fix/python nested function declaration

[nohehf]

This fixes #404.
The problem was that the stanza targeted every function first param, not only methods.
As:

let @body.class_self_scope = #null
let @body.class_member_attr_scope = #null

Was run for each function, nested function would try to create an edge to a null value:

  edge @param.def -> @first_param.class_self_scope
  edge @param.class_member_attr_scope -> @first_param.output

I actually think there might be an issue with TSG itself, as class_self_scope and class_member_attr_scope are inherited, setting those to null for the function scope should fallback to a higher parent. I might investigate on this.

[Manue1137]

Cambio

[hendrikvanantwerpen]

Thanks! I left two suggestions, but overall this looks sensible.

[hendrikvanantwerpen]

Do you have an idea what program might trigger this? Even if we don't fix it now, we can document it by adding test and giving it the .skip suffix.

[nohehf]

It does not enters this branch anymore now that we only target method definitions (first level functions in classes). But I started testing stuff on tree-sitter-graph and the following stanzas reproduce this behaviour:

inherit .scope
(module) @mod {
    let @mod.scope = "module"
}

(function_definition) @def {
    let @def.scope = #null
}

(pass_statement) @pass {
    print @pass.scope ; will be null, not module
}

def f():
    pass

I don't think it is an issue anymore in stack-graphs tho (at least for python).
Maybe this is the expected behaviour but then being able to set a property to "undefined" / unset it would be useful. Let's track this in tree-sitter-graph.

[hendrikvanantwerpen]

I'm not sure I completely understand the issue, but if this cannot be triggered by a Python program here, let's remove the comment.

[nohehf]

I'll make sure to open an issue on tree sitter graph, just to keep track of it (as it might be an issue in the future), I removed the comment.
I'm not sure those two lines are needed at all now, but I might have missed something (and it's out of this pr scope I believe)

  ; Prevent functions defined inside of method bodies from being treated like methods
  let @body.class_self_scope = #null
  let @body.class_member_attr_scope = #null