Add a dummy module.

Cargo.toml

@@ -22,5 +22,5 @@ rand = "0.8.5"
 tokenizers = "0.13.3"
 
 [features]
-default = ["cuda"]
+default = []
 cuda = ["dep:cudarc"]

src/cuda_backend.rs

@@ -1,7 +1,7 @@
 use crate::{CpuStorage, DType, Result, Shape};
 use cudarc::driver::{CudaSlice, LaunchAsync, LaunchConfig};
 
-pub(crate) type Error = cudarc::driver::DriverError;
+pub type CudaError = cudarc::driver::DriverError;
 
 #[derive(Debug, Clone)]
 pub struct CudaDevice(std::sync::Arc<cudarc::driver::CudaDevice>);

src/dummy_cuda_backend.rs

@@ -0,0 +1,46 @@
+#![allow(dead_code)]
+use crate::{CpuStorage, DType, Result, Shape};
+
+pub type CudaError = std::io::Error;
+
+#[derive(Debug, Clone)]
+pub struct CudaDevice;
+
+impl CudaDevice {
+    pub(crate) fn new(_: usize) -> Result<Self> {
+        unimplemented!("cuda support hasn't been enabled")
+    }
+
+    pub(crate) fn ordinal(&self) -> usize {
+        unimplemented!("cuda support hasn't been enabled")
+    }
+
+    pub(crate) fn zeros_impl(&self, _shape: &Shape, _dtype: DType) -> Result<CudaStorage> {
+        unimplemented!("cuda support hasn't been enabled")
+    }
+
+    pub(crate) fn cuda_from_cpu_storage(&self, _: &CpuStorage) -> Result<CudaStorage> {
+        unimplemented!("cuda support hasn't been enabled")
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct CudaStorage;
+
+impl CudaStorage {
+    pub fn dtype(&self) -> DType {
+        unimplemented!()
+    }
+
+    pub fn device(&self) -> CudaDevice {
+        unimplemented!()
+    }
+
+    pub(crate) fn to_cpu_storage(&self) -> Result<CpuStorage> {
+        unimplemented!()
+    }
+
+    pub(crate) fn affine_impl(&self, _: &Shape, _: &[usize], _: f64, _: f64) -> Result<Self> {
+        unimplemented!()
+    }
+}

src/error.rs

@@ -35,7 +35,7 @@ pub enum Error {
     },
 
     #[error(transparent)]
-    Cudarc(#[from] crate::cuda_backend::Error),
+    Cuda(#[from] crate::CudaError),
 }
 
 pub type Result<T> = std::result::Result<T, Error>;

src/lib.rs

@@ -1,7 +1,9 @@
 mod cpu_backend;
+#[cfg(feature = "cuda")]
 mod cuda_backend;
 mod device;
 mod dtype;
+mod dummy_cuda_backend;
 mod error;
 mod op;
 mod shape;
@@ -10,7 +12,6 @@ mod strided_index;
 mod tensor;
 
 pub use cpu_backend::CpuStorage;
-pub use cuda_backend::{CudaDevice, CudaStorage};
 pub use device::{Device, DeviceLocation};
 pub use dtype::{DType, WithDType};
 pub use error::{Error, Result};
@@ -18,3 +19,9 @@ pub use shape::Shape;
 pub use storage::Storage;
 use strided_index::StridedIndex;
 pub use tensor::{Tensor, TensorId};
+
+#[cfg(feature = "cuda")]
+pub use cuda_backend::{CudaDevice, CudaError, CudaStorage};
+
+#[cfg(not(feature = "cuda"))]
+pub use dummy_cuda_backend::{CudaDevice, CudaError, CudaStorage};