--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2011-09-17  Bruno Haible  <bruno@clisp.org>
+
+	inet_pton: Support for MSVC on Windows Vista or newer.
+	* lib/arpa_inet.in.h (inet_pton): Also consider REPLACE_INET_PTON.
+	* lib/inet_pton.c (rpl_inet_pton): Use a simple wrapper if
+	HAVE_DECL_INET_PTON is defined.
+	* m4/inet_pton.m4 (gl_FUNC_INET_PTON): Invoke gl_PREREQ_SYS_H_WINSOCK2.
+	On platforms with <winsock2.h>, test whether inet_pton is declared in
+	<ws2tcpip.h>. If so, arrange to replace it.
+	* m4/arpa_inet_h.m4 (gl_ARPA_INET_H_DEFAULTS): Initialize
+	REPLACE_INET_PTON.
+	* modules/arpa_inet (Makefile.am): Substitute REPLACE_INET_PTON.
+	* modules/inet_pton (Files): Add m4/sys_socket_h.m4.
+	(Depends-on, configure.ac): Update condition.
+	* doc/posix-functions/inet_pton.texi: Mention the MSVC problem.
+
 2011-09-17  Bruno Haible  <bruno@clisp.org>
 
 	inet_ntop: Support for MSVC on Windows Vista or newer.

--- a/doc/posix-functions/inet_pton.texi
+++ b/doc/posix-functions/inet_pton.texi
@@ -15,6 +15,10 @@
 This function is declared in @code{<netdb.h>} instead of @code{<arpa/inet.h>}
 on some platforms:
 NonStop Kernel.
+@item
+This function is declared in @code{<ws2tcpip.h>}, with a POSIX incompatible
+declaration, on some platforms:
+MSVC 9 on Windows >= Vista.
 @end itemize
 
 Portability problems not fixed by Gnulib:

--- a/lib/arpa_inet.in.h
+++ b/lib/arpa_inet.in.h
@@ -108,13 +108,25 @@
 #endif
 
 #if @GNULIB_INET_PTON@
-# if !@HAVE_DECL_INET_PTON@
+# if @REPLACE_INET_PTON@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef inet_pton
+#   define inet_pton rpl_inet_pton
+#  endif
+_GL_FUNCDECL_RPL (inet_pton, int,
+                  (int af, const char *restrict src, void *restrict dst)
+                  _GL_ARG_NONNULL ((2, 3)));
+_GL_CXXALIAS_RPL (inet_pton, int,
+                  (int af, const char *restrict src, void *restrict dst));
+# else
+#  if !@HAVE_DECL_INET_PTON@
 _GL_FUNCDECL_SYS (inet_pton, int,
                   (int af, const char *restrict src, void *restrict dst)
                   _GL_ARG_NONNULL ((2, 3)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (inet_pton, int,
                   (int af, const char *restrict src, void *restrict dst));
+# endif
 _GL_CXXALIASWARN (inet_pton);
 #elif defined GNULIB_POSIXCHECK
 # undef inet_pton

--- a/lib/inet_pton.c
+++ b/lib/inet_pton.c
@@ -37,13 +37,25 @@
 /* Specification.  */
 #include <arpa/inet.h>
 
-#include <c-ctype.h>
-#include <string.h>
-#include <errno.h>
+#if HAVE_DECL_INET_PTON
+
+# undef inet_pton
+
+int
+rpl_inet_pton (int af, const char *restrict src, void *restrict dst)
+{
+  return inet_pton (af, src, dst);
+}
 
-#define NS_INADDRSZ 4
-#define NS_IN6ADDRSZ 16
-#define NS_INT16SZ 2
+#else
+
+# include <c-ctype.h>
+# include <string.h>
+# include <errno.h>
+
+# define NS_INADDRSZ 4
+# define NS_IN6ADDRSZ 16
+# define NS_INT16SZ 2
 
 /*
  * WARNING: Don't even consider trying to compile this on a system where
@@ -51,9 +63,9 @@
  */
 
 static int inet_pton4 (const char *src, unsigned char *dst);
-#if HAVE_IPV6
+# if HAVE_IPV6
 static int inet_pton6 (const char *src, unsigned char *dst);
-#endif
+# endif
 
 /* int
  * inet_pton(af, src, dst)
@@ -74,10 +86,10 @@
     case AF_INET:
       return (inet_pton4 (src, dst));
 
-#if HAVE_IPV6
+# if HAVE_IPV6
     case AF_INET6:
       return (inet_pton6 (src, dst));
-#endif
+# endif
 
     default:
       errno = EAFNOSUPPORT;
@@ -141,7 +153,7 @@
   return (1);
 }
 
-#if HAVE_IPV6
+# if HAVE_IPV6
 
 /* int
  * inet_pton6(src, dst)
@@ -250,4 +262,7 @@
   memcpy (dst, tmp, NS_IN6ADDRSZ);
   return (1);
 }
+
+# endif
+
 #endif

--- a/m4/arpa_inet_h.m4
+++ b/m4/arpa_inet_h.m4
@@ -53,4 +53,5 @@
   HAVE_DECL_INET_NTOP=1;  AC_SUBST([HAVE_DECL_INET_NTOP])
   HAVE_DECL_INET_PTON=1;  AC_SUBST([HAVE_DECL_INET_PTON])
   REPLACE_INET_NTOP=0;    AC_SUBST([REPLACE_INET_NTOP])
+  REPLACE_INET_PTON=0;    AC_SUBST([REPLACE_INET_PTON])
 ])

