etree.RelaxNG fails to load RELAX NG compact (.rnc) file

[Yang Yang]

With rnc2rng 2.6.1 installed, etree.RelaxNG still fails to load a .rnc file.

test.rnc:

start = element a {empty}

test.py:

from lxml import etree
etree.RelaxNG(file='test.rnc') # ValueError: Unicode strings with encoding declaration are not supported. Please use bytes input or XML fragments without declaration.

It seems that the rng content generated by rnc2rng is rejected by etree.RelaxNG because it begins with '<?xml version="1.0" encoding="UTF-8"?>'.

Version info:

Python : sys.version_info(major=3, minor=7, micro=3, releaselevel='final', serial=0)
lxml.etree : (4, 3, 3, 0)
libxml used : (2, 9, 5)
libxml compiled : (2, 9, 5)
libxslt used : (1, 1, 30)
libxslt compiled : (1, 1, 30)

[scoder (scoder)]

Thanks for the report.
Fixed here: https://github.com/lxml/lxml/commit/bb2a4fd588d1cdf5ecd9badd618505d578ea2942

As the saying goes, it's either tested or broken. The integration tests with rnc2rng were not automatically running in CI. They are now.