Re: cost of -MP

[Noel Yap]

Boris Kolpackov wrote:

> Noel Yap <address@hidden> writes:
>
> > IOW, things dependent upon a .PHONY will be rebuilt regardless of the 
> > dependency's timestamp.  Empty targets are treated differently.
>
> I was referring to the case when target does not exist (as a file) and 
> there is not command to build it. In this case make treats it exactly 
> as if it was PHONY.

OK, but then, if you're following the newer way of generating dependency files, the dependency file will get regenerated right after the object file is rebuilt and the no-longer-existing header file would no longer be included in it.  It'll be a one time 
hit, if at all since presumably some other dependency would've changed, that shouldn't affect the build time all that much.

Noel