Validate on empty usages

wgpu-core/src/device/mod.rs

@@ -438,6 +438,10 @@ impl<B: GfxBackend> Device<B> {
             }
         }
 
+        if desc.usage.is_empty() {
+            return Err(resource::CreateBufferError::EmptyUsage);
+        }
+
         let mem_usage = {
             use gpu_alloc::UsageFlags as Uf;
             use wgt::BufferUsage as Bu;
@@ -537,6 +541,10 @@ impl<B: GfxBackend> Device<B> {
             _ => {}
         }
 
+        if desc.usage.is_empty() {
+            return Err(resource::CreateTextureError::EmptyUsage);
+        }
+
         let kind = conv::map_texture_dimension_size(desc.dimension, desc.size, desc.sample_count)?;
         let format = conv::map_texture_format(desc.format, self.private_features);
         let aspects = format.surface_desc().aspects;

wgpu-core/src/resource.rs

@@ -174,6 +174,8 @@ pub enum CreateBufferError {
     AccessError(#[from] BufferAccessError),
     #[error("buffers that are mapped at creation have to be aligned to `COPY_BUFFER_ALIGNMENT`")]
     UnalignedSize,
+    #[error("Buffers cannot have empty usage flags")]
+    EmptyUsage,
     #[error("`MAP` usage can only be combined with the opposite `COPY`, requested {0:?}")]
     UsageMismatch(wgt::BufferUsage),
 }
@@ -230,6 +232,8 @@ pub enum CreateTextureError {
     Device(#[from] DeviceError),
     #[error("D24Plus textures cannot be copied")]
     CannotCopyD24Plus,
+    #[error("Textures cannot have empty usage flags")]
+    EmptyUsage,
     #[error(transparent)]
     InvalidDimension(#[from] TextureDimensionError),
     #[error("texture descriptor mip level count ({0}) is invalid")]