If I read the error correctly:

> autoreconf: running: intltoolize --copy --force
> ERROR: 'IT_PROG_INTLTOOL' must appear in configure.ac for intltool to work.
> autoreconf: error: intltoolize failed with exit status: 1

then this is reported when it's executed on the top configure.ac. Looking into the file there is this:

   if test "$enable_gui" != "no" || test "$enable_dbus_service" != "no"; then
       IT_PROG_INTLTOOL([0.37.1])
       GETTEXT_PACKAGE=syncevolution
       AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE, "$GETTEXT_PACKAGE", [The gettext package name])
       AM_GLIB_GNU_GETTEXT
       SYNCEVOLUTION_LOCALEDIR=[${datadir}/locale]
   fi

Thus, strictly speaking, the error message the autoreconf (or the intltoolize) claims is a false positive. When I move that line above the `if`, the autoconf is happy and makes things work.

Ondrej, could you verify the error is a false positive, please?

I think moving IT_PROG_INTLTOOL before if as you said should do the trick, this error was already added here https://docs.google.com/document/d/1SAGTJZEF9z_nkHMbXTF-YTTvKRja7ygfOOMzl-DYBSk/edit and the fix seem to work fine https://src.fedoraproject.org/rpms/pidgin/c/b5598d16a9f2e36d9fb0aa3411c57d5935e8fb02?branch=rawhide

But I do not have the capacity to investigate the failure deeply. Hopefully it will work for your case.

It does work to move it before the 'if'. I thought maybe you can upstream it and they will look on the reason. As it is no change for Fedora I'll add the patch.

Fixed with https://src.fedoraproject.org/rpms/syncevolution/c/23dedb20b2d7c5a583986e161c45a9222b881d07?branch=rawhide 

I did not build the package, I guess it can wait.

I see no problem building it now if possible. But it's up to you, thanks.