How to create validation error for parent AST node?

[durianwaffle]

Hi Langium community,

I can only create validation error for node's children property not its parents.
Is there any way to create validation error for a node's parent property?

if (leftType !== rightType) {
  accept('error', `Can’t assign ${rightType} type to variable with type ${leftType} in assignment.`, 
  { node: assignemntStatement, property: 'left' });
}

For example, if the operands have different types in assignment statement, show error line for the entire line not just on left/op/right

And I am also wondering how to debug for validator since there is no output.

[ydaveluy]

Hello, if you remove the property attribute the entire statement will be on error:

if (leftType !== rightType) {
  accept('error', `Can’t assign ${rightType} type to variable with type ${leftType} in assignment.`, 
  { node: assignemntStatement });
}

[JohannesMeierSE]

Hello @durianwaffle,

you can use nearly any AstNode for the node property. Depending on your DSL, that could be e.g. assignemntStatement.value or assignemntStatement.$container or what ever you like. The property depends on the chosen value for node.