Re: ADA compilers/ difference between 83 and 95

[Marin David Condic <nobody@noplace.com>]

I've ported a LOT of VAX/VMS (DEC) Ada 83 to Gnat Ada95 and never 
encountered anything that was a problem between the two language 
versions. There may be some obscure corner-case rules that trigger 
incompatibilities but in practical use, I just never encountered any. I 
did get some warnings about using the package ASCII and maybe that's as 
close to an incompatability as I've seen.

Mostly, I had some issues where different compiler writers had different 
views of what to implement. A few instances where DEC Ada handled 
unconstrained types differently from Gnat Ada and, of course, some 
vendor specific implementation details once in a while (like packages 
that may or may not be there because they are vendor supplied) but two 
observations: I don't recall anything that got past the compiler that 
ended up being an issue - so the compiler is your friend here. I don't 
recall anything that didn't run just fine when it finally linked. I 
*have* had problems when porting between two *different* platforms - 
mostly with byte-sex issues, but that has been minimal. (Ada 95 has some 
features to help you out making byte-sex issues portable as well, but I 
have not delved into them lately)

Porting even a large body of Ada code (if reasonably well written to be 
portable - no fair throwing in compiler-specific things in every unit & 
expecting zero effort) even across platforms has not been much of an 
issue in my experience. I've done a few hundred thousand lines in a 
couple of days & had it up and running - but it was *my* code so I was 
familiar with it and I have usually had the wisdom to isolate any 
compiler specifics. Even a stranger's code being moved across platforms 
and to a different language standard ought to be minimal fuss.

MDC


Chris Albertson wrote:
> Sorry aout the last message hadno text. Here is is again
> 
> 
> I'm curious, will ada83 programs not compile under ada95?
> 


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