The compiler fails to reject this program:

import java.io.*;

class T6412514 {
    void f() {
        try {
            throw new FileNotFoundException();
        } catch (FileNotFoundException x) {
        } catch (IOException x) { // ERROR
            /*
              It is a compile-time error if a catch clause catches checked
              exception type E1 but there exists no checked exception type
              E2 such that all of the following hold:
              * E2 <: E1
              * The try block corresponding to the catch clause can throw E2
              * No preceding catch block of the immediately enclosing try
              statement catches E2 or a supertype of E2.
            */
        }
    }
}

It is actually correct according to the specification. However, the specification
requires this version to be rejected:

void f() {
    try {
        throw new IOException();
    } catch (IOException ex) {
    }
}

The specification issue is tracked in 6412514.