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Subject: Re: Cygwin 3.6: clang cannot use /usr/include/unistd.h, issue with
 |setproctitle_init()| ...
In-Reply-To: <Z8ie5ezqgXKtnmnl@calimero.vinschen.de>
Date: Wed, 5 Mar 2025 20:10:16 +0100
Cc: Corinna Vinschen <corinna-cygwin@cygwin.com>
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From: Dimitry Andric via Cygwin <cygwin@cygwin.com>
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Maybe it's because -Wsystem-headers is not enabled? I'm unsure what gcc's default behavior is with -Wall, but if you add an explicit -Wsystem-headers you might still get that warning.

-Dimitry

> On 5 Mar 2025, at 19:58, Corinna Vinschen via Cygwin <cygwin@cygwin.com> wrote:
> 
> On Mar  5 17:16, Christian Franke via Cygwin wrote:
>> Roland Mainz via Cygwin wrote:
>>> Small issue with Cygwin 3.6 (3.6.0-0.419.g3c1308ed890e.x86_64) system
>>> /usr/include/unistd.h and clang:
>>> ---- snip ----
>>> $ clang --version
>>> clang version 8.0.1 (tags/RELEASE_801/final)
>>> Target: x86_64-unknown-windows-cygnus
>>> Thread model: posix
>>> InstalledDir: /usr/bin
>>> $ clang -std=gnu17 -Wall -Wextra -g foo.c -lntdll -o foo.i686.exe
>>> In file included from foo.c:37:
>>> In file included from /usr/include/unistd.h:4:
>>> /usr/include/sys/unistd.h:218:42: error: parameter name omitted
>>> static inline void setproctitle_init (int, char *[], char *[]) {}
>> 
>> The error is valid because the addition of this very old C++ feature took a
>> very long time :-)
>> 
>> clang 15 says:
>> warning: omitting the parameter name in a function definition is a C2x
>> extension [-Wc2x-extensions]
>> 
>> gcc 12 requires '-pedantic' option:
>> warning: ISO C does not support omitting parameter names in function
>> definitions before C2X [-Wpedantic]
> 
> Weird, I can't reproduce this, neither with gcc 12 nor with gcc 15.
> 
>  $ cat <<EOF >x.c
>  #define _BSD_SOURCE
>  #include <unistd.h>
> 
>  int
>  main (int argc, char **argv, char **envp)
>  {
>    setproctitle_init (argc, argv, envp);
>  }
>  EOF
>  $ gcc -g -O2 -Wall -pedantic -std=c99 x.c -o x
>  $ 
> 
> No warning.  What am I missing?
> 
> We should still fix it.  We could change this to a macro instead:
> 
> -static inline void setproctitle_init (int, char *[], char *[]) {}
> +#define setproctitle_init(c, a, e)
> 
> Would that help?
> 
> 
> Corinna
> 
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