Am 14.02.2023 um 21:52 hat Paolo Bonzini geschrieben: > Il mar 14 feb 2023, 18:26 Kevin Wolf <kw...@redhat.com> ha scritto: > > > Am 14.02.2023 um 15:03 hat Paolo Bonzini geschrieben: > > > In the case of Python the issue is not the interpreter per se, though > > > there are a couple new feature in Python 3.7 that are quite nice (for > > > example improved data classes[1] or context variables[2]). The main > > > problem as far as I understood (and have seen in my experience) is > > > linting tools. New versions fix bugs that caused false positives, but > > > also become more strict at the same time. The newer versions at the > > > same time are very quick at dropping support for old versions of > > > Python; while older versions sometimes throw deprecation warnings on > > > new versions of Python. This makes it very hard to support a single > > > version of, say, mypy that works on all versions from RHEL8 and SLE15 > > > to Fedora 38 and Ubuntu 23.04. > > > > Why do we have to support a single version of mypy? What is wrong with > > running an old mypy version with old Python version, and a newer mypy > > with newer Python versions? > > > > Sure, they will complain about different things, but it doesn't feel > > that different from supporting multiple C compilers in various versions. > > > > It's more like having to support only C++03 on RHEL 8 and only C++20 in > Fedora 37, without even being able to use a preprocessor. > > For example old versions might not understand some type annotations and > will fail mypy altogether, therefore even with newer versions you can't > annotate the whole source and have to fall back to non-strict mode.
Sure, using old versions restricts which features can be used. But I suppose C++03 is (for the most part) a subset of C++20, and annotations understood by old mypy are a subset of annotation understood by new mypy? Which would make it something for the "shiny new feature" department. Don't get me wrong, I was among the first people advocating for using mypy and I still think any improvement in type checking is something we should take when we can. But while it may a very desirable new feature, it still is one. So I assume the real problem sits somewhere else? Or do we get lots of places where new mypy requires something that old mypy complains about and vice versa? Kevin
