[Info-vax] The future of Ada on VMS

[Ian Miller]

On Monday, May 21, 2018 at 11:13:07 PM UTC+1, johnwa... at yahoo.co.uk wrote:
> On Monday, 21 May 2018 21:06:50 UTC+1, Simon Clubley  wrote:
> > On 2018-05-21, Arne Vajhøj <arne at vajhoej.dk> wrote:
> > > On 5/21/2018 1:38 PM, Dave Froble wrote:
> > >> But once again, you're predicting without any idea of what might happen. 
> > >>   You say there will not be an Ada compiler.  How do you know that? 
> > >> Perhaps there is not one now, or any announced plans for one.  But VSI 
> > >> will look at what their customers are asking for, and if there is demand 
> > >> and good business sense to do so, do you doubt John's ability to produce 
> > >> a new up to date Ada compiler?
> > >
> > > Ada is a bit more uncertain.
> > >
> > 
> > Try a lot more uncertain (unfortunately).
> > 
> > > My understanding is that VSI has not talked about migrating
> > > the extremely old DEC Ada 83 but has talked about getting ACT
> > > to port their modern Ada. But ACT has dropped VMS as a platform,
> > >
> > 
> > This is my understanding as well.
> > 
> > When DEC/CPQ/HP management decided to go with an external vendor
> > for Ada instead of building an Ada 95 compiler in-house, that was
> > when they lost control of the long term Ada ecosystem and became
> > dependent on that external vendor's plans.
> > 
> > > I do not doubt that John could create an Ada compiler, but
> > > every indication is that he will be working on other stuff.
> > >
> > 
> > Creating an Ada compiler from scratch is a massive job. A number
> > of people (who know way more about what is involved than I do)
> > have looked at this possibility in various forms and have come
> > to the same conclusion.
> > 
> > > So it will be VSI management talking to ACT management.
> > >
> > > Or talk to the great guys that made GNAT work on VMS I64
> > > about an x86-64 version. See post some time ago!
> > >
> > 
> > That's not really a meaningful comparison unfortunately.
> > 
> > The code for Itanium already existed in the code base he used and
> > it was mostly a matter of learning how to use an existing GNAT Pro
> > compiler for Alpha VMS to build an Itanium compiler.
> > 
> > All the necessary bits for x86-64 on VMS would need to be added
> > to the code base before such an attempt could be made for x86-64.
> > 
> > This would mean however that VSI would be maintaining GCC for
> > Ada only and maintaining LLVM for all the other compilers.
> > 
> > > If I were dependent on Ada on VMS, then I would also be
> > > a bit concerned.
> > >
> > 
> > Very much agreed.
> > 
> > Simon.
> > 
> > -- 
> > Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
> > Microsoft: Bringing you 1980s technology to a 21st century world
> 
> When you refer to "Ada on VMS", what (exactly) do you mean?
> 
> There are at least two possibilities (actually more, when the
> various Ada specifications are considered, and other stuff too):
> 
> 1) Ada compilation system (it's not just a compiler) running on VMS?
> 2) Ada runtime environment running on VMS?
> 
> Quite a few folks/organisations that use Ada don't necessarily
> have the same host environment as runtime environment. ACT are
> reasonably familiar with this arrangement; it's the traditional
> host/target environment which embedded systems folks have used
> for years, with varying degrees of success.
> 
> It's also similar to the approach used by VAXELN Ada (VAX as 
> host and target, but VMS on host vs VAXELN on target).
> 
> And it's also similar to the approach used by XD Ada, or
> whatever it's currently called, which was a derivative
> of DEC Ada with VMS (on VAX, Alpha, or IA64) as host, 
> and with M68K family as the runtime instruction set.
> 
> Those words of mine are probably not clear, and certainly 
> not complete, so here's a chunk of Wikipedia's words on 
> cross compilers:
> 
> "A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a Windows 7 PC but generates code that runs on Android smartphone is a cross compiler.
> 
> A cross compiler is necessary to compile code for multiple platforms from one development host. Direct compilation on the target platform might be infeasible, for example on a microcontroller of an embedded system, because those systems contain no operating system." 
> from
> https://en.wikipedia.org/wiki/Cross_compiler
> 
> gcc is quite complicated (not necessarily in a good way), 
> and anyone who has to build their own gcc toolchain has 
> interesting times ahead of them, especially if they want 
> the compilation system to run on something other than 
> Linux. 
> 
> Which leads to the "Canadian cross compiler" concept. E.g. 
> a compiler toolchain built on Linux-x86 host, intended 
> for use on a Windows/AMD64 host, and intended to generate 
> code to run on (say) an ARM/Android target system. The 
> Wikipedia article mentioned above has more words on the 
> subject, for anyone who's interested.
> 
> An Ada-compiler discussion talking about (e.g.) safety 
> critical systems and compilation environments which doesn't 
> clarify which options apply in the bigger picture is 
> inevitably going to have lots of assumptions and mbiguities.
> 
> A possibly more important (but potentially less visible) 
> discussion is how much money might be available to make 
> some or all of these things happen.

XD ADA still exists on OpenVMS VAX/Alpha/I64, as does CORAL66 

See https://www.dxc.technology/manufacturing/offerings/140408/142256-software_engineering_products_swep