Add a union method to the extensions types. (#1125)

Add a `union` method to the extensions types.

CHANGELOG_VULKANO.md

@@ -2,6 +2,7 @@
 
 - Add support for `#include "..."` and `#include <...>` directives within source
   files.
+- Add a `union` method for the extensions types.
 
 # Version 0.11.1 (2018-11-16)
 

vulkano/src/extensions.rs

@@ -42,6 +42,17 @@ macro_rules! extensions {
                 }
             }
 
+            /// Returns the union of this list and another list.
+            #[inline]
+            pub fn union(&self, other: &$sname) -> $sname {
+                $sname {
+                    $(
+                        $ext: self.$ext || other.$ext,
+                    )*
+                    _unbuildable: Unbuildable(())
+                }
+            }
+
             /// Returns the intersection of this list and another list.
             #[inline]
             pub fn intersection(&self, other: &$sname) -> $sname {