Skip generating source links for re-exported numpy functions in docs

[dfm]

Fixes #28885

Some jnp functions (e.g. savez) link to non-existent URLs when they are re-exported from numpy. We can skip generating these links when the source file doesn't live under the jax source root.

At this change, the source link no longer appears for savez, but it does for linspace, for example.

[nicholasjng]

Looks good! Would it be possible to mark NumPy re-exports on their summary pages as such?

[dfm]

Would it be possible to mark NumPy re-exports on their summary pages as such?

I'll let Jake comment on this one, but I agree that that would probably be a good idea!

[jakevdp]

Looks good! Would it be possible to mark NumPy re-exports on their summary pages as such?

What summary pages do you have in mind?

[nicholasjng]

Mostly the jax.numpy.save(z) function family, since I didn't quite catch that they are from NumPy, and started wondering about what they return. That's also why I posted the discussion that you kindly already answered (thanks!).

For instance, even on this PR branch, the docs on jnp.save reproduce the code examples from NumPy, with np. calls. Not that that's a bad thing per se, just maybe a bit unexpected.

[jakevdp]

I see - we have a couple options here:

1. don't list jnp.save on the JAX website
2. create an explicit wrapper function for jnp.save with its own docstring
3. do some kind of special-casing in the sphinx documentation build to mark aliased functions

I think (2) is probably the cleanest solution.

[jakevdp]

Actually, there's also (4) deprecate jnp.save and jnp.savez, and suggest users use the NumPy versions directly.

I actually think this might be the clearest approach here.

[dfm]

This sounds good to me, but I don't think it makes sense to make this change here. I'd say that it's still worth merging this PR regardless because we shouldn't ever generate these broken URLs!

[dfm]

I'm happy to add these deprecations in a follow up PR!