Lombok causes com.google.errorprone.SourcePositionException in UnusedVariable

[nicu97o]

Compilation fails when lombok annotation @Slf4j is placed on a class, but the logger is not used, causing build to fail.

Example:

     @Slf4j
     class A {

       public void doSomething() {
         // logic without using log generated by @Slf4j
       }
     }

Stacktrace:

     error-prone version: 2.50.0
     BugPattern: UnusedVariable
     Stack Trace:
     com.google.errorprone.SourcePositionException: invalid source position: [759, 709)
  	at com.google.errorprone.VisitorState.getSourceCode(VisitorState.java:485)
  	at com.google.errorprone.VisitorState.getOffsetTokens(VisitorState.java:558)
  	at com.google.errorprone.fixes.SuggestedFixes.replaceIncludingComments(SuggestedFixes.java:1790)
  	at com.google.errorprone.bugpatterns.UnusedVariable.buildUnusedVarFixes(UnusedVariable.java:482)
  	at com.google.errorprone.bugpatterns.UnusedVariable.matchCompilationUnit(UnusedVariable.java:265)
  	at com.google.errorprone.scanner.ErrorProneScanner.processMatchers(ErrorProneScanner.java:541)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:658)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:180)
  	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:627)
  	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:66)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:58)
  	at com.google.errorprone.scanner.ErrorProneScannerTransformer.apply(ErrorProneScannerTransformer.java:43)
  	at com.google.errorprone.ErrorProneAnalyzer.finished(ErrorProneAnalyzer.java:231)
  	at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:133)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1423)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1370)
  	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:955)
  	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.lambda$doCall$0(JavacTaskImpl.java:104)
  	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.invocationHelper(JavacTaskImpl.java:152)
  	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:100)
  	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:94)
  	at org.jetbrains.jps.javac.JavacMain.compile(JavacMain.java:310)
  	at org.jetbrains.jps.javac.JavacMain.compile(JavacMain.java:80)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.lambda$compileJava$1(JavaBuilder.java:589)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.invokeJavac(JavaBuilder.java:651)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.compileJava(JavaBuilder.java:587)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.compile(JavaBuilder.java:429)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.doBuild(JavaBuilder.java:354)
  	at org.jetbrains.jps.incremental.java.JavaBuilder.build(JavaBuilder.java:308)
  	at org.jetbrains.jps.incremental.IncProjectBuilder.runModuleLevelBuilders(IncProjectBuilder.java:1534)
  	at org.jetbrains.jps.incremental.IncProjectBuilder.runBuildersForChunk(IncProjectBuilder.java:659)
  	at org.jetbrains.jps.incremental.IncProjectBuilder.buildTargetsChunk(IncProjectBuilder.java:1778)
  	at org.jetbrains.jps.incremental.IncProjectBuilder.buildChunkIfAffected(IncProjectBuilder.java:1336)
  	at org.jetbrains.jps.incremental.IncProjectBuilder$BuildParallelizer$1.run(IncProjectBuilder.java:1298)
  	at com.intellij.util.concurrency.BoundedTaskExecutor.doRun(BoundedTaskExecutor.java:271)
  	at com.intellij.util.concurrency.BoundedTaskExecutor.access$200(BoundedTaskExecutor.java:44)
  	at com.intellij.util.concurrency.BoundedTaskExecutor$1.executeFirstTaskAndHelpQueue(BoundedTaskExecutor.java:249)
  	at com.intellij.util.ConcurrencyUtil.runUnderThreadName(ConcurrencyUtil.java:265)
  	at com.intellij.util.concurrency.BoundedTaskExecutor$1.run(BoundedTaskExecutor.java:234)
  	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1090)
  	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:614)
  	at java.base/java.lang.Thread.run(Thread.java:1474)

[adityaanikam]

This lines up with why cushon tagged it lombok already. UnusedVariable.java's field branch calls SuggestedFixes.replaceIncludingComments on Lombok's synthesized log field with no check for generated source positions first, and other checks in this codebase, UnnecessarilyFullyQualified.java for one, do guard against exactly that. The stack trace matches current source line for line. I'd like to add that guard here too.