ElementTree won't parse comments before root element

[celinecyc]

BPO	38742
Nosy	@amauryfa, @scoder, @florentx, @celinecyc
Superseder	bpo-9521: xml.etree.ElementTree skips processing instructions when parsing

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2019-11-15.17:41:44.927>
created_at = <Date 2019-11-08.08:10:53.518>
labels = ['expert-XML', 'type-feature']
title = "ElementTree won't parse comments before root element"
updated_at = <Date 2019-11-15.17:41:44.926>
user = 'https://github.com/celinecyc'

bugs.python.org fields:

activity = <Date 2019-11-15.17:41:44.926>
actor = 'scoder'
assignee = 'none'
closed = True
closed_date = <Date 2019-11-15.17:41:44.927>
closer = 'scoder'
components = ['XML']
creation = <Date 2019-11-08.08:10:53.518>
creator = 'celinecyc'
dependencies = []
files = []
hgrepos = []
issue_num = 38742
keywords = []
message_count = 2.0
messages = ['356229', '356698']
nosy_count = 6.0
nosy_names = ['effbot', 'amaury.forgeotdarc', 'scoder', 'poke', 'flox', 'celinecyc']
pr_nums = []
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '9521'
type = 'enhancement'
url = 'https://bugs.python.org/issue38742'
versions = ['Python 3.6']

[celinecyc]

bpo-8277
It couldn't work for those comments before the root element.
It will raise an error that "xml.etree.ElementTree.ParseError: multiple elements on top level".

Example:

test.xml
--------
<?xml version="1.0" encoding="utf-8"?>
<!-- comments here doesn't work -->
<root node>
<nodeA />
<!-- comments here is ok -->
<nodeB />
</root node>

test.py
-------

from xml.etree import ElementTree
class MyTreeBuilder(ElementTree.TreeBuilder):
   def comment(self, data):
       self.start(ElementTree.Comment, {})
       self.data(data)
       self.end(ElementTree.Comment)
with open('c:/temp/t.xml', 'r') as f:
   xml = ElementTree.parse(
       f, parser=ElementTree.XMLParser(target=MyTreeBuilder()))
ElementTree.dump(xml)

[scoder]

Duplicate of bpo-9521 (and bpo-24287).