feat: Validate TypeArgs to ExtensionOp (#509)

The TypeArgs might contain malformed things like "the type List<5>" - we
can only check that they make sense (i.e. that `5` is valid as an
argument for List) *given the ExtensionRegistry*, and nowhere outside
validation has the ExtensionRegistry, so we need to do this here.

Also rename `validate_children` (in ValidateOp) to
`validate_op_children)`, and `validate_operation` to
`validate_children`.

src/hugr/validate.rs

@@ -17,6 +17,7 @@ use crate::extension::{
  validate::{ExtensionError, ExtensionValidator},
  ExtensionRegistry, ExtensionSolution, InferExtensionError,
 };
+
 use crate::ops::validate::{ChildrenEdgeData, ChildrenValidationError, EdgeValidationError};
 use crate::ops::{OpTag, OpTrait, OpType, ValidateOp};
 use crate::types::{EdgeKind, Type};
@@ -158,8 +159,17 @@ impl<'a, 'b> ValidationContext<'a, 'b> {
  }
  }
 
- // Check operation-specific constraints
- self.validate_operation(node, node_type)?;
+ // Check operation-specific constraints. Firstly that type args are correct
+ // (Good to call `resolve_extension_ops` immediately before this
+ // - see https://github.com/CQCL-DEV/hugr/issues/508 )
+ if let OpType::LeafOp(crate::ops::LeafOp::CustomOp(b)) = op_type {
+ for arg in b.args() {
+ arg.validate(self.extension_registry)
+ .map_err(|cause| ValidationError::SignatureError { node, cause })?;
+ }
+ }
+ // Secondly that the node has correct children
+ self.validate_children(node, node_type)?;
 
  // If this is a container with I/O nodes, check that the extension they
  // define match the extensions of the container.
@@ -260,7 +270,7 @@ impl<'a, 'b> ValidationContext<'a, 'b> {
  /// Check operation-specific constraints.
  ///
  /// These are flags defined for each operation type as an [`OpValidityFlags`] object.
- fn validate_operation(&self, node: Node, node_type: &NodeType) -> Result<(), ValidationError> {
+ fn validate_children(&self, node: Node, node_type: &NodeType) -> Result<(), ValidationError> {
  let op_type = &node_type.op;
  let flags = op_type.validity_flags();
 
@@ -301,7 +311,7 @@ impl<'a, 'b> ValidationContext<'a, 'b> {
  }
  // Additional validations running over the full list of children optypes
  let children_optypes = all_children.map(|c| (c.index, self.hugr.get_optype(c)));
- if let Err(source) = op_type.validate_children(children_optypes) {
+ if let Err(source) = op_type.validate_op_children(children_optypes) {
  return Err(ValidationError::InvalidChildren {
  parent: node,
  parent_optype: op_type.clone(),

src/ops.rs

@@ -229,7 +229,7 @@ pub trait ValidateOp {
 
  /// Validate the ordered list of children.
  #[inline]
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  _children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), validate::ChildrenValidationError> {

src/ops/validate.rs

@@ -3,7 +3,7 @@
 //! Adds a `validity_flags` method to [`OpType`] that returns a series of flags
 //! used by the [`crate::hugr::validate`] module.
 //!
-//! It also defines a `validate_children` method for more complex tests that
+//! It also defines a `validate_op_children` method for more complex tests that
 //! require traversing the children.
 
 use itertools::Itertools;
@@ -93,7 +93,7 @@ impl ValidateOp for super::FuncDefn {
  }
  }
 
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -118,7 +118,7 @@ impl ValidateOp for super::DFG {
  }
  }
 
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -141,7 +141,7 @@ impl ValidateOp for super::Conditional {
  }
  }
 
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -188,7 +188,7 @@ impl ValidateOp for super::TailLoop {
  }
  }
 
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -214,7 +214,7 @@ impl ValidateOp for super::CFG {
  }
  }
 
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl Iterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -334,7 +334,7 @@ impl ValidateOp for BasicBlock {
  }
 
  /// Validate the ordered list of children.
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {
@@ -369,7 +369,7 @@ impl ValidateOp for super::Case {
  }
 
  /// Validate the ordered list of children.
- fn validate_children<'a>(
+ fn validate_op_children<'a>(
  &self,
  children: impl DoubleEndedIterator<Item = (NodeIndex, &'a OpType)>,
  ) -> Result<(), ChildrenValidationError> {

src/types/type_param.rs

@@ -97,7 +97,7 @@ pub enum TypeArg {
 }
 
 impl TypeArg {
- pub(super) fn validate(
+ pub(crate) fn validate(
  &self,
  extension_registry: &ExtensionRegistry,
  ) -> Result<(), SignatureError> {