Spurious warnings about optional tags

[kwankyu]

Steps To Reproduce

From sage-devel thread

https://groups.google.com/g/sage-devel/c/kagz-697Hts

---

[David Coudert] observed some doctest warnings that I don't know how to fix. This is certainly a side effect of the modularization.

File "src/sage/plot/plot.py", line 569, in sage.plot.plot
Warning: Variable 'sig_on_count' referenced here was set only in doctest marked '# needs sage.symbolic'
    sig_on_count() # check sig_on/off pairings (virtual doctest)
**********************************************************************
File "src/sage/plot/plot.py", line 3623, in sage.plot.plot.graphics_array
Warning: Variable 'x' referenced here was set only in doctest marked '# long time, needs sage.symbolic'
    L = [plot(sin(k*x), (x,-pi,pi)) for k in [1..3]]
**********************************************************************
File "src/sage/plot/plot.py", line 3669, in sage.plot.plot.graphics_array
Warning: Variable 'x' referenced here was set only in doctest marked '# long time, needs sage.symbolic'
    p1 = plot(sin(x^2), (x, 0, 6),
              axes_labels=[r'$\theta$', r'$\sin(\theta^2)$'], fontsize=16)
**********************************************************************
File "src/sage/plot/plot.py", line 3671, in sage.plot.plot.graphics_array
Warning: Variable 'x' referenced here was set only in doctest marked '# long time, needs sage.symbolic'
    p2 = plot(x^3, (x, 1, 100), axes_labels=[r'$x$', r'$y$'],
              scale='semilogy', frame=True, gridlines='minor')

File "src/sage/repl/user_globals.py", line 52, in sage.repl.user_globals
Warning: Variable 'sig_on_count' referenced here was set only in doctest marked '# needs sage.modules'
    sig_on_count() # check sig_on/off pairings (virtual doctest)
**********************************************************************
File "src/sage/repl/user_globals.py", line 99, in sage.repl.user_globals.get_globals
Warning: Variable 'sig_on_count' referenced here was set only in doctest marked '# needs sage.modules'
    sig_on_count() # check sig_on/off pairings (virtual doctest)

An initial investigation suggests:

The string sig_on_count() # check sig_on/off pairings (virtual doctest) is from src/sage/doctest/sources.py line 234.
As I understand it, the warning is caused by a bug in the method _create_doctests() in the same file, which fails to add optional tags correctly to the string.

Expected Behavior

No warning.

Actual Behavior

Spurious warnings

Additional Information

@mkoeppe would know how to fix it.

Environment

- **OS**:
- **Sage Version**:

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[RuchitJagodara]

Hey! I was trying to post on Google Groups, but it seems that I don't have permission to do so. Therefore, I am posting it here.

@dcoudert, could you please provide more information regarding reproducing this? It seems that there have been some changes because I just saw a file described in the first warning, which is src/sage/plot/plot.py. However, I couldn't find anything similar to sig_on_count, and the line described in that warning does not contain any code; it only includes the end of a comment block.

[dcoudert]

As explained by @kwankyu above, this is a side effect of other mechanisms. I have no clue how to fix that.

[mkoeppe]

sig_on_count comes from a "virtual doctest" that the doctest framework injects, and the doctest framework also directly manipulates the "user globals" mechanism.

I'll check if I have fixes for the warnings in sage.plot already in #35095.

[RuchitJagodara]

Ok, thank you ! And if changes are needed then please tell me, I will be happy to help in this.