[gtk/wip.win32.fixes: 9/23] glcontext: Make sure get_version always return something meaningful

[Chun-wei Fan <fanchunwei src gnome org>]

commit 66249bca093871236f308a326f6907ce5a723fae
Author: Pablo Correa Gómez <ablocorrea hotmail com>
Date:   Tue May 10 00:21:40 2022 +0200

    glcontext: Make sure get_version always return something meaningful
    
    Before, if the context had not been ever made current, it would return 0. Make
    sure the return value is never 0 and discourage in the documentation against
    the use if the context is not current.

 gdk/gdkglcontext.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
---
diff --git a/gdk/gdkglcontext.c b/gdk/gdkglcontext.c
index a79a1e235f..5dbc8df165 100644
--- a/gdk/gdkglcontext.c
+++ b/gdk/gdkglcontext.c
@@ -1675,7 +1675,8 @@ gdk_gl_context_get_shared_context (GdkGLContext *context)
  *
  * Retrieves the OpenGL version of the @context.
  *
- * The @context must be realized prior to calling this function.
+ * The @context must be realized and should be current prior to calling this
+ * function.
  */
 void
 gdk_gl_context_get_version (GdkGLContext *context,
@@ -1687,6 +1688,14 @@ gdk_gl_context_get_version (GdkGLContext *context,
   g_return_if_fail (GDK_IS_GL_CONTEXT (context));
   g_return_if_fail (gdk_gl_context_is_realized (context));
 
+  if (priv->gl_version == 0)
+    {
+      GdkGLContext *current = gdk_gl_context_get_current ();
+      gdk_gl_context_make_current (context);
+      g_assert (priv->gl_version != 0);
+      gdk_gl_context_make_current (current);
+    }
+
   if (major != NULL)
     *major = priv->gl_version / 10;
   if (minor != NULL)