Rename Empty backend to Noop.

This is in preparation for making it a more substantial test stub,
able to execute nontrivial code, and usable from the safe `wgpu` API.

player/tests/test.rs

@@ -3,7 +3,7 @@
 //!  and run the tests through them.
 //!
 //!  Test requirements:
-//!    - all IDs have the backend `Empty`
+//!    - all IDs have the backend `Noop`
 //!    - all expected buffers have `MAP_READ` usage
 //!    - last action is `Submit`
 //!    - no swapchain use
@@ -74,9 +74,7 @@ impl Test<'_> {
             wgt::Backend::Gl => "Gl",
             _ => unreachable!(),
         };
-        let string = read_to_string(&path)
+        let string = read_to_string(&path).unwrap().replace("Noop", backend_name);
-            .unwrap()
-            .replace("Empty", backend_name);
         ron::de::from_str(&string)
             .unwrap_or_else(|e| panic!("{path:?}:{} {}", e.position.line, e.code))
     }

wgpu-core/src/hal_api.rs

@@ -4,8 +4,8 @@ pub trait HalApi: hal::Api + 'static + WasmNotSendSync {
     const VARIANT: Backend;
 }
 
-impl HalApi for hal::api::Empty {
+impl HalApi for hal::api::Noop {
-    const VARIANT: Backend = Backend::Empty;
+    const VARIANT: Backend = Backend::Noop;
 }
 
 #[cfg(vulkan)]

wgpu-core/src/id.rs

@@ -65,11 +65,11 @@ impl RawId {
 /// any backend, but the corresponding resource types ([`Texture<A>`], for
 /// example) are always parameterized by a specific backend `A`.
 ///
-/// So the `T` in `Id<T>` is usually a resource type like `Texture<Empty>`,
+/// So the `T` in `Id<T>` is usually a resource type like `Texture<Noop>`,
-/// where [`Empty`] is the `wgpu_hal` dummy back end. These empty types are
+/// where [`Noop`] is the `wgpu_hal` dummy back end. These empty types are
 /// never actually used, beyond just making sure you access each `Storage` with
 /// the right kind of identifier. The members of [`Hub<A>`] pair up each
-/// `X<Empty>` type with the resource type `X<A>`, for some specific backend
+/// `X<Noop>` type with the resource type `X<A>`, for some specific backend
 /// `A`.
 ///
 /// [`Global`]: crate::global::Global
@@ -77,7 +77,7 @@ impl RawId {
 /// [`Hub<A>`]: crate::hub::Hub
 /// [`Texture<A>`]: crate::resource::Texture
 /// [`Registry`]: crate::hub::Registry
-/// [`Empty`]: hal::api::Empty
+/// [`Noop`]: hal::api::Noop
 #[repr(transparent)]
 #[cfg_attr(any(feature = "serde", feature = "trace"), derive(serde::Serialize))]
 #[cfg_attr(any(feature = "serde", feature = "replay"), derive(serde::Deserialize))]

wgpu-hal/examples/halmark/main.rs

@@ -815,7 +815,7 @@ cfg_if::cfg_if! {
     }
     // Fallback
     else {
-        type Api = hal::api::Empty;
+        type Api = hal::api::Noop;
     }
 }
 

wgpu-hal/examples/ray-traced-triangle/main.rs

@@ -1129,7 +1129,7 @@ cfg_if::cfg_if! {
     }
     // Fallback
     else {
-        type Api = hal::api::Empty;
+        type Api = hal::api::Noop;
     }
 }
 

wgpu-hal/src/lib.rs

@@ -239,14 +239,14 @@ extern crate wgpu_types as wgt;
 /// DirectX12 API internals.
 #[cfg(dx12)]
 pub mod dx12;
-/// A dummy API implementation.
-pub mod empty;
 /// GLES API internals.
 #[cfg(gles)]
 pub mod gles;
 /// Metal API internals.
 #[cfg(metal)]
 pub mod metal;
+/// A dummy API implementation.
+pub mod noop;
 /// Vulkan API internals.
 #[cfg(vulkan)]
 pub mod vulkan;
@@ -255,11 +255,11 @@ pub mod auxil;
 pub mod api {
     #[cfg(dx12)]
     pub use super::dx12::Api as Dx12;
-    pub use super::empty::Api as Empty;
     #[cfg(gles)]
     pub use super::gles::Api as Gles;
     #[cfg(metal)]
     pub use super::metal::Api as Metal;
+    pub use super::noop::Api as Noop;
     #[cfg(vulkan)]
     pub use super::vulkan::Api as Vulkan;
 }

wgpu-types/src/lib.rs

@@ -75,8 +75,8 @@ pub const QUERY_SIZE: u32 = 8;
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 #[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub enum Backend {
-    /// Dummy backend, used for testing.
+    /// Dummy backend, which may be used for testing.
-    Empty = 0,
+    Noop = 0,
     /// Vulkan API (Windows, Linux, Android, MacOS via `vulkan-portability`/MoltenVK)
     Vulkan = 1,
     /// Metal API (Apple platforms)
@@ -94,7 +94,7 @@ impl Backend {
     #[must_use]
     pub const fn to_str(self) -> &'static str {
         match self {
-            Backend::Empty => "empty",
+            Backend::Noop => "noop",
             Backend::Vulkan => "vulkan",
             Backend::Metal => "metal",
             Backend::Dx12 => "dx12",