Consider this source code:
---
public class AnalyzerNotQuiteSpeculative {
    private void test() {
        Subclass1 c1 = null;
        Subclass2 c2 = null;
        Base b = null;
        
        t(new C<Base>(c1).set(c2));
        t(new C<Base>(b).set(c2));
    }

    public static class Base {}
    public static class Subclass1 extends Base {}
    public static class Subclass2 extends Base {}
    public class C<T extends Base> {
        public C(T t) {}
        public C<T> set(T t) { return this; }
    }
    <T extends Base> void t(C<? extends Base> l) {}
}
---

Compiling this with -XDfind=diamond, javac crashes with:
---
$ javac -XDfind=diamond /tmp/AnalyzerNotQuiteSpeculative.java
An exception has occurred in the compiler (14-internal). Please file a bug against the Java compiler via the Java bug reporting page (http://bugreport.java.com) after checking the Bug Database (http://bugs.java.com) for duplicates. Include your program, the following diagnostic, and the parameters passed to the Java compiler in your report. Thank you.
java.lang.AssertionError: Analyzer error when processing: t(new C<Base>(c1).set(c2));
        at jdk.compiler/com.sun.tools.javac.util.Assert.error(Assert.java:162)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer.doAnalysis(Analyzer.java:568)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer$2.flush(Analyzer.java:539)
        at jdk.compiler/com.sun.tools.javac.comp.Analyzer.flush(Analyzer.java:576)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1412)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.flow(JavaCompiler.java:1380)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:972)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:318)
        at jdk.compiler/com.sun.tools.javac.main.Main.compile(Main.java:176)
        at jdk.compiler/com.sun.tools.javac.Main.compile(Main.java:57)
        at jdk.compiler/com.sun.tools.javac.Main.main(Main.java:43)
---

Originally reported here:
https://issues.apache.org/jira/browse/NETBEANS-2956