[GROOVY-7065] ReturnAdder shouldn't add return if there's one in a finally block

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.3.8, 2.4.0-beta-4
• Assignee: Jochen Theodorou
• Reporter: Cédric Champeau
• Created: 09/Sep/14 16:59
• Updated: 17/Dec/14 13:25
• Resolved: 14/Oct/14 10:24

Description

The following code was written for a "Groovy puzzlers" talk:

 class CountDown { int counter = 10 }

CountDown finalCountDown() {
    def countDown = new CountDown()
    try {
        countDown.counter = --countDown.counter
    } catch (ignored) {
        println "That will never happen. ${ignored.message}"
        countDown.counter = Integer.MIN_VALUE
    } finally {
        return countDown
    }
}

println finalCountDown().counter

At execution, it goes to the catch because of a class cast exception:

"Cannot cast object '9' with class 'java.lang.Integer' to class 'CountDown'"

The reason is highlighted after returns have been added:

java.lang.Object countDown = new CountDown()
        try {
            return countDown .counter = --( countDown .counter)
        } 
        catch (java.lang.Exception ignored) {
            this.println("That will never happen. $ignored.message")
            return countDown .counter = java.lang.Integer.MIN_VALUE
        } 
        finally { 
            return countDown 
        } 

A "return" is added to the try branch, even though there's a return in the finally block which should always be executed. Adding a single statement after the finally block solves the issue because no return would then be added to the try block...