incorrect source ranges for `not a in b`
Open
@Eclips4 is already working on this.
Since May 31, 2026.
3.14
3.15
interpreter-core
type-bug
- Dominant language
- Python
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Description
Bug report
Bug description:
python includes the not in the source ranges with 3.14.0-rc2.
class C:
def __contains__(self, other):
assert False
print(not 1 in C())
output (Python 3.14.0rc2+):
Traceback (most recent call last):
File "/home/frank/projects/executing/example.py", line 6, in <module>
print(not 1 in C())
^^^^^^^^^^^^
File "/home/frank/projects/executing/example.py", line 3, in __contains__
assert False
^^^^^
AssertionError
This was not the case in 3.13
output (Python 3.13.1):
Traceback (most recent call last):
File "/home/frank/projects/executing/example.py", line 6, in <module>
print(not 1 in C())
^^^^^^^^
File "/home/frank/projects/executing/example.py", line 3, in __contains__
assert False
^^^^^
AssertionError
I bisected the problem down to 38642bff139bde5c0118bc75fda25badc76b85fc @WolframAlph maybe you want to take a look at it?
This was the test which I used to bisect the problem:
import dis
for inst in dis.Bytecode(compile("not a in b","","exec")):
if inst.opname=="CONTAINS_OP":
assert inst.positions.col_offset==4
CPython versions tested on:
3.14, 3.15, CPython main branch
Operating systems tested on:
No response
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