Fix issue 585 (#594)

crates/rustc_codegen_spirv/src/codegen_cx/entry.rs

@@ -177,7 +177,18 @@ impl<'tcx> CodegenCx<'tcx> {
         // Some types automatically specify a storage class. Compute that here.
         let inferred_storage_class_from_ty = match self.lookup_type(spirv_ty) {
             SpirvType::Image { .. } | SpirvType::Sampler | SpirvType::SampledImage { .. } => {
-                Some(StorageClass::UniformConstant)
+                if is_ref {
+                    Some(StorageClass::UniformConstant)
+                } else {
+                    self.tcx.sess.span_err(
+                        hir_param.ty_span,
+                        &format!(
+                            "entry parameter type must be by-reference: `&{}`",
+                            layout.ty,
+                        ),
+                    );
+                    None
+                }
             }
             _ => None,
         };

tests/ui/spirv-attr/bad-infer-storage-class.rs

@@ -5,3 +5,7 @@ use spirv_std::Image2d;
 
 #[spirv(vertex)]
 pub fn main(#[spirv(uniform)] error: &Image2d, #[spirv(uniform_constant)] warning: &Image2d) {}
+
+// https://github.com/EmbarkStudios/rust-gpu/issues/585
+#[spirv(vertex)]
+pub fn issue_585(invalid: Image2d) {}

tests/ui/spirv-attr/bad-infer-storage-class.stderr

@@ -19,5 +19,11 @@ warning: redundant storage class specifier, storage class is inferred from type
 7 | pub fn main(#[spirv(uniform)] error: &Image2d, #[spirv(uniform_constant)] warning: &Image2d) {}
   |                                                        ^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error; 1 warning emitted
+error: entry parameter type must be by-reference: `&spirv_std::Image2d`
+  --> $DIR/bad-infer-storage-class.rs:11:27
+   |
+11 | pub fn issue_585(invalid: Image2d) {}
+   |                           ^^^^^^^
+
+error: aborting due to 2 previous errors; 1 warning emitted