Optional web-specific deps for wasm32 (#7565)

.github/workflows/ci.yml

@@ -269,8 +269,8 @@ jobs:
           cargo clippy --target ${{ matrix.target }} ${{ matrix.extra-flags }} --tests --features glsl,spirv
           cargo doc --target ${{ matrix.target }} ${{ matrix.extra-flags }} --no-deps --features glsl,spirv
 
-          # check with no features
-          cargo clippy --target ${{ matrix.target }} ${{ matrix.extra-flags }} --no-default-features
+          # check with only the web feature
+          cargo clippy --target ${{ matrix.target }} ${{ matrix.extra-flags }} --no-default-features --features=web
 
           # all features
           cargo clippy --target ${{ matrix.target }} ${{ matrix.extra-flags }} --tests --all-features
@@ -480,7 +480,7 @@ jobs:
       - name: Execute tests
         run: |
           cd wgpu
-          wasm-pack test --headless --chrome --no-default-features --features wgsl,webgl --workspace
+          wasm-pack test --headless --chrome --no-default-features --features wgsl,webgl,web --workspace
 
   gpu-test:
     # runtime is normally 5-15 minutes

examples/standalone/custom_backend/Cargo.toml

@@ -4,6 +4,10 @@ edition = "2021"
 rust-version = "1.84"
 publish = false
 
+[features]
+default = ["web"]
+web = ["wgpu/web"]
+
 [dependencies]
 wgpu = { version = "25.0.0", features = [
     "custom",

examples/standalone/custom_backend/src/custom.rs

@@ -337,7 +337,7 @@ impl QueueInterface for CustomQueue {
         unimplemented!()
     }
 
-    #[cfg(target_arch = "wasm32")]
+    #[cfg(all(target_arch = "wasm32", feature = "web"))]
     fn copy_external_image_to_texture(
         &self,
         _source: &wgpu::CopyExternalImageSourceInfo,

tests/tests/wgpu-dependency/main.rs

@@ -139,6 +139,54 @@ fn wasm32_with_webgl_depends_on_glow() {
     });
 }
 
+#[test]
+fn wasm32_with_only_custom_backend_does_not_depend_on_web_specifics() {
+    check_feature_dependency(Requirement {
+        human_readable_name: "wasm32 with only the `custom` backend does not depend on web-specific bindings [`wasm-bindgen`, `js-sys`, `web-sys`]",
+        target: "wasm32-unknown-unknown",
+        packages: &["wgpu"],
+        features: &["custom"],
+        default_features: false,
+        search_terms: &[Search::Negative("wasm-bindgen"), Search::Negative("js-sys"), Search::Negative("web-sys")],
+    });
+}
+
+#[test]
+fn wasm32_with_webgpu_backend_does_depend_on_web_specifics() {
+    check_feature_dependency(Requirement {
+        human_readable_name: "wasm32 with the `webgpu` backend depends on web-specific bindings [`wasm-bindgen`, `js-sys`, `web-sys`]",
+        target: "wasm32-unknown-unknown",
+        packages: &["wgpu"],
+        features: &["webgpu"],
+        default_features: false,
+        search_terms: &[Search::Positive("wasm-bindgen"), Search::Positive("js-sys"), Search::Positive("web-sys")],
+    });
+}
+
+#[test]
+fn wasm32_with_webgl_backend_does_depend_on_web_specifics() {
+    check_feature_dependency(Requirement {
+        human_readable_name: "wasm32 with the `webgl` backend depends on web-specific bindings [`wasm-bindgen`, `js-sys`, `web-sys`]",
+        target: "wasm32-unknown-unknown",
+        packages: &["wgpu"],
+        features: &["webgl"],
+        default_features: false,
+        search_terms: &[Search::Positive("wasm-bindgen"), Search::Positive("js-sys"), Search::Positive("web-sys")],
+    });
+}
+
+#[test]
+fn windows_with_webgpu_webgl_backend_does_not_depend_on_web_specifics() {
+    check_feature_dependency(Requirement {
+        human_readable_name: "windows with the `webgpu` and `webgl` backends enabled does not depend on web-specific bindings [`wasm-bindgen`, `js-sys`, `web-sys`]",
+        target: "x86_64-pc-windows-msvc",
+        packages: &["wgpu"],
+        features: &["webgpu", "webgl"],
+        default_features: false,
+        search_terms: &[Search::Negative("wasm-bindgen"), Search::Negative("js-sys"), Search::Negative("web-sys")],
+    });
+}
+
 #[test]
 fn windows_with_webgl_does_not_depend_on_glow() {
     check_feature_dependency(Requirement {

wgpu-core/Cargo.toml

@@ -147,7 +147,7 @@ gles = [
 ]
 
 ## WebGL backend, only available on Emscripten
-webgl = ["wgpu-core-deps-wasm/webgl"]
+webgl = ["wgpu-core-deps-wasm/webgl", "wgpu-types/web"]
 ## OpenGL backend, on macOS only
 angle = ["wgpu-core-deps-apple/angle"]
 ## Vulkan portability backend, only available on macOS

wgpu-hal/Cargo.toml

@@ -118,6 +118,7 @@ gles = [
     "dep:profiling",
     "dep:wasm-bindgen",
     "dep:web-sys",
+    "wgpu-types/web",
     "windows/Win32_Graphics_OpenGL",
     "windows/Win32_Graphics_Gdi",
     "windows/Win32_System_LibraryLoader",

wgpu-types/Cargo.toml

@@ -37,7 +37,7 @@ alloc_instead_of_core = "warn"
 
