fix(input_output): keyword-only pipeline parameters crash process_args with TypeError - #1785

The bug

process_arg_type_annotation takes two required parameters:

def process_arg_type_annotation(arg, default_value):   # input_output.py:241

process_args has four call sites. The two positional-argument branches pass both parameters; the two keyword-only branches pass only one:

So any pipeline whose signature contains a keyword-only parameter fails schema generation with:

TypeError: process_arg_type_annotation() missing 1 required positional argument: 'default_value'

The second half of the same bug

Fixing only the arity is not enough. ast keeps a None placeholder in kw_defaults for every keyword-only arg declared without a default, so len(args.kw_defaults) == len(args.kwonlyargs) always holds. That makes n_kwargs - n_kwargs_default always 0, so:

• the line-311 loop iterates over an empty slice and never runs — every keyword-only arg, with or without a default, goes through the line-316 loop;
• that loop then unconditionally does dft.value and appends has_default=True, which would AttributeError on the None placeholder and mislabel a required kw-only arg as optional.

So the fix reads the default through convert_to_value — exactly what the positional branch at line 304 already does — and derives has_default from whether a default is actually present.

Verification

Ran against the real modelscope.utils.input_output (no stubs), before and after:

                                  before                                            after
positional a:int, b:str='x'       [('a','int',False,None), ('b','str',True,'x')]     unchanged
kw-only  *, mode:str='fast'       TypeError (see above)                              [..., ('mode','str',True,'fast')]
kw-only  *, mode:str              TypeError (see above)                              [..., ('mode','str',False,None)]

Three tests added as ProcessArgsTest in tests/utils/test_input_output.py. The two keyword-only tests error on master with the exact TypeError; the positional test passes both before and after, pinning that the existing path is untouched:

# master
ERROR: test_keyword_only_arg_with_default    TypeError: ... missing 1 required positional argument: 'default_value'
ERROR: test_keyword_only_arg_without_default TypeError: ... missing 1 required positional argument: 'default_value'
Ran 3 tests — FAILED (errors=2)

# with this patch
Ran 3 tests in 0.001s — OK

yapf==0.30.0 (the pinned pre-commit rev) reports no diff on either file, isort is clean, and flake8 with the setup.cfg select/ignore set reports nothing new.

Out of scope, but noticed while verifying

convert_to_value ends in return UnhandledKeyType(), and UnhandledKeyType is not defined anywhere in the repo — so a non-literal default (e.g. def f(self, a: list = [1, 2])) raises NameError: name 'UnhandledKeyType' is not defined. That is pre-existing on the positional path and reproduces on master without this patch, so I left it alone rather than guessing at the intended sentinel type. Happy to send a follow-up if you tell me what it should return.

🤖 Generated with Claude Code