Re: [tarantool-patches] Re: [PATCH] cmake: fix sync_file_range detection

[Vladimir Davydov <vdavydov.dev@gmail.com>]

On Tue, Oct 16, 2018 at 09:55:26PM +0300, Konstantin Osipov wrote:
> * Vladimir Davydov <vdavydov.dev@gmail.com> [18/10/06 19:34]:
> > sync_file_range is declared only if _GNU_SOURCE macro is defined.
> > Also, in order to be used in a source file, HAVE_SYNC_FILE_RANGE
> > must be present in config.h.cmake.
> > 
> > Fixes commit caae99e5eaa0 ("Refactor xlog writer").
> > ---
> > https://github.com/tarantool/tarantool/commits/dv/cmake-fix-gnu-symbol-detection
> > 
> >  CMakeLists.txt            | 2 ++
> >  src/trivia/config.h.cmake | 1 +
> >  2 files changed, 3 insertions(+)
> > 
> > diff --git a/CMakeLists.txt b/CMakeLists.txt
> > index bf68d187..b26d2abf 100644
> > --- a/CMakeLists.txt
> > +++ b/CMakeLists.txt
> > @@ -69,6 +69,8 @@ include(cmake/profile.cmake)
> >  include(cmake/module.cmake)
> >  include(cmake/thread.cmake)
> >  
> > +list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
> > +
> 
> Uhm, why are we defining this here and not where we check for sync
> file range? 

We check for all symbols, including sync_file_range, right below.  Some
of them (e.g. mremap) might need _GNU_SOURCE too so I reckon we'd better
define this macro before all the checks.

> 
> >  check_symbol_exists(MAP_ANON sys/mman.h HAVE_MAP_ANON)
> >  check_symbol_exists(MAP_ANONYMOUS sys/mman.h HAVE_MAP_ANONYMOUS)
> >  check_include_file(sys/time.h HAVE_SYS_TIME_H)