present but cannot be compiled (Was: autoconf bug?)

[Akim Demaille]

Please, report this to the package maintainers, as it's a configure.ac
problem.  The Autoconf 2.57 doc says:

      Previous versions of Autoconf merely checked whether the header was
   accepted by the preprocessor.  This was changed because the old test was
   inappropriate for typical uses.  Headers are typically used to compile,
   not merely to preprocess, and the old behavior sometimes accepted
   headers that clashed at compile-time.  If you need to check whether a
   header is preprocessable, you can use `AC_PREPROC_IFELSE' (*note
   Running the Preprocessor::).
   
      This scheme, which improves the robustness of the test, also requires
   that you make sure that headers that must be included before the
   HEADER-FILE be part of the INCLUDES, (*note Default Includes::).  If
   looking for `bar.h', which requires that `foo.h' be included before if
   it exists, we suggest the following scheme:
   
   
   AC_CHECK_HEADERS([foo.h])
   AC_CHECK_HEADERS([bar.h], [], [],
   [#if HAVE_FOO_H
   # include <foo.h>
   # endif
   ])

Thanks!

| I'm getting this error while trying to build cURL 7.10.3 on a Solaris 7
| box: SunOS [hostname removed] 5.7 Generic_106541-23 sun4u sparc
| SUNW,Ultra-Enterprise.
| 
| checking net/if.h usability... no
| checking net/if.h presence... yes
| configure: WARNING: net/if.h: present but cannot be compiled
| configure: WARNING: net/if.h: check for missing prerequisite headers?
| configure: WARNING: net/if.h: proceeding with the preprocessor's result
| configure: WARNING:     ## ------------------------------------ ##
| configure: WARNING:     ## Report this to address@hidden ##
| configure: WARNING:     ## ------------------------------------ ##
| checking for net/if.h... yes
| checking netinet/in.h usability... yes
| checking netinet/in.h presence... yes
| checking for netinet/in.h... yes
| checking netinet/if_ether.h usability... no
| checking netinet/if_ether.h presence... yes
| configure: WARNING: netinet/if_ether.h: present but cannot be compiled
| configure: WARNING: netinet/if_ether.h: check for missing prerequisite
| headers?
| configure: WARNING: netinet/if_ether.h: proceeding with the preprocessor's
| result
| configure: WARNING:     ## ------------------------------------ ##
| configure: WARNING:     ## Report this to address@hidden ##
| configure: WARNING:     ## ------------------------------------ ##
| checking for netinet/if_ether.h... yes
| checking netdb.h usability... yes
| checking netdb.h presence... yes
| checking for netdb.h... yes
| checking sys/select.h usability... yes
| checking sys/select.h presence... yes
| checking for sys/select.h... yes
| checking sys/socket.h usability... yes
| 
| Jason Woodrich
| - Avaya, Inc.
| - TSO Tools Development & Support: Applications Developer & Lab Manager
| - address@hidden
|