NPE in URLEqualsHashCode checker

[msridhar]

Seeing this running with master:

error-prone version: 2.0.16-SNAPSHOT
     Stack Trace:
     java.lang.NullPointerException
  	at com.google.errorprone.bugpatterns.URLEqualsHashCode$URLTypeArgumentMatcher.matches(URLEqualsHashCode.java:81)
  	at com.google.errorprone.matchers.Matchers$5.matches(Matchers.java:148)
  	at com.google.errorprone.bugpatterns.URLEqualsHashCode.matchNewClass(URLEqualsHashCode.java:62)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitNewClass(ErrorProneScanner.java:997)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitNewClass(ErrorProneScanner.java:144)
  	at com.sun.tools.javac.tree.JCTree$JCNewClass.accept(JCTree.java:1675)
  	at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:71)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:89)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:43)
  	at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
  	at com.sun.source.util.TreeScanner.visitVariable(TreeScanner.java:223)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:1201)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitVariable(ErrorProneScanner.java:144)
  	at com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:938)
  	at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:71)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:89)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:43)
  	at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:90)
  	at com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
  	at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
  	at com.sun.source.util.TreeScanner.visitClass(TreeScanner.java:187)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:635)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitClass(ErrorProneScanner.java:144)
  	at com.sun.tools.javac.tree.JCTree$JCClassDecl.accept(JCTree.java:778)
  	at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:71)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:89)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:43)
  	at com.sun.source.util.TreeScanner.scan(TreeScanner.java:105)
  	at com.sun.source.util.TreeScanner.scanAndReduce(TreeScanner.java:113)
  	at com.sun.source.util.TreeScanner.visitCompilationUnit(TreeScanner.java:144)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:650)
  	at com.google.errorprone.scanner.ErrorProneScanner.visitCompilationUnit(ErrorProneScanner.java:144)
  	at com.sun.tools.javac.tree.JCTree$JCCompilationUnit.accept(JCTree.java:561)
  	at com.sun.source.util.TreePathScanner.scan(TreePathScanner.java:52)
  	at com.google.errorprone.scanner.Scanner.scan(Scanner.java:68)
  	at com.google.errorprone.scanner.ErrorProneScannerTransformer.apply(ErrorProneScannerTransformer.java:43)
  	at com.google.errorprone.ErrorProneAnalyzer.finished(ErrorProneAnalyzer.java:145)
  	at com.sun.tools.javac.api.MultiTaskListener.finished(MultiTaskListener.java:120)
  	at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1277)
  	at com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1236)
  	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:847)
  	at com.sun.tools.javac.api.JavacTaskImpl$1.call(JavacTaskImpl.java:97)
  	at com.sun.tools.javac.api.JavacTaskImpl$1.call(JavacTaskImpl.java:93)
  	at com.sun.tools.javac.api.JavacTaskImpl.handleExceptions(JavacTaskImpl.java:128)
  	at com.sun.tools.javac.api.JavacTaskImpl.doCall(JavacTaskImpl.java:93)
  	at com.sun.tools.javac.api.JavacTaskImpl.call(JavacTaskImpl.java:87)
  	at com.facebook.buck.jvm.java.Jsr199Javac.buildWithClasspath(Jsr199Javac.java:303)
  	at com.facebook.buck.jvm.java.Jsr199Javac.buildWithClasspath(Jsr199Javac.java:164)
  	at com.facebook.buck.jvm.java.JavacStep.performBuild(JavacStep.java:200)
  	at com.facebook.buck.jvm.java.JavacStep.tryBuildWithFirstOrderDeps(JavacStep.java:190)
  	at com.facebook.buck.jvm.java.JavacStep.execute(JavacStep.java:151)
  	at com.facebook.buck.jvm.java.JavacDirectToJarStep.execute(JavacDirectToJarStep.java:95)
  	at com.facebook.buck.step.DefaultStepRunner.runStepForBuildTarget(DefaultStepRunner.java:47)
  	at com.facebook.buck.rules.CachingBuildEngine.executeCommandsNowThatDepsAreBuilt(CachingBuildEngine.java:1400)
  	at com.facebook.buck.rules.CachingBuildEngine.lambda$13(CachingBuildEngine.java:352)
  	at com.facebook.buck.util.concurrent.WeightedListeningExecutorService.lambda$0(WeightedListeningExecutorService.java:81)
  	at com.google.common.util.concurrent.AbstractTransformFuture$AsyncTransformFuture.doTransform(AbstractTransformFuture.java:211)
  	at com.google.common.util.concurrent.AbstractTransformFuture$AsyncTransformFuture.doTransform(AbstractTransformFuture.java:200)
  	at com.google.common.util.concurrent.AbstractTransformFuture.run(AbstractTransformFuture.java:130)
  	at com.google.common.util.concurrent.MoreExecutors$5$1.run(MoreExecutors.java:988)
  	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
  	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
  	at java.lang.Thread.run(Thread.java:745)

Looks like adding a null check on sym here might fix it.

[eaftan]

Thanks, Manu. I'll take a look at this.