dmd build instructions from source don't work anymore

[Laeeth Isharc via Digitalmars-d]

On Tuesday, 12 May 2015 at 17:41:16 UTC, Andrei Alexandrescu 
wrote:
> On 5/12/15 10:32 AM, Laeeth Isharc wrote:
>> But either I am mistaken, or in future years you shall still 
>> face a
>> choice between manually hacking up Phobos and DMD so they 
>> compile under
>> this last C++-based dmd (a gulf which will widen increasingly) 
>> or you
>> need to iteratively build compilers to cross the 
>> multiple-version
>> bridges where changes to the source of dmd+phobos mean that 
>> they no
>> longer compile with the last but one version.
>
> Yah, that's a classic. Usually multi-stage bootstrapping is 
> used. One simpler way to accelerate that is to just download 
> the last version's binaries (which is what 
> https://github.com/D-Programming-Language/dmd/pull/4645 does). 
> -- Andrei

I guess that is fine if the binaries exist for the new platform.  
Otherwise it should be just a screenful of code to iterate 
through the chain of versions required, calling the build process 
each time - either update_sh or perhaps it could be added to 
Cybershadow's tool.