StringIndexOutOfBoundsException in JavaParsers.scala

[vandmo]

Compiler version

3.4.0-RC1-bin-20230828-5318d68-NIGHTLY (stacktrace)
Problem since at least 3.2.2. Verified that it exists in 3.3.0 as well.

Minimized code

public class X {

  public static final char X = '\0';

}

I hade to create a dummy scala file as well for the bug to kick in.

object X {}

Output (click arrow to expand)

## Exception when compiling 2 sources to XXXX
java.lang.StringIndexOutOfBoundsException: String index out of range: 0
java.base/java.lang.StringLatin1.charAt(StringLatin1.java:47)
java.base/java.lang.String.charAt(String.java:693)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.tryConstant(JavaParsers.scala:1034)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.optConstantTpe$1(JavaParsers.scala:726)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.varDecl(JavaParsers.scala:733)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.fieldDecls(JavaParsers.scala:665)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.termDecl(JavaParsers.scala:647)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.memberDecl(JavaParsers.scala:747)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.typeBodyDecls(JavaParsers.scala:918)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.typeBody(JavaParsers.scala:897)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.classDecl(JavaParsers.scala:822)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.typeDecl(JavaParsers.scala:1022)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.compilationUnit(JavaParsers.scala:1076)
dotty.tools.dotc.parsing.JavaParsers$JavaParser.parse(JavaParsers.scala:44)
dotty.tools.dotc.parsing.Parser.parse$$anonfun$1(ParserPhase.scala:28)
dotty.tools.dotc.parsing.Parser.parse$$anonfun$adapted$1(ParserPhase.scala:40)
scala.Function0.apply$mcV$sp(Function0.scala:42)
dotty.tools.dotc.core.Phases$Phase.monitor(Phases.scala:440)
dotty.tools.dotc.parsing.Parser.parse(ParserPhase.scala:40)
dotty.tools.dotc.parsing.Parser.runOn$$anonfun$1(ParserPhase.scala:49)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
scala.collection.immutable.List.foreach(List.scala:333)
dotty.tools.dotc.parsing.Parser.runOn(ParserPhase.scala:49)
dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:246)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1321)
dotty.tools.dotc.Run.runPhases$1(Run.scala:262)
dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:270)
dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:279)
dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:71)
dotty.tools.dotc.Run.compileUnits(Run.scala:279)
dotty.tools.dotc.Run.compileSources(Run.scala:194)
dotty.tools.dotc.Run.compile(Run.scala:179)
dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:136)
dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:192)
scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:247)
sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:182)
sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:163)
sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:239)
sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:163)
sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:210)
sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:528)
sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:528)
sbt.internal.inc.Incremental$.$anonfun$apply$5(Incremental.scala:177)
sbt.internal.inc.Incremental$.$anonfun$apply$5$adapted(Incremental.scala:175)
sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:461)
sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:116)
sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:263)
sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:416)
sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:503)
sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:403)
sbt.internal.inc.Incremental$.apply(Incremental.scala:169)
sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:528)
sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:482)
sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:420)
sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
org.gradle.api.internal.tasks.scala.ZincScalaCompiler.execute(ZincScalaCompiler.java:157)
org.gradle.api.internal.tasks.scala.ZincScalaCompilerFacade.execute(ZincScalaCompilerFacade.java:39)
org.gradle.api.internal.tasks.scala.ZincScalaCompilerFacade.execute(ZincScalaCompilerFacade.java:26)
org.gradle.api.internal.tasks.compile.daemon.AbstractIsolatedCompilerWorkerExecutor$CompilerWorkAction.execute(AbstractIsolatedCompilerWorkerExecutor.java:78)
org.gradle.workers.internal.DefaultWorkerServer.execute(DefaultWorkerServer.java:63)
org.gradle.workers.internal.AbstractClassLoaderWorker$1.create(AbstractClassLoaderWorker.java:54)
org.gradle.workers.internal.AbstractClassLoaderWorker$1.create(AbstractClassLoaderWorker.java:48)
org.gradle.internal.classloader.ClassLoaderUtils.executeInClassloader(ClassLoaderUtils.java:100)
org.gradle.workers.internal.AbstractClassLoaderWorker.executeInClassLoader(AbstractClassLoaderWorker.java:48)
org.gradle.workers.internal.IsolatedClassloaderWorker.run(IsolatedClassloaderWorker.java:49)
org.gradle.workers.internal.IsolatedClassloaderWorker.run(IsolatedClassloaderWorker.java:30)
org.gradle.workers.internal.WorkerDaemonServer.run(WorkerDaemonServer.java:96)
org.gradle.workers.internal.WorkerDaemonServer.run(WorkerDaemonServer.java:65)
org.gradle.process.internal.worker.request.WorkerAction$1.call(WorkerAction.java:138)
org.gradle.process.internal.worker.child.WorkerLogEventListener.withWorkerLoggingProtocol(WorkerLogEventListener.java:41)
org.gradle.process.internal.worker.request.WorkerAction.run(WorkerAction.java:135)
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
java.base/java.lang.reflect.Method.invoke(Method.java:566)
org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:414)
org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:49)
java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
java.base/java.lang.Thread.run(Thread.java:829)
           

FAILURE: Build failed with an exception.

[som-snytt]

It reproduces with standalone scalac X.java. The scanner code is still close to Scala 2, which doesn't have the bug. I see a special case for value 0, so maybe that needs a tweak.