Re: Baby X is bor nagain

On 30/06/2024 11:18, Michael S wrote:

On Sat, 29 Jun 2024 20:55:54 +0100
bart <bc@freeuk.com> wrote:
 

On 29/06/2024 18:46, Richard Harnden wrote:

On 29/06/2024 15:14, bart wrote:
[...]

My older bcc compiler reported 4 as a hard error unless an
override was used.

>
But you didn't say anything about main's args.

>
I did, indirectly. The actual error was the use of "()" as an empty
parameter list (for any function, not just main, but my example could
also have been 'void H(){H(123);}'). If you tried to compile:
>
     int main() {
         main(123);
     }
>
then it wouldn't get past the () to the call.
>
Eventually I dropped that restriction, and the reason was that so
much code used such parameter lists, for any function.
>
Not because they wanted unchecked args (there are some legitimate
use-cases within function pointer types), but because so many people
assumed () meant zero parameters like (void).
>
Why was such code so common? Presumably because compilers said
nothing; and they couldn't because the language allowed it. If they
had required an override like mine did, more would have got the
message.
>

 I tried following code:
int foo() { return 1; }
 Both MSVC and clang warn about it at high warnings level (-Wall for
MSVC, -Wpedantic for clang). But they dont warn at levels that most
people use in practice (-W3 or -W4 for MSVC, -Wall for clang).
gcc13 produces no warning even at -Wpedantic. It does produce warning
with '-Wpedantic -std=xxx' for all values of xxx except c23 and gnu23.
The absence of warning for c23/gnu23 makes sense, the rest of gcc
behavior - less so.
 

gcc -Wpedantic makes very little sense without specifying a C standard (rather than a gnu C standard).
But why would you expect a warning from code that is perfectly legal and well-defined C code, without explicitly enabling warnings that check for particular style issues?  Non-prototype function declarations are deprecated (since C99), but not removed from the language until C23 (where that declaration is now a function prototype).