New submission from midori :
Hi all, this is probably my first issue here, so don't blame me if I do
something wrong lol
The ast.FunctionType gives syntax like (a, b) -> c for function types, this is
ok, and also since Python 3.10 we can use X | Y to denote unions, this is ok.
So Given the following two trees:
fun1 = ast.FunctionType(
argtypes=[],
returns=ast.BinOp(
left=ast.Name(id='int'),
op=ast.BitOr(),
right=ast.Name(id='float'),
)
)
fun2 = ast.BinOp(
left=ast.FunctionType(
argtypes=[],
returns=ast.Name(id='int'),
),
op=ast.BitOr(),
right=ast.Name(id='float'),
)
Calling:
print(ast.unparse(fun1))
print(ast.unparse(fun2))
The results are these:
() -> int | float
() -> int | float
So there is some ambiguity. By feeding this string to
ast.parse(mode='func_type'), I know that it means "returning a union".
Don't know if there is any impact to simply add a pair of parens, or does this
problem even matters at all.
I tested it using Python 3.10 a6 and Python 3.9.2.
--
components: Library (Lib)
messages: 389429
nosy: Batuhan Taskaya, cleoold
priority: normal
severity: normal
status: open
title: ast.unparse-ing a FunctionType gives ambiguous result
type: behavior
versions: Python 3.10
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Python tracker
<https://bugs.python.org/issue43609>
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