Fix callable script linting/typing

[elliotgunton]

Pre-bug-report checklist

1. This bug can be reproduced using YAML

• Yes 👉 Please report a bug to the Argo Workflows GitHub 👈
• No

2. This bug occurs when...

• running Hera code without submitting to Argo (e.g. when exporting to YAML)
• running Hera code and submitting to Argo

Bug report

Describe the bug
A clear and concise description of what the bug is:

When using script functions under e.g. a DAG context, the linter still doesn't know it's actually a Task necessitating casts or # type: ignores. e.g.:

workflow_template.py:15: error: Item "Step" of "Any | Task | Step" has no attribute "on_success"  [union-attr]
workflow_template.py:15: error: Argument 1 to "on_success" of "Task" has incompatible type "Any | Task | Step"; expected "Task"  [arg-type]

To Reproduce
Any Hera examples using Task functions, i.e. on_success or >> operators.

Expected behavior
A clear and concise description of what you expected to happen:
No linting errors.

Environment

• Version of Hera: 5.9.0

Additional context
Add any other context about the problem here.

Maybe we can fix it with overload functions? Depends what the linter can figure out

[flaviuvadan]

It might really be related to python/mypy#1693, in which case I am not sure if this is worth it because the type is determined at run time by the context

[elliotgunton]

We also saw issues with specifying Task dependencies, e.g.:

workflow_template.py:20: error: Unsupported operand types for >> ("list[Task]" and "Task")  [operator]
workflow_template.py:20: note: Left operand is of type "Task | list[Task]"

[elliotgunton]

Related to this issue is the fact that the script decorator fudged up the type hints for the function. The intention of the _take_annotation_from, seen here

hera/src/hera/workflows/script.py

Line 611 in 91df4de

@_take_annotation_from(Script) # type: ignore

was to allow the script decorator itself to set the Script class values, like volumes etc, which does work:

But, the unintended side effect was the function itself lost type hints because I thought I needed to add the Script type hints at the call site as well, but actually this should be the type hints for Step/Task, e.g. when doesn't show up:

because it's using the Script kwargs for the hints, not TemplateInvocatorSubNodeMixin (i.e. Steps/Tasks) kwargs.

Furthermore, types hints for the function itself broke:

[elliotgunton]

Also seeing callable scripts throwing call-arg mypy errors (against a docs example):

python -m mypy main.py
main.py:11: error: Unexpected keyword argument "name"  [call-arg]
main.py:11: error: Unexpected keyword argument "arguments"  [call-arg]
main.py:12: error: Unexpected keyword argument "name"  [call-arg]
main.py:12: error: Unexpected keyword argument "arguments"  [call-arg]
main.py:13: error: Unexpected keyword argument "name"  [call-arg]
main.py:13: error: Unexpected keyword argument "arguments"  [call-arg]
main.py:14: error: Unexpected keyword argument "name"  [call-arg]
main.py:14: error: Unexpected keyword argument "arguments"  [call-arg]
Found 8 errors in 1 file (checked 1 source file)