Add missing & caps.Pure bounds to the ClassTagSeqFactory family#26224
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bvenners wants to merge 1 commit into
Open
Add missing & caps.Pure bounds to the ClassTagSeqFactory family#26224bvenners wants to merge 1 commit into
& caps.Pure bounds to the ClassTagSeqFactory family#26224bvenners wants to merge 1 commit into
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natsukagami
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Jun 3, 2026
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This makes sense. Thanks!
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What
Adds
& caps.Pureto theCCupper bounds of three declarations inlibrary/src/scala/collection/Factory.scala:trait ClassTagSeqFactoryclass ClassTagSeqFactory.Delegatetrait StrictOptimizedClassTagSeqFactoryThis brings them in line with their non-
ClassTagcounterparts, whichalready carry the bound:
SeqFactory,SeqFactory.Delegate,StrictOptimizedSeqFactoryClassTagSeqFactory.AnySeqDelegateWhy
Factory.scalais compiled withimport language.experimental.captureChecking.When the capture-checked collections were ported in #23769, the
& caps.Purebound was added to the
SeqFactoryfamily and toAnySeqDelegate, but theparallel
ClassTagSeqFactoryfamily was left without it. The inconsistency waslatent until the purity checks were tightened in #26085 ("Tighten check of field
classifiers") and #26097 ("Don't assume classes with self aliases to be pure").
The companion stdlib patch in #26097 (commit 8748bb9, "Fix stdlib") covered other
spots but missed this family.
With the tightened checker, recompiling the capture-checked stdlib now fails on
these three declarations because their
CCparameter is passed to a context thatrequires
... & caps.Pure.How to reproduce
sbt scala3-bootstrapped/testCompilation
fails before this change and passes after it.
Notes
Pure type-bound consistency fix; no behavioral change.