Trying to compile Python 3.5 on Linux Mint 19, getting compiler warnings and failing tests

[Marcin G]

My boss wants my code to run on Python 3.5, so I thought I'd install 3.5 to be able to ascertain this.

But Linux Mint 19 ships with Python 3.6 and python.org only provides source code for 3.5.6<https://www.python.org/downloads/release/python-356/>. So I thought I'd try compiling 3.5.6 myself.

This produced compiler warnings about: comparison between signed and unsigned, switches falling though, use of deprecated macros in glibc headers and too big object sizes leading to overflows in memcpy. This worries me the most, because it looks like undefined behavior to my untrained eye. I wonder if my system is misconfigured? Or if the configure script picks wrong sizes for some reason? Is there incompatibility between Python 3.5 and newer glibc headers?

In addition, make test shows up one failing test: test_ssl.

All I want is to have an installation that is not broken. If the above failures are false positives, I can gladly ignore them; however, since (unsupressed) warnings and failing tests are usually a sign of serious problems, I wonder what should I do get a functional installation?

I do believe I should have all dependencies installed. First, I kept installing libraries until `make` stopped showing me info about missing bits for optional modules. Then, just to make sure, I did sudo apt-get build-dep python3. Problem is still not solved, however.

Pastes:

Full log<https://paste.pound-python.org/show/6cKprUH9tlULuAKxfzmp/>. Just warnings.<https://paste.pound-python.org/show/Q6pRdh4gt5VhhUaqpZrM/> Just failing tests.<https://paste.pound-python.org/show/oA8H4ck6plkALUu8SbKV/>