As for which "windows portability system" to support, my preference these days is mingw over msys/cygwin. Especially since we are going to be compiling on Linux (and I'd like to be able to produce windows binaries from Builder on Linux).

Well, I have support for windows on GXml with following code at configure.ac:

dnl Check Cross Compile
dnl ******************************
dnl Check for Operating System
dnl ******************************
dnl linklibext is the shared link library extension, which varies by platform

#EXPORT_SYM_REGEX='-export-symbols-regex "^(gxml_|fnYM49765777344607__gxml).*"'
#AC_MSG_CHECKING([for platform])
#platform_win32=no
#linklibext=".so"
case "$host" in
*-mingw*)
#    AC_MSG_RESULT([Win32 - MinGW])
    platform_win32=yes
#    AC_DEFINE([USING_MINGW],[],[Using MinGW])
#    NO_UNDEFINED='-no-undefined'
#    LIBTOOL_EXPORT_OPTIONS=
#    linklibext=".dll"
#    AC_CHECK_TOOL(WINDRES, windres, windres)
#    AC_SUBST(WINDRES)
#    AC_CHECK_TOOL(DLLTOOL, dlltool, dlltool)
#    AC_SUBST(DLLTOOL)
    ;;
*)
#    AC_MSG_RESULT([Unix])
#    NO_UNDEFINED=''
#    LIBTOOL_EXPORT_OPTIONS=$EXPORT_SYM_REGEX
#    ;;
esac


Now I'm trying to make it a m4 macro, but my skills are not enough, I have this code but doesn't work, any advise should be great!


m4_define([_PLATFORM_WIN_CHECK_INTERNAL],[
AC_MSG_CHECKING([for windows platform])
AS_CASE([$host],
[*mingw*],[
platform_win=yes
],[])
AC_MSG_RESULT([platform_win])
AM_CONDITIONAL(PLATFORM_WIN, [test x$platform_win = xyes])
])

I've made it:

m4_define([_PLATFORM_WIN_CHECK_INTERNAL],[
AC_MSG_CHECKING([for windows platform])
AS_CASE([$host],
  [*mingw*],[
    platform_win=yes
  ],
  [
    platform_win=no
  ]
)
AC_MSG_RESULT([$platform_win])
AM_CONDITIONAL(PLATFORM_WIN, [test x$platform_win = xyes])
])

Just need to check it on Windows and MSYS2.

I've finished to add Windows/MSYS2 support to Vala library projects. This is easy to be ported to C library projects, because I've added a m4 macro and make file mk to be imported to Makefile.am, making easy even for other projects to add support for Windows/MSYS2 to their own projects.

In order to show you a clean patch, I've added dependence to bug #766621. Once fixed, I've merge this work with that bug work, to provide an straight forward experience on Vala libraries build.