MSRV for rust-numpy

[mtreinish]

Following PyO3/pyo3#1420 and PyO3/pyo3#1431 PyO3's MSRV is 1.41. Right now rust-numpy advertises the msrv of 1.39 in the README, but because ndarray 0.14 is listed as a dependency the functional msrv is 1.42 since the ndarray 0.14 release bumped their msrv (https://github.com/rust-ndarray/ndarray/blob/master/RELEASES.md#other-changes-1 )

I'm hoping to clarify the rust-numpy MSRV policy because this is blocking me from upgrading pyo3 (see: Qiskit/rustworkx#238 ) because I'm trying to maintain rust 1.41 compatibility for debian users. Once the policy is clarified for rust-numpy we can add a CI job to enforce it like we have in pyo3.

[kngwyu]

Ah, sorry for my laziness about it and thank you for letting me know that!

• Checks if we support ndarray 0.13 and 0.14
• Release a patch version if we can do something
• Or just update the README

[kngwyu]

@mtreinish
I think we can support ndarray 0.13 by ndarray = ">= 0.13, < 0.15".
However, cargo doesn't nicely resolve the proper version so we have to edit Cargo.lock for making it work.
Does it sufficient for you?
Or, -Z minimal-version could work, but I haven't tried it by myself.

[davidhewitt]

If we put ndarray = ">= 0.13, < 0.15" in our Cargo.toml, then for downstream users which have ndarray = 0.13 I think cargo can deduplicate and use 0.13 correctly.

We could test this in CI with an example.

[mtreinish]

@kngwyu I think changing the ndarray dependency to ndarray = ">= 0.13, < 0.15" will work well for me. I tested that locally and it works for building with 1.41. As @davidhewitt suggested cargo is able to resolve things correctly when ndarray = 0.13 and rust-numpy has >=0.13, < 0.15.

One other place we might need to loosen the requirements in rust-numpy is num-complex. ndarray 0.13 uses num-complex 0.2: https://github.com/rust-ndarray/ndarray/blob/0.13.1/Cargo.toml#L33 while we have num-complex = 0.3. Things for me compile fine locally and cargo just builds with num-complex 0.2 for ndarray and 0.3 for rust-numpy, but I haven't tested anything which uses complex numbers so I'm not sure if there will be a version mismatch for users that use arrays with complex numbers.

[kngwyu]

Ah, OK, thank you both for pointing it out!

[kngwyu]

Released 0.13.1, which would work with Rust 1.41.1.