Cython: Crash on type annotations with 'or'

[misantroop]

Not good practice necessarily but how would one go about writing this if possible at all?

Basic example:

def func() -> list or dict: return []

Debug from a complex example:

    def next(self, asObj: bool = False) -> numpy.ndarray or list:
                                            ^
------------------------------------------------------------

src/ipo.py:351:45: Compiler crash in AnalyseExpressionsTransform
File 'Nodes.py', line 436, in analyse_expressions: StatListNode(ipo.py:2:0)
File 'Nodes.py', line 436, in analyse_expressions: StatListNode(ipo.py:337:0)
File 'Nodes.py', line 4578, in analyse_expressions: PyClassDefNode(ipo.py:337:0,
    name = 'Calendar')
File 'Nodes.py', line 436, in analyse_expressions: StatListNode(ipo.py:338:1)
File 'Nodes.py', line 5159, in analyse_expressions: SingleAssignmentNode(ipo.py:351:1)
File 'Nodes.py', line 5279, in analyse_types: SingleAssignmentNode(ipo.py:351:1)
File 'ExprNodes.py', line 9225, in analyse_types: PyCFunctionNode(ipo.py:351:1,
    binding = True,
    is_temp = 1,
    pymethdef_cname = '__pyx_mdef_9ipo_8Calendar_7next',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 9270, in analyse_default_args: PyCFunctionNode(ipo.py:351:1,
    binding = True,
    is_temp = 1,
    pymethdef_cname = '__pyx_mdef_9ipo_8Calendar_7next',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 9358, in analyse_annotation: PyCFunctionNode(ipo.py:351:1,
    binding = True,
    is_temp = 1,
    pymethdef_cname = '__pyx_mdef_9ipo_8Calendar_7next',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 11858, in analyse_types: BoolBinopNode(ipo.py:351:54,
    is_temp = True,
    operator = 'or',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 664, in analyse_types: BoolBinopResultNode(ipo.py:351:45,
    is_temp = True,
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 462, in not_implemented: BoolBinopResultNode(ipo.py:351:45,
    is_temp = True,
    result_is_used = True,
    use_managed_ref = True)


Compiler crash traceback from this point on:
  File "/home/misantroop/.local/lib/python3.7/site-packages/Cython/Compiler/ExprNodes.py", line 462, in not_implemented
    (self.__class__.__name__, method_name))
InternalError: Internal compiler error: BoolBinopResultNode.analyse_types not implemented
Traceback (most recent call last):
  File "setup.py", line 13, in <module>
    ext_modules = cythonize("src/*.py", language_level=3),
  File "/home/misantroop/.local/lib/python3.7/site-packages/Cython/Build/Dependencies.py", line 1096, in cythonize
    cythonize_one(*args)
  File "/home/misantroop/.local/lib/python3.7/site-packages/Cython/Build/Dependencies.py", line 1219, in cythonize_one
    raise CompileError(None, pyx_file)
Cython.Compiler.Errors.CompileError: src/ipo.py

[TeamSpen210]

Use object. There's nothing in common with those two types at a C-level, so Cython can't do any optimisations here. For parameters, you could potentially use fused types.

[robertwb]

The correct type to use here would be typing.Union[list, dict] (though Cython wouldn't be able to do anything with it). We shouldn't crash, however.

[scoder]

According to PEP 604, which is being discussed for Python 3.10, the future syntax for this will be list | dict. (But I agree that a crash is not a good way to signal that ;-) )