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…when called through FunctionExpression.getFunction()
Calling apply() on the function that FunctionExpression.getFunction()
returns for a lambda with no parameters threw:
java.lang.NullPointerException: Cannot read the array length because "args" is null
at org.apache.calcite.linq4j.tree.FunctionExpression.lambda$compile$0(FunctionExpression.java:88)
That function is a java.lang.reflect.Proxy. For an interface method that
takes no arguments, such as Function0.apply(), the JDK calls the proxy's
InvocationHandler with a null argument array, and the invokable built by
compile() reads its length. The handler now passes an empty array when
it receives null.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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rubenada
reviewed
Oct 14, 2026
rubenada
approved these changes
Oct 14, 2026
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Calling
apply()on the function thatFunctionExpression.getFunction()returns for a lambda with no parameters throwsjava.lang.NullPointerException: Cannot read the array length because "args" is nullfromFunctionExpression.lambda$compile$0. That function is ajava.lang.reflect.Proxy, and for an interface method with no arguments, such asFunction0.apply(), the JDK calls the proxy'sInvocationHandlerwith a null argument array (InvocationHandler.invoke). The handler now passes an empty array toInvokable.dynamicInvokewhen it receives null.ExpressionTest.testLambdaWithoutParametersViaGetFunction(new) fails with that NullPointerException without the fix and passes with it.The fix and the test come from CALCITE-7736 (#5213), which carries the same change inside the nullness migration; this PR lets it land on its own.
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