Fail to build pydantic_core on OS X 10.11 with Python 3.10

[BLKSerene]

Fail to build pydantic_core on OS X 10.11 with Python 3.10

[tiran]

Rust 1.73 is missing some features. MSRV can be lowered to 1.75, but not below. See #1315

[davidhewitt]

I think 1.73 would still be reachable but it'd be a lot more work.

[davidhewitt]

The hint here is already in your build output:

(/private/var/folders/_n/8qwtj23j0tx0bdy7ftvpg63m0000gn/T/pip-install-a3iwsm3w/pydantic-core_1e29f10ace204ee99125b93a432e3171)` cannot be built because it requires rustc 1.76 or newer, while the currently active rustc version is 1.72.1

If you update your Rust compiler (probably with rustup update) and retry, it should work.

[BLKSerene]

@davidhewitt Unfortunately, starting from Rust 1.74, the minimum supported macOS platform is macOS 10.12 (see here), so the latest Rust compiler supporting OS X 10.11 is Rust 1.73. I tried installing the latest Rust using the standalone installer, but that did not work.

If pydantic chooses to drop support for macOS < 10.12 (Python 3 still supports far back to macOS 10.9), it would be better to explicitly state that in the doc.

[davidhewitt]

That's a great point. I think we should consider downgrading our minimum Rust to 1.73, but this may not be trivial.

[davidhewitt]

^ reflecting on the above, I think downgrading is the right thing, but I think the reality is that extending support backwards to old macOS versions is not a high priority for me right now. If anyone is interested in helping downgrade, a PR is very welcome.

[BLKSerene]

Could you please give some hints about how to contribute on this specific downgrading issue?

[davidhewitt]

The idea would be that you can check the compile against Rust 1.73 (for example) by running cargo +1.73 check in this directory.

Or you could set the rust-version in Cargo.toml to 1.73 and push a PR, which will run the checks on the pipeline here.

I expect that there are a couple of language features and stdlib APIs which we use which will need replacing. If it's not clear how to replace them, perhaps post back here with examples and I can give suggestions.