Add opt-in crate feature

.github/workflows/ci.yml

@@ -138,6 +138,7 @@ jobs:
           set -e
 
           # build for WebGPU
+          cargo clippy --target ${{ matrix.target }} --tests --features glsl,spirv,fragile-send-sync-non-atomic-wasm
           cargo clippy --target ${{ matrix.target }} --tests --features glsl,spirv
           cargo doc --target ${{ matrix.target }} --no-deps --features glsl,spirv
 

wgpu-core/Cargo.toml

@@ -48,6 +48,8 @@ serial-pass = ["serde", "wgt/serde", "arrayvec/serde"]
 id32 = []
 # Enable `ShaderModuleSource::Wgsl`
 wgsl = ["naga/wgsl-in"]
+# Implement `Send` and `Sync` on Wasm.
+fragile-send-sync-non-atomic-wasm = ["hal/fragile-send-sync-non-atomic-wasm", "wgt/fragile-send-sync-non-atomic-wasm"]
 
 [dependencies]
 arrayvec = "0.7"

wgpu-core/src/command/bundle.rs

@@ -746,9 +746,21 @@ pub struct RenderBundle<A: HalApi> {
     pub(crate) life_guard: LifeGuard,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl<A: HalApi> Send for RenderBundle<A> {}
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl<A: HalApi> Sync for RenderBundle<A> {}
 
 impl<A: HalApi> RenderBundle<A> {

wgpu-core/src/device/queue.rs

@@ -37,7 +37,13 @@ pub struct SubmittedWorkDoneClosureC {
     pub user_data: *mut u8,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl Send for SubmittedWorkDoneClosureC {}
 
 pub struct SubmittedWorkDoneClosure {
@@ -46,9 +52,21 @@ pub struct SubmittedWorkDoneClosure {
     inner: SubmittedWorkDoneClosureInner,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 type SubmittedWorkDoneCallback = Box<dyn FnOnce() + Send + 'static>;
-#[cfg(target_arch = "wasm32")]
+#[cfg(not(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+)))]
 type SubmittedWorkDoneCallback = Box<dyn FnOnce() + 'static>;
 
 enum SubmittedWorkDoneClosureInner {

wgpu-core/src/error.rs

@@ -162,9 +162,21 @@ pub fn format_pretty_any(
 #[derive(Debug)]
 pub struct ContextError {
     pub string: &'static str,
-    #[cfg(not(target_arch = "wasm32"))]
+    #[cfg(any(
+        not(target_arch = "wasm32"),
+        all(
+            feature = "fragile-send-sync-non-atomic-wasm",
+            not(target_feature = "atomics")
+        )
+    ))]
     pub cause: Box<dyn Error + Send + Sync + 'static>,
-    #[cfg(target_arch = "wasm32")]
+    #[cfg(not(any(
+        not(target_arch = "wasm32"),
+        all(
+            feature = "fragile-send-sync-non-atomic-wasm",
+            not(target_feature = "atomics")
+        )
+    )))]
     pub cause: Box<dyn Error + 'static>,
     pub label_key: &'static str,
     pub label: String,

wgpu-core/src/global.rs

@@ -155,7 +155,16 @@ impl<G: GlobalIdentityHandlerFactory> Drop for Global<G> {
     }
 }
 
-#[cfg(all(test, not(target_arch = "wasm32")))]
+#[cfg(all(
+    test,
+    any(
+        not(target_arch = "wasm32"),
+        all(
+            feature = "fragile-send-sync-non-atomic-wasm",
+            not(target_feature = "atomics")
+        )
+    )
+))]
 fn _test_send_sync(global: &Global<crate::identity::IdentityManagerFactory>) {
     fn test_internal<T: Send + Sync>(_: T) {}
     test_internal(global)

wgpu-core/src/resource.rs

@@ -79,9 +79,21 @@ pub(crate) enum BufferMapState<A: hal::Api> {
     Idle,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl<A: hal::Api> Send for BufferMapState<A> {}
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl<A: hal::Api> Sync for BufferMapState<A> {}
 
