Make FloatingPoint require that Self.Magnitude == Self #17323
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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:
~~~~
func foo<T>(x: T) -> T where T: FloatingPoint {
var r = x.remainder(dividingBy: 1)
return r.magnitude
}
~~~~
with this change, it compiles correctly.
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@swift-ci Please test |
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You should be able to drop the constraint from |
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@jrose-apple Actually I think I can go further and remove the FloatingPoint |
We no longer need to have a separate `abs` defined on FloatingPoint; we can use the existing function defined on `SignedNumeric` instead. Additionally mark `fabs` deprecated in favor of the Swift name `abs`; we don't need to have two names for the same function.
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@swift-ci Please test |
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Build failed |
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Build failed |
xwu
reviewed
Jun 19, 2018
| @@ -14,8 +14,8 @@ import SwiftShims | |||
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| // Generic functions implementable directly on FloatingPoint. | |||
| @_transparent | |||
| public func fabs<T: FloatingPoint>(_ x: T) -> T | |||
| where T.Magnitude == T { | |||
| @available(swift, deprecated: 4.2, renamed: "abs") | |||
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Q: why deprecate this specifically?
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For the same reason that we deprecated other tgmath overlays whose functionality duplicates APIs available on [Binary]FloatingPoint and which don't offer compelling ergonomic advantages like sqrt or fma. We don't need to carry two names for the same function into the future, and abs is the better name for this. fabs is a curious artifact of the fact that C doesn't have overloaded functions.
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@swift-ci please test |
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Build failed |
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Build failed |
stephentyrone
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to stephentyrone/swift
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Jun 20, 2018
* 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.
stephentyrone
added a commit
that referenced
this pull request
Jun 22, 2018
* 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.
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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.
This is an ABI change, but a very minor one which should not break any currently-functioning code.