Make WindowBuilder and HeadlessRendererBuilder derive Clone.

src/platform/emscripten/mod.rs

@@ -58,7 +58,7 @@ impl GlContext for HeadlessContext {
 unsafe impl Send for HeadlessContext {}
 unsafe impl Sync for HeadlessContext {}
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificWindowBuilderAttributes;
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificHeadlessBuilderAttributes;

src/platform/ios/mod.rs

@@ -8,7 +8,7 @@ use ContextError;
 
 pub use api::ios::*;
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificHeadlessBuilderAttributes;
 
 pub struct HeadlessContext(i32);

src/platform/linux/api_dispatch.rs

@@ -22,7 +22,7 @@ use api::x11::XConnection;
 use api::x11::XError;
 use api::x11::XNotSupported;
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificWindowBuilderAttributes;
 
 enum Backend {

src/platform/linux/mod.rs

@@ -15,7 +15,7 @@ pub use self::api_dispatch::{WaitEventsIterator, PollEventsIterator};
 pub use self::api_dispatch::PlatformSpecificWindowBuilderAttributes;
 mod api_dispatch;
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificHeadlessBuilderAttributes;
 
 pub struct HeadlessContext(OsMesaContext);

src/platform/windows/mod.rs

@@ -51,9 +51,9 @@ lazy_static! {
     };
 }
 
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificWindowBuilderAttributes;
-#[derive(Default)]
+#[derive(Clone, Default)]
 pub struct PlatformSpecificHeadlessBuilderAttributes;
 
 /// The Win32 implementation of the main `Window` object.