🔒 `ast.unparse` keeps adding unwanted line breaks to any new nodes from my `NodeTransformer`

[halcyon gulch]

I've tried:

• ast.fix_missing_locations
• ast.copy_location

and I have verified in my debugger that the location fields are identical to that of the node I am replacing.

Is there something I am missing?

[tribal olive]

@halcyon gulch

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[oblique slate]

are you saying unparse returns syntactically incorrect code, or code that does something other than the ast tree would suggest?

[halcyon gulch]

Well, in this case, it was syntactically incorrect.

I was transforming a Constant into an Expr. This seems like some possibly erroneous logic inside of python's internal _Unparser class.

I managed to work around it by adding .value to the Expr node and then copied the original node's location, and then returned it.

[pine fractal]

Can we see some example?

[oblique slate]

do you have sample code that demonstrates the problem? i'm interested in this, even if you already have a workaround

[halcyon gulch]

@velvet bloom Do you have the example that you used to reproduce this?

[velvet bloom]

!e

import ast
class Foo(ast.NodeTransformer):
    def visit_Constant(self, node):
        return ast.parse('1').body[0]
f = Foo()
g = f.visit(ast.parse('a=1\nb=2'))
print(ast.unparse(g))
print(ast.dump(g, indent=2))

[tribal olive]

:white_check_mark: Your 3.12 eval job has completed with return code 0.

001 | a = 
002 | 1
003 | b = 
004 | 1
005 | Module(
006 |   body=[
007 |     Assign(
008 |       targets=[
009 |         Name(id='a', ctx=Store())],
010 |       value=Expr(
... (truncated - too many lines)

Full output: https://paste.pythondiscord.com/NYYDKIDH7YATYKZ6IR45ZZ2MME

[velvet bloom]

i don't think it's an error in python's unparser, or at least it's just unparse accepting something that isn't valid; Assign shouldn't have an Expr as a value to begin with

!e

import ast
print(ast.dump(ast.parse('a=1'), indent=2))

[tribal olive]

:white_check_mark: Your 3.12 eval job has completed with return code 0.

001 | Module(
002 |   body=[
003 |     Assign(
004 |       targets=[
005 |         Name(id='a', ctx=Store())],
006 |       value=Constant(value=1))],
007 |   type_ignores=[])

[velvet bloom]

also fwiw instead of ast.parse(...).body[0].value you should probably just do ast.parse(..., mode='eval').value

[tribal olive]

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