Bug report

Bug description:

When HTMLParser is initialized with convert_charrefs=False, it behaves incorrectly when processing an invalid named entity reference (e.g., &A, which is not a valid HTML entity). The parser silently drops the & character and only passes the subsequent A to handle_data. I think this indicates a silent data loss problem.

from html.parser import HTMLParser
class MyParser(HTMLParser):
    def handle_data(self, data):
        print(f"handle_data received: {data!r}")
parser_false = MyParser(convert_charrefs=False)
parser_false.feed('&A')
parser_false.close()

handle_data received: 'A'

CPython versions tested on:

3.12

Operating systems tested on:

Linux

Linked PRs

• gh-140875: Fix handling of unclosed charrefs before EOF in HTMLParser #140904
• [3.14] gh-140875: Fix handling of unclosed charrefs before EOF in HTMLParser (GH-140904) #141745
• [3.13] gh-140875: Fix handling of unclosed charrefs before EOF in HTMLParser (GH-140904) #141746