Make Arrays mutable types under separation checking #24649
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In capture checking, a type mismatch might happen for a synthesized tree (say from implicit search). It can be helpful to show this tree. Before capture checking a helpful message is less likely since we don't synthesize implicit trees that then don't match under the standard typing rules.
odersky
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odersky
changed the title
Fields are only allowed in stateful classes unless marked with @untrackedCaptures.
bracevac
approved these changes
Dec 18, 2025
| && !sym.field.hasAnnotation(defn.UntrackedCapturesAnnot) | ||
| else true | ||
| ) | ||
| || ccConfig.strictMutability && sym.name == nme.update && sym == defn.Array_update |
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| || ccConfig.strictMutability && sym.name == nme.update && sym == defn.Array_update | |
| || ccConfig.strictMutability && sym == defn.Array_update |
Isn't this enough?
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It might force too much (i.e. complete the Array class to find its update method). That's why we defensively test the name first.
Co-authored-by: Oliver Bračevac <bracevac@users.noreply.github.com>
He-Pin
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Dec 19, 2025
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Also: enforce that mutable fields can only be declared in
Statefulclasses, unless they are annotated withuntrackedCaptures.