Breaking change in lxml 5.0.0

[M0WUT]

Found as part of using kikit. Running pcbdraw plot --vcuts=Cmts.User --side=front <path-to-pcb> <path-to-png-out> completes successfully with lxml 4.9.3 installed. Upgrading lxml to 5.0.0 (which was released on 29th December2023) gives the following:

Traceback (most recent call last):
File "/home/runner/.local/bin/pcbdraw", line 8, in
sys.exit(run())
File "/usr/lib/python3/dist-packages/click/core.py", line 1128, in call
return self.main(*args, **kwargs)
File "/usr/lib/python3/dist-packages/click/core.py", line 1053, in main
rv = self.invoke(ctx)
File "/usr/lib/python3/dist-packages/click/core.py", line 1659, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/usr/lib/python3/dist-packages/click/core.py", line 1395, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/usr/lib/python3/dist-packages/click/core.py", line 754, in invoke
return __callback(*args, **kwargs)
File "/home/runner/.local/lib/python3.10/site-packages/pcbdraw/ui.py", line 180, in plot
image = plotter.plot()
File "/home/runner/.local/lib/python3.10/site-packages/pcbdraw/plot.py", line 1052, in plot
self._setup_document(self.render_back, self.mirror)
File "/home/runner/.local/lib/python3.10/site-packages/pcbdraw/plot.py", line 1311, in _setup_document
self._document = empty_svg(
File "/home/runner/.local/lib/python3.10/site-packages/pcbdraw/plot.py", line 394, in empty_svg
document = etree.ElementTree(etree.fromstring(
File "src/lxml/etree.pyx", line 3265, in lxml.etree.fromstring
File "src/lxml/parser.pxi", line 1975, in lxml.etree._parseMemoryDocument
File "src/lxml/parser.pxi", line 1855, in lxml.etree._parseDoc
File "src/lxml/parser.pxi", line 1086, in lxml.etree._BaseParser._parseUnicodeDoc
File "src/lxml/parser.pxi", line 618, in lxml.etree._ParserContext._handleParseResultDoc
File "src/lxml/parser.pxi", line 728, in lxml.etree._handleParseResult
File "src/lxml/parser.pxi", line 657, in lxml.etree._raiseParseError
File "", line 1
lxml.etree.XMLSyntaxError: Blank needed here, line 1, column 21

Uninstalling lxml and force installing version 4.9.3 causes it to work again.

Thanks,
Dan

[Electro707]

Can confirm this is an issue.

Trying to investigate for a bit, but I am not familiar with the lxml library

[yaqwsx]

We are not alone: python-openxml/python-docx#1302

LXML refuses to parse our empty SVG template:

PcbDraw/pcbdraw/plot.py

Lines 396 to 404 in 0a137fe

	document = etree.ElementTree(etree.fromstring(
	"""<?xml version="1.0" standalone="no"?>
	<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
	"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
	<svg xmlns="http://www.w3.org/2000/svg" version="1.1"
	width="29.7002cm" height="21.0007cm" viewBox="0 0 116930 82680 ">
	<title>Picture generated by PcbDraw </title>
	<desc>Picture generated by PcbDraw</desc>
	</svg>"""))

It complains that a space is missing before standalone... which there is. I haven't been able to identify the root cause at the moment.

[ofaurax]

It should work if you remove the standalone="no"

[ofaurax]

I reported it here: https://gitlab.gnome.org/GNOME/libxml2/-/issues/661