ruff/crates/ty_python_semantic/resources/mdtest/diagnostics/missing_argument.md

Missing argument diagnostics

If a non-union callable is called with a required parameter missing, we add a subdiagnostic showing where the parameter was defined. We don't do this for unions as we currently emit a separate diagnostic for each element of the union; having a sub-diagnostic for each element would probably be too verbose for it to be worth it.

module.py:

def f(a, b=42): ...
def g(a, b): ...

class Foo:
    def method(self, a): ...

main.py:

from module import f, g, Foo

f()  # error: [missing-argument]

def coinflip() -> bool:
    return True

h = f if coinflip() else g

# error: [missing-argument]
# error: [missing-argument]
h(b=56)

Foo().method()  # error: [missing-argument]