Support type checking when using type hints

Environment data

• VS Code version: 1.25.1
• Extension version: 2018.7.1
• OS and version: Kubuntu 18.04
• Python version: Python 3.7.0b3 64-bit
• Type of virtual environment used: N/A
• Relevant/affected Python packages and their versions: N/A

Actual behavior

1. No error shown when using type hints and wrong parameters are passed to a function
2. Code hint pop-up shows incorrect types. The type of the “wrong” parameter gets added to the type list. In the screenshot below, see how b is shown to have a type of int, str.

Expected behavior

Squiggly lines will be shown and errors will be reported when parameters of wrong types are passed

Steps to reproduce:

1. Enable the new language server (i.e. set "python.jediEnabled": false)
2. Write a simple function that uses type hints (like the one in the screenshot)
3. Call the function while passing parameters of invalid types

Logs

Starting Microsoft Python language server.
[Info  - 21:57:00] Created Microsoft.PythonTools.Interpreter.Ast.AstPythonInterpreter instance from Microsoft.PythonTools.Interpreter.Ast.AstPythonInterpreterFactory
Initializing for /usr/bin/python3.7
##########Linting Output - pylint##########

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

[Info  - 21:58:02] Found 198 completions for file:///home/<username>/Desktop/server.py at (6, 2) after filtering

[johnhargrove]

As someone learning Python, and a longtime VS Code user, I found the lack of support for this to be very surprising.

[tuhinkarmakar]

Okay, I understand. I thought since VS Code shows type errors for TypeScript code, the same will be true for code written in Python as well.