| Flags `instanceof` checks where the expression can be determined to be a |
| supertype of the type it is compared to. |
| |
| [JLS 15.28](https://docs.oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.28) |
| specifically calls `instanceof` out as *not* being a compile-time constant |
| expression, so the usage of this pattern can lead to unreachable code that won't |
| be flagged by the compiler: |
| |
| ```java |
| class Foo { |
| void doSomething() { |
| if (this instanceof Foo) { // BAD: always true |
| return; |
| } |
| interestingProcessing(); |
| } |
| } |
| ``` |
| |
| In general, an `instanceof` comparison against a superclass is equivalent to a |
| null check: |
| |
| ```java |
| foo instanceof Foo |
| ``` |
| |
| ```java |
| foo != null |
| ``` |
