I'm trying to get python3.7 as my default, and I have a lot of dependencies installed. There are many bug reports mentioning python 3.7. A tracker would be nice.
I have python3.7 successfully running now as my only python3 installation with 366 packages from dev-python/.
The blockers were:
1. adding +threads to dev-lang/python-3.7.4-r1 IUSE.
2. removing "-python_targets_python3_7" and "-python_single_target_python3_7" in profile/arch/amd64/use.stable.mask. You may be able to accomplish this using the proper entry in /etc/portage/use.stable.mask or /etc/portage/use.stable.force, but I wasn't able to do it in a timely manner.
3. keywording nearly every dev-python package because only the unstable versions have python3_7 in PYTHON_COMPAT. I now have keyworded 237 dev-python packages. For this step, I was guided by "equery hasuse python_targets_python3_7" and doing a diff against the same command with 3.6.
4. adding python3_7 to PYTHON_COMPAT for some 35 packages (in a private repo).
5. Updating cytoolz to 0.10.0 and adding python3_7 to its PYTHON_COMPAT.
6. Adding python3_7 to PYTHON_TARGETS and setting it as PYTHON_SINGLE_TARGET, then doing an "emerge --newuse -uD world".
7. Selecting python3.7 with "eselect python".
8. Removing python3_6 from PYTHON_TARGETS and doing another emerge.
I have submitted bug reports for steps 1, 2, and 5, which hopefully will reference this tracker. I'm running out of time for submitting the additional bug reports for step 4, so I'm listing the dev-python/ packages here:
anyqt, arrayfire-python, autopep8, backports, bcbio-gff, bcolz, bitstring, blaze, blist, blosc, bloscpack, bokeh, bz2file, CacheControl, cloudpickle, construct, coverage, cx_Freeze, dask, datashape, dockerpty, dynd-python, feedparser, flake8-polyfill, h4py, intervaltree, into, jsmin, jupyter, jupyter_console, keyrings_alt, kiwisolver, lockfile, mando, mmtf-python, multipledispatch, natsort, networkx, nltk, numba, numpy, odo, pandas, pint, pip-tools, promises, py2neo, pyalsa, pyconstruct, pycuda, pyparsing, pyprof2calltree, pyqtgraph, python-dateutil, pytoolz, pytz, radon, requests, seaborn, serverfiles, simplekv, twine, xopen, zc-buildout
Yes, this list is much larger than 35 because some of them represent private version bumps (e.g., pandas, numpy).