Re: About AC_CHECK_HEADERS and different locations

[Andrew W. Nosenko]

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.

PS.  Untested, I didn't compile actually these examples, but hope you
get the idea.

-- 
Andrew W. Nosenko <address@hidden>