subprocess.run on windows does not convert path to string

[kaushikghose]

BPO	41753
Nosy	@terryjreedy, @pfmoore, @ericvsmith, @tjguk, @zware, @eryksun, @zooba
Superseder	bpo-41649: Can't pass Path like objects to subprocess api's on Windows.

^{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 2020-09-12.01:25:10.406>
created_at = <Date 2020-09-09.17:54:01.855>
labels = ['type-bug', '3.7', 'OS-windows']
title = 'subprocess.run on windows does not convert path to string'
updated_at = <Date 2020-09-12.01:25:43.086>
user = 'https://bugs.python.org/kaushikghose'

bugs.python.org fields:

activity = <Date 2020-09-12.01:25:43.086>
actor = 'terry.reedy'
assignee = 'none'
closed = True
closed_date = <Date 2020-09-12.01:25:10.406>
closer = 'terry.reedy'
components = ['Windows']
creation = <Date 2020-09-09.17:54:01.855>
creator = 'kaushik.ghose'
dependencies = []
files = []
hgrepos = []
issue_num = 41753
keywords = []
message_count = 5.0
messages = ['376651', '376653', '376654', '376657', '376759']
nosy_count = 8.0
nosy_names = ['terry.reedy', 'paul.moore', 'eric.smith', 'tim.golden', 'zach.ware', 'eryksun', 'steve.dower', 'kaushik.ghose']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '41649'
type = 'behavior'
url = 'https://bugs.python.org/issue41753'
versions = ['Python 3.7']

[kaushikghose]

a call of the form subprocess.run([x, y, z]) where one of the elements is a pathlib.Path fails on windows because the path is not converted to a string as it should. This works fine (as expected) on macOS and Linux.

A typical error message is:

TypeError: argument of type 'WindowsPath' is not iterable

[ericvsmith]

Among others, see:
bpo-41649
bpo-31961

In general, I think the consensus is that the caller should convert each argument to a string. It's not subprocess's job to convert each parameter to a string.

[kaushikghose]

Thank you for your response.

There are two concerns I have here.

1. Python's promise of being straightforward. In MOST cases pathlib.Path objects do the right thing, casting to a string such that pathlib.Path is a drop in replacement. This exception is unexpected.

2. Cross platform consistency. Looks like this works on macOS and Linux. Why should it fail on Windows?

Thanks!

[eryksun]

The underlying subprocess.Popen class was updated in 3.8 to support path-like objects in args (with shell=False) and executable on Windows [1]. This change was not backported to 3.6 and 3.7.

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[1] https://docs.python.org/3/library/subprocess.html#subprocess.Popen

[terryjreedy]

Also, 3.7 only get security patches.