Allow building Epoxy without X11

Epoxy can be compiled with GLX and X11 native resources on EGL. We can
disable the former, but the latter is always built in when enabling EGL
support.

Some platforms do not support X11 at all, so we need a way to disable
X11 when configuring Epoxy.

configure.ac

@@ -59,6 +59,11 @@ AC_CHECK_HEADER([KHR/khrplatform.h],
 # uintptr_t to a void *") by default.  Kill that.
 XORG_TESTSET_CFLAG(CWARNFLAGS, [-Wno-int-conversion])
 
+AC_ARG_ENABLE([x11],
+              [AC_HELP_STRING([--enable-x11=@<:@yes,no@:>@], [Enable X11 support @<:@default=yes@:>@])],
+              [enable_x11=$enableval],
+              [enable_x11=yes])
+
 AC_ARG_ENABLE([glx],
               [AC_HELP_STRING([--enable-glx=@<:@auto,yes,no@:>@], [Enable GLX support @<:@default=auto@:>@])],
               [enable_glx=$enableval],
@@ -148,6 +153,13 @@ AS_CASE([$host_os],
 
 AC_SUBST(EPOXY_LINK_LIBS)
 
+if test x$enable_x11 = xno; then
+    if test x$enable_glx = xyes; then
+        AC_MSG_ERROR([GLX support is explicitly enabled, but X11 was disabled])
+    fi
+    build_glx=no
+fi
+
 AM_CONDITIONAL(BUILD_EGL, test x$build_egl = xyes)
 if test x$build_egl = xyes; then
     PKG_CHECK_MODULES(EGL, [egl])
@@ -214,14 +226,17 @@ AS_CASE(["$host"],
 
 AC_SUBST([VISIBILITY_CFLAGS])
 
+if test x$enable_x11 = xyes; then
+    PKG_CHECK_MODULES(X11, [x11], [x11=yes], [x11=no])
+    if test x$x11 = xno -a x$build_glx = xyes; then
+        AC_MSG_ERROR([libX11 headers (libx11-dev) are required to build with GLX support])
+    fi
+else
+    x11=no
+fi
+
 if test x$build_glx = xyes; then
-  PKG_CHECK_MODULES(X11, [x11], [x11=yes], [x11=no])
-  if test x$x11 = xno -a x$build_glx = xyes; then
-      AC_MSG_ERROR([libX11 headers (libx11-dev) required to build with GLX support])
-  fi
   AC_DEFINE(ENABLE_GLX, [1], [Whether GLX support is enabled])
-else
-  x11=no
 fi
 
 AM_CONDITIONAL(HAVE_X11, test x$x11 = xyes)

meson.build

@@ -70,6 +70,14 @@ elif enable_egl == 'no'
   build_egl = false
 endif
 
+enable_x11 = get_option('x11')
+if not enable_x11
+  if enable_glx == 'yes'
+    error('GLX support is explicitly enabled, but X11 was disabled')
+  endif
+  build_glx = false
+endif
+
 # The remaining platform specific API for GL/GLES are enabled
 # depending on the platform we're building for
 if host_system == 'windows'
@@ -88,6 +96,7 @@ endif
 
 conf.set10('ENABLE_GLX', build_glx)
 conf.set10('ENABLE_EGL', build_egl)
+conf.set10('ENABLE_X11', enable_x11)
 
 # Compiler flags, taken from the Xorg macros
 if cc.get_id() == 'msvc'

meson_options.txt

@@ -11,3 +11,7 @@ option('enable-egl',
        choices: [ 'auto', 'yes', 'no' ],
        value: 'auto',
        description: 'Enable EGL support')
+option('x11',
+       type: 'boolean',
+       value: true,
+       description: 'Enable X11 support (GLX or EGL-X11)')

src/dispatch_common.h

@@ -46,6 +46,13 @@
 #include "epoxy/glx.h"
 #endif
 #if PLATFORM_HAS_EGL
+# if !ENABLE_X11
+/* Mesa uses this symbol to avoid including X11 headers when including
+ * EGL.h; since X11 was explicitly disabled at configuration time, we
+ * should do the same
+ */
+#  define MESA_EGL_NO_X11_HEADERS 1
+# endif
 #include "epoxy/egl.h"
 #endif
 #if PLATFORM_HAS_WGL

test/meson.build

@@ -1,6 +1,6 @@
 has_gles1 = gles1_dep.found()
 has_gles2 = gles2_dep.found()
-build_x11_tests = build_glx and x11_dep.found()
+build_x11_tests = enable_x11 and x11_dep.found()
 
 test_cflags = common_cflags + [
   '-D_XOPEN_SOURCE',
@@ -39,11 +39,16 @@ if build_egl and build_x11_tests
 
   egl_tests = [
     [ 'egl_has_extension_nocontext', [], [ 'egl_has_extension_nocontext.c' ], true, ],
-    [ 'egl_gl', [], [ 'egl_gl.c' ], true, ],
     [ 'egl_gles1_without_glx', [ '-DGLES_VERSION=1', ], [ 'egl_without_glx.c' ], has_gles1, ],
     [ 'egl_gles2_without_glx', [ '-DGLES_VERSION=2', ], [ 'egl_without_glx.c' ], has_gles2, ],
   ]
 
+  if build_glx
+    egl_tests += [
+      [ 'egl_gl', [], [ 'egl_gl.c' ], true, ],
+    ]
+  endif
+
   foreach test: egl_tests
     test_name = test[0]
     test_source = test[2]