I ran into this problem on my Fedora 23 installation;
Emacs configured but did not build when --with-xwidgets was specified.
* configure.ac (HAVE_WEBKIT, HAVE_GIR): Omit unnecessary initializations.
(DOES_XWIDGETS_USE_GIR): New var.
If --with-xwidgets is specified, report an error if not
doable, to be consistent with the other --with options.
Require webkitgtk3 to use Xwidgets, as the Xwidgets code does
not work at all without webkitgtk3. Simplify use of
EMACS_CHECK_MODULES. Output message about gobject
introspection only if xwidgets are used.
* etc/NEWS: Users need webkitgtk3, not merely webkit.
* src/xwidget.c (syms_of_xwidget): Don’t worry about HAVE_WEBKIT_OSR,
since this file is no longer compiled if webkitgtk3 is not available.
This directory contains the architecture-independent files used by or
with Emacs. This includes some text files of documentation for GNU
Emacs or of interest to Emacs users, and the file of dumped docstrings
for Emacs functions and variables.
COPYRIGHT AND LICENSE INFORMATION FOR IMAGE FILES
File: emacs.icon
Author: Sun Microsystems, Inc
Copyright (C) 1999, 2001-2016 Free Software Foundation, Inc.
License: GNU General Public License version 3 or later (see COPYING)