import resolving issue around namespace package.

[heejaechang]

Describe the bug
Pyright shows an unresolvable import squiggles involving namespace package, but if F5, it runs fine.

To Reproduce
repo code is here
https://github.com/microsoft/pyright/blob/main/packages/pyright-internal/src/tests/fourslash/completions.importSubmodule.fourslash.ts

Expected behavior
"setup" not showing squiggles for "from submodule.setup import ... "

Screenshots or Code

VS Code extension or command-line
vs code extension

Additional context
it looks like due to extra path, submodule.setup is considered not resolvable even if it is considered resolvable from project root (where test.py file is). and one (extra path) that contains __ init __ wins over and show squiggles. but if run test.py, it works fine by python interpreter.

[erictraut]

I think the behavior is correct.

The example is adding an extraPaths of "submodule". If you add that path to the pyright configuration, you also need to add it to the PYTHONPATH at runtime. If you do that before running test.py, you will receive an import error from the interpreter:

  File "/Users/eric/Desktop/Test/test.py", line 6, in <module>
    from submodule.setup import bar

If you don't want to edit the PYTHONPATH variable, you can also manually manipulate the sys.paths at the top of test.py to add the extra path at runtime.

import os.path
import sys
sys.path.append(os.path.dirname(__file__) + "/submodule")

As before, the import submodule.setup cannot be resolved, consistent with the diagnostic.

If you remove the extraPaths configuration (and correspondingly do not add the extra path at runtime), pyright resolves the import without error, and you don't receive a runtime exception.