How to test for gnu extensions

[Alexander Neundorf]

On Thursday 09 February 2006 21:25, David Faure wrote:
...
> I tried porting the check from acinclude.m4.in to define _GNU_SOURCE, which
> gives something like:
>
> --- ConfigureChecks.cmake       (revision 507577)
> +++ ConfigureChecks.cmake       (working copy)
> @@ -5,6 +5,7 @@ include(CheckFunctionExists)
>  include(CheckLibraryExists)
>  include(CheckPrototypeExists)
>  include(CheckTypeSize)
> +include(CheckCSourceCompiles)
>
>  #check for libz using the cmake supplied FindZLIB.cmake
>  if(ZLIB_FOUND)
> @@ -148,6 +149,13 @@ check_include_files( "X11/Xlib.h;X11/ext
>  check_include_files( X11/ICE/ICElib.h       HAVE_X11_ICE_ICELIB_H)
>  check_include_files( X11/extensions/Xrender.h HAVE_XRENDER)
>
> +# Check if we need GNU extensions. E.g. for S_ISSOCK etc.
> +CheckCSourceCompiles("
> +#include <features.h>
> +#ifndef __GNU_LIBRARY__
> +#error no gnu here
> +#endif
> +" _GNU_SOURCE)
>
>  #check_symbol_exists(sockaddr_in6 "netinet/in.h" HAVE_STRUCT_SOCKADDR_IN6)
>  check_symbol_exists(LC_MESSAGES "locale.h" HAVE_LC_MESSAGES)
>
>
> But this gives me:
>
> CMake Error: Error in cmake code at
> /devel/kde/src/4/kdelibs/ConfigureChecks.cmake:153:
> Unknown CMake command "CheckCSourceCompiles".

I guess you already found out, the name of the command is 
"check_c_source_compiles(), see CheckCSourceCompiles.cmake . 

Bye
Alex
-- 
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