Anonymous specialization constants support (#1338)

CHANGELOG_VULKANO.md

@@ -1,5 +1,8 @@
 # Unreleased
 
+- Fixed Vulkano Shaders bug when compute shader local group layout values bound to specialization constants.
+  Now it is possible to define the layout in form of `layout(local_size_x_id = 12, local_size_y_id = 13, local_size_z = 1) in;`
+  and then set the values as `SpecializationConstants {constant_12: 8, constant_13: 4, ...}`.
 - Allow applications to access the instance and device pointers
 
 # Version 0.18.0 (2020-03-11)

vulkano-shaders/src/spec_consts.rs

@@ -72,11 +72,19 @@ pub fn write_specialization_constants(doc: &Spirv) -> TokenStream {
         let (rust_ty, rust_size, rust_alignment) = spec_const_type_from_id(doc, type_id);
         let rust_size = rust_size.expect("Found runtime-sized specialization constant");
 
-        let constant_id = doc.get_decoration_params(result_id, Decoration::DecorationSpecId)
-            .unwrap()[0];
+        let constant_id = doc.get_decoration_params(result_id, Decoration::DecorationSpecId);
+
+        if let Some(constant_id) = constant_id {
+            let constant_id = constant_id[0];
+
+            let mut name = spirv_search::name_from_id(doc, result_id);
+
+            if name == "__unnamed".to_owned() {
+                name = String::from(format!("constant_{}", constant_id));
+            }
 
             spec_consts.push(SpecConst {
-            name: spirv_search::name_from_id(doc, result_id),
+                name,
                 constant_id,
                 rust_ty,
                 rust_size,
@@ -84,6 +92,7 @@ pub fn write_specialization_constants(doc: &Spirv) -> TokenStream {
                 default_value,
             });
         }
+    }
 
     let map_entries = {
         let mut map_entries = Vec::new();