Path: csiph.com!eternal-september.org!feeder.eternal-september.org!reader01.eternal-september.org!.POSTED!not-for-mail
From: Keith Thompson <kst-u@mib.org>
Newsgroups: comp.lang.c++
Subject: Re: An example: code to list exports of a Windows DLL.
Date: Tue, 20 Aug 2019 02:18:24 -0700
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David Brown <david.brown@hesbynett.no> writes:
> On 20/08/2019 03:31, Keith Thompson wrote:
>> "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> writes:
>>> On 19.08.2019 21:44, Richard wrote:
>>>> "Alf P. Steinbach" <alf.p.steinbach+usenet@gmail.com> spake the secret code
>>>> <qi042o$if8$1@dont-email.me> thusly:
>>>>
>>>>> The $ things in the following code are macros from the specified
>>>>> header-only library on GitHub.
>>>>
>>>> Can you tell me where in the standard it allows for $ to be part of an
>>>> identifier?
>>>>
>>>> I'm looking at 5.10 in N4659 (Draft C++17) and don't see it.
>>>
>>> In the future you might risk that people think you're a total novice,
>>> one who doesn't even know the basics of identifiers in C++.
>> 
>> Then I'll risk the same thing.  Can you explain where C++17 permits $
>> in identifiers (or where it permits compilers to permit it)?
>
> It doesn't.
>
>> I believe that both foo$bar and foo\u0024bar violate a diagnosable rule
>> and therefore require a diagnostic from any conforming compiler (which
>> implies that gcc is non-conforming).
>
> You get the warning with "-Wpedantic" and an appropriate "-std" C++ 
> standard (and perhaps an appropriate version of gcc).

Can you demonstrate that?  I haven't been able to do so, with several
versions of g++ (up to and including a bleeding-edge version I built
from source a week and a half ago).  Here's the test case I used:

#include <iostream>
int main() {
    const int foo$bar = 42;
    std::cout << foo$bar << "\n";
}

compiled with "g++ -Wpedantic -std=c++17".  No warning from any version
I have on my system.

>> Or perhaps I'm missing something (always a real possibility).
>
> What you are missing is that $ is accepted in identifiers in many 
> compilers, and Alf simply does not care that it is not supported in the 
> standards as long as it is supported in the compilers he uses.

Please don't assume that I missed it just because I didn't discuss it.

My post was about whether the C++ standard permits compilers to
permit $ in identifiers.  (I presume we can all agree that compilers
aren't *required* to accept $ in identifiers.)  C++11 clearly does
permit it, since it explicitly allows "other implementation-defined
characters" in identifiers.  C++17 apparently does not, since it
dropped that wording (apparently in the belief that it was redundant,
but I don't believe it was).

[...]

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
Will write code for food.
void Void(void) { Void(); } /* The recursive call of the void */