fix ParamType.to_info_dict() with no name

CHANGES.rst

@@ -48,6 +48,8 @@ Version 8.1.0
 -   A ``Group`` with ``invoke_without_command=True`` and ``chain=False``
     will invoke its result callback with the group function's return
     value. :issue:`2124`
+-   ``to_info_dict`` will not fail if a ``ParamType`` doesn't define a
+    ``name``. :issue:`2168`
 
 
 Version 8.0.4

docs/shell-completion.rst

@@ -132,6 +132,8 @@ with the incomplete value.
 .. code-block:: python
 
     class EnvVarType(ParamType):
+        name = "envvar"
+
         def shell_complete(self, ctx, param, incomplete):
             return [
                 CompletionItem(name)

src/click/types.py

@@ -63,7 +63,14 @@ def to_info_dict(self) -> t.Dict[str, t.Any]:
         # The class name without the "ParamType" suffix.
         param_type = type(self).__name__.partition("ParamType")[0]
         param_type = param_type.partition("ParameterType")[0]
-        return {"param_type": param_type, "name": self.name}
+
+        # Custom subclasses might not remember to set a name.
+        if hasattr(self, "name"):
+            name = self.name
+        else:
+            name = param_type
+
+        return {"param_type": param_type, "name": name}
 
     def __call__(
         self,

tests/test_info_dict.py

@@ -266,3 +266,10 @@ def test_context():
         "ignore_unknown_options": False,
         "auto_envvar_prefix": None,
     }
+
+
+def test_paramtype_no_name():
+    class TestType(click.ParamType):
+        pass
+
+    assert TestType().to_info_dict()["name"] == "TestType"