[AutoDiff] Added support for 'withoutDerivative(at:)'.

[eaplatanios]

@rxwei following from our discussion in tensorflow/swift-apis#150.

[eaplatanios]

One question that remains is, given these new helpers do we want to keep the Differentiable.withoutDerivative() helper? Removing it would likely result in a more consistent API with respect to how we denote code segments without derivatives.

[rxwei]

One question that remains is, given these new helpers do we want to keep the Differentiable.withoutDerivative() helper? Removing it would likely result in a more consistent API with respect to how we denote code segments without derivatives.

No, please feel free to remove it.

[eaplatanios]

Sounds good. I'll do that but I need to know how to replace this. Is there something along the lines of fixItInsertAround(sourceLoc, { x in "withoutDerivative(at: \(x))")?

[rxwei]

There is a fixItInsert (before) and a fixItInsertAfter. A call to each will work.

[eaplatanios]

Thanks! I made these edits and also changed the relevant tests. I cannot currently test locally so could you please run the CI tests so I check if the error reporting test modifications are correct?

[rxwei]

@swift-ci please test tensorflow

[rxwei]

@swift-ci please test tensorflow

[eaplatanios]

The CI errors are due to swift-apis. I'll make a corresponding PR there and try to test locally a bit later today.

[eaplatanios]

@rxwei Tests seem to pass locally now. Could you please start the CI tests?

[rxwei]

@swift-ci please test tensorflow

[rxwei]

@swift-ci please test tensorflow

[rxwei]

@swift-ci please clean test tensorflow