[jira] [Commented] (GROOVY-9079) STC: NPE in StaticTypeCheckingVisitor.inferSAMTypeGenericsInAssignment

["Eric Milles (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/GROOVY-9079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16815787#comment-16815787 ] 

Eric Milles commented on GROOVY-9079:
-------------------------------------

This can be fixed with a guard condition:
{code:java}
    private ClassNode inferSAMTypeGenericsInAssignment(ClassNode samUsage, MethodNode sam, ClassNode closureType, ClosureExpression closureExpression) {
        // if the sam type or closure type do not provide generics information,
        // we cannot infer anything, thus we simply return the provided samUsage
        GenericsType[] samGt = samUsage.getGenericsTypes();
        GenericsType[] closureGt = closureType.getGenericsTypes();
        if (samGt == null || closureGt == null) return samUsage;

        // extract the generics from the return type
        Map<GenericsTypeName, GenericsType> connections = new HashMap<GenericsTypeName, GenericsType>();
        extractGenericsConnections(connections, getInferredReturnType(closureExpression), sam.getReturnType());

        // GRECLIPSE add
        if (closureExpression.isParameterSpecified()) {
        // GRECLIPSE end
        // next we get the block parameter types and set the generics
        // information just like before
        // TODO: add vargs handling
        Parameter[] closureParams = closureExpression.getParameters();
        Parameter[] methodParams = sam.getParameters();
        for (int i = 0; i < closureParams.length; i++) {
            ClassNode fromClosure = closureParams[i].getType();
            ClassNode fromMethod = methodParams[i].getType();
            extractGenericsConnections(connections, fromClosure, fromMethod);
        }
        // GRECLIPSE add
        }
        // GRECLIPSE end
        ClassNode result = applyGenericsContext(connections, samUsage.redirect());
        return result;
    }
{code}

There may also be a latent NPE in the AutoFinal xform, which uses ClosureExpression.getParameters() unguarded as well.

> STC: NPE in StaticTypeCheckingVisitor.inferSAMTypeGenericsInAssignment
> ----------------------------------------------------------------------
>
>                 Key: GROOVY-9079
>                 URL: https://issues.apache.org/jira/browse/GROOVY-9079
>             Project: Groovy
>          Issue Type: Bug
>            Reporter: Eric Milles
>            Priority: Major
>
> Consider the following:
> {code:groovy}
> @groovy.transform.CompileStatic
> void meth() {
>   java.util.concurrent.Callable<String> call = { -> }
> }
> {code}
> This code produces:
> {code}
> BUG! exception in phase 'instruction selection' in source unit 'Blah.groovy' unexpected NullpointerException
> 	at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:1148)
> 	at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:654)
> 	at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:632)
> 	at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:609)
> 	...
> Caused by: java.lang.NullPointerException
> 	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.inferSAMTypeGenericsInAssignment(StaticTypeCheckingVisitor.java:4282)
> 	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.getResultType(StaticTypeCheckingVisitor.java:4133)
> 	at org.codehaus.groovy.transform.stc.StaticTypeCheckingVisitor.visitBinaryExpression(StaticTypeCheckingVisitor.java:831)
> 	...
> {code}
> The method in StaticTypeCheckingVisitor calls ClosureExpression.getParameters(), which returns null for a closure expression like "{ -> }".



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