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Re: g++ and linking

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"james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> writes:

> On Tuesday, February 1, 2022 at 10:18:25 AM UTC-5, Tim Rentsch wrote:
>
>> Richard Damon <Ric...@Damon-Family.org> writes:
>>
>> [...]
>>
>>> The early versions of the standard, while not limiting identifier
>>> length, does limit the 'significant' length for external identifiers,
>>> allowing the implementation to truncate the name of the symbol in the
>>> output to the linker.
>>>
>>> In C99, 6.4.2.1p5 makes that length Implementation Defined.  I would
>>> have to search to see if somewhere there is a guarantee of a minimum
>>> value for this length
>>
>> Section 5.2.4.1 paragraph 1 says
>
> "The implementation shall be able to translate and execute at
> least one program that contains at least one instance of every one
> of the following limits:"
>
>> 63 significant initial characters in an internal identifier
>> or a macro name
>>
>> 31 significant initial characters in an external identifier
>
> Keep in mind that these are NOT minimum permitted values for the
> maximum number of significant characters in an identifier (the
> so-called minimum maximum that I heard a lot about when C90 first
> came out).  Strictly speaking, the only requirement that they
> impose is on the "one program".  It is not a requirement that the
> implementation treat that many characters as significant if they
> occur in any other program

I think you're just wrong about that.  Clearly the intended
reading of section 5.2.4, and how essentially everyone else
reads this section, is that 5.2.4.1 paragraph 1 gives minimum
translation limits, and also requires all conforming
implementations to be able to translate *and execute* a program
that has at least one instance of each of the minimums.
Conversely, any programming language standard that does not
give a requirement for minimum supported identifier length
would be grossly negligent.  So it would be quite astonishing
to interpret 5.2.4.1 paragraph 1 as giving minimums that
apply to just the one program rather than stating minimum
requirements that apply to the implementation generally.

>> By the way I think you mean requirement rather than guarantee.
>
> A requirement that must be met by an implementation of a language in
> order to qualify as conforming to a given standard also serves as a
> guarantee that anything that does qualify as conforming
> implementation of that language meets that requirement.

It is not a guarantee in the usual sense of the word guarantee.
And even if it were, it's a pointless observation.

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g++ and linking Joseph Hesse <joeh@gmail.com> - 2022-01-22 06:32 +0200
  Re: g++ and linking "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-01-22 09:39 +0100
    Re: g++ and linking Richard Damon <Richard@Damon-Family.org> - 2022-01-22 06:30 -0500
      Re: g++ and linking David Brown <david.brown@hesbynett.no> - 2022-01-22 12:53 +0100
      Re: g++ and linking Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-22 16:45 +0100
        Re: g++ and linking Richard Damon <Richard@Damon-Family.org> - 2022-01-22 11:13 -0500
          Re: g++ and linking Bonita Montero <Bonita.Montero@gmail.com> - 2022-01-22 19:00 +0100
      Re: g++ and linking Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-02-01 07:17 -0800
        Re: g++ and linking "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-02-01 08:19 -0800
          Re: g++ and linking Tim Rentsch <tr.17687@z991.linuxsc.com> - 2022-04-25 07:19 -0700
            Re: g++ and linking "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2022-04-25 09:06 -0700
  Re: g++ and linking Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-01-22 10:24 -0800

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