--- a/m4/inet_pton.m4
+++ b/m4/inet_pton.m4
@@ -1,4 +1,4 @@
-# inet_pton.m4 serial 14
+# inet_pton.m4 serial 15
 dnl Copyright (C) 2006, 2008-2011 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -9,36 +9,53 @@
   dnl Persuade Solaris <arpa/inet.h> to declare inet_pton.
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
 
+  AC_REQUIRE([AC_C_RESTRICT])
+
   dnl Most platforms that provide inet_pton define it in libc.
   dnl Solaris 8..10 provide inet_pton in libnsl instead.
+  dnl Native Windows provides it in -lws2_32 instead, with a declaration in
+  dnl <ws2tcpip.h>, and it uses stdcall calling convention, not cdecl
+  dnl (hence we cannot use AC_CHECK_FUNCS, AC_SEARCH_LIBS to find it).
   HAVE_INET_PTON=1
-  gl_save_LIBS=$LIBS
-  AC_SEARCH_LIBS([inet_pton], [nsl], [],
-    [AC_CHECK_FUNCS([inet_pton])
-     if test $ac_cv_func_inet_pton = no; then
-       HAVE_INET_PTON=0
-     fi
-    ])
-  LIBS=$gl_save_LIBS
-
   INET_PTON_LIB=
-  if test "$ac_cv_search_inet_pton" != "no" &&
-     test "$ac_cv_search_inet_pton" != "none required"; then
-    INET_PTON_LIB="$ac_cv_search_inet_pton"
-  fi
-  AC_SUBST([INET_PTON_LIB])
+  gl_PREREQ_SYS_H_WINSOCK2
+  if test $HAVE_WINSOCK2_H = 1; then
+    AC_CHECK_DECLS([inet_pton],,, [[#include <ws2tcpip.h>]])
+    if test $ac_cv_have_decl_inet_pton = yes; then
+      dnl It needs to be overridden, because the stdcall calling convention
+      dnl is not compliant with POSIX.
+      REPLACE_INET_PTON=1
+      INET_PTON_LIB="-lws2_32"
+    else
+      HAVE_DECL_INET_PTON=0
+      HAVE_INET_PTON=0
+    fi
+  else
+    gl_save_LIBS=$LIBS
+    AC_SEARCH_LIBS([inet_pton], [nsl], [],
+      [AC_CHECK_FUNCS([inet_pton])
+       if test $ac_cv_func_inet_pton = no; then
+         HAVE_INET_PTON=0
+       fi
+      ])
+    LIBS=$gl_save_LIBS
 
-  AC_CHECK_HEADERS_ONCE([netdb.h])
-  AC_CHECK_DECLS([inet_pton],,,
-    [[#include <arpa/inet.h>
-      #if HAVE_NETDB_H
-      # include <netdb.h>
-      #endif
-    ]])
-  if test $ac_cv_have_decl_inet_pton = no; then
-    HAVE_DECL_INET_PTON=0
-    AC_REQUIRE([AC_C_RESTRICT])
-  fi
+    if test "$ac_cv_search_inet_pton" != "no" \
+       && test "$ac_cv_search_inet_pton" != "none required"; then
+      INET_PTON_LIB="$ac_cv_search_inet_pton"
+    fi
+
+    AC_CHECK_HEADERS_ONCE([netdb.h])
+    AC_CHECK_DECLS([inet_pton],,,
+      [[#include <arpa/inet.h>
+        #if HAVE_NETDB_H
+        # include <netdb.h>
+        #endif
+      ]])
+    if test $ac_cv_have_decl_inet_pton = no; then
+      HAVE_DECL_INET_PTON=0
+    fi
+  AC_SUBST([INET_PTON_LIB])
 ])
 
 # Prerequisites of lib/inet_pton.c.

--- a/modules/arpa_inet
+++ b/modules/arpa_inet
@@ -37,6 +37,7 @@
 	      -e 's|@''HAVE_DECL_INET_NTOP''@|$(HAVE_DECL_INET_NTOP)|g' \
 	      -e 's|@''HAVE_DECL_INET_PTON''@|$(HAVE_DECL_INET_PTON)|g' \
 	      -e 's|@''REPLACE_INET_NTOP''@|$(REPLACE_INET_NTOP)|g' \
+	      -e 's|@''REPLACE_INET_PTON''@|$(REPLACE_INET_PTON)|g' \
 	      -e '/definitions of _GL_FUNCDECL_RPL/r $(CXXDEFS_H)' \
 	      -e '/definition of _GL_ARG_NONNULL/r $(ARG_NONNULL_H)' \
 	      -e '/definition of _GL_WARN_ON_USE/r $(WARN_ON_USE_H)' \

--- a/modules/inet_pton
+++ b/modules/inet_pton
@@ -8,14 +8,14 @@
 Depends-on:
 arpa_inet
 extensions
-c-ctype         [test $HAVE_INET_PTON = 0]
-sys_socket      [test $HAVE_INET_PTON = 0]
-errno           [test $HAVE_INET_PTON = 0]
-netinet_in      [test $HAVE_INET_PTON = 0]
+c-ctype         [test $HAVE_INET_PTON = 0 || test $REPLACE_INET_NTOP = 1]
+sys_socket      [test $HAVE_INET_PTON = 0 || test $REPLACE_INET_NTOP = 1]
+errno           [test $HAVE_INET_PTON = 0 || test $REPLACE_INET_NTOP = 1]
+netinet_in      [test $HAVE_INET_PTON = 0 || test $REPLACE_INET_NTOP = 1]
 
 configure.ac:
 gl_FUNC_INET_PTON
-if test $HAVE_INET_PTON = 0; then
+if test $HAVE_INET_PTON = 0 || test $REPLACE_INET_NTOP = 1; then
   AC_LIBOBJ([inet_pton])
   gl_PREREQ_INET_PTON
 fi