Add copysign

[XAMPPRocky]

Resolves #152
Closes #155

[XAMPPRocky]

@cuviper Would you be able to help out with why the CI is failing? I don't really understand what the macro is generating or how it works, and the diff looks identical to PRs that have succeeded to me.

[cuviper]

The standard library didn't get copysign until 1.35. In CI for earlier versions, you're hitting #![deny(unconditional_recursion)], as the attempted macro-forwarding actually ends up calling the trait method again, instead of the newer inherent method. You'll need to add a build.rs check for the method, and then cfg the forwarding based on that, leaving it to the default impl otherwise.

[XAMPPRocky]

You'll need to add a build.rs check for the method, and then cfg the forwarding based on that, leaving it to the default impl otherwise.

I think I've implemented that, but it's still failing the tests, and I still can't really tell what I need to do to fix it.

[XAMPPRocky]

The workflow needs to be approved :)

[XAMPPRocky]

@tspiteri Thanks for that, it seems like it's passing now.

[XAMPPRocky]

@cuviper Friendly review ping 🙂

[cuviper]

Do we really need a feature for this? I'd rather leave it to autocfg, unless there's a strong reason to expose that condition.

[XAMPPRocky]

Yes, because autocfg is not something that can be used on custom targets (related rust-lang/cargo#7501). I would go as far as saying that autocfg is an anti-pattern for supporting custom targets currently, the way probing capabilities currently works is very incompatible if your project requires being built in a specialised way. One example a project that needs num-traits and a custom target is rust-gpu.

[cuviper]

Yeah, even as the autocfg author I am frustrated by that situation, but I haven't found time to design/push for tool changes that would alleviate it. I think having something like TARGET_RUSTFLAGS from cargo set for build scripts would solve a lot of issues. Might you be interested in pursuing this, since it impacts targets you work with?

[cuviper]

FWIW, autocfg uses CARGO_ENCODED_RUSTFLAGS now, which should be more reliable.

If you're not even happy with that, then I'd prefer a plain version check rather than a feature for every little implementation detail. ("i128" is a little different because it actually adds to the API.)

[XAMPPRocky]

@cuviper I believe I've fixed the issues, but you'll need to approve the workflow first to check.

[ctrlcctrlv]

(Merged into MFEK@ce9a7df due to #189 (comment).)

[cuviper]

bors r+

[bors]

Build succeeded:

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