Python: How do I find all functions that return tuples explicitly?

I would like to find all functions that return an explicit tuple. E.g.,

    ...
    return x, y

would be in, but

    ...
    return {"x":x, "y":y}

would be out, so regexp searching for return .*, would return too many false positives.

I suspect that pylint/astroid might do what I want, but I am open to all suggestions.

PS. There are no type annotations - I would rather have something generate them automatically, like in ocaml.

Here's a pylint plugin that does what you want.

from astroid import nodes

from pylint.checkers import BaseChecker


class TupleReturnChecker(BaseChecker):
    msgs = {
        "W5100": (
            "Tuple in return %s",
            "tuple-in-return",
            "Raised when a tuple is returned.",
        )
    }

    def visit_return(self, node: nodes.Return) -> None:
        if isinstance(node.value, nodes.Tuple):
            self.add_message("tuple-in-return", args=node.as_string())

But you don't need to use astroid/pylint for that simple case, an ast.NodeVisitor would looks pretty much the same.

import ast

class TupleDetector(ast.NodeVisitor):
   def visit_Return(self, node: ast.Return) -> None:
       if isinstance(node.value, ast.Tuple):
            print(f"{node} is a tuple")

detector = TupleDetector()
with open(code_path) as f:
    detector.visit(ast.parse(f.read()))

pylint would be useful if you have something possibly returning a tuple and you need inference.