From 2205bdd469fd9616916b7a56fb05517374b8a70e Mon Sep 17 00:00:00 2001
From: Camilla Berglund <elmindreda@elmindreda.org>
Date: Mon, 6 Jul 2015 14:38:00 +0200
Subject: [PATCH] Improved X11 display opening failure.

---
 src/x11_init.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/x11_init.c b/src/x11_init.c
index 0bd38485..8b7c7204 100644
--- a/src/x11_init.c
+++ b/src/x11_init.c
@@ -719,7 +719,18 @@ int _glfwPlatformInit(void)
     _glfw.x11.display = XOpenDisplay(NULL);
     if (!_glfw.x11.display)
     {
-        _glfwInputError(GLFW_PLATFORM_ERROR, "X11: Failed to open X display");
+        const char* display = getenv("DISPLAY");
+        if (display)
+        {
+            _glfwInputError(GLFW_PLATFORM_ERROR,
+                            "X11: Failed to open display %s", display);
+        }
+        else
+        {
+            _glfwInputError(GLFW_PLATFORM_ERROR,
+                            "X11: The DISPLAY environment variable is missing");
+        }
+
         return GL_FALSE;
     }