 #[repr(C)]
@@ -90,7 +102,13 @@ pub struct BufferMapCallbackC {
     pub user_data: *mut u8,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl Send for BufferMapCallbackC {}
 
 pub struct BufferMapCallback {
@@ -99,9 +117,21 @@ pub struct BufferMapCallback {
     inner: Option<BufferMapCallbackInner>,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 type BufferMapCallbackCallback = Box<dyn FnOnce(BufferAccessResult) + Send + 'static>;
-#[cfg(target_arch = "wasm32")]
+#[cfg(not(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+)))]
 type BufferMapCallbackCallback = Box<dyn FnOnce(BufferAccessResult) + 'static>;
 
 enum BufferMapCallbackInner {

wgpu-hal/Cargo.toml

@@ -43,6 +43,7 @@ dx12 = ["naga/hlsl-out", "d3d12", "bit-set", "range-alloc", "winapi/std", "winap
 windows_rs = ["gpu-allocator"]
 dxc_shader_compiler = ["hassle-rs"]
 renderdoc = ["libloading", "renderdoc-sys"]
+fragile-send-sync-non-atomic-wasm = ["wgt/fragile-send-sync-non-atomic-wasm"]
 
 [[example]]
 name = "halmark"

wgpu-hal/src/gles/adapter.rs

@@ -936,6 +936,19 @@ impl super::AdapterShared {
     }
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for super::Adapter {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for super::Adapter {}
+
 #[cfg(test)]
 mod tests {
     use super::super::Adapter;

wgpu-hal/src/gles/device.rs

@@ -1320,3 +1320,16 @@ impl crate::Device<super::Api> for super::Device {
         }
     }
 }
+
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for super::Device {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for super::Device {}

wgpu-hal/src/gles/mod.rs

@@ -246,6 +246,19 @@ pub struct Buffer {
     data: Option<Arc<std::sync::Mutex<Vec<u8>>>>,
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for Buffer {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for Buffer {}
+
 #[derive(Clone, Debug)]
 pub enum TextureInner {
     Renderbuffer {
@@ -262,6 +275,19 @@ pub enum TextureInner {
     },
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for TextureInner {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for TextureInner {}
+
 impl TextureInner {
     fn as_native(&self) -> (glow::Texture, BindTarget) {
         match *self {
@@ -450,6 +476,19 @@ struct UniformDesc {
     utype: u32,
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for UniformDesc {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for UniformDesc {}
+
 /// For each texture in the pipeline layout, store the index of the only
 /// sampler (in this layout) that the texture is used with.
 type SamplerBindMap = [Option<u8>; MAX_TEXTURE_SLOTS];
@@ -512,10 +551,36 @@ pub struct RenderPipeline {
     alpha_to_coverage_enabled: bool,
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for RenderPipeline {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for RenderPipeline {}
+
 pub struct ComputePipeline {
     inner: Arc<PipelineInner>,
 }
 
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for ComputePipeline {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for ComputePipeline {}
+
 #[derive(Debug)]
 pub struct QuerySet {
     queries: Box<[glow::Query]>,
@@ -528,9 +593,21 @@ pub struct Fence {
     pending: Vec<(crate::FenceValue, glow::Fence)>,
 }
 
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl Send for Fence {}
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(any(
+    not(target_arch = "wasm32"),
+    all(
+        feature = "fragile-send-sync-non-atomic-wasm",
+        not(target_feature = "atomics")
+    )
+))]
 unsafe impl Sync for Fence {}
 
 impl Fence {

wgpu-hal/src/gles/queue.rs

@@ -1524,3 +1524,16 @@ impl crate::Queue<super::Api> for super::Queue {
         1.0
     }
 }
+
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Sync for super::Queue {}
+#[cfg(all(
+    target_arch = "wasm32",
+    feature = "fragile-send-sync-non-atomic-wasm",
+    not(target_feature = "atomics")
+))]
+unsafe impl Send for super::Queue {}