invalid start position with var

[navaneeth-spotnana]

Description of the problem:

I was setting up Error Prone for our codebase, and when running it as a maven plugin, EP threw a unhandled exception:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.8.0:compile (default-compile) on project foobar: Compilation failure
[ERROR] /Users/foo/Documents/codes/fooo/src/java/foobar/src/main/java/com/bar/fuu/fee/FooBar.java:[95,24] An unhandled exception was thrown by the Error Prone static analysis plugin.
[ERROR]      Please report this at https://github.com/google/error-prone/issues/new and include the following:
[ERROR]   
[ERROR]      error-prone version: 2.3.4
[ERROR]      BugPattern: DefaultCharset
[ERROR]      Stack Trace:
[ERROR]      java.lang.IllegalArgumentException: invalid start position
[ERROR]   	at com.google.common.base.Preconditions.checkArgument(Preconditions.java:141)
[ERROR]   	at com.google.errorprone.fixes.SuggestedFix$ReplacementFix.<init>(SuggestedFix.java:390)
[ERROR]   	at com.google.errorprone.fixes.SuggestedFix$Builder.replace(SuggestedFix.java:192)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset$1.visitVariable(DefaultCharset.java:381)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset$1.visitVariable(DefaultCharset.java:377)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:974)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:248)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1032)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitTry(TreeScanner.java:374)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCTry.accept(JCTree.java:1328)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:248)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1032)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitMethod(TreeScanner.java:206)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:898)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:808)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:86)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:144)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:591)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset.variableTypeFix(DefaultCharset.java:376)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset.nioFileWriterFix(DefaultCharset.java:446)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset.handleFileWriter(DefaultCharset.java:403)
[ERROR]   	at com.google.errorprone.bugpatterns.DefaultCharset.matchNewClass(DefaultCharset.java:269)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.processMatchers(ErrorProneScanner.java:451)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitNewClass(ErrorProneScanner.java:775)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitNewClass(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1711)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitVariable(TreeScanner.java:223)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:887)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:974)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:248)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:522)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1032)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitTry(TreeScanner.java:374)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitTry(ErrorProneScanner.java:847)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitTry(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCTry.accept(JCTree.java:1328)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitBlock(TreeScanner.java:248)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:522)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitBlock(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:1032)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitMethod(TreeScanner.java:206)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitMethod(ErrorProneScanner.java:742)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitMethod(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:898)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:550)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:808)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:82)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:72)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:46)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:144)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:562)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:591)
[ERROR]   	at jdk.compiler/com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:56)
[ERROR]   	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:56)
[ERROR]   	at com.google.errorprone.scanner.ErrorProneScannerTransformer.apply(ErrorProneScannerTransformer.java:43)
[ERROR]   	at com.google.errorprone.ErrorProneAnalyzer.finished(ErrorProneAnalyzer.java:152)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:132)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1418)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1365)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:960)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.lambda$doCall$0(JavacTaskImpl.java:104)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.handleExceptions(JavacTaskImpl.java:147)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:100)
[ERROR]   	at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:94)
[ERROR]   	at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess(JavaxToolsCompiler.java:126)
[ERROR]   	at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile(JavacCompiler.java:174)
[ERROR]   	at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:1129)
[ERROR]   	at org.apache.maven.plugin.compiler.CompilerMojo.execute(CompilerMojo.java:188)
[ERROR]   	at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
[ERROR]   	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
[ERROR]   	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
[ERROR]   	at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
[ERROR]   	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
[ERROR]   	at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
[ERROR]   	at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
[ERROR]   	at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
[ERROR]   	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
[ERROR]   	at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
[ERROR]   	at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
[ERROR]   	at org.apache.maven.cli.MavenCli.execute(MavenCli.java:956)
[ERROR]   	at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:288)
[ERROR]   	at org.apache.maven.cli.MavenCli.main(MavenCli.java:192)
[ERROR]   	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[ERROR]   	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[ERROR]   	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[ERROR]   	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
[ERROR]   	at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
[ERROR]   	at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
[ERROR]   	at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
[ERROR]   	at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
[ERROR]   	at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
[ERROR] 
[ERROR] -> [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
[ERROR] 
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR]   mvn <goals> -rf :objectstore

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

The line in question is:

      var fileWriter = new FileWriter(file);

It's pointing to the new keyword.

My pom.xml (parent pom) is set like this:

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        <version>2.2.6.RELEASE</version>
        <executions>
          <execution>
            <goals>
              <goal>repackage</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.0</version>
        <configuration>
          <source>${java.version}</source>
          <target>${java.version}</target>
          <compilerArgs>
            <arg>-XDcompilePolicy=simple</arg>
            <arg>-Xplugin:ErrorProne</arg>
          </compilerArgs>
          <annotationProcessorPaths>
            <path>
              <groupId>com.google.errorprone</groupId>
              <artifactId>error_prone_core</artifactId>
              <version>2.3.4</version>
            </path>
          </annotationProcessorPaths>
        </configuration>
      </plugin>
    </plugins>
  </build>

where ${java.version} is 11.

What version of Error Prone are you using?

error-prone version: 2.3.4

Have you found anything relevant by searching the web?

#1124
#1129

Also I got this error, don't know if it's relevant:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.google.errorprone.util.FindIdentifiers (file:/Users/spotnana/.m2/repository/com/google/errorprone/error_prone_check_api/2.3.4/error_prone_check_api-2.3.4.jar) to method com.sun.tools.javac.comp.Resolve.findIdent(com.sun.tools.javac.comp.Env,com.sun.tools.javac.util.Name,com.sun.tools.javac.code.Kinds$KindSelector)
WARNING: Please consider reporting this to the maintainers of com.google.errorprone.util.FindIdentifiers
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

[navaneeth-spotnana]

It goes away if I split the line in question into two:

      FileWriter fileWriter;
      fileWriter = new FileWriter(file);

[cushon]

The issue is that javac is replacing var in the AST with a synthetic node for the inferred type (FileWriter), and when the check tries to replace the synthetic node it doesn't have source position information.