Check CustomType has correct bound

src/builder/dataflow.rs

@@ -428,12 +428,7 @@ pub(crate) mod test {
  f_build.finish_with_outputs([id.out_wire(0)])?;
  }
 
- assert_eq!(
- module_builder
- .finish_hugr(&EMPTY_REG)?
- .node_count(),
- 7
- );
+ assert_eq!(module_builder.finish_hugr(&EMPTY_REG)?.node_count(), 7);
 
  Ok(())
  }

src/extension.rs

@@ -15,7 +15,7 @@ use crate::ops;
 use crate::ops::custom::{ExtensionOp, OpaqueOp};
 use crate::types::type_param::{check_type_arg, TypeArgError};
 use crate::types::type_param::{TypeArg, TypeParam};
-use crate::types::CustomType;
+use crate::types::{CustomType, TypeBound};
 
 mod infer;
 pub use infer::{infer_extensions, ExtensionSolution, InferExtensionError};
@@ -81,6 +81,12 @@ pub enum SignatureError {
  /// The Extension was found in the registry, but did not contain the Type(Def) referenced in the Signature
  #[error("Extension '{exn}' did not contain expected TypeDef '{typ}'")]
  ExtensionTypeNotFound { exn: SmolStr, typ: SmolStr },
+ /// The bound recorded for a CustomType doesn't match what the TypeDef would compute
+ #[error("Bound on CustomType did not match TypeDef")]
+ WrongBound {
+ actual: TypeBound,
+ expected: TypeBound,
+ },
 }
 
 /// Concrete instantiations of types and operations defined in extensions.

src/extension/type_def.rs

@@ -61,7 +61,16 @@ impl TypeDef {
  /// This function will return an error if the type of the instance does not
  /// match the definition.
  pub fn check_custom(&self, custom: &CustomType) -> Result<(), SignatureError> {
- self.check_concrete_impl(custom)
+ self.check_concrete_impl(custom)?;
+ let calc_bound = self.bound(custom.args());
+ if calc_bound == custom.bound() {
+ Ok(())
+ } else {
+ Err(SignatureError::WrongBound {
+ expected: calc_bound,
+ actual: custom.bound(),
+ })
+ }
  }
 
  /// Instantiate a concrete [`CustomType`] by providing type arguments.