re.escape('\n') returns '\\\n', i.e. a string consisting of a backslash and a newline. I believe it should return '\\n', i.e. a backslash and an 'n'. If the escape-result still contains a verbatim newline, why escape this character at all?

Note that Python's regular expressions engine allows newlines, so re.match(re.escape('\n'), '\n') gives a match. Thus, while this looks like an undesired behavior, it is not functionally broken.

The same problem applies to some other characters: \t\r\v\f

In a regex, putting a backslash before any character that's not an ASCII-range letter or digit makes it a literal. re.escape doesn't special-case control characters. Its purpose is to make a string that might contain metacharacters into one that's a literal, and it already does that, although it sometimes escapes more than necessary.

> If the escape-result still contains a verbatim newline, why escape this character at all?

Because in verbose mode it is ignored. This is why \n and other ASCII whitespace characters, and '#', which starts a comment, should be escaped.

'\\\n' and '\\n' has identical meaning independent of mode and context, so there is no bug here. Escaping '\n' as '\\\n' is slightly simpler.

Thanks for the explanation, I did not know re.VERBOSE. I still think the behavior is a bit confusing, but it's probably not worth the effort to change this.