Re: various headers reporting "present but cannot be compiled"

[Chris Tracy]

> If you look at Autoconf 2.59's manual in the `Generic Header Checks'
> node:
> 
>      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::).
> 
> So, in your case, this typically means that the header in question was
> found (ie. the preprocessor did not fail) but then it was impossible to
> compile a simple C file including it (maybe because some other required
> header was not included).  Looking at your `config.log' file may give
> you clues.

Ah, thanks for the clues -- I really should be more familiar with
autoconf.  I pasted a few of the errors in config.log below.

Please excuse my ignorance here...  is this a FreeBSD problem?  or an
autoconf problem?  The autoconf errors didn't stop Zebra from
compiling, and I have Zebra's OSPF daemon setup as part of an OSPF
area now and haven't hit any major problems yet with the package
itself.

Thanks for your help!

-Chris

---
configure:3730: checking net/if_var.h usability
configure:3743: gcc -c -g -O2 -Wall  conftest.c >&5
In file included from configure:3794:
/usr/include/net/if_var.h:146: field `if_data' has incomplete type
/usr/include/net/if_var.h:152: warning: `struct sockaddr' declared inside 
parameter list
/usr/include/net/if_var.h:152: warning: its scope is only this definition or 
declaration, which is probably not what you want.
/usr/include/net/if_var.h:178: warning: `struct sockaddr' declared inside 
parameter list
/usr/include/net/if_var.h:314: field `if_data' has incomplete type
---

---
configure:3730: checking netinet/in_var.h usability
configure:3743: gcc -c -g -O2 -Wall  conftest.c >&5
In file included from configure:3798:
/usr/include/netinet/in_var.h:50: field `ia_ifa' has incomplete type
/usr/include/netinet/in_var.h:58: field `ia_netbroadcast' has incomplete type
/usr/include/netinet/in_var.h:61: field `ia_addr' has incomplete type
/usr/include/netinet/in_var.h:62: field `ia_dstaddr' has incomplete type
/usr/include/netinet/in_var.h:64: field `ia_sockmask' has incomplete type
/usr/include/netinet/in_var.h:68: `IFNAMSIZ' undeclared here (not in a function)
/usr/include/netinet/in_var.h:69: field `ifra_addr' has incomplete type
/usr/include/netinet/in_var.h:70: field `ifra_broadaddr' has incomplete type
/usr/include/netinet/in_var.h:72: field `ifra_mask' has incomplete type
/usr/include/netinet/in_var.h:157: field `inm_addr' has incomplete type
In file included from /usr/include/netinet/in_var.h:241,
                 from configure:3798:
/usr/include/netinet6/in6_var.h:94: field `ia_ifa' has incomplete type
/usr/include/netinet6/in6_var.h:97: field `ia_addr' has incomplete type
/usr/include/netinet6/in6_var.h:98: field `ia_net' has incomplete type
/usr/include/netinet6/in6_var.h:99: field `ia_dstaddr' has incomplete type
/usr/include/netinet6/in6_var.h:100: field `ia_prefixmask' has incomplete type
/usr/include/netinet6/in6_var.h:233: `IFNAMSIZ' undeclared here (not in a 
function)
/usr/include/netinet6/in6_var.h:235: field `ifru_addr' has incomplete type
/usr/include/netinet6/in6_var.h:236: field `ifru_dstaddr' has incomplete type
/usr/include/netinet6/in6_var.h:249: `IFNAMSIZ' undeclared here (not in a 
function)
/usr/include/netinet6/in6_var.h:250: field `ifra_addr' has incomplete type
/usr/include/netinet6/in6_var.h:251: field `ifra_broadaddr' has incomplete type
/usr/include/netinet6/in6_var.h:252: field `ifra_prefixmask' has incomplete type
/usr/include/netinet6/in6_var.h:284: `IFNAMSIZ' undeclared here (not in a 
function)
/usr/include/netinet6/in6_var.h:290: field `ipr_prefix' has incomplete type
/usr/include/netinet6/in6_var.h:307: `IFNAMSIZ' undeclared here (not in a 
function)
/usr/include/netinet6/in6_var.h:322: field `irr_matchprefix' has incomplete type
/usr/include/netinet6/in6_var.h:323: field `irr_useprefix' has incomplete type
/usr/include/netinet6/in6_var.h:503: field `in6m_addr' has incomplete type
---



> 
> Ludovic.
>