Exclusive capabilities revised #22544
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When printing a type `C^` where `C` extends `Capability`, don't show the `^`. This is overridden under -Yprint-debug.
- Add Mutable trait and mut modifier.
- Add dedicated tests `isMutableVar` and `isMutableVarOrAccessor`
so that update methods can share the same flag `Mutable` with mutable vars.
- Disallow update methods overriding normal methods
- Disallow update methods which are not members of classes extending Mutable
- Add design document from papers repo to docs/internals
- Add readOnly capabilities
- Implement raeadOnly access
- Check that update methods are only called on references with exclusive capture sets.
- Use cap.rd as default capture set of Capability subtypes
- Make Mutable a Capability, this means Mutable class references get {cap.rd} as
default capture set.
- Use {cap} as captu
….toCap If existentials are mapped to fresh, it matters where they are opened. Pure or not arguments don't have anything to do with that.
These are represented as Fresh.Cap(hidden) where hidden is the set of
capabilities subsumed by a fresh. The underlying representation is as
an annotated type `T @annotation.internal.freshCapability`.
Require -source `3.7` for caps to be converted to Fresh.Cap
Also:
- Refacture and document CaputureSet
- Make SimpleIdentitySets showable
- Refactor VarState
- Drop Frozen enum
- Make VarState subclasses inner classes of companion object
- Rename them
- Give implicit parameter VarState of subCapture method a default value
- Fix printing of capturesets containing cap and some other capability
- Revise handing of @uncheckedAnnotation
Check separation from source 3.7 on. We currently only check applications, other areas of separation checking are still to be implemented.
Check that a capability that gets hidden in the (result-)type of some definition is not used afterwards in the same or a nested scope.
When checking whether two items overlap we should always check their deep capture sets. Buried aliases should count as well.
This is necessary since capability sets are IdentitySets.
Downgrade to -source 3.6 to turn it off.
Allow them only in @consume methods
Also: Fixes to computations of overlapWith and -- on Refs that take account of pathss, where shorter paths cover deeper ones.
Use a coarser prediction of hidden sets. Any Fresh.Cap instance in a capture set means that we should do the hidden check. Previously this was the case only if the Fresh.Cap instance hid something non maximal, element, but only directly, not via another Cap. Another version searched for non-maximal references deeply, but this one caused infinite looping in the CI. But in any case it's fine to over-approximate and assume that any Fresh.Cap hides something.
odersky
changed the title
bracevac
approved these changes
Feb 7, 2025
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This time hopefully without the timeout in the CI