[4.2] Make FloatingPoint require that Self.Magnitude == Self #17382
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* Make FloatingPoint require that Self.Magnitude == Self
We didn't have the where clause to express this constraint at the time that the FloatingPoint protocol was implemented, but we do now. This is not a semantic change to FloatingPoint, which has always bound IEEE-754 arithmetic types, for which this constraint would necessarily hold, but it does effect the type system.
For example, currently the following function does not type check:
~~~~
func foo<T>(x: T) -> T where T: FloatingPoint {
var r = x.remainder(dividingBy: 1)
return r.magnitude
}
~~~~
with this change, it compiles correctly.
Having done this, we no longer need to have a separate `abs` defined on FloatingPoint; we can use the existing function defined on `SignedNumeric` instead. Additionally mark the global `fabs` defined in the platform C module deprecated in favor of the Swift `abs`; we don't need to carry two names for this function going forward.
|
@swift-ci Please test |
airspeedswift
approved these changes
Jun 21, 2018
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We didn't have the where clause to express this constraint at the time that the FloatingPoint protocol was implemented, but we do now. This is not a semantic change to FloatingPoint, which has always bound IEEE-754 arithmetic types, for which this constraint would necessarily hold, but it does effect the type system.
For example, currently the following function does not type check:
with this change, it compiles correctly.
Having done this, we no longer need to have a separate
absdefined on FloatingPoint; we can use the existing function defined onSignedNumericinstead. Additionally mark the globalfabsdefined in the platform C module deprecated in favor of the Swiftabs; we don't need to carry two names for this function going forward.