Re: Ada standard and maximum line lengths

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 13-01-29 19:51 , Georg Bauhaus wrote:
> On 29.01.13 17:58, Niklas Holsti wrote:
>> On 13-01-29 17:29 , Georg Bauhaus wrote:
>>> On 29.01.13 13:31, Niklas Holsti wrote:
>>>> Even for hypothetical SW of some sort that generates Ada source code
>>>> automatically, I think it very unlikely that it would generate
>>>> identifiers of that length, since Ada identifiers can be qualified and
>>>> sorted into packages etc. much more flexibly than is the case for linker
>>>> symbols.
>>>
>>> GNAT writes similar identifiers into object files, and
>>> the same hysterical raisins spoil the cake. At least the
>>> names---those to be exported to other compilers---seem shorter
>>> if package hierarchies are not used extensively.
>>
>> So what? These are *linker symbols*, not Ada (source) identifiers. I
>> don't understand why you bring them into a discussion of source-code
>> identifier lengths.
> 
> Linker symbols reappear in source text.

Show an example, please, where it is necessary to write a linker symbol
verbatim as an Ada identifier.

> So, linker symbols are two-sided creatures: on the one side, they
> are intended for use by linkers; on the other side, they reappear
> in source text, even when "just in a pragma" or some such.

If they are written in a pragma as a string, they are not Ada
identifiers, and the ARM limit on identifier length does not apply.

> By the response above, I need to accept long identifiers in
> practice; it is a fact that compilers support the reality
> of excessively long identifiers and so these reappear in source
> text,

Not as identifiers. As strings, occasionally.

>    valid standard C++ program     valid standard Ada program
>               |                             |
>                               _
>                               |  (non-standard pragmas)
>                               _
>                  /                       \
>             compilers A+B            compilers C+E
>                  |                       |
>                 OK                      NOK
> 
> The same valid programs, translated on the same platform, can
> be rejected because the program needs to imports the long,
> non-standard, non-portable names.

Sure, using link-name pragmas is unportable, since different compilers
mangle identifiers into symbols in different ways.

Sure, this is a poor mess and should be improved.

But it has nothing to do with limits on identifier length in Ada.

> Going back to my initial question. Suppose linker symbols
> were structured. Won't the rather technical need for allowing
> long identifiers in Ada source text just vanish?

There has never been, and is not now, such a need.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .