Implement override-expression evaluation

naga/src/valid/mod.rs

@@ -172,6 +172,7 @@ pub struct Validator {
     switch_values: FastHashSet<crate::SwitchValue>,
     valid_expression_list: Vec<Handle<crate::Expression>>,
     valid_expression_set: BitSet,
+    override_ids: BitSet,
 }
 
 #[derive(Clone, Debug, thiserror::Error)]
@@ -186,6 +187,8 @@ pub enum ConstantError {
 pub enum OverrideError {
     #[error("Override name and ID are missing")]
     MissingNameAndID,
+    #[error("Override ID must be unique")]
+    DuplicateID,
     #[error("The type doesn't match the override")]
     InvalidType,
     #[error("The type is not constructible")]
@@ -309,6 +312,7 @@ impl Validator {
             switch_values: FastHashSet::default(),
             valid_expression_list: Vec::new(),
             valid_expression_set: BitSet::new(),
+            override_ids: BitSet::new(),
         }
     }
 
@@ -321,6 +325,7 @@ impl Validator {
         self.switch_values.clear();
         self.valid_expression_list.clear();
         self.valid_expression_set.clear();
+        self.override_ids.clear();
     }
 
     fn validate_constant(
@@ -346,7 +351,7 @@ impl Validator {
     }
 
     fn validate_override(
-        &self,
+        &mut self,
         handle: Handle<crate::Override>,
         gctx: crate::proc::GlobalCtx,
         mod_info: &ModuleInfo,
@@ -357,6 +362,12 @@ impl Validator {
             return Err(OverrideError::MissingNameAndID);
         }
 
+        if let Some(id) = o.id {
+            if !self.override_ids.insert(id as usize) {
+                return Err(OverrideError::DuplicateID);
+            }
+        }
+
         let type_info = &self.types[o.ty.index()];
         if !type_info.flags.contains(TypeFlags::CONSTRUCTIBLE) {
             return Err(OverrideError::NonConstructibleType);