Add -Yfuture-lazy-vals for Scala 3.3.x builds#3059
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Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag (scala/scala3-lts#637) to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict Unsafe access. Modification: Add -Yfuture-lazy-vals to DefaultScalacOptions in PekkoBuild.scala, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion. Result: Pekko's Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions. Tests: - sbt "++3.3.8; actor/compile" passed (exit 0, 54 pre-existing warnings) References: Refs scala/scala3-lts#637
The -Yfuture-lazy-vals flag changes the generated bytecode for companion objects containing lazy vals: the static <clinit> initializer produced by the old sun.misc.Unsafe-based implementation is no longer emitted. Add a MiMa filter to exclude this expected binary incompatibility for RemoteWatcher#Stats. Tests: - sbt "++3.3.8; remote/mimaReportBinaryIssues" passed (exit 0)
pjfanning
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Jun 13, 2026
Motivation: PR apache#3059 review feedback from pjfanning requested simplifying the conditional CrossVersion.partialVersion match for -Yfuture-lazy-vals. Modification: Add -Yfuture-lazy-vals directly to the Scala 3 scalac options Seq instead of using a CrossVersion.partialVersion conditional match. Result: Cleaner, simpler build configuration that still applies the flag to all Scala 3.x builds. Tests: Not run - build config simplification only References: Refs apache#3059
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add -release:17 required by -Yfuture-lazy-vals The -Yfuture-lazy-vals flag requires explicit -java-output-version set to minimum version 9 or higher. Add -release:17 to satisfy this requirement for Scala 3.3.x builds.
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add -release:17 required by -Yfuture-lazy-vals The -Yfuture-lazy-vals flag requires explicit -java-output-version set to minimum version 9 or higher. Add -release:17 to satisfy this requirement for Scala 3.3.x builds.
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Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add -release:17 required by -Yfuture-lazy-vals The -Yfuture-lazy-vals flag requires explicit -java-output-version set to minimum version 9 or higher. Add -release:17 to satisfy this requirement for Scala 3.3.x builds.
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add -release:17 required by -Yfuture-lazy-vals The -Yfuture-lazy-vals flag requires explicit -java-output-version set to minimum version 9 or higher. Add -release:17 to satisfy this requirement for Scala 3.3.x builds.
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add MiMa filter for HttpBootstrapJsonProtocol <clinit> -Yfuture-lazy-vals changes the generated bytecode for companion objects containing lazy vals: the static <clinit> initializer is no longer emitted. Add MiMa filter to exclude this expected binary compatibility change.
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add MiMa filters for <clinit> removed by -Yfuture-lazy-vals -Yfuture-lazy-vals changes the generated bytecode for companion objects containing lazy vals: the static <clinit> initializer is no longer emitted. Add MiMa filters to exclude these expected binary compatibility changes for: - aws-spi-pekko-http: PekkoHttpClient - google-cloud-bigquery: BigQueryJsonProtocol, BigQueryRestJsonProtocol - google-cloud-pub-sub-grpc: ScalaPB-generated grpc objects * fix: Add missing Handshaker* MiMa filters in google-cloud-pub-sub-grpc Add 4 DirectMissingMethodProblem filters for HandshakerReq, HandshakerResp, HandshakerResult, and HandshakerStatus companion object <clinit> methods that are no longer generated with -Yfuture-lazy-vals.
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* feat: Add -Yfuture-lazy-vals for Scala 3.3.x builds Motivation: The Scala 3.3.8 compiler introduced the -Yfuture-lazy-vals flag to optionally use VarHandle instead of sun.misc.Unsafe for lazy val implementation. This prepares libraries for upcoming JDK releases that restrict sun.misc.Unsafe access. Modification: Add -Yfuture-lazy-vals to scalacOptions, conditionally applied only for Scala 3.3.x via CrossVersion.partialVersion or scalaBinaryVersion. Result: Scala 3.3.x build uses the future-proof VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrict sun.misc.Unsafe. References: Refs scala/scala3-lts#637 Refs apache/pekko#3059 * fix: Add -release:17 required by -Yfuture-lazy-vals The -Yfuture-lazy-vals flag requires explicit -java-output-version set to minimum version 9 or higher. Add -release:17 to satisfy this requirement for Scala 3.3.x builds.
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Motivation
The Scala 3.3.8 compiler introduced the
-Yfuture-lazy-valsflag (scala/scala3-lts#637) to optionally useVarHandleinstead ofsun.misc.Unsafefor lazy val implementation. This prepares libraries for upcoming JDK releases that restrictsun.misc.Unsafeaccess.Modification
-Yfuture-lazy-valstoDefaultScalacOptionsinproject/PekkoBuild.scala, conditionally applied only for Scala 3.3.x viaCrossVersion.partialVersionremote/src/main/mima-filters/2.0.x.backwards.excludes/future-lazy-vals.excludesto exclude the expected<clinit>bytecode change forRemoteWatcher#Stats(the new VarHandle-based lazy val implementation no longer generates the static initializer that the old Unsafe-based implementation produced)Result
Pekko's Scala 3.3.x build uses the future-proof
VarHandle-based lazy val implementation, compatible with all JDK 9+ versions including future releases that restrictsun.misc.Unsafe.Tests
sbt "++3.3.8; actor/compile"— passed (exit 0, only pre-existing warnings)sbt "++3.3.8; remote/mimaReportBinaryIssues"— passed (exit 0)References
Refs scala/scala3-lts#637