The following program triggers an assertion failure in code generation:

import java.util.List;
import java.util.Objects;

public class X {

    public static final __ByValue class V {
        private final int i;
        V() {
            this.i = 0;
        }

        public static V make(int i) {
            V v = __MakeDefault V();
            v = __WithField(v.i, i);
            return v;
        }
    }

    public static void main(String... args) throws Throwable {
        V v = __WithField(V.make(10).i, 20);
    }
}

java.lang.AssertionError
at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:155)
at jdk.compiler/com.sun.tools.javac.util.Assert.check(Assert.java:46)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitWithField(Gen.java:1150)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCWithField.accept(JCTree.java:1116)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:819)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.visitVarDef(Gen.java:1095)
at jdk.compiler/com.sun.tools.javac.tree.JCTree$JCVariableDecl.accept(JCTree.java:960)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genDef(Gen.java:597)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:632)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStat(Gen.java:618)
at jdk.compiler/com.sun.tools.javac.jvm.Gen.genStats(Gen.java:669)
...