core: (trait) Polish HasParent trait (#1438)

Main change is the use of `*args` for `parameters`. Another change is
using generators instead of list.

tests/test_builtin_traits.py

@@ -66,7 +66,7 @@ class HasMultipleParentOp(IRDLOperation):
 
     name = "test.has_multiple_parent"
 
-    traits = frozenset([HasParent((ParentOp, Parent2Op))])
+    traits = frozenset([HasParent(ParentOp, Parent2Op)])
 
 
 def test_has_parent_no_parent():

xdsl/dialects/irdl/irdl.py

@@ -145,7 +145,7 @@ class ParametersOp(IRDLOperation):
 
     args: VarOperand = var_operand_def(AttributeType)
 
-    traits = frozenset([HasParent((TypeOp, AttributeOp))])
+    traits = frozenset([HasParent(TypeOp, AttributeOp)])
 
     def __init__(self, args: Sequence[SSAValue]):
         super().__init__(operands=[args])

xdsl/traits.py

@@ -42,22 +42,20 @@ class HasParent(OpTrait):
 
     parameters: tuple[type[Operation], ...]
 
-    def __init__(self, parameters: type[Operation] | tuple[type[Operation], ...]):
-        if not isinstance(parameters, tuple):
-            parameters = (parameters,)
-        if len(parameters) == 0:
+    def __init__(self, *parameters: type[Operation]):
+        if not parameters:
             raise ValueError("parameters must not be empty")
         super().__init__(parameters)
 
     def verify(self, op: Operation) -> None:
         parent = op.parent_op()
-        if isinstance(parent, tuple(self.parameters)):
+        if isinstance(parent, self.parameters):
             return
         if len(self.parameters) == 1:
             raise VerifyException(
                 f"'{op.name}' expects parent op '{self.parameters[0].name}'"
             )
-        names = ", ".join([f"'{p.name}'" for p in self.parameters])
+        names = ", ".join(f"'{p.name}'" for p in self.parameters)
         raise VerifyException(f"'{op.name}' expects parent op to be one of {names}")