Issue with variant selection in f-strings.

[flaree]

Environment data

• Language Server version: Pylance language server 2020.8.0
• OS and version: Win 10 - 2004, 20175.1000
• Python version (& distribution if applicable, e.g. Anaconda): 3.8.5

Expected behaviour

Correctly identify the variant selector following a unicode emoji in an f-string.

Actual behaviour

Raises a warning stating unexpected token and "VARIATION" is not defined.

Code Snippet / Additional information

variable = f"\N{BLACK QUESTION MARK ORNAMENT}\N{VARIATION SELECTOR-16}"

This is pretty much what produced the output below.

[erictraut]

I didn't realize that "-" was an allowed character in a "\N" escape. The Python spec on lexical analysis is vague about what it accepts here. It simply says:

\N{name} : Character named name in the Unicode database

Do you happen to know if there are other characters besides a-zA-Z0-9 and "-" within a Unicode name?

[flaree]

I haven't had any other warning/error occur apart from this specific one.

[erictraut]

Thanks again for reporting this. I've introduced a fix, and it will be included in an upcoming version of Pylance. I don't know if it will make it into this week's build.

[jakebailey]

This issue has been fixed in version 2020.8.2, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/master/CHANGELOG.md#202082-20-august-2020