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I tried some debugging code:
diff --git a/Python/ceval.c b/Python/ceval.c
index f745067069..a8668dbac2 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -4864,6 +4864,18 @@ get_exception_handler(PyCodeObject *code, int index)
 return res;
 }
 scan = skip_to_next_entry(scan);
+ if (scan
+ >= (unsigned char *)PyBytes_AS_STRING(code->co_exceptiontable)
+ + PyBytes_GET_SIZE(code->co_exceptiontable))
+ {
+ printf("co_name: --------------------------\n");
+ _PyObject_Dump(code->co_name);
+ printf("co_filename: ----------------------\n");
+ _PyObject_Dump(code->co_filename);
+ printf("co_exceptiontable: -------------\n");
+ _PyObject_Dump(code->co_exceptiontable);
+ printf("\n\n\n\n\n");
+ }
 }
 res.b_handler = -1;
 return res;
It output this:
Python 3.11.0a0 (heads/main-dirty:092f9ddb5e, May 9 2021, 18:45:56) [MSC v.1927 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from test.test_statistics import *
co_name: --------------------------
object address : 00000254B63EFB80
object refcount : 7
object type : 00007FFA1C7E71C0
object type name: str
object repr : '_find_and_load'
co_filename: ----------------------
object address : 00000254B63967A0
object refcount : 76
object type : 00007FFA1C7E71C0
object type name: str
object repr : '<frozen importlib._bootstrap>'
co_exceptiontable: -------------
object address : 00000254B63EB290
object refcount : 1
object type : 00007FFA1C7C9A40
object type name: bytes
object repr : b'\x84\x10"\x03\xa2\x04&\x0b\xa7\x03&\x0b'
>>> unittest.main()
............................................................................................................................................................................................................................................................................................................................................................................
----------------------------------------------------------------------
Ran 364 tests in 24.409s
OK
Here is the disassembly of the offending function:
>>> from dis import dis
>>> from importlib._bootstrap import _find_and_load
>>> dis(_find_and_load)
1024 0 LOAD_GLOBAL 0 (_ModuleLockManager)
 2 LOAD_FAST 0 (name)
 4 CALL_FUNCTION 1
 6 BEFORE_WITH
 8 POP_TOP
1025 10 LOAD_GLOBAL 1 (sys)
 12 LOAD_ATTR 2 (modules)
 14 LOAD_METHOD 3 (get)
 16 LOAD_FAST 0 (name)
 18 LOAD_GLOBAL 4 (_NEEDS_LOADING)
 20 CALL_METHOD 2
 22 STORE_FAST 2 (module)
1026 24 LOAD_FAST 2 (module)
 26 LOAD_GLOBAL 4 (_NEEDS_LOADING)
 28 IS_OP 0
 30 POP_JUMP_IF_FALSE 27 (to 54)
1027 32 LOAD_GLOBAL 5 (_find_and_load_unlocked)
 34 LOAD_FAST 0 (name)
 36 LOAD_FAST 1 (import_)
 38 CALL_FUNCTION 2
1024 40 ROT_TWO
 42 LOAD_CONST 1 (None)
 44 DUP_TOP
 46 DUP_TOP
 48 CALL_FUNCTION 3
 50 POP_TOP
1027 52 RETURN_VALUE
1026 >> 54 NOP
1024 56 LOAD_CONST 1 (None)
 58 DUP_TOP
 60 DUP_TOP
 62 CALL_FUNCTION 3
 64 POP_TOP
 66 JUMP_FORWARD 11 (to 90)
 >> 68 PUSH_EXC_INFO
 70 WITH_EXCEPT_START
 72 POP_JUMP_IF_TRUE 39 (to 78)
 74 RERAISE 4
 >> 76 POP_EXCEPT_AND_RERAISE
 >> 78 POP_TOP
 80 POP_TOP
 82 POP_TOP
 84 POP_EXCEPT
 86 POP_TOP
 88 POP_TOP
1029 >> 90 LOAD_FAST 2 (module)
 92 LOAD_CONST 1 (None)
 94 IS_OP 0
 96 POP_JUMP_IF_FALSE 60 (to 120)
1030 98 LOAD_CONST 2 ('import of {} halted; None in sys.modules')
1031 100 LOAD_METHOD 6 (format)
 102 LOAD_FAST 0 (name)
 104 CALL_METHOD 1
1030 106 STORE_FAST 3 (message)
1032 108 LOAD_GLOBAL 7 (ModuleNotFoundError)
 110 LOAD_FAST 3 (message)
 112 LOAD_FAST 0 (name)
 114 LOAD_CONST 3 (('name',))
 116 CALL_FUNCTION_KW 2
 118 RAISE_VARARGS 1
1034 >> 120 LOAD_GLOBAL 8 (_lock_unlock_module)
 122 LOAD_FAST 0 (name)
 124 CALL_FUNCTION 1
 126 POP_TOP
1035 128 LOAD_FAST 2 (module)
 130 RETURN_VALUE
ExceptionTable:
 8 to 38 -> 68 [1] lasti
 68 to 74 -> 76 [5] lasti
 78 to 82 -> 76 [5] lasti
I don't know whether there just needs to be a sentinel 128 appended to all co_exceptiontable, or if there is a more subtle bug.