SE-0113 + residual SE-0067 work

[stephentyrone]

What's in this pull request?

This pull request adds the following to FloatingPoint:

func rounded(_ rule: FloatingPointRoundingRule) -> Self
mutating func round(_ rule: FloatingPointRoundingRule)
func remainder(dividingBy other: Self) -> Self
mutating func formRemainder(dividingBy other: Self)
func squareRoot() -> Self
mutating func formSquareRoot()
func addingProduct(_ lhs: Self, _ rhs: Self) -> Self
mutating func addProduct(_ lhs: Self, _ rhs: Self)

The first two are SE-0113. The others are residual work for SE-0067.

Resolved bug number: (SR-2010)

---

Before merging this pull request to apple/swift repository:

• Test pull request on Swift continuous integration.

Triggering Swift CI

The swift-ci is triggered by writing a comment on this PR addressed to the GitHub user @swift-ci. Different tests will run depending on the specific comment that you use. The currently available comments are:

Smoke Testing

Platform	Comment
All supported platforms	@swift-ci Please smoke test
All supported platforms	@swift-ci Please smoke test and merge
OS X platform	@swift-ci Please smoke test OS X platform
Linux platform	@swift-ci Please smoke test Linux platform

Validation Testing

Platform	Comment
All supported platforms	@swift-ci Please test
All supported platforms	@swift-ci Please test and merge
OS X platform	@swift-ci Please test OS X platform
OS X platform	@swift-ci Please benchmark
Linux platform	@swift-ci Please test Linux platform

Lint Testing

Language	Comment
Python	@swift-ci Please Python lint

Note: Only members of the Apple organization can trigger swift-ci.

[stephentyrone]

@swift-ci Please test.

[xwu]

Is this a stopgap or really the way nextDown is intended to be implemented?

[stephentyrone]

It's a default provided to simplify the implementation burden on types that want to conform. (FWIW however, I don't expect most types will override this, as it's fairly efficient for any reasonable conforming type, and these operations tend not to be used in performance-sensitive contexts).

[xwu]

Makes sense. I only asked because, above, you seem to have removed CGFloat.nextDown in favor of this default implementation.

[stephentyrone]

@swift-ci please test.