`configparser.RawConfigParser` stub does not account for non-string options

[jpy-git]

The stub for configparser.RawConfigParser.set has its value argument typed as str | None (source) when it can accept lots of other types and is leading to a false positive in mypy for me.

Consider this valid script:

from configparser import RawConfigParser

cfg = RawConfigParser()
cfg.add_section("default")

cfg.set("default", "some_option1", True)
r1 = cfg.get("default", "some_option1")
print(r1, type(r1))


cfg.set("default", "some_option2", 1)
r2 = cfg.get("default", "some_option2")
print(r2, type(r2))

cfg.set("default", "some_option3", b"bytes")
r3 = cfg.get("default", "some_option3")
print(r3, type(r3))

It prints:

True <class 'bool'>
1 <class 'int'>
b'bytes' <class 'bytes'>

However, mypy flags this code for the reason described above:

test.py:6: error: Argument 3 to "set" of "RawConfigParser" has incompatible type "bool"; expected "Optional[str]"
test.py:11: error: Argument 3 to "set" of "RawConfigParser" has incompatible type "int"; expected "Optional[str]"
test.py:15: error: Argument 3 to "set" of "RawConfigParser" has incompatible type "bytes"; expected "Optional[str]"

[jpy-git]

Looking at the stub it also looks like get (and probably other methods) doesn't account for non-str options:

from configparser import RawConfigParser

cfg = RawConfigParser()
cfg.add_section("default")

cfg.set("default", "some_option", b"something")
r_bytes = cfg.get("default", "some_option")
r_str = r_bytes.decode()
print(r_str, type(r_str))

gives mypy errors:

test.py:6: error: Argument 3 to "set" of "RawConfigParser" has incompatible type "bytes"; expected "Optional[str]"
test.py:8: error: "str" has no attribute "decode"; maybe "encode"?
Found 2 errors in 1 file (checked 1 source file)

[jpy-git]

note that ConfigParser, which inherits from RawConfigParser, does indeed only accept str options (test by switching out RawConfigParser in provided script). So we can use the current RawConfigParser stubs for ConfigParser.

[jpy-git]

For context this came up when doing a code review and the docs suggest RawConfigParser is the legacy version of ConfigParser so I advised updating the code to use ConfigParser and converting the options to str.

Given that it's legacy fixing this stub is relatively low prio, but will leave the issue open should someone want to pick it up 😄