[BUG] Compiler crash with class method and memory view with default None value

[cphyc]

Describe the bug

The cython compiler crashes when analysing a class method that has a memory view with a default None value with the following traceback

analyse_types not implemented
Called from: CoerceToMemViewSliceNode.not_implemented 485
Called from: CoerceToMemViewSliceNode.analyse_types 719
Called from: TupleNode.analyse_types 8084
Called from: PyCFunctionNode.analyse_default_args 9493
Called from: PyCFunctionNode.analyse_types 9410
Called from: SingleAssignmentNode.analyse_types 5827
Called from: SingleAssignmentNode.analyse_expressions 5707
Called from: <listcomp> 396
Called from: StatListNode.analyse_expressions 396
Called from: CClassDefNode.analyse_expressions 5233
Called from: <listcomp> 396
Called from: StatListNode.analyse_expressions 396
Called from: AnalyseExpressionsTransform.visit_ModuleNode 2351
Called from: run 352
Called from: run_pipeline 372
Called from: run_pipeline 505
Called from: compile_multiple 607
Called from: compile 630
Called from: main 732
Called from: setuptools_main 714
Called from: <module> 8
----------------------------------------------------------------------

Error compiling Cython file:
------------------------------------------------------------
...
cdef class Foo:
    def test(self, int[:] bar = None):
                               ^
------------------------------------------------------------

test.pyx:2:32: Compiler crash in AnalyseExpressionsTransform

File 'Nodes.py', line 396, in analyse_expressions: StatListNode(test.pyx:1:5)
File 'Nodes.py', line 5233, in analyse_expressions: CClassDefNode(test.pyx:1:5,
    as_name = 'Foo',
    class_name = 'Foo',
    module_name = '',
    punycode_class_name = 'Foo',
    visibility = 'private')
File 'Nodes.py', line 396, in analyse_expressions: StatListNode(test.pyx:2:4)
File 'Nodes.py', line 5707, in analyse_expressions: SingleAssignmentNode(test.pyx:2:4)
File 'Nodes.py', line 5827, in analyse_types: SingleAssignmentNode(test.pyx:2:4)
File 'ExprNodes.py', line 9410, in analyse_types: PyCFunctionNode(test.pyx:2:4,
    binding = True,
    is_temp = 1,
    pymethdef_cname = '__pyx_mdef_4test_3Foo_1test',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 9493, in analyse_default_args: PyCFunctionNode(test.pyx:2:4,
    binding = True,
    is_temp = 1,
    pymethdef_cname = '__pyx_mdef_4test_3Foo_1test',
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 8084, in analyse_types: TupleNode(test.pyx:2:4,
    is_sequence_constructor = 1,
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 719, in analyse_types: CoerceToMemViewSliceNode(test.pyx:2:32,
    is_temp = 1,
    result_is_used = True,
    use_managed_ref = True)
File 'ExprNodes.py', line 486, in not_implemented: CoerceToMemViewSliceNode(test.pyx:2:32,
    is_temp = 1,
    result_is_used = True,
    use_managed_ref = True)

Compiler crash traceback from this point on:
  File "/home/ccc/anaconda3/envs/py39/lib/python3.9/site-packages/Cython/Compiler/ExprNodes.py", line 486, in not_implemented
    raise InternalError(
InternalError: Internal compiler error: CoerceToMemViewSliceNode.analyse_types not implemented

To Reproduce
Minimal code to reproduce the behaviour:

# This results in a compiler crash
cdef class Foo:
    def test(self, int[:] bar = None):
        pass

Note that the compiler properly handles the following

# This compiles fine
def test(int[:] bar = None):
    pass

Expected behavior
The code should compile fine.

Environment (please complete the following information):

• OS: Linux
• Python version 3.7.11 and 3.9.5
• Cython version 3.0a7, 3.0.0a8, 3.0.0a9 (works on any version <=3.0a6)

Additional information:
The traceback above is with Python 3.9.5 and Cython 3.0.0a9.

[cphyc]

After a git bisection, it seems the crash appeared in ee7ae0b. Reverting the aforementioned commit fixes this specific issue (see attached patch).
patch.txt

[scoder]

Interesting. Thanks for reporting this. I was sure that default arguments are tested, but yeah, the usage in a method of an extension type might not be.

[neutrinoceros]

Any chance this could be triaged into the 3.0 milestone ? I would also like to point out that #4315 isn't currently linked as a fix.