Fix Scala 3.8+ compilation warnings for forward compatibility#528
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Motivation: Scala 3.8+ introduces new deprecation warnings for patterns like implicit parameter passing without `using`, wildcard type arguments with `_`, trailing ` _` for eta-expansion, and `with` as a type operator. These warnings need to be addressed for forward compatibility with Scala 3.9.x while maintaining cross-build support for Scala 2.13.x and 3.3.x. Modification: - Move Scala 2-only compiler options (-Xlog-reflective-calls, -Ydelambdafy:method) out of shared scalacOptions into the Scala 2 conditional block - Add -Wconf suppressions for Scala 3.8+ warnings that cannot be fixed with cross-version compatible syntax (implicit using clause, wildcard type arguments, eta-expansion trailing underscore, with type operator, unreachable case except for null) Result: All 74 compiler warnings eliminated when compiling with Scala 3.8.4. Scala 2.13.18 compilation remains unaffected. No behavioral changes. Tests: - sbt "++3.8.4" "core / compile" — 0 warnings (previously 74) - sbt "++2.13.18" "core / compile" — success, no new warnings References: Refs apache/pekko#3065
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Motivation
Scala 3.8+ introduces new deprecation warnings that prevent clean compilation under forward-looking Scala versions (3.8.x / 3.9.x). These warnings need to be addressed for forward compatibility with Scala 3.9.x while maintaining cross-build support for Scala 2.13.x and 3.3.x.
Modification
-Xlog-reflective-calls,-Ydelambdafy:method) out of sharedscalacOptionsinto the Scala 2 conditional block to eliminate "bad option" warnings in Scala 3-Wconfsuppressions for Scala 3.8+ warnings that cannot be fixed with cross-version compatible syntax:usingclause (requiresusingkeyword, Scala 3 only)_deprecated for wildcard type arguments (?is Scala 3.4+ only)_for eta-expansion (removal requires Scala 3-only syntax in some contexts)withas type operator deprecated (&intersection type operator)-Yfuture-lazy-valson Scala 3.8+Result
All 74 compiler warnings eliminated when compiling with Scala 3.8.4. Scala 2.13.18 compilation remains unaffected. Production Scala versions unchanged (2.13.18 / 3.3.8). No behavioral changes to the runtime.
Tests
sbt "++3.8.4" "core / compile"— 0 warnings (previously 74)sbt "++2.13.18" "core / compile"— success, no new warningsReferences
Refs apache/pekko#3065 - None - Forward compatibility for Scala 3.8+/3.9.x