Re: About AC_CHECK_HEADERS and different locations

[Ralf Corsepius]

On 09/28/2010 04:52 PM, Andrew W. Nosenko wrote:
> On Tue, Sep 28, 2010 at 06:13, Sergio Belkin<address@hidden>  wrote:
> > Hi,
> >
> > I am autoconfiscating a project that has a header file with a line:
> >
> > #include<postgresql/libpq-fe.h>
> >
> > configure.ac has:
> >
> > AC_CHECK_HEADERS(postgresql/libpq-fe.h)
> >
> > The problem is that Ubuntu has such a header file on
> > /usr/include/postgresq  but fedora has it on  /usr/include. So how can
> > I make that configure script checks  for differents paths?
>
> Assuming that
>    o  Fedora has requested header as /usr/include/libpq-fe.h
>    o  Ubuntu has requested header as /usr/include/postgresql/libpq-fe.h
>        (otherwise I see no problems at all, just use CPPFLAGS approrach
> as already suggested)
>
> Then you can to check both in configure.ac and use result in the source code:
>
> configure.ac:
>
> AC_CHECK_HEADERS([postgresql/libpq-fe.h libpq-fe.h],
>                   [break],
>                   [AC_MSG_ERROR([PostgreSQL headers not found or not usable])])
>
> Source code:
>
> #if defined(POSTGRESQL_LIBPQ_FE_H)
> #  include<postgresql/libpq-fe.h>
> #elif defined(LIBPQ_FE_H)
> #  include<libpq-fe.h>
> #else
> #  error impossible because of AC_MSG_ERROR(), but...
> #endif
>
> Of cource you can play with [action-not-found] (for example remove
> AC_MSG_ERROR() completely and don't abort configure if nither header
> found), and simplify "#include" dance to
>
> #if defined(POSTGRESQL_LIBPQ_FE_H)
> #  include<postgresql/libpq-fe.h>
> #else
> #  include<libpq-fe.h>
> #endif
>
> for allow tuning CPPFLAGS by hands at the make(1) invocation, for
> example...  Or anything what you want.

Much easier than this is modifying the source code to
#include <libpq-fe.h>
instead of
#include <postresql/libpq-fe.h>
and to rely on the user passing appropriate CPPFLAGS.

Ralf