jdk-24/test/langtools/tools/javac/patterns/GuardsErrors.java

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 * 2 along with this work; if not, write to the Free Software Foundation,
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/*
 * @test
 * @bug 8262891 8310133
 * @summary Check errors reported for guarded patterns.
 * @compile/fail/ref=GuardsErrors.out -XDrawDiagnostics GuardsErrors.java
 */

//TODO: tests and error recovery for misplaced guards
public class GuardsErrors {

    void typeTestPatternSwitchTest(Object o, int check) {
        switch (o) {
            case Integer i when i == check -> System.err.println(); //error: check is not effectivelly final
            default -> {}
        }
        check = 0;

    }

    void variablesInGuards(Object o) {
        final int i1;
              int i2 = 0;
        switch (o) {
            case Integer v when (i1 = 0) == 0 -> {}
            case Integer v when i2++ == 0 -> {}
            case Integer v when ++i2 == 0 -> {}
            case Integer v when new Predicate() {
                public boolean test() {
                    final int i;
                    i = 2;
                    return i == 2;
                }
            }.test() -> {}
            case Integer v when v != null -> {
                v = null;
            }
            case Number v1 when v1 instanceof Integer v2 && (v2 = 0) == 0 -> {}
            default -> {}
        }
    }

    GuardsErrors(Object o) {
        switch (o) {
            case Integer v when (f = 0) == 0 -> {}
            default -> throw new RuntimeException();
        }
    }

    final int f;

    interface Predicate {
        public boolean test();
    }
}