[Bug] tvm_ffi.get_global_func_metdata failed for functions that don't have metadata #208
Description
To reproduce this issue:
@tvm_ffi.register_global_func("my.add")
def add(a, b):
return a + b
tvm_ffi.get_global_func_metadata("my.add")Python-side global functions don't have metadata right now, which triggers the json parser to fail:
File ~/Projects/tvm-ffi/python/tvm_ffi/registry.py:271, in get_global_func_metadata(name)
236 def get_global_func_metadata(name: str) -> dict[str, Any]:
237 """Get metadata (including type schema) for a global function.
238
239 Parameters
(...) 269
270 """
--> 271 return json.loads(get_global_func("ffi.GetGlobalFuncMetadata")(name))
File ~/.local/share/uv/python/cpython-3.14.0-macos-aarch64-none/lib/python3.14/json/__init__.py:346, in loads(s, cls, object_hook, parse_float, parse_int, parse_constant, object_pairs_hook, **kw)
341 s = s.decode(detect_encoding(s), 'surrogatepass')
343 if (cls is None and object_hook is None and
344 parse_int is None and parse_float is None and
345 parse_constant is None and object_pairs_hook is None and not kw):
--> 346 return _default_decoder.decode(s)
347 if cls is None:
348 cls = JSONDecoder
File ~/.local/share/uv/python/cpython-3.14.0-macos-aarch64-none/lib/python3.14/json/decoder.py:345, in JSONDecoder.decode(self, s, _w)
340 def decode(self, s, _w=WHITESPACE.match):
341 """Return the Python representation of ``s`` (a ``str`` instance
342 containing a JSON document).
343
344 """
--> 345 obj, end = self.raw_decode(s, idx=_w(s, 0).end())
346 end = _w(s, end).end()
347 if end != len(s):
File ~/.local/share/uv/python/cpython-3.14.0-macos-aarch64-none/lib/python3.14/json/decoder.py:363, in JSONDecoder.raw_decode(self, s, idx)
361 obj, end = self.scan_once(s, idx)
362 except StopIteration as err:
--> 363 raise JSONDecodeError("Expecting value", s, err.value) from None
364 return obj, end
JSONDecodeError: Expecting value: line 1 column 1 (char 0)
A quick fix should be really easy - basically checking in registry.py::get_global_func_metadata if it's an empty string. Further improvement would be adding metadata to Python-side registered functions, etc