 [features]
 default = ["std"]
-std = ["js-sys/std", "web-sys/std", "thiserror/std"]
+std = ["js-sys?/std", "web-sys?/std", "thiserror/std"]
 strict_asserts = []
 fragile-send-sync-non-atomic-wasm = []
 serde = ["dep:serde", "bitflags/serde"]
@@ -45,6 +45,8 @@ serde = ["dep:serde", "bitflags/serde"]
 counters = []
 # Enables variants of `Trace` other than `Trace::Off`
 trace = ["std"]
+# Enable web-specific dependencies for wasm.
+web = ["dep:js-sys", "dep:web-sys"]
 
 [dependencies]
 bitflags = { workspace = true, features = ["serde"] }
@@ -57,8 +59,8 @@ serde = { workspace = true, default-features = false, features = [
 ], optional = true }
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
-js-sys = { workspace = true, default-features = false }
-web-sys = { workspace = true, default-features = false, features = [
+js-sys = { workspace = true, optional = true, default-features = false }
+web-sys = { workspace = true, optional = true, default-features = false, features = [
     "ImageBitmap",
     "ImageData",
     "HtmlImageElement",

wgpu-types/src/lib.rs

@@ -6894,7 +6894,7 @@ pub type ImageCopyTexture<T> = TexelCopyTextureInfo<T>;
 ///
 /// Corresponds to [WebGPU `GPUCopyExternalImageSourceInfo`](
 /// https://gpuweb.github.io/gpuweb/#dictdef-gpuimagecopyexternalimage).
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(target_arch = "wasm32", feature = "web"))]
 #[derive(Clone, Debug)]
 pub struct CopyExternalImageSourceInfo {
     /// The texture to be copied from. The copy source data is captured at the moment
@@ -6918,14 +6918,14 @@ pub struct CopyExternalImageSourceInfo {
     since = "24.0.0",
     note = "This has been renamed to `CopyExternalImageSourceInfo`, and will be removed in 25.0.0."
 )]
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(target_arch = "wasm32", feature = "web"))]
 pub type ImageCopyExternalImage = CopyExternalImageSourceInfo;
 
 /// Source of an external texture copy.
 ///
 /// Corresponds to the [implicit union type on WebGPU `GPUCopyExternalImageSourceInfo.source`](
 /// https://gpuweb.github.io/gpuweb/#dom-gpuimagecopyexternalimage-source).
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(target_arch = "wasm32", feature = "web"))]
 #[derive(Clone, Debug)]
 pub enum ExternalImageSource {
     /// Copy from a previously-decoded image bitmap.
@@ -6947,7 +6947,7 @@ pub enum ExternalImageSource {
     VideoFrame(web_sys::VideoFrame),
 }
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(target_arch = "wasm32", feature = "web"))]
 impl ExternalImageSource {
     /// Gets the pixel, not css, width of the source.
     pub fn width(&self) -> u32 {
@@ -6978,7 +6978,7 @@ impl ExternalImageSource {
     }
 }
 
-#[cfg(target_arch = "wasm32")]
+#[cfg(all(target_arch = "wasm32", feature = "web"))]
 impl core::ops::Deref for ExternalImageSource {
     type Target = js_sys::Object;
 
@@ -6998,12 +6998,14 @@ impl core::ops::Deref for ExternalImageSource {
 
 #[cfg(all(
     target_arch = "wasm32",
+    feature = "web",
     feature = "fragile-send-sync-non-atomic-wasm",
     not(target_feature = "atomics")
 ))]
 unsafe impl Send for ExternalImageSource {}
 #[cfg(all(
     target_arch = "wasm32",
+    feature = "web",
     feature = "fragile-send-sync-non-atomic-wasm",
     not(target_feature = "atomics")
 ))]

wgpu/Cargo.toml

@@ -48,6 +48,7 @@ gles = ["wgpu-core?/gles"]
 
 ## Enables the WebGPU backend on WebAssembly.
 webgpu = [
+    "web",
     "naga?/wgsl-out",
     "dep:wasm-bindgen-futures",
     "web-sys/Document",
@@ -68,7 +69,7 @@ angle = ["wgpu-core?/angle"]
 vulkan-portability = ["wgpu-core?/vulkan-portability"]
 
 ## Enables the GLES backend on WebAssembly only.
-webgl = ["wgpu-core/webgl", "dep:wgpu-hal", "dep:smallvec"]
+webgl = ["web", "wgpu-core/webgl", "dep:wgpu-hal", "dep:smallvec"]
 
 ## Enables the noop backend for testing.
 ##
@@ -148,6 +149,13 @@ fragile-send-sync-non-atomic-wasm = [
     "wgpu-types/fragile-send-sync-non-atomic-wasm",
 ]
 
