Differential D7910 Diff 24601 test/lint/lint-python-mutable-default-parameters.sh

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Property	Old Value	New Value
File Mode	null	100755

				#!/usr/bin/env bash
				#
				# Copyright (c) 2019 The Bitcoin Core developers
				# Distributed under the MIT software license, see the accompanying
				# file COPYING or http://www.opensource.org/licenses/mit-license.php.
				#
				# Detect when a mutable list or dict is used as a default parameter value in a Python function.

				export LC_ALL=C
				EXIT_CODE=0
				OUTPUT=$(git grep -E '^\sdef [a-zA-Z0-9_]+\(.=\s(\[\|\{)' -- ".py")
				if [[ ${OUTPUT} != "" ]]; then
				echo "A mutable list or dict seems to be used as default parameter value:"
				echo
				echo "${OUTPUT}"
				echo
				cat << EXAMPLE
				This is how mutable list and dict default parameter values behave:

				>>> def f(i, j=[], k={}):
				... j.append(i)
				... k[i] = True
				... return j, k
				...
				>>> f(1)
				([1], {1: True})
				>>> f(1)
				([1, 1], {1: True})
				>>> f(2)
				([1, 1, 2], {1: True, 2: True})

				The intended behaviour was likely:

				>>> def f(i, j=None, k=None):
				... if j is None:
				... j = []
				... if k is None:
				... k = {}
				... j.append(i)
				... k[i] = True
				... return j, k
				...
				>>> f(1)
				([1], {1: True})
				>>> f(1)
				([1], {1: True})
				>>> f(2)
				([2], {2: True})
				EXAMPLE
				EXIT_CODE=1
				fi
				exit ${EXIT_CODE}