JDK-8059922 : NPE in Scope.includes with exception inference
  • Type: Bug
  • Component: tools
  • Sub-Component: javac
  • Affected Version: 8u20,8u40
  • Priority: P4
  • Status: Closed
  • Resolution: Duplicate
  • OS: linux_ubuntu
  • CPU: x86_64
  • Submitted: 2014-10-02
  • Updated: 2014-10-13
  • Resolved: 2014-10-13
Related Reports
Duplicate :  
JDK-8054210 - NullPointerException when compiling specific code.
Description
FULL PRODUCT VERSION :
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Linux 3.13.0-35-generic #62-Ubuntu SMP Fri Aug 15 01:58:42 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
The compiler exits with a NullPointerException for the provided source file, unless an exception type parameter is provided explicitly.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Save the provided source as ExceptionInference.java
2. javac ExceptionInference.java
3. Apply workaround.
4. Code compiles (and runs) successfully.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Normal compilation, ending either in errors or successful compilation.
ACTUAL -
NullPointerException during compilation.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
An exception has occurred in the compiler (1.8.0_20). Please file a bug at the Java Developer Connection (http://java.sun.com/webapps/bugreport)  after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report.  Thank you.
java.lang.NullPointerException
	at com.sun.tools.javac.code.Scope.includes(Scope.java:296)
	at com.sun.tools.javac.comp.Flow$1.trackable(Flow.java:247)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.visitVarDef(Flow.java:1832)
	at com.sun.tools.javac.comp.Flow$AssignAnalyzer.visitVarDef(Flow.java:2569)
	at com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:852)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
	at com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:398)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.scan(Flow.java:1376)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.visitLambda(Flow.java:2256)
	at com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1624)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
	at com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:398)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.scan(Flow.java:1376)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.scanExpr(Flow.java:1627)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.scanExprs(Flow.java:1639)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.visitApply(Flow.java:2236)
	at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1465)
	at com.sun.tools.javac.tree.TreeScanner.scan(TreeScanner.java:49)
	at com.sun.tools.javac.comp.Flow$BaseAnalyzer.scan(Flow.java:398)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.scan(Flow.java:1376)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.analyzeTree(Flow.java:2423)
	at com.sun.tools.javac.comp.Flow$AbstractAssignAnalyzer.analyzeTree(Flow.java:2406)
	at com.sun.tools.javac.comp.Flow.analyzeLambdaThrownTypes(Flow.java:250)
	at com.sun.tools.javac.comp.Attr.visitLambda(Attr.java:2423)
	at com.sun.tools.javac.tree.JCTree$JCLambda.accept(JCTree.java:1624)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.DeferredAttr$2.complete(DeferredAttr.java:284)
	at com.sun.tools.javac.comp.DeferredAttr$DeferredType.check(DeferredAttr.java:245)
	at com.sun.tools.javac.comp.DeferredAttr$DeferredType.check(DeferredAttr.java:232)
	at com.sun.tools.javac.comp.Resolve$MethodResultInfo.check(Resolve.java:993)
	at com.sun.tools.javac.comp.Resolve$4.checkArg(Resolve.java:826)
	at com.sun.tools.javac.comp.Resolve$AbstractMethodCheck.argumentsAcceptable(Resolve.java:731)
	at com.sun.tools.javac.comp.Resolve$4.argumentsAcceptable(Resolve.java:835)
	at com.sun.tools.javac.comp.Infer.instantiateMethod(Infer.java:162)
	at com.sun.tools.javac.comp.Resolve.rawInstantiate(Resolve.java:564)
	at com.sun.tools.javac.comp.Resolve.checkMethod(Resolve.java:601)
	at com.sun.tools.javac.comp.Attr.checkMethod(Attr.java:3809)
	at com.sun.tools.javac.comp.Attr.checkIdInternal(Attr.java:3615)
	at com.sun.tools.javac.comp.Attr.checkMethodIdInternal(Attr.java:3522)
	at com.sun.tools.javac.comp.Attr.checkMethodId(Attr.java:3501)
	at com.sun.tools.javac.comp.Attr.checkId(Attr.java:3488)
	at com.sun.tools.javac.comp.Attr.visitSelect(Attr.java:3370)
	at com.sun.tools.javac.tree.JCTree$JCFieldAccess.accept(JCTree.java:1897)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.visitApply(Attr.java:1843)
	at com.sun.tools.javac.tree.JCTree$JCMethodInvocation.accept(JCTree.java:1465)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribExpr(Attr.java:656)
	at com.sun.tools.javac.comp.Attr.visitExec(Attr.java:1611)
	at com.sun.tools.javac.tree.JCTree$JCExpressionStatement.accept(JCTree.java:1296)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:692)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1142)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:909)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
	at com.sun.tools.javac.comp.Attr.visitTry(Attr.java:1372)
	at com.sun.tools.javac.tree.JCTree$JCTry.accept(JCTree.java:1173)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
	at com.sun.tools.javac.comp.Attr.attribStats(Attr.java:692)
	at com.sun.tools.javac.comp.Attr.visitBlock(Attr.java:1142)
	at com.sun.tools.javac.tree.JCTree$JCBlock.accept(JCTree.java:909)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
	at com.sun.tools.javac.comp.Attr.visitMethodDef(Attr.java:1035)
	at com.sun.tools.javac.tree.JCTree$JCMethodDecl.accept(JCTree.java:778)
	at com.sun.tools.javac.comp.Attr.attribTree(Attr.java:607)
	at com.sun.tools.javac.comp.Attr.attribStat(Attr.java:676)
	at com.sun.tools.javac.comp.Attr.attribClassBody(Attr.java:4342)
	at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4252)
	at com.sun.tools.javac.comp.Attr.attribClass(Attr.java:4181)
	at com.sun.tools.javac.comp.Attr.attrib(Attr.java:4156)
	at com.sun.tools.javac.main.JavaCompiler.attribute(JavaCompiler.java:1248)
	at com.sun.tools.javac.main.JavaCompiler.compile2(JavaCompiler.java:901)
	at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:860)
	at com.sun.tools.javac.main.Main.compile(Main.java:523)
	at com.sun.tools.javac.main.Main.compile(Main.java:381)
	at com.sun.tools.javac.main.Main.compile(Main.java:370)
	at com.sun.tools.javac.main.Main.compile(Main.java:361)
	at com.sun.tools.javac.Main.compile(Main.java:56)
	at com.sun.tools.javac.Main.main(Main.java:42)

