Test that Renderer + Scene are Send. (#556)

Test that `Renderer` is `Send`, `Scene` is `Send` + `Sync`.

The `Renderer` will no be `Send` on wasm32 targets due to
differences in the underlying `wgpu` library (unless a
feature is enabled for `wgpu`).

Usages within Bevy and other frameworks are simpler when these
types are `Send`.

Cargo.toml

@@ -61,6 +61,7 @@ peniko = { workspace = true }
 wgpu = { workspace = true, optional = true }
 log = { workspace = true }
 raw-window-handle = { workspace = true }
+static_assertions = { workspace = true }
 futures-intrusive = { workspace = true }
 wgpu-profiler = { workspace = true, optional = true }
 
@@ -76,6 +77,7 @@ peniko = "0.1.0"
 futures-intrusive = "0.5.0"
 raw-window-handle = "0.6.0"
 smallvec = "1.13.2"
+static_assertions = "1.1.0"
 
 # NOTE: Make sure to keep this in sync with the version badge in README.md
 wgpu = { version = "0.19.3" }

src/lib.rs

@@ -202,6 +202,13 @@ pub struct Renderer {
     #[cfg(feature = "wgpu-profiler")]
     pub profile_result: Option<Vec<wgpu_profiler::GpuTimerQueryResult>>,
 }
+// This is not `Send` (or `Sync`) on WebAssembly as the
+// underlying wgpu types are not. This can be enabled with the
+// `fragile-send-sync-non-atomic-wasm` feature in wgpu.
+// See https://github.com/gfx-rs/wgpu/discussions/4127 for
+// further discussion of this topic.
+#[cfg(all(feature = "wgpu", not(target_arch = "wasm32")))]
+static_assertions::assert_impl_all!(Renderer: Send);
 
 /// Parameters used in a single render that are configurable by the client.
 pub struct RenderParams {

src/scene.rs

@@ -22,6 +22,7 @@ pub struct Scene {
     #[cfg(feature = "bump_estimate")]
     estimator: vello_encoding::BumpEstimator,
 }
+static_assertions::assert_impl_all!(Scene: Send, Sync);
 
 impl Scene {
     /// Creates a new scene.