What is the recommended way to deal with platform-specific imports?

[Bruntaz]

We have a function which returns a string for identifying the user, which will return the user's actual name if possible, and their username if not. The function looks like:

import getpass

def get_author() -> str:
    try:
        from win32api import GetUserNameEx
        return GetUserNameEx(3)
    except Exception:
        return getpass.getuser()

The win32api module is, unsurprisingly, Windows exclusive, but when Pyright runs on Linux in our CI, we get the following warning:

Import "win32api" could not be resolved from source

I've tried refactoring the code to:

import getpass
import sys

def get_author() -> str:
    if sys.platform in ["win32", "cygwin"]:
        try:
            from win32api import GetUserNameEx
            return GetUserNameEx(3)
        except Exception:
            pass
    return getpass.getuser()

But we still get the warning on Linux. What is the suggested way to write this code to avoid any warnings from Pyright?

[erictraut]

Your refactored code is on the right path, but you're using a conditional expression form that type checkers do not recognize. If you change it to if sys.platform == "win32" or sys.platform == "cygwin":, you'll get the effect you're looking for. Type checkers are required by the typing standard to recognize a few specific conditional forms when checking for platforms and Python versions. If you use some alternative form, it won't be recognized.

As an alternative, you can add a # pyright: ignore[reportMissingModuleSource] to suppress the warning on that line. Or you can add a # pyright: reportMissingModuleSource=false at the top of the file to suppress it for the entire file.

[Bruntaz]

We're not using venv at all actually. We're calling Pyright like this:

PYTHONROOT=$(ROOTDIR)/auxd/python
ifeq ($(SYSTEM),linux)
PYTHON=$(PYTHONROOT)/bin/python3.12
else
PYTHON=$(PYTHONROOT)/python3.12.exe
endif

lint_python:
	@$(PYTHON) -m pyright -p $(ROOTDIR)/pyproject.toml --pythonpath $(PYTHON)

where Python is installed locally in our repo and modules are installed directly into the local Python rather than using venv. Our pyproject.toml file looks like this:

[tool.pyright]

exclude = [
    ...  # A bunch of stuff we haven't expanded the scope to include yet
]

ignore = []
extraPaths = [
    ... # A couple of common paths
]

verboseOutput = true
typeCheckingMode = "standard"

pythonVersion = "3.12"
pythonPlatform = "All"

reportPrivateUsage = true            
reportMissingTypeStubs = false       
strictParameterNoneValue = false     
reportOptionalSubscript = false      
reportOptionalMemberAccess = false   
reportOptionalCall = false           
reportOptionalIterable = false       
reportOptionalContextManager = false 
reportOptionalOperand = false        

[[tool.pyright.executionEnvironments]]  # Each subproject in our monorepo with the other paths it needs access to
root = "..."
extraPaths = [
    ...
]

[erictraut]

Your pyproject.toml configuration is specifying pythonPlatform = "All". That explains the behavior you're seeing. By default, pyright assumes that you're using the platform that it runs on (in your case, is presumably Linux). By overriding this default with "All", you're telling pyright to type check for all platforms. If you want it to assume that it's running on linux, delete the pythonPlatform config setting or change it to pythonPlatform = "Linux".

[Bruntaz]

No, as I mentioned in my previous comments, that's how it was originally set, but I found this bug when removing the setting. Sorry that wasn't clear.

I've created a minimal recreation project which should make it more obvious what's going on (it runs on any OS): pyright_platform.zip

It's 3 identical files like this:

# file.py
import sys

if sys.platform == "win32":
    _ = 1 + "win32"
elif sys.platform == "linux":
    _ = 1 + "linux"
elif sys.platform == "darwin":
    _ = 1 + "darwin"
else:
    _ = 1 + "other"

in a structure:

pyproject.toml
file.py
dir1/  # executionEnvironment
| file.py
dir2/
| file.py

with pyproject.toml as:

[tool.pyright]

# When pythonPlatform is set explicitly, it is inherited correctly down the tree.
# When pythonPlatform is **not** set, `dir1/file.py` is treated as `pythonPlatform = "All"`

#pythonPlatform = "All" # Works correctly when commented in
#pythonPlatform = "Linux" # Works correctly when commented in

[[tool.pyright.executionEnvironments]]
root = "dir1"

And the log from Pyright is:

$ pyright
WARNING: there is a new pyright version available (v1.1.376 -> v1.1.382.post0).
Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`

c:\dev\test\pyright_platform\file.py
  c:\dev\test\pyright_platform\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
c:\dev\test\pyright_platform\dir1\file.py
  c:\dev\test\pyright_platform\dir1\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
  c:\dev\test\pyright_platform\dir1\file.py:6:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['linux']" (reportOperatorIssue)
  c:\dev\test\pyright_platform\dir1\file.py:8:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['darwin']" (reportOperatorIssue)
  c:\dev\test\pyright_platform\dir1\file.py:10:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['other']" (reportOperatorIssue)
c:\dev\test\pyright_platform\dir2\file.py
  c:\dev\test\pyright_platform\dir2\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
6 errors, 0 warnings, 0 informations

[erictraut]

Thanks for putting together the repro. Unfortunately, I'm not able to repro the behavior you're seeing with the latest version.

I noticed that you're on a version of pyright that's many months old. Could you try updating to the latest version?

If that doesn't fix it, I've added some additional logging that will be in the next release (1.1.383) that should help us further diagnose the issue. For reference, this additional information is logged if you use the --verbose switch on the command line or the verboseOutput: true in the config file.

[Bruntaz]

Ah yes that does fix it! Glad it's working properly in the newer versions. Thanks very much for your help with both of these issues 🙂

$ pyright
WARNING: there is a new pyright version available (v1.1.382 -> v1.1.382.post0).
Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`

c:\dev\test\pyright_platform\file.py
  c:\dev\test\pyright_platform\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
c:\dev\test\pyright_platform\dir1\file.py
  c:\dev\test\pyright_platform\dir1\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
c:\dev\test\pyright_platform\dir2\file.py
  c:\dev\test\pyright_platform\dir2\file.py:4:9 - error: Operator "+" not supported for types "Literal[1]" and "Literal['win32']" (reportOperatorIssue)
3 errors, 0 warnings, 0 informations