From 5159c34ea8923bf0c17fd31e183c5803b72b97f3 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Mon, 5 Feb 2018 13:10:24 +0100
Subject: [PATCH 2/2] ovs: fix compiler error for passing NMDevice pointer to
 NM_DEVICE_OVS_INTERFACE_GET_PRIVATE()
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NM_DEVICE_OVS_INTERFACE_GET_PRIVATE() is implemented via the _NM_GET_PRIVATE()
macro. This macro uses C11's _Generic() to provide additional compiler checks
when casting from an incompatible pointer type.

As such,

  NMDevice *device = ...;
  NMDeviceOvsInterfacePrivate *priv;

  priv = NM_DEVICE_OVS_INTERFACE_GET_PRIVATE (device);

causes a compilation error:

    error: ‘_Generic’ selector of type ‘NMDevice * {aka struct _NMDevice *}’ is not compatible with any association

One workaround would be to cast the pointer first:

  priv = NM_DEVICE_OVS_INTERFACE_GET_PRIVATE ((NMDeviceOvsInterface *) device);

A better fix is to mark NMDevice as a compatible pointer in _NM_GET_PRIVATE(),
which this patch does.

Previously, this went unnoticed, because due to bug "a43bf3388 build: fix configure
check for CC support of _Generic() and __auto_type", we failed to detect support
for _Generic() when compiling with -Werror. That essentially disables this check,
and NM_DEVICE_OVS_INTERFACE_GET_PRIVATE() would do a direct cast.

A workaround for this build failure might be to build with -Werror, which accidentally
results in not using _Generic().

https://bugzilla.gnome.org/show_bug.cgi?id=793183

Fixes: 8ad310f8e3cb0157cfa5fa8ff10f313555cf8e3c
(cherry picked from commit 782578122c6cb23bdbee0b01eddceee1b967a673)
---
 src/devices/ovs/nm-device-ovs-interface.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/devices/ovs/nm-device-ovs-interface.c b/src/devices/ovs/nm-device-ovs-interface.c
index e746a3fd2..ce32c2dd7 100644
--- a/src/devices/ovs/nm-device-ovs-interface.c
+++ b/src/devices/ovs/nm-device-ovs-interface.c
@@ -50,7 +50,7 @@ struct _NMDeviceOvsInterfaceClass {
 
 G_DEFINE_TYPE (NMDeviceOvsInterface, nm_device_ovs_interface, NM_TYPE_DEVICE)
 
-#define NM_DEVICE_OVS_INTERFACE_GET_PRIVATE(self) _NM_GET_PRIVATE (self, NMDeviceOvsInterface, NM_IS_DEVICE_OVS_INTERFACE)
+#define NM_DEVICE_OVS_INTERFACE_GET_PRIVATE(self) _NM_GET_PRIVATE (self, NMDeviceOvsInterface, NM_IS_DEVICE_OVS_INTERFACE, NMDevice)
 
 /*****************************************************************************/
 
-- 
2.14.3