dmd build instructions from source don't work anymore

[Laeeth Isharc via Digitalmars-d]

On Tuesday, 12 May 2015 at 03:35:34 UTC, Daniel Murphy wrote:
>
>> "Timothee Cour via Digitalmars-d" 
>> <digitalmars-d at puremagic.com> wrote in message > 
>> news:mailman.875.1431359641.4581.digitalmars-d at puremagic.com...
>> note, that this seems to be only happening on master:
>> if I checkout another tag (git checkout v2.067.1-b1 or any 
>> other I've tried) it builds fine.
>> So it must be a very recent regression
>
> It's not a regression.  Shortly after 2.067 was released, dmd 
> got the new requirement of a host D compiler to build.  You can 
> explicitly set which compiler to use by setting the HOST_DC 
> environment variable.  If you also want to build ddmd, then 
> 2.067 is recommended as it is known to work on all autotester 
> platforms.  In posix.mak HOST_DC defaults to 'dmd' which will 
> correctly pick up a dmd installation in path, as long as you 
> don't have a sc.ini file in the dmd src dir.

I wonder what the long term plan for porting to new platforms 
will be.

Currently you compile dmd 2.066 (or whatever the tag of breakage 
was) which is pure C++ so you have an outdated DMD binary, which 
you can then use to compile the latest dmd and phobos.

But as time passes - and when I tried it seemed we are already 
there - phobos and DMD may no longer be compileable using earlier 
versions of Dmd.  So you need to repeatedly bootstrap over 
breaking changes in the source (eg using dip25) until you have 
caught up.  Unless you hack up the source by hand.

Is this correct, or am I missing something ?  If accurate, maybe 
it is worth automating the process...