Go to def fails because we can't find this attribute

[lolpack]

Describe the Bug

ERROR 14:31-45: Instance-only attribute args of class arguments is not visible on the class [missing-attribute] https://github.com/lolpack/type_coverage_py/blob/main/analyzer/coverage_calculator.py#L52

Unable to find instance variable: https://pyrefly.org/sandbox/?code=MYGwhgzhAECCDKAVAXAKGh6AHSFWtF2jACcBzAVwFsBTAOwBcIAKBRASjU2PImWhABLCAwDaIkgF18hKNABiFOsAaCA9nQAiNAGaskndJlJkYAXh6VajPEYwATXdAD6zwXUENXzCDRA6AGks+S2p6JnZoAFoAPmgAOQ0afgA6NPxURx1oMhovHBIwKhY6NUd+RWVVDW0dQ25MEjyKEjpoURNoHTUSS2h3aFLHFJMIEd5pIA

It works in Pyright strict mode: https://pyright-play.net/?pyrightVersion=1.1.374&pythonVersion=3.13&strict=true&code=MYGwhgzhAECCDKAVAXAKGh6AHSFWtF2jACcBzAVwFsBTAOwBcIAKBRASjU2PImWhABLCAwDaIkgF18hKNABiFOsAaCA9nQAiNAGaskndJlJkYAXh6VajPEYwATXdAD6zwXUENXzCDRA6AGks%2BS2p6JnZoAFoAPmgAOQ0afgA6NPxURx1oMhovHBIwKhY6NUd%2BRWVVDW0dQ25MEjyKEjpoURNoHTUSS2h3aFLHFJMIEd5pIA

Sandbox Link

No response

(Only applicable for extension issues) IDE Information

No response

[indivisible]

looks like a pyright issue to me, the code is badly typed. Here are two possible correct versions: one, two

[lolpack]

@indivisible you are right, the example sandbox I provided above is wrong. I don't think I accurately recreated a minimal example. If you open the file I attached above https://github.com/lolpack/type_coverage_py/blob/main/analyzer/coverage_calculator.py#L52 and try to click on the second "args" in node.args.args Pyrefly can't find it while Pyright can

[lolpack]

Adding reveal type shows that for some reason node is being widened

                        if func_name in analyzed_functions:
                            reveal_type(node) # FunctionDef
                            continue

                        reveal_type(node) # AST

                        analyzed_functions.add(func_name)

                        # Exclude 'self' and 'cls' from parameters
                        params = [
                            arg for arg in node.args.args if arg.arg not in ('self', 'cls')]
                        param_count = len(params)

So node becomes AST again after previously being narrowed to FunctionDef

[grievejia]

This is definitely a type checking issue. Minimal repro:

class A: pass
class B(A):
    x: int

def foo(node: B) -> str: ...
def test(node: A, d: dict[str, int]) -> None:
    for n in [node]:
        if isinstance(n, B):
            x = foo(n)
            if False:
                continue
            foo(n)  # E: Argument `A` is not assignable to parameter `node` with type `B` in function `foo`
            if True:
                d[x] = 0