Decorators not being printed in `st.echo()`

[SiddhantSadangi]

Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

st.echo() does not print a decorator if there is no other line of code before the decorator.

To reproduce, run the below script:

import streamlit as st


def decorator(*args):
    pass


with st.echo():

    @decorator
    def function():
        pass

The output will be as shown below:

Note that @decorator is not printed.

Now, add anything above the decorator in the context of st.echo():

import streamlit as st


def decorator(*args):
    pass


with st.echo():
    "lorem ipsum"

    @decorator
    def function():
        pass

The decorator is now printed:

Reproducible Code Example

No response

Steps To Reproduce

No response

Expected Behavior

No response

Current Behavior

No response

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: 1.31.1
• Python version: 3.10.11
• Operating System: Windows11
• Browser: Edge

Additional Information

No response

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[kajarenc]

Hey @SiddhantSadangi thank you for opening this issue!

I was able to reproduce it locally and can confirm that it is a bug

[Asaurus1]

The echo function also doesn't handle very well comments at the beginning or end of a echoed block. I'm thinking these are all three related to the way it is parsing the AST in order to figure out what lines of code to print, I'm not sure if there's a fix for the comment issue but there might be a fix for the decorator issue.

[sahilmathur254]

Hi! I’m interested in working on this st.echo bug. I’ll reproduce it against the current develop branch and add focused regression coverage for a decorated function appearing as the first statement in the echoed block.
Should this contribution remain limited to preserving decorator lines, or would you also like it to cover the related leading/trailing comment behaviour mentioned in the discussion?