[BUG] TypeTransformerFailedError when using empty dict

[linhai-fn]

Describe the bug

Before flyteorg/flytekit#2743 introduced in 1.13.6, the workflow/task like below can handle empty dict.

from flytekit import task, workflow

@task
def print_dict(x: dict[str, str]) -> None:
    for k, v in x.items():
        print(f"{k}: {v}")

@workflow
def print_workflow() -> None:
    print_dict(x={})


if __name__ == "__main__":
    print(f"Running print_workflow() {print_workflow()}")

With >=1.13.6, the flyte will throw a TypeTransformerFailedError error:

% pyflyte run workflow.py print_workflow
Running Execution on local.
TypeTransformerFailedError: Failed to convert inputs of task 'workflow.print_dict':
  Failed argument 'x': Not all values in '{}' are of type <class 'str'>

Expected behavior

The workflow/task should be able to accept empty dict like they used to in <1.13.6. Unless this breaking change is intentional?

Additional context to reproduce

The cause of the error is due to this part of the code. Similar error will raise for empty list/tuple/set due to similar logic.

Screenshots

No response

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes

[welcome]

Thank you for opening your first issue here! 🛠

[charliemoriarty]

We are also encountering this issue, and it has broken several of our tasks and unit tests. As a temporary workaround, we've switched to using the deprecated typing.List and typing.Dict types for lists/dicts that need support for being empty, but this feels quite messy..

[wild-endeavor]

will be in v1.13.9 and later.