test/langtools/tools/javac/patterns/LambdaCannotCapturePatternVariables.java

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/*
 * @test
 * @bug 8267610 8269738
 * @summary LambdaToMethod cannot capture pattern variables. So the TransPatterns should
 *          transform the pattern variables and symbols to normal variables and symbols.
 */

import java.util.function.Supplier;

public class LambdaCannotCapturePatternVariables {

    static Number num1 = 1;
    static Number num2 = null;
    static Number staticNum1 = (num1 instanceof Integer i) ? ((Supplier<Integer>) () -> i).get() : null;
    static Number staticNum2 = (num2 instanceof Integer i) ? ((Supplier<Integer>) () -> i).get() : null;
    Number instanceNum1 = (num1 instanceof Integer i) ? ((Supplier<Integer>) () -> i).get() : null;
    Number instanceNum2 = (num2 instanceof Integer i) ? ((Supplier<Integer>) () -> i).get() : null;

    public static void main(String[] args) {
        var testVar = new LambdaCannotCapturePatternVariables();
        testVar.testInstanceOfPatternVariable(Integer.valueOf(1));
        testVar.testSwitchPatternVariable(Integer.valueOf(1));
        testVar.test(Integer.valueOf(1));
        assertTrue(staticNum1 != null, "staticNum1 is null unexpectedly");
        assertTrue(staticNum2 == null, "staticNum1 is not null unexpectedly");
        assertTrue(testVar.instanceNum1 != null, "instanceNum1 is null unexpectedly");
        assertTrue(testVar.instanceNum2 == null, "instanceNum2 is not null unexpectedly");
        assertTrue(staticNum1.intValue() == 1, "staticNum1.intValue() is not equal to 1");
        assertTrue(testVar.instanceNum1.intValue() == 1, "instanceNum1.intValue() is not equal to 1");
    }

    public Integer testInstanceOfPatternVariable(Object x) {
        if(x instanceof Number y) {
            return ((Supplier<Integer>) (() -> {
                return ((y instanceof Integer z) ? z : 1);
            })).get();
        }
        return null;
    }

    public Integer testSwitchPatternVariable(Object x) {
        switch (x) {
            case Number n: {
                return ((Supplier<Integer>) (() -> {
                    return ((n instanceof Integer i) ? i : 1);
                })).get();
            }
            default: return null;
        }
    }

    // Provided by the user
    public Integer test(Object x) {
        Integer bar = 1;
        return ((x instanceof Number y) ?
                ((Supplier<Integer>) (() -> {
                    return ((y instanceof Integer z) ? z : bar);
                })).get() : bar);
    }

    static void assertTrue(boolean cond, String info) {
        if (!cond)
            throw new AssertionError(info);
    }
}