Special handling of experimental.captureChecking import #17427
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Linyxus
approved these changes
May 14, 2023
| .updated(NonEmptyTupleClass, ProductClass) | ||
| .updated(PairClass, ObjectClass) | ||
| @tu lazy val specialErasure: collection.Map[Symbol, ClassSymbol] = | ||
| val m = mutable.Map[Symbol, ClassSymbol]() |
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The map changes from an immutable one to a mutable one. Shall we freeze it after initializing it?
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It can't be changed from outside, since it is declared as a collection.Map. So in that sense it is frozen.
| @@ -363,8 +363,6 @@ object SymUtils: | |||
| self.hasAnnotation(defn.ExperimentalAnnot) | |||
| || isDefaultArgumentOfExperimentalMethod | |||
| || (!self.is(Package) && self.owner.isInExperimentalScope) | |||
| || self.topLevelClass.ownersIterator.exists(p => | |||
| p.is(Package) && p.owner.isRoot && p.name == tpnme.dotty) | |||
|
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Shall we drop this special case in the main compiler as well?
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Oh, I overlooked it was in the wrong codebase!
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The Pure marker trait is now a class in the scala package that gets erased to Object.
The question is, how do we introduce capture checking safely. There are two conflicting requirements: - Capture checking should not leak into standard Scala. It should be meaningful only in code that has capture checking explicitly enabled. - We need to be able to build up libraries that express capture information and that can be consumed from other code. This needs to start with the standard library itself. So far, everything related to capture checking was marked experimental. This means all code that refers to a capture checking abstraction in any way whatsoever needs to be declared experimental. That clearly does not work for the new use cases. But fortunately, capture checking has some properties that enable a different scheme. Specifically, a file compiled under capture checking looks like a completely normal component (both Tasty and binary) to any other file that uses it and that is not compiled with captureChecking. Only when the consumer is also compiled with capture checking, the capturing types of the original file will be revealed. The same holds for binaries. Capture checking has no effect at all on the binaries that get generated and all types and annotations needed for capture checking are erased. This allows the following more flexible scheme: - We can turn capture checking on with a setting or language import in any source file. The sources do not have to be @experimental. - If capture checking is turned on, a number of annotations and other symbols that are normally experimental are also made available. The important property is that capture checking in one component cannot poison other normal components. Like @experimental itself, the whole scheme is transitive. With the new scheme we do not need a special exemption for the dotty package anymore, so that part is dropped.
Previously: test was exempted because it was in dotty package Now: test is exempted since it language imports captureChecking
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The question is, how do we introduce capture checking safely. There are
two conflicting requirements:
meaningful only in code that has capture checking explicitly enabled.
and that can be consumed from other code. This needs to start with
the standard library itself.
So far, everything related to capture checking was marked experimental. This means
all code that refers to a capture checking abstraction in any way whatsoever needs
to be declared experimental. That clearly does not work for the new use cases.
But fortunately, capture checking has some properties that enable a different scheme.
Specifically, a file compiled under capture checking looks like a completely normal
component (both Tasty and binary) to any other file that uses it and that is not compiled
with captureChecking. Only when the consumer is also compiled with capture checking,
the capturing types of the original file will be revealed. The same holds for binaries.
Capture checking has no effect at all on the binaries that get generated and all types
and annotations needed for capture checking are erased.
This allows the following more flexible scheme:
The sources do not have to be @experimental.
are needed for capture checking and are normally experimental are also made available.
The important property is that capture checking in one component cannot poison other normal components. Like
@experimental itself, the whole scheme is transitive.
With the new scheme we do not need a special exemption for the dotty package anymore, so the code
implementing the exception is dropped.