[gtk+/wip/alexl/broadway4] vulkan: Don't crash if vkEnumeratePhysicalDevices fails

[Alexander Larsson <alexl src gnome org>]

commit a415f4de0d46b56de445a84a8107bd05a988480b
Author: Alexander Larsson <alexl redhat com>
Date:   Thu Nov 30 14:48:15 2017 +0100

    vulkan: Don't crash if vkEnumeratePhysicalDevices fails

 gdk/gdkvulkancontext.c |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)
---
diff --git a/gdk/gdkvulkancontext.c b/gdk/gdkvulkancontext.c
index f442534..3fd697a 100644
--- a/gdk/gdkvulkancontext.c
+++ b/gdk/gdkvulkancontext.c
@@ -599,10 +599,9 @@ gdk_display_create_vulkan_device (GdkDisplay  *display,
 {
   uint32_t i, j;
 
-  uint32_t n_devices;
+  uint32_t n_devices = 0;
   GDK_VK_CHECK(vkEnumeratePhysicalDevices, display->vk_instance, &n_devices, NULL);
-  VkPhysicalDevice *devices = g_newa (VkPhysicalDevice, n_devices);
-  GDK_VK_CHECK(vkEnumeratePhysicalDevices, display->vk_instance, &n_devices, devices);
+  VkPhysicalDevice *devices;
 
   if (n_devices == 0)
     {
@@ -612,6 +611,9 @@ gdk_display_create_vulkan_device (GdkDisplay  *display,
       return FALSE;
     }
 
+  devices = g_newa (VkPhysicalDevice, n_devices);
+  GDK_VK_CHECK(vkEnumeratePhysicalDevices, display->vk_instance, &n_devices, devices);
+
   for (i = 0; i < n_devices; i++)
     {
       VkPhysicalDeviceProperties props;