Emacs/flycheck already highlights compilation errors in just 
> one file.

I don't understand. C++ compiles files one at a time. You can do the same in D. 
How can this model be useful in C++ but not with D?