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.io.IOException;

public class ExceptionInference {
    public static void main(String[] args) {
        try {
            Either.left("This will explode!").with(s -> { throw new IOException(s); }, i -> System.out.println("" + i));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public interface Either<T, U> {

        static <T, U> Either<T, U> left(T t) {
            return new Either<T, U>() {
                @Override
                public <R, E extends Exception> R map(FunctionE<T, R, E> withLeft, FunctionE<U, R, E> withRight) throws E {
                    return withLeft.apply(t);
                }
                @Override
                public <E extends Exception> void with(ConsumerE<T, E> withLeft, ConsumerE<U, E> withRight) throws E {
                    withLeft.accept(t);
                }
            };
        }

        static <T, U> Either<T, U> right(U u) {
            return new Either<T, U>() {
                @Override
                public <R, E extends Exception> R map(FunctionE<T, R, E> withLeft, FunctionE<U, R, E> withRight) throws E {
                    return withRight.apply(u);
                }
                @Override
                public <E extends Exception> void with(ConsumerE<T, E> withLeft, ConsumerE<U, E> withRight) throws E {
                    withRight.accept(u);
                }
            };
        }

        <R, E extends Exception> R map(FunctionE<T, R, E> withLeft, FunctionE<U, R, E> withRight) throws E;

        <E extends Exception> void with(ConsumerE<T, E> withLeft, ConsumerE<U, E> withRight) throws E;
    }

    public interface ConsumerE<T, E extends Exception> {
        void accept(T t) throws E;
    }
    public interface FunctionE<T, R, E extends Exception> {
        R apply(T elt) throws E;
    }
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Explicitly specifying the exception type parameter allows compilations to complete successfully. That is, change `.with(...)` to `.<IOException>with(...)`, and there is no error.
Comments
Duplicate of JDK-8054210.
13-10-2014
Original code compiled with errors with 7u67, however threw NPE with 8u20 and 8u40 (build 8).
08-10-2014