wip #5

	name: Version check
	on: [ push ]
	jobs:
	check:
	runs-on: ubuntu-20.04
	steps:
	- uses: actions/checkout@v4
	with:
	# So that we get the branch for `GITHUB_HEAD_REF`.
	fetch-depth: 0
	- name: Check version
	run: \|

	import os
	import re
	import subprocess
	import sys

	# Parses version number from the SConstruct file.
	def version() :

	versions = {}
	versionRe = re.compile( r"^(gaffer.Version.) = (\S+)" )
	with open( "SConstruct" ) as sconstruct :
	for line in sconstruct.readlines() :
	versionMatch = versionRe.match( line )
	if versionMatch :
	versions[versionMatch.group( 1 )] = versionMatch.group( 2 ).strip( "'\"" )

	return [
	int( versions["gafferMilestoneVersion"] ),
	int( versions["gafferMajorVersion"] ),
	]

	# Check that versions match between source and target branches, to avoid
	# common mistake of targeting a PR to `main` rather than a maintenance branch.
	#
	# > Note : We compare the source version to the merged version rather than the
	# > version from the target branch itself, to allow a PR to change version number
	# > if necessary. That will just be subject to the usual human review process.

	mergeVersion = version()
	subprocess.check_call( [ "git", "checkout", "1.4_maintenance" ] ) #os.environ["GITHUB_HEAD_REF"] ] )
	sourceVersion = version()

	if sourceVersion != mergeVersion :
	sys.stderr.write(
	"ERROR : Source version {} does not match target version {}. Did you choose the wrong target branch?\n".format(
	".".join( str( v ) for v in sourceVersion ),
	".".join( str( v ) for v in mergeVersion )
	)
	)
	sys.exit( 1 )

	shell: python

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