Better printing of capabilities in error messages #23701
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odersky
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If the closure has an expected function type with a fully defined result type, take the internalized result type as the local return type of the closure. This has the effect that some conformance tests are now done with Fresh instead Result caps. This means a now can widen a local reference to a result cap, since the comparison is done between the local reference and the internalized FreshCap. Previously this failed since we compared a local cap with result cap, and result caps only subtype other result caps. It also propagates types more aggressively into closure bodies, which sometimes reduces the error span and improves the error message.
- Special case in some situations so that we only print the name, not the underlying type. - Print TermParamRefs like other singleton types
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natsukagami
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Aug 11, 2025
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| def levelOK = | ||
| if ccConfig.useFreshLevels && !CCState.collapseFresh then | ||
| val yOwner = y.levelOwner | ||
| yOwner.isStaticOwner || x.ccOwner.isContainedIn(yOwner) | ||
| else y.core match | ||
| case ResultCap(_) | _: ParamRef => false | ||
| case _ => true | ||
|
|
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This is a surprising removal, is it intended?
natsukagami
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Aug 11, 2025
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not the underlying type.