Remove python dependency

[netkgk]

Remove this:
python 2.6 or later (but not 3.x)
from dependency list

[lifthrasiir]

We are already discussing about getting rid of Perl dependency (#12913). We would still need to depend on at least one scripting language for various purposes (/src/etc has plenty of them as an example).

[huonw]

Just to be clear: this issue is filed about moving from Python 2.x to Python 3.x, not removing the Python dependency completely, right?

[thestinger]

AFAIK, the dependency on Python 2 is mostly from LLVM.

[brson]

Our 2.x dependency is from LLVM; Rust itself used to be able to cope with 3.x, but LLVM (at least as of 1+ years ago) can not.

[brson]

I'm also not clear on what this bug is about. If it's to move just to 3 without supporting 2, then I would need more persuading.

[netkgk]

I'm not clear what python is needed for at all. If it's about build process, there's more appropriate tools for that. Make compiled programming language dependent on python looks stupid for me.

[lifthrasiir]

@netkgk Python is being widely used for checking commits (e.g. /src/etc/licenseck.py), handling and making snapshots (for bootstrapping the compiler, e.g. /src/etc/snapshot.py), generating Rust codes (e.g. /src/etc/unicode.py) and so on. I think there are no "appropriate" tools for them, simply because they have to be custom-made for Rust (and LLVM, as others pointed out). Also please note that your Rust program wouldn't depend on Python in any way, unless you choose to do so.

[thestinger]

The Python dependency is only a build dependency. If you're not building Rust yourself, and most people won't be, you don't need to have it installed. The only reason to build Rust yourself once there are a solid set of distribution packages and first-party builds in place would be if you want to contribute to the project.

[brson]

Sounds like this is a misunderstanding about how Rust uses Python. Closing.