升级至Scala 3后Scala/Java混合项目managedSourceDirectories编译顺序异常

环境与问题概述 #

• 运行环境：Play 3.0.5，Java 21.0.4，sbt 1.10.3
• 现象：Scala 2.13.14环境下执行sbt clean compile可正常编译；切换至Scala 3.3.3后出现scalac编译错误
• 核心矛盾：自定义注解处理器生成的查询类未被正确生成，导致Java文件找不到依赖

构建配置与注解处理器说明 #

build.sbt相关配置 #

Compile / compile := (Compile / compile dependsOn Def.task({
  (Compile / managedSourceDirectories).value.head.mkdirs()
})).value,
Compile / javacOptions ++= Seq("-s", (Compile / managedSourceDirectories).value.head.getAbsolutePath)

Carbide注解处理器信息 #

• 独立Maven项目打包的jar，放置于app/lib目录
• 功能：扫描带有*@Entity*注解的实体类，通过反射生成关联的DAO查询方法，输出至target/scala-3.3.3/src_managed/main/目录

错误详情 #

• Scala 3.3.3下target/scala-3.3.3/src_managed/main/目录被创建但为空，javac编译环节未触发
• 编译错误日志：

[error] -- [E008] Not Found Error:.../DefaultCompetitionYearResource.java:8:39
[error] 8 |import shared.models.core.querybuilder.CompetitionYearQueryBuilder;
[error]   |                                       ^
[error]   |                  value querybuilder is not a member of shared.models.core

• 根本原因：Scala 3.3.3的scalac在注解处理器生成代码前就扫描了Java文件；由于Scala与Java代码存在相互依赖（如Scala路由与Java代码交互），必须保留compileOrder := CompileOrder.Mixed配置

Scala 2.13.14下的正常编译流程 #

编译日志片段显示正确执行顺序：

[debug] Scala compilation took 2.762843833 s
[debug] Attempting to call com.sun.tools.javac.api.JavacTool@2137f8f8 directly...
[info] Annotation processing is enabled because one or more processors were found
[querybuilders are put into src_managed dir]
[info] Carbide warning: Unknown type: com.fasterxml.jackson.databind.JsonNode - skipping field: MasterSurveySchedule.template [These warnings are expected and okay]
[info] Carbide warning: Unknown type: byte[] - skipping field: ResourceBlob.resourceFile
[info] /Users/jludy/shared/app/shared/models/core/UnitTagGroup.java: Recompile with -Xlint:unchecked for details.
[debug] Java compilation took 11.978637459 s
[debug] [zinc] classfile.Parser parsing shared.models.core.querybuilder.support.DefaultAccountResolutionTypeQueryBuilderNode
[classfile.Parser then looks at all our java classses]
....
[debug] Java compilation + analysis took 14.683763333 s
[debug] done compiling
[debug] Registering generated classes:
[debug]     SsoRequireSetting$2.class
[debug]     Exceptions$FillRecursionException.class
[Then the rest are registered]
....

• 正常执行顺序：Scala编译完成 → 注解处理器生成代码 → Java编译执行

已尝试的无效方案 #

• 切换compileOrder为JavaThenScala或ScalaThenJava，因Scala与Java代码相互依赖无法生效
• 升级至Scala 3.3.0之后的其他稳定版本，问题复现

期望解决方案方向 #

1. 调整构建流程，让scalac编译前先执行注解处理器生成src_managed目录下的代码
2. 配置scalac，使其忽略依赖QueryBuilder类的Java文件的检查

内容的提问来源于stack exchange，提问作者Joseph Fish Ludy