Fails to install Spyder4.0.0rc2 on Windows due to ujson dependency

Problem Description

First of all, this is a dependency issue so it may be not solved by the Spyder-team but I thought that you may want to know about it.

Spyder 4.0.0rc2 actually fails to install (via pip) on Windows if MSVC compiler is not installed. This is related to the fact that some dependencies depend on ujson package, which require MSVC 14 as shown in the log below.

So the dependency tree goes like that: rc2 requires python-language-server 0.31.0, which requires ujson and python-jsonrpc-server 0.3.0, which requires ujson too:

spyder 4.0.0rc2
    python-language-server 0.31.0
        ujson (since python-language-server 0.31.0, previous 0.30.0)
        python-jsonrpc-server 0.3.0
            ujson (since python-jsonrpc-server 0.3.0, previous 0.2.0)

This is working with rc1 when pre-installing first python-jsonrpc-server v0.2.0, then python-language-server 0.30.0.

What steps reproduce the problem?

1. Install release candidate 2 on W10 pip install --pre spyder

Error

[...]
  Running setup.py install for ujson ... error
[...]
    Warning: 'classifiers' should be a list, got type 'filter'
    running install
    running build
    running build_ext
    building 'ujson' extension
    error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": https://visualstudio.microsoft.com/downloads/
    ----------------------------------------

Versions

• Spyder version: -
• Python version: 3.7.5
• Qt version: -
• PyQt version: -
• Operating System name/version: Windows 10, AMD64

[ccordoba12]

Therefore, I hope spyder doesn’t become incompatible to standard python distributions when it integrates further with Anaconda

It won’t. We just plan to add more functionality based on conda (like environment management).

You have a large winpython fanbase out there!

Ok, thanks for letting us know about it! We didn’t know, so we’re leaned towards Anaconda.

---

In any case, this is an easy to fix error and @dalthviz already created two PRs for it.

[ccordoba12]

On a second thought, we’re going to address this because members of our team are also suffering from it. Sorry if I sounded harsh before.