Refactor: merge duplicate HasTypeVars query visitors (#18222)

`mypy.checkexpr.HasTypeVarQuery` has only one usage and is virtually[^1]
identical to `mypy.types.HasTypeVars`. Merging them seems sensible. The
latter has wider usage via `has_type_vars`, so it seems like the better
one to keep.

Some history for the record:
* `mypy.checkexpr.HasTypeVarQuery` was added in 12 years ago
a40efb4
* `mypy.types.HasTypeVars` was added 5 years ago in
59617e8

[^1]: the only difference is that `HasTypeVars` sets
`self.skip_alias_target = True`, but this seem to fit the usage of
`HasTypeVarQuery` just as well.

Author: brianschubert

mypy/checkexpr.py

@@ -181,6 +181,7 @@
     get_proper_type,
     get_proper_types,
     has_recursive_types,
+    has_type_vars,
     is_named_instance,
     split_with_prefix_and_suffix,
 )
@@ -6350,23 +6351,7 @@ def __init__(self) -> None:
 
     def visit_callable_type(self, t: CallableType) -> bool:
         # TODO: we need to check only for type variables of original callable.
-        return self.query_types(t.arg_types) or t.accept(HasTypeVarQuery())
-
-
-class HasTypeVarQuery(types.BoolTypeQuery):
-    """Visitor for querying whether a type has a type variable component."""
-
-    def __init__(self) -> None:
-        super().__init__(types.ANY_STRATEGY)
-
-    def visit_type_var(self, t: TypeVarType) -> bool:
-        return True
-
-    def visit_param_spec(self, t: ParamSpecType) -> bool:
-        return True
-
-    def visit_type_var_tuple(self, t: TypeVarTupleType) -> bool:
-        return True
+        return self.query_types(t.arg_types) or has_type_vars(t)
 
 
 def has_erased_component(t: Type | None) -> bool:

mypy/types.py

@@ -3612,6 +3612,8 @@ def visit_type_alias_type(self, typ: TypeAliasType) -> None:
 
 
 class HasTypeVars(BoolTypeQuery):
+    """Visitor for querying whether a type has a type variable component."""
+
     def __init__(self) -> None:
         super().__init__(ANY_STRATEGY)
         self.skip_alias_target = True