Recognize missing brackets for assignment expression

[cdce8p]

It would be nice if Pylance could recognize that the example below would result in a SyntaxError.

l = lambda s: val if val := s.capitalize() else None

$ python test.py
  File "/.../test.py", line 1
    l = lambda s: val if val := s.capitalize() else None
                  ^^^^^^^^^^
SyntaxError: expected 'else' after 'if' expression

--
To be valid, brackets around the assignment expression are necessary. This only applies to if expressions. Normal if statements will work, even without them.

l = lambda s: val if (val := s.capitalize()) else None

--
Tested with Pylance: v2021.9.2

[erictraut]

Thanks for the bug report. There was indeed a bug in pyright's parser that resulted in a false negative in this case. The fix will be in the next release.

[jakebailey]

This issue has been fixed in version 2021.9.3, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/main/CHANGELOG.md#202193-22-september-2021