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From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: Recursion, Yo
Date: Thu, 11 Apr 2024 00:54:41 -0000 (UTC)
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On 2024-04-11, Lawrence D'Oliveiro <ldo@nz.invalid> wrote:
> On Wed, 10 Apr 2024 16:46:43 +0200, David Brown wrote:
>
>> Just for your entertainment, with C++ lambdas this is now legal code:
>> 
>> void foo(void) {
>> 	[](){}();
>> }
>
> C programmer still has habit of writing “(void)” when C++ allows “()” 
> instead.

That is backwards. (void) is the dud that C++ "allows"; () is the
"native" empty parameter list in C++, and has been from the early
beginning.

C++ (originally C With Classes) introduced () as a prototyped, declared
parameter list. At that time there was no (void) in C, and therefore not
in C++ either.

In C, the () list, in a declaration, didn't say anything about the
number of parameters.

ANSI C came along and invented (void) in order not to change the meaning
of () for compatibility.

Then C++ adopted (void) for ANSI C compatibility.

I.e. (void) is concession that that C++ "allows", and did not always;
() is the "native" empty parameter list it always had.

It's monumentally stupid when you see (void) on feature that only exists
in C++ and therefore C compatibility is not involved:

  myclass::myclass(void)
  {
     // default constructor
  }

> Does the latest C spec now also take “()” to mean “no args” (synonymous 
> with “(void)”) instead of “unspecified args”?

The N3320 working draft says:

"The special case of an unnamed parameter of type void as the only item
in the list specifies that the function has no parameters."
(6.7.7.4 Function declarators)

"For a function declarator without a parameter type list: the effect is
as if it were declared with a parameter type list consisting of the
keyword void. A function declarator provides a prototype for the
function." (ibid.)

The last sentence assures us that function declartions are now protypes;
there are no function declarators that do not prototype the parameters.

(Apologies to Kenny for the "ibid.")

-- 
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca