( Replying to http://forum.dlang.org/post/54FB47B8.5060204@dawg.eu - sorry, can't post to the ML right now )

> First step towards self-hosting DDMD compiler.
> Please update your builds scripts and setups.
> https://github.com/D-Programming-Language/dmd/pull/3970

Congratulations are in order.

I have a question from Digger's perspective:

Which version of DMD will be required to build DDMD?

Will DDMD code be constrained to the feature set of DMD 2.067?

Will future DMD versions promise to never break any DDMD code from any point in time?

I certainly hope we aren't going to need a long daisy chain of DMD versions in order to build DMD completely from source...

"Vladimir Panteleev"  wrote in message news:berkxxqbqoxzitsulufd@forum.dlang.org...

> Congratulations are in order.
>
> I have a question from Digger's perspective:
>
> Which version of DMD will be required to build DDMD?

For now, 2.067.

> Will DDMD code be constrained to the feature set of DMD 2.067?

For now, yes.  If any critical issues come up between now and the eventual switch we'll have to bump it.

> Will future DMD versions promise to never break any DDMD code from any point in time?

I don't think that would be practical.

> I certainly hope we aren't going to need a long daisy chain of DMD versions in order to build DMD completely from source...

I would prefer long periods between host compiler version bumps, but is building completely from source really a concern? 

On Sunday, 8 March 2015 at 15:18:25 UTC, Daniel Murphy wrote:
>> I certainly hope we aren't going to need a long daisy chain of DMD versions in order to build DMD completely from source...
>
> I would prefer long periods between host compiler version bumps, but is building completely from source really a concern?

I don't think it would be, especially since building the successive stages can be trivially automated using a script if one is so inclined.

 — David

On 3/8/2015 7:49 AM, Vladimir Panteleev wrote:
> Congratulations are in order.

Yes.

> I have a question from Digger's perspective:
>
> Which version of DMD will be required to build DDMD?
>
> Will DDMD code be constrained to the feature set of DMD 2.067?
>
> Will future DMD versions promise to never break any DDMD code from any point in
> time?
>
> I certainly hope we aren't going to need a long daisy chain of DMD versions in
> order to build DMD completely from source...

Hmm. That does leave us with the problem of bootstrapping it on a new platform. That would suggest constraining it to be compilable with 2.067.

On 3/8/2015 9:00 AM, David Nadlinger wrote:
> On Sunday, 8 March 2015 at 15:18:25 UTC, Daniel Murphy wrote:
>>> I certainly hope we aren't going to need a long daisy chain of DMD versions
>>> in order to build DMD completely from source...
>>
>> I would prefer long periods between host compiler version bumps, but is
>> building completely from source really a concern?
>
> I don't think it would be, especially since building the successive stages can
> be trivially automated using a script if one is so inclined.

Trivial in theory, but we all know how fragile that can be in practice.

On Sunday, 8 March 2015 at 15:18:25 UTC, Daniel Murphy wrote:
> I would prefer long periods between host compiler version bumps, but is building completely from source really a concern?

From a release building standpoint a new release must be buildable with the last release. I'd even opt for two release versions to prevent the use of bleeding edge features.

On Sunday, 8 March 2015 at 19:58:52 UTC, Walter Bright wrote:
> On 3/8/2015 7:49 AM, Vladimir Panteleev wrote:
>> Congratulations are in order.
>
> Yes.
>
>> I have a question from Digger's perspective:
>>
>> Which version of DMD will be required to build DDMD?
>>
>> Will DDMD code be constrained to the feature set of DMD 2.067?
>>
>> Will future DMD versions promise to never break any DDMD code from any point in
>> time?
>>
>> I certainly hope we aren't going to need a long daisy chain of DMD versions in
>> order to build DMD completely from source...
>
> Hmm. That does leave us with the problem of bootstrapping it on a new platform. That would suggest constraining it to be compilable with 2.067.

Also: https://issues.dlang.org/show_bug.cgi?id=14255

On Sunday, 8 March 2015 at 19:58:52 UTC, Walter Bright wrote:
> Hmm. That does leave us with the problem of bootstrapping it on a new platform. That would suggest constraining it to be compilable with 2.067.

Once you fix DMD so that it can cross-compile (or use GDC/LDC), this is no longer an issue. Well, if you do not have a C toolchain for cross-compilation on your system, linking would be a bit tricky, but it would still be doable.

It might be a mild inconvenience, but certainly not an insurmountable problem.

 — David

"David Nadlinger"  wrote in message news:ghztksvvlcgmaoycaxcz@forum.dlang.org...

> Once you fix DMD so that it can cross-compile (or use GDC/LDC), this is no longer an issue. Well, if you do not have a C toolchain for cross-compilation on your system, linking would be a bit tricky, but it would still be doable.
>
> It might be a mild inconvenience, but certainly not an insurmountable problem.

I agree, cross-compiling is the way forward. 

"Walter Bright"  wrote in message news:mdi9ls$o10$1@digitalmars.com...

> Hmm. That does leave us with the problem of bootstrapping it on a new platform. That would suggest constraining it to be compilable with 2.067.

If it's a new platform, why would 2.067 be able to target it?