inspect.signature(math.log) raises ValueError

[remilapeyre]

BPO	36306
Nosy	@larryhastings, @remilapeyre
Superseder	bpo-29299: Argument Clinic: Fix signature of optional positional-only arguments

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2019-03-15.17:22:08.833>
created_at = <Date 2019-03-15.16:44:25.059>
labels = ['3.8', 'type-bug', '3.7', 'expert-argument-clinic']
title = 'inspect.signature(math.log) raises ValueError'
updated_at = <Date 2019-03-15.17:24:08.720>
user = 'https://github.com/remilapeyre'

bugs.python.org fields:

activity = <Date 2019-03-15.17:24:08.720>
actor = 'SilentGhost'
assignee = 'none'
closed = True
closed_date = <Date 2019-03-15.17:22:08.833>
closer = 'remi.lapeyre'
components = ['Argument Clinic']
creation = <Date 2019-03-15.16:44:25.059>
creator = 'remi.lapeyre'
dependencies = []
files = []
hgrepos = []
issue_num = 36306
keywords = []
message_count = 4.0
messages = ['338002', '338008', '338010', '338012']
nosy_count = 3.0
nosy_names = ['larry', 'SilentGhost', 'remi.lapeyre']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '29299'
type = 'behavior'
url = 'https://bugs.python.org/issue36306'
versions = ['Python 3.7', 'Python 3.8']

[remilapeyre]

>>> import math, inspect
>>> inspect.signature(math.log)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/remi/src/cpython/Lib/inspect.py", line 3081, in signature
    return Signature.from_callable(obj, follow_wrapped=follow_wrapped)
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2830, in from_callable
    return _signature_from_callable(obj, sigcls=cls,
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2284, in _signature_from_callable
    return _signature_from_builtin(sigcls, obj,
  File "/Users/remi/src/cpython/Lib/inspect.py", line 2109, in _signature_from_builtin
    raise ValueError("no signature found for builtin {!r}".format(func))
ValueError: no signature found for builtin <built-in function log>
>>>

This is the only function from math to do so, it may be related to issue 29299 but the patch from Victor Stinner does not fix this.

[SilentGhost]

It's the only function with an optional argument in math, on 3.7 all such function result in ValueError, e.g. getattr, iter, max.

[SilentGhost]

In fact, I don't see anything warranting a separate issue. I'd suggest to close this and perhaps ping Larry instead on the bpo-29299 which you mentioned.

[remilapeyre]

Yes you are right, this is actually the same issue. I will try to look for the other attempts Serhiy Storchaka talks about in bpo-29299 and ping Larry on this issue.

(I can't set the superseeded flag on this issue thought)