# HG changeset patch
# User Gaël PORTAY <gael.portay@gmail.com>
# Date 1430566414 -7200
# Node ID f2a3570b511090e2e1ca5864bd98c5f66dde12c4
# Parent  3cb73e8d6122ba87c5afec34cbcf5bd6c079d7f5
Test struct existance against sizeof() operator

Instead of declaring an "unused-variable" or "unused-but-set-variable"
structure.

This avoid unexpected broken configurations when using something like:
$ ./configure CFLAGS="-Wall -Wextra -Werror"
It causes AC_COMPILE_IFELSE to fail and thus leading to a mismatch
configuration (because the CFLAGS are passed to the macro).

diff -r 3cb73e8d6122 -r f2a3570b5110 configure.ac
--- a/configure.ac	Sat May 02 22:59:55 2015 +0800
+++ b/configure.ac	Sat May 02 13:33:34 2015 +0200
@@ -265,7 +265,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 		]],
-		[[ struct sockaddr_storage s; ]])],
+		[[ if (sizeof(struct sockaddr_storage)) return 0 ]])],
 		[ ac_cv_have_struct_sockaddr_storage="yes" ],
 		[ ac_cv_have_struct_sockaddr_storage="no" ]
 	)
@@ -279,7 +279,7 @@
 #include <sys/types.h>
 #include <netinet/in.h>
 		]],
-		[[ struct sockaddr_in6 s; s.sin6_family = 0; ]])],
+		[[ if (sizeof(struct sockaddr_in6)) return 0 ]])],
 		[ ac_cv_have_struct_sockaddr_in6="yes" ],
 		[ ac_cv_have_struct_sockaddr_in6="no" ]
 	)
@@ -293,7 +293,7 @@
 #include <sys/types.h>
 #include <netinet/in.h>
 		]],
-		[[ struct in6_addr s; s.s6_addr[0] = 0; ]])],
+		[[ if (sizeof(struct in6_addr)) return 0 ]])],
 		[ ac_cv_have_struct_in6_addr="yes" ],
 		[ ac_cv_have_struct_in6_addr="no" ]
 	)
@@ -308,7 +308,7 @@
 #include <sys/socket.h>
 #include <netdb.h>
 		]],
-		[[ struct addrinfo s; s.ai_flags = AI_PASSIVE; ]])],
+		[[ if (sizeof(struct addrinfo)) return 0 ]])],
 		[ ac_cv_have_struct_addrinfo="yes" ],
 		[ ac_cv_have_struct_addrinfo="no" ]
 	)