dsl: fix python 3.11 dataclasses error and mypy fixes

docs/configurators.rst

@@ -2,7 +2,7 @@
 Configurators
 ===============
 
-To use a configurator, set it as the ``implementation`` field of an `operation`
+To use a configurator, set it in the ``implementation`` field of an :std:ref:`Operation`
 and set its inputs as documented below. Configurator names are case-sensitive;
 if a configurator name isn't found it is treated as an external command.
 

tosca-package/tosca/_tosca.py

@@ -919,6 +919,10 @@ def __repr__(self):
     def to_yaml(self, dict_cls=dict):
         return self.expr
 
+    # note: we need this to prevent dataclasses error on 3.11+: mutable default for field
+    def __hash__(self) -> int:
+        return hash(str(self.expr))
+
     def __eq__(self, __value: object) -> bool:
         if isinstance(__value, type(self.expr)):
             return self.expr == __value
@@ -966,7 +970,7 @@ class FieldProjection(_Ref):
     def __init__(self, field: _Tosca_Field, parent: Optional["FieldProjection"] = None):
         # currently don't support projections that are requirements
         expr = field.as_ref_expr()
-        if parent:
+        if parent and parent.expr:
             # XXX map to tosca name but we can't do this now because it might be too early to resolve the attribute's type
             expr = parent.expr["eval"] + "::" + expr
         super().__init__(dict(eval=expr))

tosca-package/tosca/loader.py

@@ -584,9 +584,9 @@ def restricted_exec(
         namespace["__package__"] = package
     policy = SafeToscaDslNodeTransformer if safe_mode else ToscaDslNodeTransformer
     result = compile_restricted_exec(python_src, policy=policy)
-    if PRINT_AST_SRC:
+    if PRINT_AST_SRC and sys.version_info.minor >= 9:
         c_ast = result.used_names[":top"]
-        print(ast.unparse(c_ast))
+        print(ast.unparse(c_ast))  # type: ignore
     if result.errors:
         raise SyntaxError("\n".join(result.errors))
     temp_module = None