Sphinx changes number system from hexadecimal to decimal for function default arguments

[dybber]

Describe the bug

When documenting a function, which requires a default argument specified in hexadecimal:

.. function:: lcd.print(msg, x, y, color=0xffffff, transparent=False)

Sphinx 3.2.1 will render HTML documentation where the hexadecimal value is in a different number system, than what was specified by the user (decimal), as seen in the following output from the above input:

Expected behavior
The expected behaviour would be to present the default argument in the same radix/number system as the user typed in, thus in this case the documentation would also display the value in hexadecimal.

In the above example of with colors, it is unintuitive what the color 16777215 might refer to, but it's easy read RGB colors in hexadecimal format - e.g. 0xffffff is white, thus which number system is used can make a huge difference. The same for example goes for e.g. specifying access rights for files (chmod)

Screenshots

Environment info

• OS: Mac OS X 10.14.6
• Python version: 3.8.5
• Sphinx version: 3.2.1
• Sphinx extensions: None
• Extra tools: None