crash in 4.0.0b5 related to non-ascii characters and tooltips

Issue Report Checklist

• Searched the issues page for similar reports
• Read the relevant sections of the Spyder Troubleshooting Guide and followed its advice
• Reproduced the issue after updating with conda update spyder (or pip, if not using Anaconda)
• Could not reproduce inside jupyter qtconsole (if console-related)
• Tried basic troubleshooting (if a bug/error)
  • Restarted Spyder
  • Reset preferences with spyder --reset
  • Reinstalled the latest version of Anaconda
  • Tried the other applicable steps from the Troubleshooting Guide
• Completed the Problem Description, Steps to Reproduce and Version sections below

Problem Description

The program crashes as described below. It seems to be related to the non-ascii character in the function signature; when I tried replacing blah(λ,x) with blah(w,x), everything works fine.

What steps reproduce the problem?

1. Copy the following into a new python file, and save it:

# -*- coding: utf-8 -*-

def blah(λ,x):
    return λ + x

1. On a new line, type “bla”. The tooltip / autocomplete thing will prompt with the completion: blah(λ,x).

2. Press tab to accept this suggestion.

What is the expected output? What do you see instead?

It should fill in the missing letter “h” to make the word “blah”. Instead, the program crashed.

Versions

• Spyder version: 4.0.0b5
• Python version: 3.7.4 64-bit
• Qt version: 5.9.6
• PyQt version: 5.9.2
• Operating System name/version: Windows 10

Dependencies

cloudpickle >=0.5.0          :  1.2.2 (OK)
pygments >=2.0               :  2.4.2 (OK)
qtconsole >=4.5.5            :  4.5.5 (OK)
nbconvert >=4.0              :  5.5.0 (OK)
sphinx >=0.6.6               :  2.1.2 (OK)
pylint >=0.25                :  2.3.1 (OK)
psutil >=0.3                 :  5.6.3 (OK)
qtawesome >=0.5.7            :  0.5.7 (OK)
qtpy >=1.5.0                 :  1.9.0 (OK)
pickleshare >=0.4            :  0.7.5 (OK)
zmq >=17                     :  18.1.0 (OK)
chardet >=2.0.0              :  3.0.4 (OK)
numpydoc >=0.6.0             :  0.9.1 (OK)
spyder_kernels >=1.5.0;<2.0.0:  1.5.0 (OK)
qdarkstyle >=2.7             :  2.7 (OK)
atomicwrites >=1.2.0         :  1.3.0 (OK)
diff_match_patch >=20181111  :  20181111 (OK)
watchdog                     :  None (OK)
keyring                      :  None (OK)
pexpect >=4.4.0              :  4.7.0 (OK)
pympler                      :  None (OK)
sympy >=0.7.3                :  None (NOK)
cython >=0.21                :  None (NOK)
IPython >=4.0                :  7.8.0 (OK)
matplotlib >=2.0.0           :  3.1.0 (OK)
pandas >=0.13.1              :  0.25.0 (OK)
numpy >=1.7                  :  1.16.4 (OK)
scipy >=0.17.0               :  1.3.1 (OK)
pyls >=0.28.2;<0.29.0        :  0.28.3 (OK)
rtree >=0.8.3                :  0.8.3 (OK)

[dalthviz]

@ccordoba12 after testing PR https://github.com/spyder-ide/spyder/pull/10256 Spyder doesn’t hang but the symbols are encoded incorrectly:

[ccordoba12]

@dalthviz, please test PR #10256. @andfoy’s last change there should fix this problem.