Indicating the javac version (Re: Eager enum class initialization with enum switch)

[Jonathan Gibbons]

+1 to good practice when writing any bug report.

In the case of the original message, it would also be pertinent to note 
the versions of any other tools that were involved.

-- Jon

On 2/19/19 1:22 PM, Alex Buckley wrote:
> Anyone on this list has a good chance of contributing to multiple 
> versions of javac, not just the version in the current JDK GA release. 
> (GA: General Availability)  So, when raising questions about javac, 
> please indicate the version of javac that you're using. `javac 
> -version` should be enough. `java -version` is fine too.
>
> Also, please indicate the edition of the JLS or JVMS that you're 
> referring to.
>
> Alex
>
> On 2/16/2019 12:59 AM, Tagir Valeev wrote:
>> Hello!
>>
>> Consider the following program (Test.java):
>>
>> class Test {
>>    enum A{
>>      X;
>>      static { System.out.println("A is initialized!"); }
>>    }
>>    enum B{
>>      Y;
>>      static { System.out.println("B is initialized!"); }
>>    }
>>
>>    static void testA(A a) { switch(a) {} }
>>
>>    static void testB(B b) { switch(b) {} }
>>
>>    public static void main(String[] args) {
>>      testA(A.X);
>>    }
>> }
>>
>> When I compile it via javac and run it I see:
>> A is initialized!
>> B is initialized!
>>
>> Despite the fact that testB is never called, and no references to the
>> B enum actually used during the program execution. According to JLS
>> 12.4.1 B should not be initialized. Am I missing something?
>>
>> If I use the Eclipse compiler, I got the expected result
>>
>> A is initialized!
>>
>> This occurs because javac spins an additional class Test$1 which holds
>> enum constant mapping and its static initializer initializes mappings
>> for all the enums used. In contrast, Eclipse creates synthetic static
>> methods (one per enum) in the same Test class which lazily initialize
>> the corresponding fields. Such approach better follows the spec, to my
>> opinion.
>>
>> So is this javac problem or I don't understand the spec?
>>
>> With best regards,
>> Tagir Valeev.
>>