From bb9765a926588ebfe1eb324fbbe8fc22d419eebe Mon Sep 17 00:00:00 2001
From: Max Krummenacher <max.krummenacher@toradex.com>
Date: Thu, 25 Jun 2020 11:27:40 +0000
Subject: [PATCH] configure.ac: don't require eglmesaext.h

E.g. the Vivante EGL implementation does not provide eglmesaext.h.

The commit moves the check for header file existence outside of the
check for existence of a egl packageconfig and makes the existence
of eglmesaext.h optional.

fixes commit fb1acfec ("Fix building against libglvnd-provided EGL headers")
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>

Upstream-Status: Submitted [https://gitlab.gnome.org/GNOME/cogl/-/merge_requests/28]
Signed-off-by: Max Krummenacher <max.krummenacher@toradex.com>
---
 configure.ac | 51 ++++++++++++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/configure.ac b/configure.ac
index b7ba95d..0d1d8de 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1212,22 +1212,6 @@ AS_IF([test "x$NEED_EGL" = "xyes" && test "x$EGL_CHECKED" != "xyes"],
         PKG_CHECK_EXISTS([egl],
           [COGL_PKG_REQUIRES="$COGL_PKG_REQUIRES egl"],
           [
-            AC_CHECK_HEADERS(
-              [EGL/egl.h],
-              [],
-              [AC_MSG_ERROR([Unable to locate required EGL headers])])
-            AC_CHECK_HEADERS(
-              [EGL/eglext.h],
-              [],
-              [AC_MSG_ERROR([Unable to locate required EGL headers])],
-              [#include <EGL/egl.h>])
-            AC_CHECK_HEADERS(
-              [EGL/eglmesaext.h],
-              [],
-              [AC_MSG_ERROR([Unable to locate required EGL headers])],
-              [#include <EGL/egl.h>
-#include <EGL/eglext.h>])
-
             AC_CHECK_LIB(EGL, [eglInitialize],
               [COGL_EXTRA_LDFLAGS="$COGL_EXTRA_LDFLAGS -lEGL"],
               [AC_MSG_ERROR([Unable to locate required EGL library])])
@@ -1236,9 +1220,38 @@ AS_IF([test "x$NEED_EGL" = "xyes" && test "x$EGL_CHECKED" != "xyes"],
           ]
           )
 
-        COGL_EGL_INCLUDES="#include <EGL/egl.h>
-#include <EGL/eglext.h>
-#include <EGL/eglmesaext.h>"
+dnl Test for the existence of egl headers.
+dnl egl*.h includes eglplatform.h which on __unix__ defaults to a X11 platform.
+dnl In that case AC_CHECK_HEADERS failes if X11 headers are not available.
+dnl Set the usual include guard define and, if the EGL implementation doesn't
+dnl use that guard fall back to USE_OZONE and EGL_NO_X11 platforms which don't
+dnl require additional headers.
+        AC_CHECK_HEADERS(
+          [EGL/egl.h],
+          [COGL_EGL_INCLUDES="#include <EGL/egl.h>"],
+          [AC_MSG_ERROR([Unable to locate required EGL headers])],
+          [#define __egl_h_
+ #define USE_OZONE
+ #define EGL_NO_X11])
+        AC_CHECK_HEADERS(
+          [EGL/eglext.h],
+          [COGL_EGL_INCLUDES="$COGL_EGL_INCLUDES
+#include <EGL/eglext.h>"],
+          [AC_MSG_ERROR([Unable to locate required EGL headers])],
+          [#define __eglext_h_
+ #define USE_OZONE
+ #define EGL_NO_X11
+$COGL_EGL_INCLUDES])
+        AC_CHECK_HEADERS(
+          [EGL/eglmesaext.h],
+          [COGL_EGL_INCLUDES="$COGL_EGL_INCLUDES
+#include <EGL/eglmesaext.h>"],
+          [],
+          [#define __eglmesaext_h_
+#define USE_OZONE
+#define EGL_NO_X11
+$COGL_EGL_INCLUDES])
+
         AC_SUBST([COGL_EGL_INCLUDES])
       ])
 
-- 
2.20.1