Replace Constructor.newInstance with MethodHandle for code generator loading#782
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pjfanning
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Jul 6, 2026
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pjfanning
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Jul 7, 2026
Motivation: Avoid reflective constructor, method, and Scala module invocation in gRPC code generation and plugin bridge paths while keeping generator loading compatible across Scala versions. Modification: Cache MethodHandles for logger forwarding and extra generator constructors. Use public MethodHandles for Scala singleton module access and generator bridge calls. Remove the Scala 2.12 ToolBox path in ReflectiveCodeGen and use fixed-arity invoke() call sites with explicit Object values where needed. Result: Codegen, Maven plugin, sbt plugin, and reflective test build generation use MethodHandles consistently while preserving public access semantics and avoiding avoidable invokeWithArguments boxing. Tests: - JDK 17: sbt "codegen / compile" "maven-plugin / compile" "sbt-plugin / compile" - success - JDK 17: sbt "++2.13.18!" codegen/test "++3.3.8!" codegen/test - success, 2 tests per version - JDK 17: sbt "++2.13.*" "sbt-plugin/scripted gen-scala-server/06-compatibility-plugins" - first failed because protoc-gen-go was missing; installed protoc-gen-go v1.32.0, rerun success - JDK 17: sbt "++3.8.4!" "sbt-plugin/scripted scala3/*" - success, 3 scripted tests - JDK 17: sbt "++2.13.*" "sbt-plugin/scripted gen-scala-server/06-compatibility-plugins" "++3.8.4!" "sbt-plugin/scripted scala3/03-sbt2-basic" - success after explicit Object annotations - scalafmt --mode diff-ref=origin/main - success - scalafmt --list --mode diff-ref=origin/main - success - git diff --check - success - Qoder stdout review: /tmp/project-qoder-review.log - No must-fix findings References: None - internal refactoring
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Motivation
Replace reflection-based generator loading and bridge calls with MethodHandle-based access, avoiding reflective constructor, method, and Scala module invocation in code generation paths.
Modification
ReflectiveCodeGenand use the same MethodHandle target construction across Scala versions.invoke()with explicitObjectcall-site values where the JVM adapts MethodHandle types.Result
Codegen, Maven plugin, sbt plugin, and reflective test build generation use MethodHandles consistently while preserving public access semantics.
Tests
sbt "codegen / compile" "maven-plugin / compile" "sbt-plugin / compile"- successsbt "++2.13.18!" codegen/test "++3.3.8!" codegen/test- success, 2 tests per versionsbt "++2.13.*" "sbt-plugin/scripted gen-scala-server/06-compatibility-plugins"- first failed becauseprotoc-gen-gowas missing; installedprotoc-gen-go v1.32.0, rerun successsbt "++3.8.4!" "sbt-plugin/scripted scala3/*"- success, 3 scripted testssbt "++2.13.*" "sbt-plugin/scripted gen-scala-server/06-compatibility-plugins" "++3.8.4!" "sbt-plugin/scripted scala3/03-sbt2-basic"- success after explicitObjectannotationsscalafmt --mode diff-ref=origin/main- successscalafmt --list --mode diff-ref=origin/main- successgit diff --check- successReferences
None - internal refactoring