+## Use web-specific libraries on WASM
+##
+## Those libraties (wasm-bindgen, web-sys, js-sys) can only be used when there is a JavaScript
+## context around the WASM VM, e.g., when the WASM binary is used in a browser.
+web = ["dep:wasm-bindgen", "dep:js-sys", "dep:web-sys", "wgpu-types/web"]
+
+
 #########################
 # Standard Dependencies #
 #########################
@@ -192,9 +200,9 @@ smallvec.workspace = true
 ###############
 [target.'cfg(all(target_arch = "wasm32", not(target_os = "emscripten")))'.dependencies]
 # Needed for all backends
-js-sys = { workspace = true, features = ["default"] }
-wasm-bindgen.workspace = true
-web-sys = { workspace = true, features = [
+js-sys = { workspace = true, optional = true, features = ["default"] }
+wasm-bindgen = { workspace = true, optional = true }
+web-sys = { workspace = true, optional = true, features = [
     "HtmlCanvasElement",
     "OffscreenCanvas",
 ] }

wgpu/build.rs

@@ -2,6 +2,7 @@ fn main() {
     cfg_aliases::cfg_aliases! {
         native: { not(target_arch = "wasm32") },
         Emscripten: { all(target_arch = "wasm32", target_os = "emscripten") },
+        web: { all(target_arch = "wasm32", not(Emscripten), feature = "web") },
 
         send_sync: { any(
             native,

wgpu/src/api/instance.rs

@@ -303,7 +303,7 @@ impl Instance {
                 surface
             }?,
 
-            #[cfg(any(webgpu, webgl))]
+            #[cfg(web)]
             SurfaceTarget::Canvas(canvas) => {
                 handle_source = None;
 
@@ -322,7 +322,7 @@ impl Instance {
                 }?
             }
 
-            #[cfg(any(webgpu, webgl))]
+            #[cfg(web)]
             SurfaceTarget::OffscreenCanvas(canvas) => {
                 handle_source = None;
 

wgpu/src/api/queue.rs

@@ -232,7 +232,7 @@ impl Queue {
     }
 
     /// Schedule a copy of data from `image` into `texture`.
-    #[cfg(any(webgpu, webgl))]
+    #[cfg(web)]
     pub fn copy_external_image_to_texture(
         &self,
         source: &wgt::CopyExternalImageSourceInfo,

wgpu/src/api/surface.rs

@@ -243,7 +243,7 @@ pub enum SurfaceTarget<'window> {
     ///
     /// - On WebGL2: surface creation will return an error if the browser does not support WebGL2,
     ///   or declines to provide GPU access (such as due to a resource shortage).
-    #[cfg(any(webgpu, webgl))]
+    #[cfg(web)]
     Canvas(web_sys::HtmlCanvasElement),
 
     /// Surface from a `web_sys::OffscreenCanvas`.
@@ -255,7 +255,7 @@ pub enum SurfaceTarget<'window> {
     ///
     /// - On WebGL2: surface creation will return an error if the browser does not support WebGL2,
     ///   or declines to provide GPU access (such as due to a resource shortage).
-    #[cfg(any(webgpu, webgl))]
+    #[cfg(web)]
     OffscreenCanvas(web_sys::OffscreenCanvas),
 }
 

wgpu/src/backend/wgpu_core.rs

@@ -1874,7 +1874,7 @@ impl dispatch::QueueInterface for CoreQueue {
 
     // This method needs to exist if either webgpu or webgl is enabled,
     // but we only actually have an implementation if webgl is enabled.
-    #[cfg(any(webgpu, webgl))]
+    #[cfg(web)]
     #[cfg_attr(not(webgl), expect(unused_variables))]
     fn copy_external_image_to_texture(
         &self,

wgpu/src/dispatch.rs

@@ -210,7 +210,7 @@ pub trait QueueInterface: CommonTraits {
         data_layout: crate::TexelCopyBufferLayout,
         size: crate::Extent3d,
     );
-    #[cfg(any(webgpu, webgl))]
+    #[cfg(web)]
     fn copy_external_image_to_texture(
         &self,
         source: &crate::CopyExternalImageSourceInfo,

wgpu/src/lib.rs

@@ -95,10 +95,10 @@ pub use wgt::{
 pub use wgt::{ImageCopyBuffer, ImageCopyTexture, ImageCopyTextureTagged, ImageDataLayout};
 // wasm-only types, we try to keep as many types non-platform
 // specific, but these need to depend on web-sys.
-#[cfg(any(webgpu, webgl))]
+#[cfg(web)]
 #[expect(deprecated)]
 pub use wgt::ImageCopyExternalImage;
-#[cfg(any(webgpu, webgl))]
+#[cfg(web)]
 pub use wgt::{CopyExternalImageSourceInfo, ExternalImageSource};
 
 /// Re-export of our `naga` dependency.
@@ -120,7 +120,7 @@ pub use raw_window_handle as rwh;
 
 /// Re-export of our `web-sys` dependency.
 ///
-#[cfg(any(webgl, webgpu))]
+#[cfg(web)]
 pub use web_sys;
 
 #[doc(hidden)]